package app

import (
	"context"
	"database/sql"
	"fmt"
	"net/url"
	"strings"
)

func (a *App) ensureProjectDatabase(ctx context.Context, p *Project) error {
	if !a.cfg.DBProvisionEnabled {
		return nil
	}
	adminDB, err := sql.Open("pgx", a.cfg.DBProvisionAdminURL)
	if err != nil {
		return fmt.Errorf("db provisioning connect failed: %w", err)
	}
	defer adminDB.Close()
	if err := adminDB.PingContext(ctx); err != nil {
		return fmt.Errorf("db provisioning ping failed: %w", err)
	}

	if p.DBName == "" {
		p.DBName = fmt.Sprintf("app_%d", p.ID)
	}
	if p.DBUser == "" {
		p.DBUser = fmt.Sprintf("appu_%d", p.ID)
	}
	if p.DBPassword == "" {
		pw, err := newDeployToken()
		if err != nil {
			return err
		}
		p.DBPassword = pw
	}

	if _, err := adminDB.ExecContext(ctx, fmt.Sprintf(`DO $$
BEGIN
	IF NOT EXISTS (SELECT 1 FROM pg_roles WHERE rolname = %s) THEN
		CREATE ROLE %s LOGIN PASSWORD %s;
	ELSE
		ALTER ROLE %s LOGIN PASSWORD %s;
	END IF;
END $$;`, sqlQuoteLiteral(p.DBUser), sqlQuoteIdent(p.DBUser), sqlQuoteLiteral(p.DBPassword), sqlQuoteIdent(p.DBUser), sqlQuoteLiteral(p.DBPassword))); err != nil {
		return fmt.Errorf("create/alter role failed: %w", err)
	}

	var dbExists bool
	if err := adminDB.QueryRowContext(ctx, `SELECT EXISTS (SELECT 1 FROM pg_database WHERE datname = $1)`, p.DBName).Scan(&dbExists); err != nil {
		return fmt.Errorf("check database existence failed: %w", err)
	}
	if !dbExists {
		if _, err := adminDB.ExecContext(ctx, fmt.Sprintf(`CREATE DATABASE %s OWNER %s TEMPLATE template0`, sqlQuoteIdent(p.DBName), sqlQuoteIdent(p.DBUser))); err != nil {
			return fmt.Errorf("create database failed: %w", err)
		}
	}

	if _, err := a.db.ExecContext(ctx, `UPDATE projects SET db_name=$1, db_user=$2, db_password=$3 WHERE id=$4`, p.DBName, p.DBUser, p.DBPassword, p.ID); err != nil {
		return fmt.Errorf("persist db credentials failed: %w", err)
	}
	return nil
}

func (a *App) dropProjectDatabase(ctx context.Context, p Project) error {
	if !a.cfg.DBProvisionEnabled {
		return nil
	}
	if strings.TrimSpace(p.DBName) == "" || strings.TrimSpace(p.DBUser) == "" {
		return nil
	}
	adminDB, err := sql.Open("pgx", a.cfg.DBProvisionAdminURL)
	if err != nil {
		return fmt.Errorf("db provisioning connect failed: %w", err)
	}
	defer adminDB.Close()
	if err := adminDB.PingContext(ctx); err != nil {
		return fmt.Errorf("db provisioning ping failed: %w", err)
	}
	// Terminate active sessions so DROP DATABASE succeeds.
	_, _ = adminDB.ExecContext(ctx, `SELECT pg_terminate_backend(pid) FROM pg_stat_activity WHERE datname = $1 AND pid <> pg_backend_pid()`, p.DBName)
	if _, err := adminDB.ExecContext(ctx, fmt.Sprintf(`DROP DATABASE IF EXISTS %s`, sqlQuoteIdent(p.DBName))); err != nil {
		return fmt.Errorf("drop database failed: %w", err)
	}
	if _, err := adminDB.ExecContext(ctx, fmt.Sprintf(`DROP ROLE IF EXISTS %s`, sqlQuoteIdent(p.DBUser))); err != nil {
		return fmt.Errorf("drop role failed: %w", err)
	}
	return nil
}

func (a *App) projectDatabaseURL(p Project) (string, error) {
	if p.DBName == "" || p.DBUser == "" || p.DBPassword == "" {
		return "", nil
	}
	base, err := url.Parse(a.cfg.DBProvisionAdminURL)
	if err != nil {
		return "", err
	}
	base.User = url.UserPassword(p.DBUser, p.DBPassword)
	base.Path = "/" + p.DBName
	return base.String(), nil
}

func sqlQuoteIdent(s string) string {
	return `"` + strings.ReplaceAll(s, `"`, `""`) + `"`
}

func sqlQuoteLiteral(s string) string {
	return `'` + strings.ReplaceAll(s, `'`, `''`) + `'`
}