gotlin/internal/lang/generate_go.go

package lang

import (
	"bytes"
	"fmt"
	"go/format"
	"regexp"
	"sort"
	"strconv"
	"strings"
)

func GenerateGo(program *Program) ([]byte, error) {
	return generateGo(program, "", nil)
}

func GenerateGoMain(program *Program) ([]byte, error) {
	return generateGo(program, "main", nil)
}

func GenerateGoWithMetadata(program *Program, metadata []*PackageMetadata) ([]byte, error) {
	return generateGo(program, "", metadata)
}

func GenerateGoMainWithMetadata(program *Program, metadata []*PackageMetadata) ([]byte, error) {
	return generateGo(program, "main", metadata)
}

func generateGo(program *Program, packageOverride string, metadata []*PackageMetadata) ([]byte, error) {
	semantic, diagnostics := AnalyzeWithMetadata(program, metadata)
	if len(diagnostics) > 0 {
		return nil, diagnostics[0]
	}
	g := goGenerator{semantic: semantic}
	if err := g.program(program, packageOverride); err != nil {
		return nil, err
	}
	src := g.buf.Bytes()
	formatted, err := format.Source(src)
	if err != nil {
		return src, fmt.Errorf("generated invalid Go: %w", err)
	}
	return formatted, nil
}

type goGenerator struct {
	semantic              *SemanticProgram
	buf                   bytes.Buffer
	indentLevel           int
	needsFmt              bool
	needsRunCatch         bool
	needsGoUnwrap         bool
	needsTime             bool
	needsJSONDecode       bool
	needsCoroutines       bool
	sqlContextAlias       string
	sqlPGXAlias           string
	currentFunc           FunctionDecl
	currentClass          *ClassDecl
	currentCoroutineScope string
	scopes                []map[string]bool
	semanticScope         *Scope
	matchCounter          int
	resultCounter         int
}

func (g *goGenerator) program(program *Program, packageOverride string) error {
	containsSQL := programContainsSQL(program)
	containsSQLExecution := programContainsSQLExecution(program)
	g.needsCoroutines = programUsesCoroutines(program)
	if g.needsCoroutines {
		g.needsTime = true
	}
	if containsSQLExecution {
		g.needsGoUnwrap = true
		g.sqlContextAlias = runtimeImportAlias(program, "context", "gotlincontext")
		g.sqlPGXAlias = runtimeImportAlias(program, "github.com/jackc/pgx/v5", "gotlinpgx")
	}
	packageName := goPackageName(program.PackagePath)
	if packageOverride != "" {
		packageName = packageOverride
	}
	g.line("package " + packageName)
	g.line("")

	for _, fn := range program.Functions {
		if usesPrintln(fn.Body) {
			g.needsFmt = true
			break
		}
	}
	if !g.needsFmt {
		for _, class := range program.Classes {
			for _, method := range class.Methods {
				if usesPrintln(method.Body) {
					g.needsFmt = true
					break
				}
			}
			if g.needsFmt {
				break
			}
		}
	}
	if !g.needsRunCatch {
		for _, fn := range program.Functions {
			if usesRunCatching(fn.Body) {
				g.needsRunCatch = true
				break
			}
		}
	}
	if !g.needsGoUnwrap {
		for _, fn := range program.Functions {
			if usesGoUnwrap(fn.Body) {
				g.needsGoUnwrap = true
				break
			}
		}
	}
	if !g.needsGoUnwrap {
		for _, class := range program.Classes {
			for _, method := range class.Methods {
				if usesGoUnwrap(method.Body) {
					g.needsGoUnwrap = true
					break
				}
			}
			if g.needsGoUnwrap {
				break
			}
		}
	}
	if !g.needsRunCatch {
		for _, class := range program.Classes {
			for _, method := range class.Methods {
				if usesRunCatching(method.Body) {
					g.needsRunCatch = true
					break
				}
			}
			if g.needsRunCatch {
				break
			}
		}
	}
	runtimeImports := map[string]string{}
	if containsSQLExecution {
		runtimeImports["context"] = g.sqlContextAlias
		runtimeImports["github.com/jackc/pgx/v5"] = g.sqlPGXAlias
	}
	if g.needsCoroutines {
		runtimeImports["context"] = "context"
		runtimeImports["sync"] = "sync"
	}
	imports := collectImports(program, g.needsFmt, g.needsTime, runtimeImports)
	if len(program.Embeds) > 0 {
		hasEmbed := false
		for _, imp := range program.Imports {
			if imp.Path == "embed" {
				hasEmbed = true
				break
			}
		}
		if !hasEmbed {
			imports = append(imports, `_ "embed"`)
			sort.Strings(imports)
		}
	}
	if len(imports) == 1 {
		g.line("import " + imports[0])
		g.line("")
	} else if len(imports) > 1 {
		g.line("import (")
		g.indentLevel++
		for _, imp := range imports {
			g.line(imp)
		}
		g.indentLevel--
		g.line(")")
		g.line("")
	}

	if g.needsRunCatch {
		g.emitRunCatchingSupport()
		g.line("")
	}
	if g.needsGoUnwrap {
		g.emitGoUnwrapSupport()
		g.line("")
	}
	if g.needsCoroutines {
		g.emitCoroutineSupport()
		g.line("")
	}
	g.line("type GotlinResult[T any] struct { Value T; Err error }")
	g.line("func gotlinResultUnwrap[T any](result GotlinResult[T]) T { if result.Err != nil { panic(result.Err) }; return result.Value }")
	g.line("func gotlinResultUnwrapOr[T any](result GotlinResult[T], fallback T) T { if result.Err != nil { return fallback }; return result.Value }")
	g.line("")
	for _, embedded := range program.Embeds {
		g.line("//go:embed " + embedded.Path)
		g.line("var " + embedded.Name + " " + g.goType(embedded.Type))
		g.line("")
	}

	emitted := false
	if containsSQL {
		g.emitSQLSupport(program, containsSQLExecution)
		emitted = true
	}
	for _, decl := range program.Interfaces {
		if emitted {
			g.line("")
		}
		g.interfaceDecl(decl)
		emitted = true
	}
	for _, enum := range program.Enums {
		if emitted {
			g.line("")
		}
		g.enumDecl(enum)
		emitted = true
	}
	for _, class := range program.Classes {
		if emitted {
			g.line("")
		}
		if err := g.classDecl(class); err != nil {
			return err
		}
		emitted = true
	}
	for _, fn := range program.Functions {
		if emitted {
			g.line("")
		}
		if err := g.function(fn); err != nil {
			return err
		}
		emitted = true
	}
	for i := 0; i < len(g.semantic.Mappings.pairs); i++ {
		g.line("")
		if err := g.emitMapping(g.semantic.Mappings.pairs[i]); err != nil {
			return err
		}
	}
	if g.needsJSONDecode {
		if emitted {
			g.line("")
		}
		g.emitJSONDecodeSupport()
	}
	return nil
}

func (g *goGenerator) function(fn FunctionDecl) error {
	g.currentClass = nil
	g.currentFunc = fn
	previousScope := g.currentCoroutineScope
	hasCoroutineEffect := g.hasCoroutineEffect(fn)
	if hasCoroutineEffect && fn.Name == "main" {
		return fmt.Errorf("contextual function main requires a runBlocking boundary")
	}
	if hasCoroutineEffect {
		g.currentCoroutineScope = "gotlinScope"
	}
	defer func() { g.currentCoroutineScope = previousScope }()
	g.scopes = nil
	g.semanticScope = nil
	g.pushScope()
	for _, param := range fn.Params {
		g.defineType(param.Name, param.Type)
	}
	g.write("func ")
	g.write(fn.Name)
	g.write(renderGoTypeParameters(fn.TypeParams))
	g.write(g.renderGoFunctionParams(fn))
	if ret := g.goReturnType(fn.ReturnType); ret != "" {
		g.write(" ")
		g.write(ret)
	}
	g.write(" {\n")
	g.indentLevel++
	if err := g.block(fn.Body); err != nil {
		return fmt.Errorf("function %s: %w", fn.Name, err)
	}
	g.indentLevel--
	g.line("}")
	g.popScope()
	return nil
}

func (g *goGenerator) interfaceDecl(decl InterfaceDecl) {
	g.line("type " + decl.Name + " interface {")
	g.indentLevel++
	for _, method := range decl.Methods {
		g.line(method.Name + g.renderGoParamsWithPrefix(method.Params, "") + g.renderGoReturnSuffix(method.ReturnType))
	}
	g.indentLevel--
	g.line("}")
}

func (g *goGenerator) enumDecl(decl EnumDecl) {
	if enumIsString(decl) {
		g.line("type " + decl.Name + " string")
		g.line("const (")
		g.indentLevel++
		for _, variant := range decl.Variants {
			g.line(decl.Name + variant.Name + " " + decl.Name + " = " + strconv.Quote(enumStringValue(variant)))
		}
		g.indentLevel--
		g.line(")")
		return
	}
	g.line("type " + decl.Name + " interface { is" + decl.Name + "() }")
	for _, variant := range decl.Variants {
		name := decl.Name + variant.Name
		g.line("")
		g.line("type " + name + " struct {")
		g.indentLevel++
		for i, typ := range variant.PayloadTypes {
			g.line(fmt.Sprintf("Value%d %s", i, g.goType(typ)))
		}
		g.indentLevel--
		g.line("}")
		g.line("func (*" + name + ") is" + decl.Name + "() {}")
	}
}

func enumIsString(decl EnumDecl) bool {
	for _, variant := range decl.Variants {
		if len(variant.PayloadTypes) > 0 {
			return false
		}
	}
	return true
}

func enumStringValue(variant EnumVariant) string {
	if variant.StringValue != "" {
		return variant.StringValue
	}
	return variant.Name
}

func enumVariant(decl EnumDecl, name string) *EnumVariant {
	for i := range decl.Variants {
		if decl.Variants[i].Name == name {
			return &decl.Variants[i]
		}
	}
	return nil
}

func (g *goGenerator) classDecl(class ClassDecl) error {
	g.line("type " + class.Name + renderGoTypeParameters(class.TypeParams) + " struct {")
	g.indentLevel++
	for _, field := range class.Fields {
		name := field.Name
		tag := ""
		if class.Data {
			if field.Private {
				tag = " `json:\"-\"`"
			} else {
				name = exportedGoName(name)
				tag = fmt.Sprintf(" `json:\"%s\"`", jsonFieldName(field.Name, class.JSONNaming))
			}
		}
		g.line(name + " " + g.goType(field.Type) + tag)
	}
	g.indentLevel--
	g.line("}")
	g.line("")
	g.write("func New")
	g.write(class.Name)
	g.write(renderGoTypeParameters(class.TypeParams))
	g.write("(")
	for i, field := range class.Fields {
		if i > 0 {
			g.write(", ")
		}
		g.write(field.Name)
		g.write(" ")
		g.write(g.goType(field.Type))
	}
	g.write(") *")
	g.write(class.Name)
	g.write(renderGoTypeArguments(class.TypeParams))
	g.write(" {\n")
	g.indentLevel++
	g.writeIndent()
	g.write("return &")
	g.write(class.Name)
	g.write(renderGoTypeArguments(class.TypeParams))
	g.write("{")
	for i, field := range class.Fields {
		if i > 0 {
			g.write(", ")
		}
		if class.Data && !field.Private {
			g.write(exportedGoName(field.Name))
		} else {
			g.write(field.Name)
		}
		g.write(": ")
		g.write(field.Name)
	}
	g.write("}\n")
	g.indentLevel--
	g.line("}")

	for _, method := range class.Methods {
		g.line("")
		if err := g.method(class, method); err != nil {
			return err
		}
	}
	return nil
}

func (g *goGenerator) method(class ClassDecl, fn FunctionDecl) error {
	g.currentClass = &class
	g.currentFunc = fn
	previousScope := g.currentCoroutineScope
	if g.hasCoroutineEffect(fn) {
		g.currentCoroutineScope = "gotlinScope"
	}
	defer func() { g.currentCoroutineScope = previousScope }()
	g.scopes = nil
	g.semanticScope = nil
	g.pushScope()
	g.define("self")
	g.define("this")
	for _, param := range fn.Params {
		g.defineType(param.Name, param.Type)
	}

