Add fakes library: recursive JSON template engine, i18n locales, Docker workflow

locale.go

@@ -0,0 +1,66 @@
+package fakes
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"regexp"
+	"sort"
+	"strings"
+)
+
+// loadLocale parses and compiles every JSON file in dir into a category node
+// tree, keyed by the file's base name without extension (address.json ->
+// "address"). Compiling here means structural errors surface at New, not at
+// Fake time.
+func loadLocale(dir string) (map[string]node, error) {
+	info, err := os.Stat(dir)
+	if err != nil {
+		return nil, err
+	}
+	if !info.IsDir() {
+		return nil, fmt.Errorf("%s is not a directory", dir)
+	}
+	files, err := filepath.Glob(filepath.Join(dir, "*.json"))
+	if err != nil {
+		return nil, err
+	}
+	sort.Strings(files)
+	if len(files) == 0 {
+		return nil, fmt.Errorf("no .json files in %s", dir)
+	}
+	categories := make(map[string]node, len(files))
+	for _, file := range files {
+		b, err := os.ReadFile(file)
+		if err != nil {
+			return nil, err
+		}
+		var raw any
+		if err := json.Unmarshal(b, &raw); err != nil {
+			return nil, fmt.Errorf("%s: %w", filepath.Base(file), err)
+		}
+		n, err := compile(raw)
+		if err != nil {
+			return nil, fmt.Errorf("%s: %w", filepath.Base(file), err)
+		}
+		categories[strings.TrimSuffix(filepath.Base(file), ".json")] = n
+	}
+	return categories, nil
+}
+
+var localeTag = regexp.MustCompile(`^[a-z]{2,3}_[A-Z]{2}$`)
+
+// canonicalLocale normalises a tag to "lang_REGION" form, accepting '-' or '_'
+// separators and any casing. It reports whether the result is a full tag.
+func canonicalLocale(s string) (string, bool) {
+	parts := strings.Split(strings.ReplaceAll(strings.TrimSpace(s), "-", "_"), "_")
+	if len(parts) != 2 {
+		return "", false
+	}
+	tag := strings.ToLower(parts[0]) + "_" + strings.ToUpper(parts[1])
+	if !localeTag.MatchString(tag) {
+		return "", false
+	}
+	return tag, true
+}