init

internal/platform/id.go

@@ -0,0 +1,25 @@
+package platform
+
+import (
+	"crypto/rand"
+	"encoding/hex"
+	"fmt"
+)
+
+func NewID() (string, error) {
+	buf := make([]byte, 16)
+	if _, err := rand.Read(buf); err != nil {
+		return "", fmt.Errorf("read random id bytes: %w", err)
+	}
+
+	return hex.EncodeToString(buf), nil
+}
+
+func NewToken() (string, error) {
+	buf := make([]byte, 32)
+	if _, err := rand.Read(buf); err != nil {
+		return "", fmt.Errorf("read random token bytes: %w", err)
+	}
+
+	return hex.EncodeToString(buf), nil
+}

internal/platform/money.go

@@ -0,0 +1,79 @@
+package platform
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+func FormatCZK(amountMinor int64) string {
+	sign := ""
+	if amountMinor < 0 {
+		sign = "-"
+		amountMinor = -amountMinor
+	}
+
+	whole := amountMinor / 100
+	fraction := amountMinor % 100
+
+	return fmt.Sprintf("%s%s,%02d CZK", sign, formatThousands(whole), fraction)
+}
+
+func ParseCZK(input string) (int64, error) {
+	clean := strings.TrimSpace(strings.ReplaceAll(input, " ", ""))
+	clean = strings.ReplaceAll(clean, ",", ".")
+	if clean == "" {
+		return 0, fmt.Errorf("amount is required")
+	}
+
+	parts := strings.Split(clean, ".")
+	if len(parts) > 2 {
+		return 0, fmt.Errorf("invalid amount")
+	}
+
+	whole, err := strconv.ParseInt(parts[0], 10, 64)
+	if err != nil {
+		return 0, fmt.Errorf("invalid whole amount")
+	}
+
+	var fraction int64
+	if len(parts) == 2 {
+		frac := parts[1]
+		if len(frac) > 2 {
+			return 0, fmt.Errorf("too many decimal places")
+		}
+		if len(frac) == 1 {
+			frac += "0"
+		}
+		if len(frac) == 0 {
+			frac = "00"
+		}
+
+		fraction, err = strconv.ParseInt(frac, 10, 64)
+		if err != nil {
+			return 0, fmt.Errorf("invalid decimal amount")
+		}
+	}
+
+	if whole < 0 || fraction < 0 {
+		return 0, fmt.Errorf("amount must be positive")
+	}
+
+	return whole*100 + fraction, nil
+}
+
+func formatThousands(value int64) string {
+	plain := strconv.FormatInt(value, 10)
+	if len(plain) <= 3 {
+		return plain
+	}
+
+	var parts []string
+	for len(plain) > 3 {
+		parts = append([]string{plain[len(plain)-3:]}, parts...)
+		plain = plain[:len(plain)-3]
+	}
+	parts = append([]string{plain}, parts...)
+
+	return strings.Join(parts, " ")
+}

internal/platform/money_test.go

@@ -0,0 +1,31 @@
+package platform
+
+import "testing"
+
+func TestParseCZK(t *testing.T) {
+	tests := []struct {
+		input string
+		want  int64
+	}{
+		{input: "100", want: 10000},
+		{input: "100.50", want: 10050},
+		{input: "100,5", want: 10050},
+	}
+
+	for _, tt := range tests {
+		got, err := ParseCZK(tt.input)
+		if err != nil {
+			t.Fatalf("ParseCZK(%q) returned error: %v", tt.input, err)
+		}
+		if got != tt.want {
+			t.Fatalf("ParseCZK(%q) = %d, want %d", tt.input, got, tt.want)
+		}
+	}
+}
+
+func TestFormatCZK(t *testing.T) {
+	got := FormatCZK(1234567)
+	if got != "12 345,67 CZK" {
+		t.Fatalf("FormatCZK() = %q", got)
+	}
+}