	g.write("func (self *")
	g.write(class.Name)
	g.write(renderGoTypeArguments(class.TypeParams))
	g.write(") ")
	g.write(fn.Name)
	g.write(g.renderGoFunctionParams(fn))
	if ret := g.goReturnType(fn.ReturnType); ret != "" {
		g.write(" ")
		g.write(ret)
	}
	g.write(" {\n")
	g.indentLevel++
	if err := g.block(fn.Body); err != nil {
		return fmt.Errorf("method %s.%s: %w", class.Name, fn.Name, err)
	}
	g.indentLevel--
	g.line("}")
	g.popScope()
	g.currentClass = nil
	return nil
}

func (g *goGenerator) block(stmts []Stmt) error {
	for i, stmt := range stmts {
		if err := g.stmt(stmt, stmts[i+1:]); err != nil {
			return fmt.Errorf("%T: %w", stmt, err)
		}
	}
	return nil
}

func (g *goGenerator) tryVarDecl(decl VarDecl, attempt TryExpr, tail []Stmt) error {
	base, resultArgs, ok := parseGenericType(g.currentFunc.ReturnType)
	if !ok || base != "Result" || len(resultArgs) != 2 {
		return fmt.Errorf("? can only be used inside a function returning Result<T, Error>")
	}
	g.resultCounter++
	errorName := fmt.Sprintf("gotlinError%d", g.resultCounter)
	valueName := decl.Name
	if !nameUsedInStmts(decl.Name, tail) {
		valueName = "_"
	}
	innerType := g.exprType(attempt.Value)
	resolvedAttempt := exprMeta(attempt.Value)
	rawGoCall := resolvedAttempt != nil && resolvedAttempt.Meaning == GoCallExpr
	if innerBase, innerArgs, isResult := parseGenericType(innerType); isResult && innerBase == "Result" && len(innerArgs) == 2 && !rawGoCall {
		resultName := fmt.Sprintf("gotlinResult%d", g.resultCounter)
		value, err := g.expr(attempt.Value, innerType)
		if err != nil {
			return err
		}
		g.line(resultName + " := " + value)
		g.line("if " + resultName + ".Err != nil { return GotlinResult[" + g.goType(resultArgs[0]) + "]{Err: " + resultName + ".Err} }")
		g.line(valueName + " := " + resultName + ".Value")
		if decl.Type == "" {
			decl.Type = innerArgs[0]
		}
	} else {
		value, err := g.expr(attempt.Value, "")
		if err != nil {
			return err
		}
		g.line(valueName + ", " + errorName + " := " + value)
		g.line("if " + errorName + " != nil { return GotlinResult[" + g.goType(resultArgs[0]) + "]{Err: " + errorName + "} }")
	}
	if valueName != "_" {
		g.defineType(decl.Name, decl.Type)
	}
	return nil
}

func (g *goGenerator) stmt(stmt Stmt, tail []Stmt) error {
	switch s := stmt.(type) {
	case VarDecl:
		if _, isNull := s.Value.(NullExpr); isNull && s.Type == "" {
			return fmt.Errorf("null requires an explicit nullable type")
		}
		if attempt, ok := s.Value.(TryExpr); ok {
			return g.tryVarDecl(s, attempt, tail)
		}
		value, err := g.expr(s.Value, s.Type)
		if err != nil {
			return err
		}
		value = g.passthroughValue(s.Value, value)
		if !nameUsedInStmts(s.Name, tail) {
			g.line(fmt.Sprintf("_ = %s", value))
			return nil
		}
		if s.Type == "" {
			g.line(fmt.Sprintf("%s := %s", s.Name, value))
		} else {
			g.line(fmt.Sprintf("var %s %s = %s", s.Name, g.goType(s.Type), value))
		}
		typ := s.Type
		if typ == "" {
			typ = g.exprType(s.Value)
		}
		g.defineType(s.Name, typ)
	case MultiVarDecl:
		value, err := g.expr(s.Value, "")
		if err != nil {
			return err
		}
		assigned := make([]string, len(s.Names))
		usedCount := 0
		for i, name := range s.Names {
			if nameUsedInStmts(name, tail) {
				assigned[i] = name
				usedCount++
			} else {
				assigned[i] = "_"
			}
		}
		if usedCount == 0 {
			g.line(fmt.Sprintf("%s = %s", strings.Join(assigned, ", "), value))
			return nil
		}
		g.line(fmt.Sprintf("%s := %s", strings.Join(assigned, ", "), value))
		for i, name := range s.Names {
			if assigned[i] != "_" {
				g.define(name)
			}
		}
	case AssignStmt:
		value, err := g.expr(s.Value, g.lookupType(s.Name))
		if err != nil {
			return err
		}
		value = g.passthroughValue(s.Value, value)
		g.line(fmt.Sprintf("%s = %s", g.assignTarget(s.Name), value))
	case AddAssignStmt:
		value, err := g.expr(s.Value, "")
		if err != nil {
			return err
		}
		value = g.passthroughValue(s.Value, value)
		g.line(fmt.Sprintf("%s += %s", g.assignTarget(s.Name), value))
	case MultiAssignStmt:
		value, err := g.expr(s.Value, "")
		if err != nil {
			return err
		}
		names := make([]string, 0, len(s.Names))
		for _, name := range s.Names {
			names = append(names, g.assignTarget(name))
		}
		g.line(fmt.Sprintf("%s = %s", strings.Join(names, ", "), value))
	case ReturnStmt:
		if s.Value == nil {
			g.line("return")
		} else {
			value, err := g.expr(s.Value, g.currentFunc.ReturnType)
			if err != nil {
				return err
			}
			value = g.passthroughValue(s.Value, value)
			g.line(fmt.Sprintf("return %s", value))
		}
	case ThrowStmt:
		value, err := g.expr(s.Value, "")
		if err != nil {
			return err
		}
		g.line(fmt.Sprintf("panic(%s)", value))
	case DeferStmt:
		value, err := g.expr(s.Value, "")
		if err != nil {
			return err
		}
		g.line("defer " + value)
	case ExprStmt:
		value, err := g.expr(s.Value, "")
		if err != nil {
			return err
		}
		g.line(value)
	case IfStmt:
		cond, err := g.expr(s.Cond, "")
		if err != nil {
			return err
		}
		g.writeIndent()
		g.write(fmt.Sprintf("if %s {\n", cond))
		g.indentLevel++
		g.pushScope()
		if name, thenNonNull, _ := nullableCondition(s.Cond); thenNonNull {
			if typ := g.lookupType(name); strings.HasSuffix(typ, "?") {
				g.defineType(name, strings.TrimSuffix(typ, "?"))
			}
		}
		if err := g.block(s.Then); err != nil {
			return err
		}
		g.popScope()
		g.indentLevel--
		g.writeIndent()
		g.write("}")
		if len(s.Else) > 0 {
			g.write(" else {\n")
			g.indentLevel++
			g.pushScope()
			if name, _, elseNonNull := nullableCondition(s.Cond); elseNonNull {
				if typ := g.lookupType(name); strings.HasSuffix(typ, "?") {
					g.defineType(name, strings.TrimSuffix(typ, "?"))
				}
			}
			if err := g.block(s.Else); err != nil {
				return err
			}
			g.popScope()
			g.indentLevel--
			g.writeIndent()
			g.write("}")
		}
		g.write("\n")
		if len(s.Else) == 0 && blockAlwaysTerminates(s.Then) {
			if name, _, elseNonNull := nullableCondition(s.Cond); elseNonNull {
				if typ := g.lookupType(name); strings.HasSuffix(typ, "?") {
					g.defineType(name, strings.TrimSuffix(typ, "?"))
				}
			}
		}
	case WhileStmt:
		cond, err := g.expr(s.Cond, "")
		if err != nil {
			return err
		}
		g.writeIndent()
		g.write(fmt.Sprintf("for %s {\n", cond))
		g.indentLevel++
		g.pushScope()
		if err := g.block(s.Body); err != nil {
			return err
		}
		g.popScope()
		g.indentLevel--
		g.line("}")
	case ForEachStmt:
		source, err := g.expr(s.Source, "")
		if err != nil {
			return err
		}
		g.line(fmt.Sprintf("for _, %s := range %s {", s.Name, source))
		g.indentLevel++
		g.pushScope()
		g.define(s.Name)
		if err := g.block(s.Body); err != nil {
			return err
		}
		g.popScope()
		g.indentLevel--
		g.line("}")
	case MatchStmt:
		enumName := strings.TrimPrefix(g.exprType(s.Value), "*")
		if enumName == "" && len(s.Cases) > 0 {
			enumName = s.Cases[0].EnumName
		}
		decl := g.semantic.Enums[enumName]
		value, err := g.expr(s.Value, enumName)
		if err != nil {
			return err
		}
		g.matchCounter++
		matchName := fmt.Sprintf("gotlinMatch%d", g.matchCounter)
		if enumIsString(decl) {
			g.line("switch " + value + " {")
			g.indentLevel++
			for _, c := range s.Cases {
				g.line("case " + enumName + c.VariantName + ":")
				g.indentLevel++
				g.pushScope()
				if err := g.block(c.Body); err != nil {
					return err
				}
				g.popScope()
				g.indentLevel--
			}
			g.indentLevel--
			g.line("}")
			break
		}
		hasBindings := false
		for _, c := range s.Cases {
			if len(c.Bindings) > 0 {
				hasBindings = true
				break
			}
		}
		if hasBindings {
			g.line(fmt.Sprintf("switch %s := %s.(type) {", matchName, value))
		} else {
			g.line(fmt.Sprintf("switch %s.(type) {", value))
		}
		g.indentLevel++
		for _, c := range s.Cases {
			variant := enumVariant(decl, c.VariantName)
			g.line("case *" + enumName + c.VariantName + ":")
			g.indentLevel++
			g.pushScope()
			for i, binding := range c.Bindings {
				g.line(fmt.Sprintf("%s := %s.Value%d", binding, matchName, i))
				g.defineType(binding, variant.PayloadTypes[i])
			}
			if err := g.block(c.Body); err != nil {
				return err
			}
			g.popScope()
			g.indentLevel--
		}
		g.indentLevel--
		g.line("}")
	case TryCatchStmt:
		g.writeIndent()
		g.write("func() {\n")
		g.indentLevel++
		g.writeIndent()
		g.write("defer func() {\n")
		g.indentLevel++
		g.writeIndent()
		g.write("if recovered := recover(); recovered != nil {\n")
		g.indentLevel++
		g.pushScope()
		g.define(s.CatchName)
		g.line(fmt.Sprintf("%s := recovered", s.CatchName))
		if err := g.block(s.CatchBody); err != nil {
			return err
		}
		g.popScope()
		g.indentLevel--
		g.line("}")
		g.indentLevel--
		g.line("}()")
		g.pushScope()
		if err := g.block(s.TryBody); err != nil {
			return err
		}
		g.popScope()
		g.indentLevel--
		g.line("}()")
	default:
		return fmt.Errorf("unsupported statement %T", stmt)
	}
	return nil
}

