feat: site languages, setup and site URL settings

internal/domain/site/sitePublicURLPattern.go

@@ -0,0 +1,117 @@
+package site
+
+import (
+	"net/url"
+	"strings"
+	"unicode/utf8"
+)
+
+const (
+	MaxPublicURLPatternRunes = 512
+
+	LangPlaceholder = "{lang}"
+	SlugPlaceholder = "{slug}"
+
+	placeholderFiller = "x"
+	allowedURLSymbols = "-._~:/?#[]@!$&'()*+,;=%"
+)
+
+func NormalizePublicURLPattern(pattern *string) (*string, error) {
+	if pattern == nil {
+		return nil, nil
+	}
+	trimmed := strings.TrimSpace(*pattern)
+	if trimmed == "" {
+		return nil, nil
+	}
+	if utf8.RuneCountInString(trimmed) > MaxPublicURLPatternRunes {
+		return nil, ErrInvalidPublicURLPattern
+	}
+	if err := checkPublicURLScheme(trimmed); err != nil {
+		return nil, err
+	}
+	if err := checkPlaceholders(trimmed); err != nil {
+		return nil, err
+	}
+	filled := fillPlaceholders(trimmed)
+	if err := checkEncoding(filled); err != nil {
+		return nil, err
+	}
+	if !strings.Contains(trimmed, SlugPlaceholder) {
+		return nil, ErrPublicURLMissingSlug
+	}
+	if err := checkPublicURLHost(filled); err != nil {
+		return nil, err
+	}
+	return &trimmed, nil
+}
+
+func checkPublicURLScheme(pattern string) error {
+	lowered := strings.ToLower(pattern)
+	if !strings.HasPrefix(lowered, "https://") && !strings.HasPrefix(lowered, "http://") {
+		return ErrPublicURLScheme
+	}
+	return nil
+}
+
+func checkPlaceholders(pattern string) error {
+	remaining := pattern
+	for {
+		open := strings.IndexAny(remaining, "{}")
+		if open < 0 {
+			return nil
+		}
+		if remaining[open] == '}' {
+			return ErrPublicURLPlaceholder
+		}
+		rest := remaining[open:]
+		switch {
+		case strings.HasPrefix(rest, LangPlaceholder):
+			remaining = rest[len(LangPlaceholder):]
+		case strings.HasPrefix(rest, SlugPlaceholder):
+			remaining = rest[len(SlugPlaceholder):]
+		default:
+			return ErrPublicURLPlaceholder
+		}
+	}
+}
+
+func fillPlaceholders(pattern string) string {
+	return strings.NewReplacer(LangPlaceholder, placeholderFiller, SlugPlaceholder, placeholderFiller).Replace(pattern)
+}
+
+func checkEncoding(filled string) error {
+	for index := 0; index < len(filled); index++ {
+		character := filled[index]
+		if character == '%' {
+			if index+2 >= len(filled) || !isHex(filled[index+1]) || !isHex(filled[index+2]) {
+				return ErrPublicURLNotEncoded
+			}
+			index += 2
+			continue
+		}
+		if !isAllowedURLByte(character) {
+			return ErrPublicURLNotEncoded
+		}
+	}
+	return nil
+}
+
+func isHex(character byte) bool {
+	return character >= '0' && character <= '9' || character >= 'a' && character <= 'f' || character >= 'A' && character <= 'F'
+}
+
+func isAllowedURLByte(character byte) bool {
+	if character >= '0' && character <= '9' || character >= 'a' && character <= 'z' || character >= 'A' && character <= 'Z' {
+		return true
+	}
+	return strings.IndexByte(allowedURLSymbols, character) >= 0
+}
+
+func checkPublicURLHost(filled string) error {
+	parsed, err := url.Parse(filled)
+	if err != nil || parsed.Hostname() == "" {
+		return ErrPublicURLHost
+	}
+	return nil
+}