func (g *goGenerator) expr(expr Expr, expectedType string) (string, error) {
	resolved := exprMeta(expr)
	resolvedSQL := false
	if resolved != nil {
		_, resolvedSQL = resolved.Node.(HIRSQL)
	}
	if resolved == nil || resolvedSQL {
		if lowered, handled, err := g.lowerSQLQuery(expr); handled || err != nil {
			return lowered, err
		}
	}
	if expectedType != "" && expectedType != "Any" {
		if actualType := g.exprType(expr); strings.HasSuffix(actualType, "?") && !strings.HasSuffix(expectedType, "?") {
			return "", fmt.Errorf("nullable value of type %s cannot be used as non-nullable %s; use ?. or !!", actualType, expectedType)
		}
	}
	switch e := expr.(type) {
	case IdentExpr:
		if g.currentClass != nil {
			if e.Name == "this" {
				return "self", nil
			}
			if field, found := classFieldByName(*g.currentClass, e.Name); found && !g.isDefined(e.Name) {
				return "self." + mappingFieldName(*g.currentClass, field), nil
			}
		}
		return e.Name, nil
	case IntExpr:
		return e.Value, nil
	case FloatExpr:
		return e.Value, nil
	case StringExpr:
		return e.Value, nil
	case BoolExpr:
		if e.Value {
			return "true", nil
		}
		return "false", nil
	case NullExpr:
		if expectedType != "" && !strings.HasSuffix(expectedType, "?") {
			return "", fmt.Errorf("null is not allowed for non-nullable type %s", expectedType)
		}
		return "nil", nil
	case NonNullExpr:
		sourceType := g.exprType(e.Value)
		if !strings.HasSuffix(sourceType, "?") {
			return "", fmt.Errorf("non-null assertion requires a nullable value, got %s", sourceType)
		}
		innerType := strings.TrimSuffix(sourceType, "?")
		value, err := g.expr(e.Value, sourceType)
		if err != nil {
			return "", err
		}
		_, innerIsClass := g.classForType(innerType)
		if innerIsClass || strings.HasPrefix(innerType, "*") {
			return fmt.Sprintf("func(value %s) %s { if value == nil { panic(\"non-null assertion failed\") }; return value }(%s)", g.goType(sourceType), g.goType(innerType), value), nil
		}
		return fmt.Sprintf("func(value %s) %s { if value == nil { panic(\"non-null assertion failed\") }; return *value }(%s)", g.goType(sourceType), g.goType(innerType), value), nil
	case TryExpr:
		return "", fmt.Errorf("? propagation is only supported on variable declarations")
	case UnaryExpr:
		value, err := g.wrapExpr(e.Value, "")
		if err != nil {
			return "", err
		}
		return e.Op + value, nil
	case BinaryExpr:
		if e.Op == "==" || e.Op == "!=" {
			if _, ok := e.Left.(NullExpr); ok {
				if typ := g.exprType(e.Right); typ != "" && !strings.HasSuffix(typ, "?") {
					return "", fmt.Errorf("null comparison requires a nullable value, got %s", typ)
				}
			}
			if _, ok := e.Right.(NullExpr); ok {
				if typ := g.exprType(e.Left); typ != "" && !strings.HasSuffix(typ, "?") {
					return "", fmt.Errorf("null comparison requires a nullable value, got %s", typ)
				}
			}
		}
		left, err := g.wrapExpr(e.Left, "")
		if err != nil {
			return "", err
		}
		right, err := g.wrapExpr(e.Right, "")
		if err != nil {
			return "", err
		}
		return fmt.Sprintf("%s %s %s", left, e.Op, right), nil
	case CallExpr:
		resolvedCall := exprMeta(e)
		if resolvedCall == nil || resolvedCall.Meaning == EnumConstructionExpr {
			selector, ok := e.Callee.(SelectorExpr)
			if ok {
				if receiver, ok := selector.Receiver.(IdentExpr); ok {
					if receiver.Name == "Result" {
						return g.expr(EnumVariantExpr{EnumName: receiver.Name, VariantName: selector.Name, Values: e.Args}, expectedType)
					}
					if _, ok := g.semantic.Enums[receiver.Name]; ok {
						return g.expr(EnumVariantExpr{EnumName: receiver.Name, VariantName: selector.Name, Values: e.Args}, expectedType)
					}
				}
			}
		}
		if ident, ok := e.Callee.(IdentExpr); ok && coroutineBuiltins[ident.Name] {
			switch ident.Name {
			case "runBlocking":
				lambda, err := coroutineLambdaArg(e, "runBlocking")
				if err != nil {
					return "", err
				}
				block, err := g.coroutineLambda(lambda, "Unit")
				if err != nil {
					return "", err
				}
				return "gotlinRunBlocking(" + block + ")", nil
			case "coroutineScope", "launch":
				if g.currentCoroutineScope == "" {
					return "", fmt.Errorf("%s requires a coroutine scope", ident.Name)
				}
				lambda, err := coroutineLambdaArg(e, ident.Name)
				if err != nil {
					return "", err
				}
				block, err := g.coroutineLambda(lambda, "Unit")
				if err != nil {
					return "", err
				}
				method := "Scope"
				if ident.Name == "launch" {
					method = "Launch"
				}
				return g.currentCoroutineScope + "." + method + "(" + block + ")", nil
			case "async":
				if g.currentCoroutineScope == "" {
					return "", fmt.Errorf("async requires a coroutine scope")
				}
				if len(e.TypeArgs) != 1 {
					return "", fmt.Errorf("async expects one result type")
				}
				lambda, err := coroutineLambdaArg(e, "async")
				if err != nil {
					return "", err
				}
				block, err := g.coroutineLambda(lambda, e.TypeArgs[0])
				if err != nil {
					return "", err
				}
				return "gotlinAsync[" + g.goType(e.TypeArgs[0]) + "](" + g.currentCoroutineScope + ", " + block + ")", nil
			case "delay":
				if g.currentCoroutineScope == "" || len(e.Args) != 1 {
					return "", fmt.Errorf("delay(ms) requires a coroutine scope")
				}
				ms, err := g.expr(e.Args[0], "Int")
				if err != nil {
					return "", err
				}
				return g.currentCoroutineScope + ".Delay(" + ms + ")", nil
			case "withTimeout":
				if g.currentCoroutineScope == "" || len(e.Args) != 2 {
					return "", fmt.Errorf("withTimeout expects milliseconds and a lambda")
				}
				ms, err := g.expr(e.Args[0], "Int")
				if err != nil {
					return "", err
				}
				lambda, ok := e.Args[1].(LambdaExpr)
				if !ok {
					return "", fmt.Errorf("withTimeout expects a lambda")
				}
				block, err := g.coroutineLambda(lambda, "Unit")
				if err != nil {
					return "", err
				}
				return g.currentCoroutineScope + ".WithTimeout(" + ms + ", " + block + ")", nil
			case "isActive":
				if g.currentCoroutineScope == "" {
					return "", fmt.Errorf("isActive requires a coroutine scope")
				}
				return g.currentCoroutineScope + ".IsActive()", nil
			case "coroutineContext":
				if g.currentCoroutineScope == "" {
					return "", fmt.Errorf("coroutineContext requires a coroutine scope")
				}
				return g.currentCoroutineScope + ".Context()", nil
			}
		}
		if selector, ok := e.Callee.(SelectorExpr); ok && selector.Name == "await" && len(e.Args) == 0 {
			receiver, err := g.expr(selector.Receiver, "")
			if err != nil {
				return "", err
			}
			return receiver + ".await()", nil
		}
		if selector, ok := e.Callee.(SelectorExpr); ok && selector.Name == "unwrap" && len(e.Args) == 0 {
			receiverType := g.exprType(selector.Receiver)
			resolvedReceiver := exprMeta(selector.Receiver)
			receiverExpected := receiverType
			if resolvedReceiver != nil && resolvedReceiver.Meaning == GoCallExpr {
				receiverExpected = ""
			}
			receiver, err := g.expr(selector.Receiver, receiverExpected)
			if err != nil {
				return "", err
			}
			if base, _, ok := parseGenericType(receiverType); ok && base == "Result" && (resolvedReceiver == nil || resolvedReceiver.Meaning != GoCallExpr) {
				return "gotlinResultUnwrap(" + receiver + ")", nil
			}
			return "gotlinUnwrapGo(" + receiver + ")", nil
		}
		if selector, ok := e.Callee.(SelectorExpr); ok && selector.Name == "unwrapOr" && len(e.Args) == 1 {
			receiverType := g.exprType(selector.Receiver)
			base, args, ok := parseGenericType(receiverType)
			if !ok || base != "Result" || len(args) != 2 {
				return "", fmt.Errorf("unwrapOr requires a Result value")
			}
			receiver, err := g.expr(selector.Receiver, receiverType)
			if err != nil {
				return "", err
			}
			fallback, err := g.expr(e.Args[0], args[0])
			if err != nil {
				return "", err
			}
			return "gotlinResultUnwrapOr(" + receiver + ", " + fallback + ")", nil
		}
		if safe, ok := e.Callee.(SafeSelectorExpr); ok {
			receiverType := g.exprType(safe.Receiver)
			if !strings.HasSuffix(receiverType, "?") {
				return "", fmt.Errorf("safe call requires a nullable receiver, got %s", receiverType)
			}
			innerType := strings.TrimSuffix(receiverType, "?")
			class, ok := g.classForType(innerType)
			if !ok {
				return "", fmt.Errorf("safe call receiver %s is not a Gotlin class", receiverType)
			}
			var method *FunctionDecl
			for i := range class.Methods {
				if class.Methods[i].Name == safe.Name {
					method = &class.Methods[i]
					break
				}
			}
			if method == nil {
				return "", fmt.Errorf("unknown safe-call method %s.%s", class.Name, safe.Name)
			}
			if len(e.Args) != len(method.Params) {
				return "", fmt.Errorf("%s.%s expects %d arguments", class.Name, safe.Name, len(method.Params))
			}
			receiver, err := g.expr(safe.Receiver, receiverType)
			if err != nil {
				return "", err
			}
			args := make([]string, 0, len(e.Args))
			for i, arg := range e.Args {
				value, err := g.expr(arg, method.Params[i].Type)
				if err != nil {
					return "", err
				}
				args = append(args, value)
			}
			call := "value." + safe.Name + "(" + strings.Join(args, ", ") + ")"
			if method.ReturnType == "Unit" {
				return fmt.Sprintf("func(value %s) { if value != nil { %s } }(%s)", g.goType(receiverType), call, receiver), nil
			}
			_, returnsClass := g.classForType(method.ReturnType)
			if returnsClass || strings.HasPrefix(method.ReturnType, "*") || strings.HasSuffix(method.ReturnType, "?") {
				return fmt.Sprintf("func(value %s) %s { if value == nil { return nil }; return %s }(%s)", g.goType(receiverType), g.goType(nullableType(method.ReturnType)), call, receiver), nil
			}
			return fmt.Sprintf("func(value %s) %s { if value == nil { return nil }; result := %s; return &result }(%s)", g.goType(receiverType), g.goType(nullableType(method.ReturnType)), call, receiver), nil
		}
		if selector, ok := e.Callee.(SelectorExpr); ok && selector.Name == "mapTo" && (resolvedCall == nil || resolvedCall.Meaning == MappingExpression) {
			if len(e.TypeArgs) > 1 || len(e.Args) != 0 || len(e.NamedArgs) != 0 {
				return "", fmt.Errorf("mapTo expects at most one type argument and no value arguments")
			}
			sourceType := g.exprType(selector.Receiver)
			if sourceType == "" {
				return "", fmt.Errorf("mapTo source requires a known type")
			}
			targetType := expectedType
			if len(e.TypeArgs) == 1 {
				targetType = g.mappingTopLevelTarget(e.TypeArgs[0])
			}
			if targetType == "" {
				return "", fmt.Errorf("mapTo target type cannot be inferred; use mapTo<Target>() or provide a typed context")
			}
			function, err := g.ensureMapping(sourceType, targetType, strings.TrimPrefix(sourceType, "*"))
			if err != nil {
				return "", err
			}
			source, err := g.expr(selector.Receiver, sourceType)
			if err != nil {
				return "", err
			}
			return function + "(" + source + ")", nil
		}
		if len(e.NamedArgs) > 0 {
			callee, err := g.expr(e.Callee, "")
			if err != nil {
				return "", err
			}
			fields := make([]string, 0, len(e.NamedArgs))
			for _, arg := range e.NamedArgs {
				value, err := g.expr(arg.Value, "")
				if err != nil {
					return "", err
				}
				fields = append(fields, exportedGoFieldName(arg.Name)+": "+value)
			}
			return "&" + callee + "{" + strings.Join(fields, ", ") + "}", nil
		}
		if selector, ok := e.Callee.(SelectorExpr); ok {
			if receiver, ok := selector.Receiver.(IdentExpr); ok && receiver.Name == "json" && selector.Name == "decode" {
				if len(e.TypeArgs) != 1 || len(e.Args) != 1 {
					return "", fmt.Errorf("json.decode expects one type argument and one body argument")
				}
				body, err := g.expr(e.Args[0], "")
				if err != nil {
					return "", err
				}
				g.needsJSONDecode = true
				return fmt.Sprintf("gotlinJSONDecode[%s](%s)", g.goType(e.TypeArgs[0]), body), nil
			}
		}
		if ident, ok := e.Callee.(IdentExpr); ok {
			switch ident.Name {
			case "goAssert":
				if len(e.TypeArgs) != 1 || len(e.Args) != 1 {
					return "", fmt.Errorf("goAssert<T>(value) expects one type and one value")
				}
				value, err := g.expr(e.Args[0], "")
				if err != nil {
					return "", err
				}
				return "(" + value + ").(" + g.goType(e.TypeArgs[0]) + ")", nil
			case "listOf", "mutableListOf":
				return g.listLiteral(e.Args, e.TypeArgs, expectedType)
			case "mapOf", "mutableMapOf":
				return g.mapLiteral(e.Args, e.TypeArgs, expectedType)
			case "Channel":
				return g.channelMakeExpr(e.Args, e.TypeArgs, expectedType)
			case "keys":
				if len(e.Args) != 1 {
					return "", fmt.Errorf("keys(map) expects exactly one argument")
				}
				_, mapTypes, ok := parseGenericType(g.exprType(e.Args[0]))
				if !ok || len(mapTypes) != 2 {
					return "", fmt.Errorf("keys(map) requires a typed map")
				}
				value, err := g.expr(e.Args[0], "")
				if err != nil {
					return "", err
				}
				keyType := g.goType(mapTypes[0])
				mapType := g.goType(g.exprType(e.Args[0]))
				return fmt.Sprintf("func(values %s) []%s { result := make([]%s, 0, len(values)); for key := range values { result = append(result, key) }; return result }(%s)", mapType, keyType, keyType, value), nil
			}
		}
		if selector, ok := e.Callee.(SelectorExpr); ok {
			switch selector.Name {
			case "read":
				if len(e.Args) != 0 {
					return "", fmt.Errorf("read() expects no arguments")
				}
				receiver, err := g.expr(selector.Receiver, "")
				if err != nil {
					return "", err
				}
				return "<-" + receiver, nil
			case "send":
				if len(e.Args) != 1 {
					return "", fmt.Errorf("send(value) expects exactly one argument")
				}
				receiver, err := g.expr(selector.Receiver, "")
				if err != nil {
					return "", err
				}
				arg, err := g.expr(e.Args[0], "")
				if err != nil {
					return "", err
				}
				return receiver + " <- " + arg, nil
			}
		}

		args := make([]string, 0, len(e.Args))
		argTypes := g.callArgTypes(e.Callee, len(e.Args))
		for i, arg := range e.Args {
			argType := ""
			if i < len(argTypes) {
				argType = argTypes[i]
			}
			value, err := g.expr(arg, argType)
			if err != nil {
				return "", err
			}
			if spread, ok := arg.(UnaryExpr); ok && spread.Op == "*" {
				inner, err := g.expr(spread.Value, "")
				if err != nil {
					return "", err
				}
				value = inner + "..."
			}
			args = append(args, value)
		}
		if ident, ok := e.Callee.(IdentExpr); ok && ident.Name == "println" {
			return fmt.Sprintf("fmt.Println(%s)", strings.Join(args, ", ")), nil
		}
		if ident, ok := e.Callee.(IdentExpr); ok && ident.Name == "ByteSlice" {
			if len(args) != 1 {
				return "", fmt.Errorf("ByteSlice expects exactly one argument")
			}
			if g.exprType(e.Args[0]) == "Int" {
				return "make([]byte, " + args[0] + ")", nil
			}
			return "[]byte(" + args[0] + ")", nil
		}
		if ident, ok := e.Callee.(IdentExpr); ok && ident.Name == "runCatching" {
			if len(args) != 1 {
				return "", fmt.Errorf("runCatching expects exactly one argument")
			}
			return fmt.Sprintf("gotlinRunCatching(%s)", args[0]), nil
		}
		if ident, ok := e.Callee.(IdentExpr); ok {
			if _, ok := g.semantic.Classes[ident.Name]; ok && (resolvedCall == nil || resolvedCall.Meaning == ClassConstructionExpr) {
				return fmt.Sprintf("New%s%s(%s)", ident.Name, g.renderCallTypeArguments(e.TypeArgs), strings.Join(args, ", ")), nil
			}
		}
		if resolvedCall != nil {
			if call, ok := resolvedCall.Node.(HIRGotlinCall); ok && call.Target != nil && call.Target.Effects.Has(CoroutineEffect) {
				if g.currentCoroutineScope == "" {
					return "", fmt.Errorf("contextual function %s requires a coroutine scope", call.Target.Name)
				}
				args = append([]string{g.currentCoroutineScope}, args...)
			}
		}
		callee, err := g.expr(e.Callee, "")
		if err != nil {
			return "", err
		}
		if len(e.TypeArgs) > 0 {
			callee += g.renderCallTypeArguments(e.TypeArgs)
		}
		call := fmt.Sprintf("%s(%s)", callee, strings.Join(args, ", "))
		if result, ok := g.goErrorResult(e, call, expectedType); ok {
			return result, nil
		}
		return call, nil
	case SelectorExpr:
		resolvedSelector := exprMeta(e)
		if resolvedSelector == nil || resolvedSelector.Meaning == EnumReferenceExpr {
			if receiver, ok := e.Receiver.(IdentExpr); ok {
				if decl, ok := g.semantic.Enums[receiver.Name]; ok {
					variant := enumVariant(decl, e.Name)
					if variant == nil {
						return "", fmt.Errorf("unknown variant %s.%s", receiver.Name, e.Name)
					}
					if len(variant.PayloadTypes) != 0 {
						return "", fmt.Errorf("variant %s.%s requires %d values", receiver.Name, e.Name, len(variant.PayloadTypes))
					}
					return g.expr(EnumVariantExpr{EnumName: receiver.Name, VariantName: e.Name}, expectedType)
				}
			}
		}
		if receiverType := g.exprType(e.Receiver); strings.HasSuffix(receiverType, "?") {
			return "", fmt.Errorf("nullable receiver %s requires ?. or !! before .%s", receiverType, e.Name)
		}
		receiver, err := g.expr(e.Receiver, "")
		if err != nil {
			return "", err
		}
		if call, ok := e.Receiver.(CallExpr); ok && len(call.NamedArgs) > 0 {
			receiver = "(" + receiver + ")"
		}
		name := e.Name
		if g.exprType(e.Receiver) == "GotlinSQLQuery" {
			if name == "sql" {
				name = "SQL"
			}
			if name == "args" {
				name = "Args"
			}
		}
		if ident, ok := e.Receiver.(IdentExpr); ok && g.semantic.Imports[ident.Name] {
			name = exportedGoName(name)
		} else if class, ok := g.classForType(g.exprType(e.Receiver)); ok {
			resolvedType, _ := g.semantic.ResolveType(g.exprType(e.Receiver))
			if isImportedClassType(resolvedType) {
				name = exportedGoName(name)
			} else {
				for _, field := range class.Fields {
					if field.Name == name && class.Data && !field.Private {
						name = exportedGoName(name)
						break
					}
				}
			}
		} else if ident, ok := e.Receiver.(IdentExpr); ok && (ident.Name == "this" || ident.Name == "self") && g.currentClass != nil {
			for _, field := range g.currentClass.Fields {
				if field.Name == name && g.currentClass.Data && !field.Private {
					name = exportedGoName(name)
					break
				}
			}
		} else if typ := g.exprType(e.Receiver); typ == "" || strings.Contains(typ, ".") {
			name = exportedGoName(name)
		}
		return fmt.Sprintf("%s.%s", receiver, name), nil
	case SafeSelectorExpr:
		receiverType := g.exprType(e.Receiver)
		if !strings.HasSuffix(receiverType, "?") {
			return "", fmt.Errorf("safe access requires a nullable receiver, got %s", receiverType)
		}
		innerType := strings.TrimSuffix(receiverType, "?")
		class, ok := g.classForType(innerType)
		if !ok {
			return "", fmt.Errorf("safe access receiver %s is not a Gotlin class", receiverType)
		}
		field, ok := classFieldByName(class, e.Name)
		if !ok {
			return "", fmt.Errorf("unknown field %s.%s", class.Name, e.Name)
		}
		receiver, err := g.expr(e.Receiver, receiverType)
		if err != nil {
			return "", err
		}
		fieldName := mappingFieldName(class, field)
		_, fieldIsClass := g.classForType(field.Type)
		if fieldIsClass || strings.HasPrefix(field.Type, "*") || strings.HasSuffix(field.Type, "?") {
			return fmt.Sprintf("func(value %s) %s { if value == nil { return nil }; return value.%s }(%s)", g.goType(receiverType), g.goType(nullableType(field.Type)), fieldName, receiver), nil
		}
		return fmt.Sprintf("func(value %s) %s { if value == nil { return nil }; result := value.%s; return &result }(%s)", g.goType(receiverType), g.goType(nullableType(field.Type)), fieldName, receiver), nil
	case IndexExpr:
		receiver, err := g.expr(e.Receiver, "")
		if err != nil {
			return "", err
		}
		index, err := g.expr(e.Index, "")
		if err != nil {
			return "", err
		}
		return receiver + "[" + index + "]", nil
	case MatchExpr:
		return g.valueMatch(e, expectedType)
	case EnumVariantExpr:
		if e.EnumName == "Result" {
			base, args, ok := parseGenericType(expectedType)
			if !ok || base != "Result" || len(args) != 2 {
				return "", fmt.Errorf("Result.%s requires an expected Result<T, Error> type", e.VariantName)
			}
			if e.VariantName == "Ok" {
				if len(e.Values) != 1 {
					return "", fmt.Errorf("Result.Ok expects one value")
				}
				value, err := g.expr(e.Values[0], args[0])
				if err != nil {
					return "", err
				}
				return fmt.Sprintf("GotlinResult[%s]{Value: %s}", g.goType(args[0]), value), nil
			}
			if e.VariantName == "Err" {
				if len(e.Values) != 1 {
					return "", fmt.Errorf("Result.Err expects one error")
				}
				value, err := g.expr(e.Values[0], "Error")
				if err != nil {
					return "", err
				}
				return fmt.Sprintf("GotlinResult[%s]{Err: %s}", g.goType(args[0]), value), nil
			}
			return "", fmt.Errorf("unknown Result variant %s", e.VariantName)
		}
		decl, ok := g.semantic.Enums[e.EnumName]
		if !ok {
			return "", fmt.Errorf("unknown enum %s", e.EnumName)
		}
		var variant *EnumVariant
		for i := range decl.Variants {
			if decl.Variants[i].Name == e.VariantName {
				variant = &decl.Variants[i]
				break
			}
		}
		if variant == nil {
			return "", fmt.Errorf("unknown variant %s.%s", e.EnumName, e.VariantName)
		}
		if len(e.Values) != len(variant.PayloadTypes) {
			return "", fmt.Errorf("variant %s.%s expects %d values", e.EnumName, e.VariantName, len(variant.PayloadTypes))
		}
		if enumIsString(decl) {
			return e.EnumName + e.VariantName, nil
		}
		fields := make([]string, 0, len(e.Values))
		for i, valueExpr := range e.Values {
			value, err := g.expr(valueExpr, variant.PayloadTypes[i])
			if err != nil {
				return "", err
			}
			fields = append(fields, fmt.Sprintf("Value%d: %s", i, value))
		}
		return "&" + e.EnumName + e.VariantName + "{" + strings.Join(fields, ", ") + "}", nil
	case LambdaExpr:
		return g.lambda(e, expectedType)
	default:
		return "", fmt.Errorf("unsupported expression %T", expr)
	}
}

func (g *goGenerator) valueMatch(match MatchExpr, expectedType string) (string, error) {
	enumName := strings.TrimPrefix(g.exprType(match.Value), "*")
	if enumName == "" && len(match.Cases) > 0 {
		enumName = match.Cases[0].EnumName
	}
	decl := g.semantic.Enums[enumName]
	resultType := expectedType
	if resultType == "" || resultType == "Any" {
		resultType = g.exprType(match)
	}
	value, err := g.expr(match.Value, enumName)
	if err != nil {
		return "", err
	}
	g.matchCounter++
	matchName := fmt.Sprintf("gotlinMatch%d", g.matchCounter)
	var out strings.Builder
	out.WriteString("func() ")
	out.WriteString(g.goType(resultType))
	out.WriteString(" { ")
	if enumIsString(decl) {
		out.WriteString("switch ")
		out.WriteString(value)
		out.WriteString(" { ")
		for _, c := range match.Cases {
			arm, err := g.expr(c.Value, resultType)
			if err != nil {
				return "", err
			}
			out.WriteString("case ")
			out.WriteString(enumName + c.VariantName)
			out.WriteString(": return ")
			out.WriteString(arm)
			out.WriteString("; ")
		}
		out.WriteString("}; ")
	} else {
		out.WriteString("switch ")
		out.WriteString(matchName)
		out.WriteString(" := ")
		out.WriteString(value)
		out.WriteString(".(type) { ")
		for _, c := range match.Cases {
			variant := enumVariant(decl, c.VariantName)
			g.pushScope()
			out.WriteString("case *")
			out.WriteString(enumName + c.VariantName)
			out.WriteString(": ")
			for i, binding := range c.Bindings {
				g.defineType(binding, variant.PayloadTypes[i])
				out.WriteString(binding)
				out.WriteString(" := ")
				out.WriteString(matchName)
				out.WriteString(fmt.Sprintf(".Value%d; ", i))
			}
			arm, err := g.expr(c.Value, resultType)
			g.popScope()
			if err != nil {
				return "", err
			}
			out.WriteString("return ")
			out.WriteString(arm)
			out.WriteString("; ")
		}
		out.WriteString("}; ")
	}
	out.WriteString(`panic("unreachable exhaustive match") }()`)
	return out.String(), nil
}

func (g *goGenerator) emitJSONDecodeSupport() {
	g.line("func gotlinJSONDecode[T any](body []byte) GotlinResult[T] {")
	g.indentLevel++
	g.line("var value T")
	g.line("if err := json.Unmarshal(body, &value); err != nil { return GotlinResult[T]{Err: err} }")
	g.line("return GotlinResult[T]{Value: value}")
	g.indentLevel--
	g.line("}")
}

func (g *goGenerator) emitSQLSupport(program *Program, execution bool) {
	g.line("type GotlinSQLQuery struct {")
	g.indentLevel++
	g.line("SQL string")
	g.line("Args []any")
	g.indentLevel--
	g.line("}")
	if !execution {
		return
	}
	g.line("")
	g.line("type gotlinSQLQuerier interface {")
	g.indentLevel++
	g.line("Query(" + g.sqlContextAlias + ".Context, string, ...any) (" + g.sqlPGXAlias + ".Rows, error)")
	g.indentLevel--
	g.line("}")
	g.line("")
	g.line("type gotlinSQLRow interface {")
	g.indentLevel++
	g.line("Scan(...any) error")
	g.indentLevel--
	g.line("}")
	g.line("")
	g.line("type gotlinSQLScanner[T any] func(gotlinSQLRow) (*T, error)")
	g.line("")
	g.line("type gotlinSQLError string")
	g.line("")
	g.line("func (err gotlinSQLError) Error() string {")
	g.indentLevel++
	g.line("return string(err)")
	g.indentLevel--
	g.line("}")
	g.line("")
	g.line("func gotlinSQLFetch[T any](pool gotlinSQLQuerier, ctx " + g.sqlContextAlias + ".Context, query GotlinSQLQuery, scan gotlinSQLScanner[T]) GotlinResult[[]*T] {")
	g.indentLevel++
	g.line("rows, err := pool.Query(ctx, query.SQL, query.Args...)")
	g.line("if err != nil { return GotlinResult[[]*T]{Err: err} }")
	g.line("defer rows.Close()")
	g.line("values := make([]*T, 0)")
	g.line("for rows.Next() {")
	g.indentLevel++
	g.line("value, err := scan(rows)")
	g.line("if err != nil { return GotlinResult[[]*T]{Err: err} }")
	g.line("values = append(values, value)")
	g.indentLevel--
	g.line("}")
	g.line("if err := rows.Err(); err != nil { return GotlinResult[[]*T]{Err: err} }")
	g.line("return GotlinResult[[]*T]{Value: values}")
	g.indentLevel--
	g.line("}")
	g.line("")
	g.line("func gotlinSQLSingle[T any](pool gotlinSQLQuerier, ctx " + g.sqlContextAlias + ".Context, query GotlinSQLQuery, scan gotlinSQLScanner[T]) GotlinResult[*T] {")
	g.indentLevel++
	g.line("rows, err := pool.Query(ctx, query.SQL, query.Args...)")
	g.line("if err != nil { return GotlinResult[*T]{Err: err} }")
	g.line("defer rows.Close()")
	g.line("if !rows.Next() {")
	g.indentLevel++
	g.line("if err := rows.Err(); err != nil { return GotlinResult[*T]{Err: err} }")
	g.line(`return GotlinResult[*T]{Err: gotlinSQLError("SQL single() expected exactly one row, got zero")}`)
	g.indentLevel--
	g.line("}")
	g.line("value, err := scan(rows)")
	g.line("if err != nil { return GotlinResult[*T]{Err: err} }")
	g.line("if rows.Next() {")
	g.indentLevel++
	g.line(`return GotlinResult[*T]{Err: gotlinSQLError("SQL single() expected exactly one row, got more than one")}`)
	g.indentLevel--
	g.line("}")
	g.line("if err := rows.Err(); err != nil { return GotlinResult[*T]{Err: err} }")
	g.line("return GotlinResult[*T]{Value: value}")
	g.indentLevel--
	g.line("}")
	g.line("")
	g.line("type GotlinSQLIterator[T any] struct {")
	g.indentLevel++
	g.line("rows " + g.sqlPGXAlias + ".Rows")
	g.line("scan gotlinSQLScanner[T]")
	g.line("current *T")
	g.line("streamErr error")
	g.indentLevel--
	g.line("}")
	g.line("")
	g.line("func gotlinSQLIterate[T any](pool gotlinSQLQuerier, ctx " + g.sqlContextAlias + ".Context, query GotlinSQLQuery, scan gotlinSQLScanner[T]) GotlinResult[*GotlinSQLIterator[T]] {")
	g.indentLevel++
	g.line("rows, err := pool.Query(ctx, query.SQL, query.Args...)")
	g.line("if err != nil { return GotlinResult[*GotlinSQLIterator[T]]{Err: err} }")
	g.line("return GotlinResult[*GotlinSQLIterator[T]]{Value: &GotlinSQLIterator[T]{rows: rows, scan: scan}}")
	g.indentLevel--
	g.line("}")
	g.line("")
	g.line("func (iterator *GotlinSQLIterator[T]) next() bool {")
	g.indentLevel++
	g.line("iterator.current = nil")
	g.line("if iterator.rows == nil || !iterator.rows.Next() {")
	g.indentLevel++
	g.line("if iterator.rows != nil {")
	g.indentLevel++
	g.line("iterator.streamErr = iterator.rows.Err()")
	g.indentLevel--
	g.line("}")
	g.line("return false")
	g.indentLevel--
	g.line("}")
	g.line("value, err := iterator.scan(iterator.rows)")
	g.line("if err != nil {")
	g.indentLevel++
	g.line("iterator.streamErr = err")
	g.line("return false")
	g.indentLevel--
	g.line("}")
	g.line("iterator.current = value")
	g.line("return true")
	g.indentLevel--
	g.line("}")
	g.line("")
	g.line("func (iterator *GotlinSQLIterator[T]) value() *T {")
	g.indentLevel++
	g.line("if iterator.current == nil {")
	g.indentLevel++
	g.line(`panic("SQL iterator value() requires a successful next()")`)
	g.indentLevel--
	g.line("}")
	g.line("return iterator.current")
	g.indentLevel--
	g.line("}")
	g.line("")
	g.line("func (iterator *GotlinSQLIterator[T]) close() {")
	g.indentLevel++
	g.line("if iterator.rows != nil {")
	g.indentLevel++
	g.line("iterator.rows.Close()")
	g.indentLevel--
	g.line("}")
	g.indentLevel--
	g.line("}")
	g.line("")
	g.line("func (iterator *GotlinSQLIterator[T]) err() error {")
	g.indentLevel++
	g.line("if iterator.streamErr != nil {")
	g.indentLevel++
	g.line("return iterator.streamErr")
	g.indentLevel--
	g.line("}")
	g.line("if iterator.rows != nil {")
	g.indentLevel++
	g.line("return iterator.rows.Err()")
	g.indentLevel--
	g.line("}")
	g.line("return nil")
	g.indentLevel--
	g.line("}")

	for _, class := range program.Classes {
		if !class.Data {
			continue
		}
		g.line("")
		g.line("func gotlinSQLScan" + class.Name + "(row gotlinSQLRow) (*" + class.Name + ", error) {")
		g.indentLevel++
		g.line("value := new(" + class.Name + ")")
		destinations := make([]string, 0, len(class.Fields))
		for _, field := range class.Fields {
			name := field.Name
			if !field.Private {
				name = exportedGoName(name)
			}
			destinations = append(destinations, "&value."+name)
		}
		g.line("err := row.Scan(" + strings.Join(destinations, ", ") + ")")
		g.line("return value, err")
		g.indentLevel--
		g.line("}")
	}
}

func exportedGoName(name string) string {
	if name == "" || name[0] < 'a' || name[0] > 'z' {
		return name
	}
	return strings.ToUpper(name[:1]) + name[1:]
}

func exportedGoFieldName(name string) string {
	name = exportedGoName(name)
	for _, pair := range [][2]string{{"Jwks", "JWKS"}, {"Jwt", "JWT"}, {"Url", "URL"}, {"Api", "API"}, {"Sql", "SQL"}, {"Id", "ID"}} {
		name = strings.ReplaceAll(name, pair[0], pair[1])
	}
	return name
}

func snakeCase(name string) string {
	var b strings.Builder
	for i, r := range name {
		if i > 0 && r >= 'A' && r <= 'Z' {
			b.WriteByte('_')
		}
		b.WriteRune(rune(strings.ToLower(string(r))[0]))
	}
	return b.String()
}

func jsonFieldName(name, policy string) string {
	switch policy {
	case "", "snakeCase":
		return snakeCase(name)
	case "camelCase":
		if name == "" {
			return name
		}
		return strings.ToLower(name[:1]) + name[1:]
	case "pascalCase":
		return exportedGoName(name)
	case "kebabCase":
		return strings.ReplaceAll(snakeCase(name), "_", "-")
	default:
		return snakeCase(name)
	}
}

func (g *goGenerator) listLiteral(args []Expr, typeArgs []string, expectedType string) (string, error) {
	elemType := ""
	if len(typeArgs) > 0 {
		if len(typeArgs) != 1 {
			return "", fmt.Errorf("listOf expects exactly one type argument")
		}
		elemType = typeArgs[0]
	}
	if base, genericArgs, ok := parseGenericType(expectedType); ok && (base == "List" || base == "MutableList") && len(genericArgs) == 1 {
		if elemType == "" {
			elemType = genericArgs[0]
		}
	}
	goElemType := "any"
	if elemType != "" {
		goElemType = g.goType(elemType)
	}

	values := make([]string, 0, len(args))
	for _, arg := range args {
		value, err := g.expr(arg, elemType)
		if err != nil {
			return "", err
		}
		values = append(values, value)
	}
	return "[]" + goElemType + "{" + strings.Join(values, ", ") + "}", nil
}

func (g *goGenerator) mapLiteral(args []Expr, typeArgs []string, expectedType string) (string, error) {
	if len(args)%2 != 0 {
		return "", fmt.Errorf("mapOf expects an even number of arguments (key/value pairs)")
	}

	keyType := ""
	valType := ""
	if len(typeArgs) > 0 {
		if len(typeArgs) != 2 {
			return "", fmt.Errorf("mapOf expects exactly two type arguments")
		}
		keyType = typeArgs[0]
		valType = typeArgs[1]
	}
	if base, genericArgs, ok := parseGenericType(expectedType); ok && (base == "Map" || base == "MutableMap") && len(genericArgs) == 2 {
		if keyType == "" {
			keyType = genericArgs[0]
		}
		if valType == "" {
			valType = genericArgs[1]
		}
	}
	goKeyType := "any"
	goValType := "any"
	if keyType != "" {
		goKeyType = g.goType(keyType)
	}
	if valType != "" {
		goValType = g.goType(valType)
	}

	var entries []string
	for i := 0; i < len(args); i += 2 {
		key, err := g.expr(args[i], keyType)
		if err != nil {
			return "", err
		}
		val, err := g.expr(args[i+1], valType)
		if err != nil {
			return "", err
		}
		entries = append(entries, key+": "+val)
	}
	return "map[" + goKeyType + "]" + goValType + "{" + strings.Join(entries, ", ") + "}", nil
}

func (g *goGenerator) channelMakeExpr(args []Expr, typeArgs []string, expectedType string) (string, error) {
	elemType := ""
	if len(typeArgs) > 0 {
		if len(typeArgs) != 1 {
			return "", fmt.Errorf("Channel expects exactly one type argument")
		}
		elemType = typeArgs[0]
	}
	if elemType == "" {
		if base, genericArgs, ok := parseGenericType(expectedType); ok && base == "Channel" && len(genericArgs) == 1 {
			elemType = genericArgs[0]
		}
	}
	goElemType := "any"
	if elemType != "" {
		goElemType = g.goType(elemType)
	}

	if len(args) > 1 {
		return "", fmt.Errorf("Channel() expects at most one capacity argument")
	}
	if len(args) == 1 {
		capacity, err := g.expr(args[0], "Int")
		if err != nil {
			return "", err
		}
		return "make(chan " + goElemType + ", " + capacity + ")", nil
	}
	return "make(chan " + goElemType + ")", nil
}

func (g *goGenerator) wrapExpr(expr Expr, expectedType string) (string, error) {
	switch expr.(type) {
	case BinaryExpr:
		value, err := g.expr(expr, expectedType)
		if err != nil {
			return "", err
		}
		return "(" + value + ")", nil
	default:
		return g.expr(expr, expectedType)
	}
}

func (g *goGenerator) line(text string) {
	g.writeIndent()
	g.write(text)
	g.write("\n")
}

func (g *goGenerator) writeIndent() {
	g.write(strings.Repeat("\t", g.indentLevel))
}

func (g *goGenerator) write(text string) {
	g.buf.WriteString(text)
}

func (g *goGenerator) goType(name string) string { return g.semantic.GoType(name) }

func nullableType(name string) string {
	if strings.HasSuffix(name, "?") {
		return name
	}
	return name + "?"
}

func nullableCondition(expr Expr) (name string, thenNonNull bool, elseNonNull bool) {
	binary, ok := expr.(BinaryExpr)
	if !ok || (binary.Op != "==" && binary.Op != "!=") {
		return "", false, false
	}
	ident, leftIdent := binary.Left.(IdentExpr)
	_, rightNull := binary.Right.(NullExpr)
	if !leftIdent || !rightNull {
		ident, leftIdent = binary.Right.(IdentExpr)
		_, rightNull = binary.Left.(NullExpr)
	}
	if !leftIdent || !rightNull {
		return "", false, false
	}
	if binary.Op == "!=" {
		return ident.Name, true, false
	}
	return ident.Name, false, true
}

func blockAlwaysTerminates(stmts []Stmt) bool {
	if len(stmts) == 0 {
		return false
	}
	switch last := stmts[len(stmts)-1].(type) {
	case ReturnStmt, ThrowStmt:
		return true
	case IfStmt:
		return len(last.Else) > 0 && blockAlwaysTerminates(last.Then) && blockAlwaysTerminates(last.Else)
	default:
		return false
	}
}

func (g *goGenerator) goReturnType(name string) string {
	return g.goType(name)
}

func usesPrintln(stmts []Stmt) bool {
	for _, stmt := range stmts {
		switch s := stmt.(type) {
		case ExprStmt:
			if call, ok := s.Value.(CallExpr); ok && isBuiltinPrintln(call.Callee) {
				return true
			}
			if exprUsesPrintln(s.Value) {
				return true
			}
		case VarDecl:
			if exprUsesPrintln(s.Value) {
				return true
			}
		case AssignStmt:
			if exprUsesPrintln(s.Value) {
				return true
			}
		case AddAssignStmt:
			if exprUsesPrintln(s.Value) {
				return true
			}
		case MultiAssignStmt:
			if exprUsesPrintln(s.Value) {
				return true
			}
		case MultiVarDecl:
			if exprUsesPrintln(s.Value) {
				return true
			}
		case ReturnStmt:
			if s.Value != nil && exprUsesPrintln(s.Value) {
				return true
			}
		case ThrowStmt:
			if exprUsesPrintln(s.Value) {
				return true
			}
		case DeferStmt:
			if exprUsesPrintln(s.Value) {
				return true
			}
		case IfStmt:
			if exprUsesPrintln(s.Cond) || usesPrintln(s.Then) || usesPrintln(s.Else) {
				return true
			}
		case WhileStmt:
			if exprUsesPrintln(s.Cond) || usesPrintln(s.Body) {
				return true
			}
		case ForEachStmt:
			if exprUsesPrintln(s.Source) || usesPrintln(s.Body) {
				return true
			}
		case MatchStmt:
			if exprUsesPrintln(s.Value) {
				return true
			}
			for _, c := range s.Cases {
				if usesPrintln(c.Body) {
					return true
				}
			}
		case TryCatchStmt:
			if usesPrintln(s.TryBody) || usesPrintln(s.CatchBody) {
				return true
			}
		}
	}
	return false
}

func usesRunCatching(stmts []Stmt) bool {
	for _, stmt := range stmts {
		switch s := stmt.(type) {
		case VarDecl:
			if exprUsesRunCatching(s.Value) {
				return true
			}
		case MultiVarDecl:
			if exprUsesRunCatching(s.Value) {
				return true
			}
		case AssignStmt:
			if exprUsesRunCatching(s.Value) {
				return true
			}
		case AddAssignStmt:
			if exprUsesRunCatching(s.Value) {
				return true
			}
		case MultiAssignStmt:
			if exprUsesRunCatching(s.Value) {
				return true
			}
		case ReturnStmt:
			if s.Value != nil && exprUsesRunCatching(s.Value) {
				return true
			}
		case ThrowStmt:
			if exprUsesRunCatching(s.Value) {
				return true
			}
		case ExprStmt:
			if exprUsesRunCatching(s.Value) {
				return true
			}
		case IfStmt:
			if exprUsesRunCatching(s.Cond) || usesRunCatching(s.Then) || usesRunCatching(s.Else) {
				return true
			}
		case WhileStmt:
			if exprUsesRunCatching(s.Cond) || usesRunCatching(s.Body) {
				return true
			}
		case TryCatchStmt:
			if usesRunCatching(s.TryBody) || usesRunCatching(s.CatchBody) {
				return true
			}
		}
	}
	return false
}

func usesGoUnwrap(stmts []Stmt) bool {
	for _, stmt := range stmts {
		switch s := stmt.(type) {
		case VarDecl:
			if _, ok := s.Value.(CallExpr); ok {
				return true
			}
		case AssignStmt:
			if _, ok := s.Value.(CallExpr); ok {
				return true
			}
		case AddAssignStmt:
			if _, ok := s.Value.(CallExpr); ok {
				return true
			}
		case ReturnStmt:
			if s.Value != nil {
				if _, ok := s.Value.(CallExpr); ok {
					return true
				}
			}
		case IfStmt:
			if usesGoUnwrap(s.Then) || usesGoUnwrap(s.Else) {
				return true
			}
		case WhileStmt:
			if usesGoUnwrap(s.Body) {
				return true
			}
		case TryCatchStmt:
			if usesGoUnwrap(s.TryBody) || usesGoUnwrap(s.CatchBody) {
				return true
			}
		}
	}
	return false
}

func (g *goGenerator) lambda(lambda LambdaExpr, expectedType string) (string, error) {
	params := lambda.Params
	returnType := ""
	paramTypes := []string(nil)

	if lambda.ImplicitIt {
		expectedReturnType := ""
		ok := false
		paramTypes, expectedReturnType, ok = parseFunctionType(expectedType)
		if !ok {
			return "", fmt.Errorf("lambda with implicit it requires a function type context")
		}
		if len(paramTypes) == 1 {
			params = []Param{{Name: "it", Type: paramTypes[0]}}
		} else if len(paramTypes) == 0 {
			params = nil
		} else {
			params = make([]Param, 0, len(paramTypes))
			for _, typ := range paramTypes {
				params = append(params, Param{Name: "_", Type: typ})
			}
		}
		returnType = expectedReturnType
	} else if parsedParamTypes, expectedReturnType, ok := parseFunctionType(expectedType); ok && len(parsedParamTypes) == len(params) {
		paramTypes = parsedParamTypes
		returnType = expectedReturnType
	}

	if returnType == "" && lambdaHasValueReturn(lambda.Body) {
		return "", fmt.Errorf("lambda with value return requires a function type context")
	}

	for i := range params {
		if params[i].Type == "" {
			if i >= len(paramTypes) || paramTypes[i] == "" {
				return "", fmt.Errorf("lambda parameter %q requires a type or typed call context", params[i].Name)
			}
			params[i].Type = paramTypes[i]
		}
	}

	var b strings.Builder
	b.WriteString("func(")
	for i, param := range params {
		if i > 0 {
			b.WriteString(", ")
		}
		b.WriteString(param.Name)
		b.WriteString(" ")
		b.WriteString(g.goType(param.Type))
	}
	b.WriteString(")")
	if goRet := g.goType(returnType); goRet != "" {
		b.WriteString(" ")
		b.WriteString(goRet)
	}
	b.WriteString(" {\n")

	sub := goGenerator{
		indentLevel:  1,
		needsFmt:     g.needsFmt,
		semantic:     g.semantic,
		currentFunc:  FunctionDecl{ReturnType: returnType},
		currentClass: g.currentClass,
	}
	if g.currentClass != nil {
		classCopy := *g.currentClass
		sub.currentClass = &classCopy
	}
	sub.scopes = g.cloneScopes()
	sub.semanticScope = g.semanticScope
	sub.pushScope()
	if lambda.ImplicitIt {
		if len(params) == 1 {
			sub.defineType("it", params[0].Type)
		} else {
			sub.define("it")
		}
	}
	for _, param := range params {
		sub.defineType(param.Name, param.Type)
	}
	if err := sub.block(lambda.Body); err != nil {
		return "", err
	}
	b.Write(sub.buf.Bytes())
	b.WriteString("}")
	return b.String(), nil
}

func (g *goGenerator) callArgTypes(callee Expr, argCount int) []string {
	ident, ok := callee.(IdentExpr)
	if ok {
		if ident.Name == "runCatching" {
			return []string{"() -> Unit"}
		}
		fn, ok := g.semantic.Functions[ident.Name]
		if ok {
			argTypes := make([]string, 0, min(argCount, len(fn.Params)))
			for i := 0; i < argCount && i < len(fn.Params); i++ {
				argTypes = append(argTypes, fn.Params[i].Type)
			}
			return argTypes
		}
		class, ok := g.semantic.Classes[ident.Name]
		if ok {
			argTypes := make([]string, 0, min(argCount, len(class.Fields)))
			for i := 0; i < argCount && i < len(class.Fields); i++ {
				argTypes = append(argTypes, class.Fields[i].Type)
			}
			return argTypes
		}
		return nil
	}

	selector, ok := selectorPath(callee)
	if !ok {
		return nil
	}
	switch selector {
	case "http.HandleFunc":
		return []string{"String", "(http.ResponseWriter, *http.Request) -> Unit"}
	case "sort.Slice", "sort.slice":
		return []string{"Any", "(Int, Int) -> Boolean"}
	default:
		return nil
	}
}

func nameUsedInStmts(name string, stmts []Stmt) bool {
	return nameUsedInStmtsWithShadow(name, stmts, false)
}

func nameUsedInStmtsWithShadow(name string, stmts []Stmt, shadowed bool) bool {
	localShadowed := shadowed
	for _, stmt := range stmts {
		switch s := stmt.(type) {
		case VarDecl:
			if exprUsesName(s.Value, name, localShadowed) {
				return true
			}
			if s.Name == name {
				localShadowed = true
			}
		case MultiVarDecl:
			if exprUsesName(s.Value, name, localShadowed) {
				return true
			}
			for _, declared := range s.Names {
				if declared == name {
					localShadowed = true
					break
				}
			}
		case AssignStmt:
			if !localShadowed && s.Name == name {
				return true
			}
			if exprUsesName(s.Value, name, localShadowed) {
				return true
			}
		case AddAssignStmt:
			if !localShadowed && s.Name == name {
				return true
			}
			if exprUsesName(s.Value, name, localShadowed) {
				return true
			}
		case MultiAssignStmt:
			if !localShadowed {
				for _, assigned := range s.Names {
					if assigned == name {
						return true
					}
				}
			}
			if exprUsesName(s.Value, name, localShadowed) {
				return true
			}
		case ReturnStmt:
			if s.Value != nil && exprUsesName(s.Value, name, localShadowed) {
				return true
			}
		case ThrowStmt:
			if exprUsesName(s.Value, name, localShadowed) {
				return true
			}
		case DeferStmt:
			if exprUsesName(s.Value, name, localShadowed) {
				return true
			}
		case ExprStmt:
			if exprUsesName(s.Value, name, localShadowed) {
				return true
			}
		case IfStmt:
			if exprUsesName(s.Cond, name, localShadowed) {
				return true
			}
			if nameUsedInStmtsWithShadow(name, s.Then, localShadowed) {
				return true
			}
			if nameUsedInStmtsWithShadow(name, s.Else, localShadowed) {
				return true
			}
		case WhileStmt:
			if exprUsesName(s.Cond, name, localShadowed) {
				return true
			}
			if nameUsedInStmtsWithShadow(name, s.Body, localShadowed) {
				return true
			}
		case ForEachStmt:
			if exprUsesName(s.Source, name, localShadowed) {
				return true
			}
			if nameUsedInStmtsWithShadow(name, s.Body, localShadowed || s.Name == name) {
				return true
			}
		case MatchStmt:
			if exprUsesName(s.Value, name, localShadowed) {
				return true
			}
			for _, c := range s.Cases {
				caseShadowed := localShadowed
				for _, binding := range c.Bindings {
					if binding == name {
						caseShadowed = true
					}
				}
				if nameUsedInStmtsWithShadow(name, c.Body, caseShadowed) {
					return true
				}
			}
		case TryCatchStmt:
			if nameUsedInStmtsWithShadow(name, s.TryBody, localShadowed) {
				return true
			}
			catchShadowed := localShadowed || s.CatchName == name
			if nameUsedInStmtsWithShadow(name, s.CatchBody, catchShadowed) {
				return true
			}
		}
	}
	return false
}

func exprUsesName(expr Expr, name string, shadowed bool) bool {
	switch e := expr.(type) {
	case IdentExpr:
		return !shadowed && e.Name == name
	case UnaryExpr:
		return exprUsesName(e.Value, name, shadowed)
	case NonNullExpr:
		return exprUsesName(e.Value, name, shadowed)
	case TryExpr:
		return exprUsesName(e.Value, name, shadowed)
	case BinaryExpr:
		return exprUsesName(e.Left, name, shadowed) || exprUsesName(e.Right, name, shadowed)
	case CallExpr:
		if exprUsesName(e.Callee, name, shadowed) {
			return true
		}
		for _, arg := range e.Args {
			if exprUsesName(arg, name, shadowed) {
				return true
			}
		}
		return false
	case SelectorExpr:
		return exprUsesName(e.Receiver, name, shadowed)
	case IndexExpr:
		return exprUsesName(e.Receiver, name, shadowed) || exprUsesName(e.Index, name, shadowed)
	case EnumVariantExpr:
		for _, value := range e.Values {
			if exprUsesName(value, name, shadowed) {
				return true
			}
		}
		return false
	case MatchExpr:
		if exprUsesName(e.Value, name, shadowed) {
			return true
		}
		for _, matchCase := range e.Cases {
			caseShadowed := shadowed
			for _, binding := range matchCase.Bindings {
				if binding == name {
					caseShadowed = true
				}
			}
			if exprUsesName(matchCase.Value, name, caseShadowed) {
				return true
			}
		}
		return false
	case LambdaExpr:
		lambdaShadowed := shadowed
		if e.ImplicitIt && name == "it" {
			lambdaShadowed = true
		}
		for _, param := range e.Params {
			if param.Name == name {
				lambdaShadowed = true
				break
			}
		}
		return nameUsedInStmtsWithShadow(name, e.Body, lambdaShadowed)
	default:
		return false
	}
}

func (g *goGenerator) pushScope() {
	g.scopes = append(g.scopes, map[string]bool{})
	g.semanticScope = NewScope(g.semanticScope)
}

func (g *goGenerator) popScope() {
	if len(g.scopes) == 0 {
		return
	}
	g.scopes = g.scopes[:len(g.scopes)-1]
	g.semanticScope = g.semanticScope.Parent
}

func (g *goGenerator) define(name string) {
	g.defineType(name, "")
}

func (g *goGenerator) defineType(name, typ string) {
	if len(g.scopes) == 0 {
		g.pushScope()
	}
	g.scopes[len(g.scopes)-1][name] = true
	resolved, err := g.semantic.ResolveType(typ)
	if err != nil {
		resolved = UnknownType{}
	}
	g.semanticScope.Symbols[name] = &Symbol{Name: name, Kind: VariableSymbol, Type: resolved}
}

func (g *goGenerator) lookupType(name string) string {
	if g.semanticScope != nil {
		if symbol, ok := g.semanticScope.Lookup(name); ok {
			if isUnknownType(symbol.Type) {
				return ""
			}
			return symbol.Type.String()
		}
	}
	return ""
}

func (g *goGenerator) exprType(expr Expr) string {
	if ident, ok := expr.(IdentExpr); ok {
		if typ := g.lookupType(ident.Name); typ != "" {
			return typ
		}
	}
	if resolved := exprMeta(expr); resolved != nil && !isUnknownType(resolved.Type) {
		return resolved.Type.String()
	}
	// Generator-created expressions do not pass through semantic analysis.
	typ := g.semantic.TypeOf(expr, TypeEnvironment{Scope: g.semanticScope, Class: g.currentClassSymbol()})
	if isUnknownType(typ) {
		return ""
	}
	return typ.String()
}

func (g *goGenerator) currentClassSymbol() *ClassSymbol {
	if g.currentClass == nil {
		return nil
	}
	return g.semantic.ClassInfo[g.currentClass.Name]
}

func (g *goGenerator) goErrorResult(call CallExpr, rendered, expectedType string) (string, bool) {
	base, args, ok := parseGenericType(expectedType)
	resolved := exprMeta(call)
	external := false
	if resolved != nil {
		_, external = resolved.Node.(HIRGoCall)
	}
	if !external {
		external = g.isExternalGoCall(call.Callee)
	}
	if !ok || base != "Result" || len(args) != 2 || args[1] != "Error" || !external {
		return "", false
	}
	if actualBase, _, actualIsResult := parseGenericType(g.exprType(call)); actualIsResult && actualBase == "Result" && (resolved == nil || resolved.Meaning != GoCallExpr) {
		return "", false
	}
	valueType := g.goType(args[0])
	if args[0] == "Unit" {
		valueType = "struct{}"
		return fmt.Sprintf("func() GotlinResult[%s] { err := %s; return GotlinResult[%s]{Err: err} }()", valueType, rendered, valueType), true
	}
	return fmt.Sprintf("func() GotlinResult[%s] { value, err := %s; return GotlinResult[%s]{Value: value, Err: err} }()", valueType, rendered, valueType), true
}

func (g *goGenerator) isExternalGoCall(callee Expr) bool {
	switch value := callee.(type) {
	case IdentExpr:
		if _, ok := g.semantic.Functions[value.Name]; ok {
			return false
		}
		if _, ok := g.semantic.Classes[value.Name]; ok {
			return false
		}
		return true
	case SelectorExpr:
		if receiver, ok := value.Receiver.(IdentExpr); ok && g.semantic.Imports[receiver.Name] {
			return true
		}
		if _, ok := g.classForType(g.exprType(value.Receiver)); ok {
			return false
		}
		return true
	default:
		return false
	}
}

func (g *goGenerator) classForType(typ string) (ClassDecl, bool) {
	resolved, err := g.semantic.ResolveType(typ)
	if err != nil {
		return ClassDecl{}, false
	}
	class, _ := classInstance(resolved)
	if class == nil || class.Decl == nil {
		return ClassDecl{}, false
	}
	return *class.Decl, true
}

func (g *goGenerator) isDefined(name string) bool {
	for i := len(g.scopes) - 1; i >= 0; i-- {
		if g.scopes[i][name] {
			return true
		}
	}
	return false
}

func (g *goGenerator) assignTarget(name string) string {
	if g.currentClass != nil && !g.isDefined(name) {
		if field, found := classFieldByName(*g.currentClass, name); found {
			return "self." + mappingFieldName(*g.currentClass, field)
		}
	}
	return name
}

func (g *goGenerator) cloneScopes() []map[string]bool {
	dup := make([]map[string]bool, 0, len(g.scopes))
	for _, scope := range g.scopes {
		copyScope := make(map[string]bool, len(scope))
		for k, v := range scope {
			copyScope[k] = v
		}
		dup = append(dup, copyScope)
	}
	return dup
}

func (g *goGenerator) renderGoFunctionParams(function FunctionDecl) string {
	prefix := ""
	if g.hasCoroutineEffect(function) {
		prefix = "gotlinScope *GotlinCoroutineScope"
	}
	return g.renderGoParamsWithPrefix(function.Params, prefix)
}

func (g *goGenerator) hasCoroutineEffect(function FunctionDecl) bool {
	key := function.Name
	if g.currentClass != nil {
		key = g.currentClass.Name + "." + function.Name
	}
	return g.semantic.FunctionEffects[key].Has(CoroutineEffect)
}

func renderGoTypeParameters(params []string) string {
	if len(params) == 0 {
		return ""
	}
	values := make([]string, len(params))
	for index, param := range params {
		values[index] = param + " any"
	}
	return "[" + strings.Join(values, ", ") + "]"
}

func renderGoTypeArguments(params []string) string {
	if len(params) == 0 {
		return ""
	}
	return "[" + strings.Join(params, ", ") + "]"
}

func (g *goGenerator) renderCallTypeArguments(args []string) string {
	if len(args) == 0 {
		return ""
	}
	values := make([]string, len(args))
	for index, argument := range args {
		values[index] = g.goType(argument)
	}
	return "[" + strings.Join(values, ", ") + "]"
}

func (g *goGenerator) renderGoParamsWithPrefix(params []Param, prefix string) string {
	var b strings.Builder
	b.WriteString("(")
	if prefix != "" {
		b.WriteString(prefix)
		if len(params) > 0 {
			b.WriteString(", ")
		}
	}
	for i, param := range params {
		if i > 0 {
			b.WriteString(", ")
		}
		b.WriteString(param.Name)
		b.WriteString(" ")
		b.WriteString(g.goType(param.Type))
	}
	b.WriteString(")")
	return b.String()
}

func (g *goGenerator) renderGoReturnSuffix(returnType string) string {
	if ret := g.goReturnType(returnType); ret != "" {
		return " " + ret
	}
	return ""
}

func exprUsesPrintln(expr Expr) bool {
	switch e := expr.(type) {
	case CallExpr:
		if isBuiltinPrintln(e.Callee) {
			return true
		}
		for _, arg := range e.Args {
			if exprUsesPrintln(arg) {
				return true
			}
		}
	case UnaryExpr:
		return exprUsesPrintln(e.Value)
	case BinaryExpr:
		return exprUsesPrintln(e.Left) || exprUsesPrintln(e.Right)
	case SelectorExpr:
		return exprUsesPrintln(e.Receiver)
	case MatchExpr:
		if exprUsesPrintln(e.Value) {
			return true
		}
		for _, matchCase := range e.Cases {
			if exprUsesPrintln(matchCase.Value) {
				return true
			}
		}
	case LambdaExpr:
		return usesPrintln(e.Body)
	}
	return false
}

func exprUsesRunCatching(expr Expr) bool {
	switch e := expr.(type) {
	case CallExpr:
		if ident, ok := e.Callee.(IdentExpr); ok && ident.Name == "runCatching" {
			return true
		}
		if exprUsesRunCatching(e.Callee) {
			return true
		}
		for _, arg := range e.Args {
			if exprUsesRunCatching(arg) {
				return true
			}
		}
	case UnaryExpr:
		return exprUsesRunCatching(e.Value)
	case BinaryExpr:
		return exprUsesRunCatching(e.Left) || exprUsesRunCatching(e.Right)
	case SelectorExpr:
		return exprUsesRunCatching(e.Receiver)
	case MatchExpr:
		if exprUsesRunCatching(e.Value) {
			return true
		}
		for _, matchCase := range e.Cases {
			if exprUsesRunCatching(matchCase.Value) {
				return true
			}
		}
	case LambdaExpr:
		return usesRunCatching(e.Body)
	}
	return false
}

func isBuiltinPrintln(expr Expr) bool {
	ident, ok := expr.(IdentExpr)
	return ok && ident.Name == "println"
}

func collectImports(program *Program, needsFmt bool, needsTime bool, runtimeImports map[string]string) []string {
	seen := map[string]bool{}
	runtimePaths := map[string]bool{}
	var imports []string
	usedAliases := usedImportAliases(program)

	if needsFmt {
		seen[`"fmt"`] = true
		imports = append(imports, `"fmt"`)
	}
	if needsTime {
		seen[`"time"`] = true
		imports = append(imports, `"time"`)
	}
	for path, alias := range runtimeImports {
		rendered := alias + ` "` + path + `"`
		seen[rendered] = true
		runtimePaths[path] = true
		imports = append(imports, rendered)
	}
	for _, imp := range program.Imports {
		path := imp.Path
		goPath := path
		if !strings.HasPrefix(path, `"`) {
			goPath = importPathToGoPath(path)
			path = `"` + goPath + `"`
		}
		if runtimePaths[goPath] {
			continue
		}
		rendered := path
		if imp.Alias != "" {
			rendered = imp.Alias + " " + path
		} else if !usedAliases[defaultImportAlias(imp)] {
			rendered = "_ " + path
		}
		if seen[rendered] {
			continue
		}
		seen[rendered] = true
		imports = append(imports, rendered)
	}

	return imports
}

func runtimeImportAlias(program *Program, goPath, fallback string) string {
	for _, imp := range program.Imports {
		path := strings.Trim(imp.Path, `"`)
		if !strings.Contains(path, "/") {
			path = importPathToGoPath(path)
		}
		if path != goPath {
			continue
		}
		if imp.Alias != "" && imp.Alias != "_" {
			return imp.Alias
		}
		parts := strings.Split(goPath, "/")
		return parts[len(parts)-1]
	}
	return fallback
}

func goPackageName(packagePath string) string {
	if packagePath == "" {
		return "main"
	}
	parts := strings.Split(packagePath, ".")
	return parts[len(parts)-1]
}

func usedImportAliases(program *Program) map[string]bool {
	used := map[string]bool{}
	markType := func(typ string) {
		for _, alias := range typeImportAliases(typ) {
			used[alias] = true
		}
	}
	var walkExpr func(expr Expr)
	var walkStmt func(stmt Stmt)
	walkExpr = func(expr Expr) {
		switch e := expr.(type) {
		case IdentExpr:
			used[e.Name] = true
		case UnaryExpr:
			walkExpr(e.Value)
		case NonNullExpr:
			walkExpr(e.Value)
		case TryExpr:
			walkExpr(e.Value)
		case BinaryExpr:
			walkExpr(e.Left)
			walkExpr(e.Right)
		case CallExpr:
			walkExpr(e.Callee)
			for _, arg := range e.Args {
				walkExpr(arg)
			}
			for _, arg := range e.NamedArgs {
				walkExpr(arg.Value)
			}
		case SelectorExpr:
			if alias, ok := selectorRootAlias(e); ok {
				used[alias] = true
			}
			walkExpr(e.Receiver)
		case SafeSelectorExpr:
			walkExpr(e.Receiver)
		case IndexExpr:
			walkExpr(e.Receiver)
			walkExpr(e.Index)
		case EnumVariantExpr:
			for _, value := range e.Values {
				walkExpr(value)
			}
		case MatchExpr:
			walkExpr(e.Value)
			for _, matchCase := range e.Cases {
				walkExpr(matchCase.Value)
			}
		case LambdaExpr:
			for _, param := range e.Params {
				markType(param.Type)
			}
			for _, stmt := range e.Body {
				walkStmt(stmt)
			}
		}
	}
	walkStmt = func(stmt Stmt) {
		switch s := stmt.(type) {
		case VarDecl:
			markType(s.Type)
			walkExpr(s.Value)
		case MultiVarDecl:
			walkExpr(s.Value)
		case AssignStmt:
			walkExpr(s.Value)
		case AddAssignStmt:
			walkExpr(s.Value)
		case MultiAssignStmt:
			walkExpr(s.Value)
		case ReturnStmt:
			if s.Value != nil {
				walkExpr(s.Value)
			}
		case ThrowStmt:
			walkExpr(s.Value)
		case DeferStmt:
			walkExpr(s.Value)
		case ExprStmt:
			walkExpr(s.Value)
		case IfStmt:
			walkExpr(s.Cond)
			for _, inner := range s.Then {
				walkStmt(inner)
			}
			for _, inner := range s.Else {
				walkStmt(inner)
			}
		case WhileStmt:
			walkExpr(s.Cond)
			for _, inner := range s.Body {
				walkStmt(inner)
			}
		case ForEachStmt:
			walkExpr(s.Source)
			for _, inner := range s.Body {
				walkStmt(inner)
			}
		case MatchStmt:
			walkExpr(s.Value)
			for _, c := range s.Cases {
				for _, inner := range c.Body {
					walkStmt(inner)
				}
			}
		case TryCatchStmt:
			for _, inner := range s.TryBody {
				walkStmt(inner)
			}
			for _, inner := range s.CatchBody {
				walkStmt(inner)
			}
		}
	}

	for _, decl := range program.Interfaces {
		for _, method := range decl.Methods {
			for _, param := range method.Params {
				markType(param.Type)
			}
			markType(method.ReturnType)
		}
	}
	for _, decl := range program.Classes {
		for _, field := range decl.Fields {
			markType(field.Type)
		}
		for _, method := range decl.Methods {
			for _, param := range method.Params {
				markType(param.Type)
			}
			markType(method.ReturnType)
			for _, stmt := range method.Body {
				walkStmt(stmt)
			}
		}
	}
	for _, fn := range program.Functions {
		for _, param := range fn.Params {
			markType(param.Type)
		}
		markType(fn.ReturnType)
		for _, stmt := range fn.Body {
			walkStmt(stmt)
		}
	}
	for _, embedded := range program.Embeds {
		markType(embedded.Type)
	}
	return used
}

func selectorRootAlias(expr SelectorExpr) (string, bool) {
	switch r := expr.Receiver.(type) {
	case IdentExpr:
		return r.Name, true
	case SelectorExpr:
		return selectorRootAlias(r)
	default:
		return "", false
	}
}

func typeImportAliases(typ string) []string {
	if typ == "" {
		return nil
	}
	matches := regexp.MustCompile(`([A-Za-z_][A-Za-z0-9_]*)\.`).FindAllStringSubmatch(typ, -1)
	out := make([]string, 0, len(matches))
	for _, m := range matches {
		if len(m) == 2 {
			out = append(out, m[1])
		}
	}
	return out
}

func defaultImportAlias(imp ImportDecl) string {
	if imp.Alias != "" {
		return imp.Alias
	}
	path := imp.Path
	if strings.HasPrefix(path, `"`) {
		path = strings.Trim(path, `"`)
		parts := strings.Split(path, "/")
		return parts[len(parts)-1]
	}
	parts := strings.Split(path, ".")
	return parts[len(parts)-1]
}

func importPathToGoPath(path string) string {
	trimmed := strings.TrimPrefix(path, "go.")
	parts := strings.Split(trimmed, ".")
	if len(parts) >= 3 && isDomainTLD(parts[1]) {
		return parts[0] + "." + parts[1] + "/" + strings.Join(parts[2:], "/")
	}
	return strings.ReplaceAll(trimmed, ".", "/")
}

func isDomainTLD(segment string) bool {
	switch segment {
	case "com", "org", "net", "io", "dev", "app", "ai":
		return true
	default:
		return false
	}
}

func selectorPath(expr Expr) (string, bool) {
	switch e := expr.(type) {
	case IdentExpr:
		return e.Name, true
	case SelectorExpr:
		left, ok := selectorPath(e.Receiver)
		if !ok {
			return "", false
		}
		return left + "." + e.Name, true
	default:
		return "", false
	}
}

func (g *goGenerator) emitRunCatchingSupport() {
	g.line("type gotlinResult struct {")
	g.indentLevel++
	g.line("exception any")
	g.indentLevel--
	g.line("}")
	g.line("")
	g.line("func gotlinRunCatching(fn func()) (result gotlinResult) {")
	g.indentLevel++
	g.line("defer func() {")
	g.indentLevel++
	g.line("if recovered := recover(); recovered != nil {")
	g.indentLevel++
	g.line("result.exception = recovered")
	g.indentLevel--
	g.line("}")
	g.indentLevel--
	g.line("}()")
	g.line("fn()")
	g.line("return")
	g.indentLevel--
	g.line("}")
	g.line("")
	g.line("func (r gotlinResult) isSuccess() bool {")
	g.indentLevel++
	g.line("return r.exception == nil")
	g.indentLevel--
	g.line("}")
	g.line("")
	g.line("func (r gotlinResult) exceptionOrNull() any {")
	g.indentLevel++
	g.line("return r.exception")
	g.indentLevel--
	g.line("}")
}

func (g *goGenerator) emitGoUnwrapSupport() {
	g.line("func gotlinUnwrapGo[T any](value T, rest ...any) T {")
	g.indentLevel++
	g.line("if len(rest) == 1 {")
	g.indentLevel++
	g.line("if rest[0] == nil {")
	g.indentLevel++
	g.line("return value")
	g.indentLevel--
	g.line("}")
	g.line("if err, ok := rest[0].(error); ok {")
	g.indentLevel++
	g.line("if err != nil {")
	g.indentLevel++
	g.line("panic(err)")
	g.indentLevel--
	g.line("}")
	g.line("return value")
	g.indentLevel--
	g.line("}")
	g.indentLevel--
	g.line("}")
	g.line("if len(rest) == 0 {")
	g.indentLevel++
	g.line("if any(value) == nil {")
	g.indentLevel++
	g.line("return value")
	g.indentLevel--
	g.line("}")
	g.line("if err, ok := any(value).(error); ok {")
	g.indentLevel++
	g.line("if err != nil {")
	g.indentLevel++
	g.line("panic(err)")
	g.indentLevel--
	g.line("}")
	g.line("var zero T")
	g.line("return zero")
	g.indentLevel--
	g.line("}")
	g.line("return value")
	g.indentLevel--
	g.line("}")
	g.line(`panic("multi-value Go call requires explicit destructuring unless second value is error")`)
	g.indentLevel--
	g.line("}")
}

func (g *goGenerator) passthroughValue(original Expr, rendered string) string {
	return rendered
}

func parseFunctionType(text string) ([]string, string, bool) {
	text = strings.TrimSpace(text)
	if !strings.HasPrefix(text, "(") {
		return nil, "", false
	}

	depth := 0
	end := -1
	for i, r := range text {
		switch r {
		case '(':
			depth++
		case ')':
			depth--
			if depth == 0 {
				end = i
				goto done
			}
		}
	}

done:
	if end == -1 {
		return nil, "", false
	}
	rest := strings.TrimSpace(text[end+1:])
	if !strings.HasPrefix(rest, "->") {
		return nil, "", false
	}

	paramsText := strings.TrimSpace(text[1:end])
	retText := strings.TrimSpace(strings.TrimPrefix(rest, "->"))
	var params []string
	if paramsText != "" {
		params = splitTopLevel(paramsText, ',')
	}
	return params, retText, true
}

func splitTopLevel(text string, sep rune) []string {
	var parts []string
	depthParen := 0
	depthAngle := 0
	start := 0
	for i, r := range text {
		switch r {
		case '(':
			depthParen++
		case ')':
			depthParen--
		case '<':
			depthAngle++
		case '>':
			if depthAngle > 0 {
				depthAngle--
			}
		default:
			if r == sep && depthParen == 0 && depthAngle == 0 {
				parts = append(parts, strings.TrimSpace(text[start:i]))
				start = i + 1
			}
		}
	}
	parts = append(parts, strings.TrimSpace(text[start:]))
	return parts
}

func parseGenericType(text string) (string, []string, bool) {
	text = strings.TrimSpace(text)
	start := strings.Index(text, "<")
	if start <= 0 || !strings.HasSuffix(text, ">") {
		return "", nil, false
	}

	depth := 0
	end := -1
	for i, r := range text {
		switch r {
		case '<':
			depth++
		case '>':
			depth--
			if depth == 0 {
				end = i
			}
		}
	}
	if end != len(text)-1 || depth != 0 {
		return "", nil, false
	}

	base := strings.TrimSpace(text[:start])
	argsText := strings.TrimSpace(text[start+1 : end])
	if base == "" || argsText == "" {
		return "", nil, false
	}
	return base, splitTopLevel(argsText, ','), true
}

func lambdaHasValueReturn(stmts []Stmt) bool {
	for _, stmt := range stmts {
		switch s := stmt.(type) {
		case ReturnStmt:
			if s.Value != nil {
				return true
			}
		case IfStmt:
			if lambdaHasValueReturn(s.Then) || lambdaHasValueReturn(s.Else) {
				return true
			}
		case WhileStmt:
			if lambdaHasValueReturn(s.Body) {
				return true
			}
		}
	}
	return false
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}