[client] UI refactor (#6069)

Refactor UI

---------

Co-authored-by: Eduard Gert <kontakt@eduardgert.de>
Co-authored-by: braginini <bangvalo@gmail.com>
Co-authored-by: Pascal Fischer <32096965+pascal-fischer@users.noreply.github.com>
Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: riccardom <riccardomanfrin@gmail.com>

client/ui/i18n/bundle.go

@@ -0,0 +1,196 @@
+//go:build !android && !ios && !freebsd && !js
+
+// Package i18n loads and serves translation strings for both the tray (Go)
+// and the React UI (via the services.I18n facade).
+//
+// The locale tree is passed in as an fs.FS so the embed directive can live in
+// the main binary.
+package i18n
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io/fs"
+	"path"
+	"sort"
+	"strings"
+	"sync"
+
+	log "github.com/sirupsen/logrus"
+)
+
+const (
+	localeIndexFile = "_index.json"
+
+	// commonBundleFile shape is Chrome-extension JSON (key -> "message" plus
+	// optional Crowdin "description"); loadBundle flattens to key->message.
+	commonBundleFile = "common.json"
+)
+
+// LanguageCode is a BCP-47-ish locale identifier ("en", "hu", ...).
+type LanguageCode string
+
+// DefaultLanguage is the fallback bundle for missing keys and the default
+// when no preference is on disk.
+const DefaultLanguage LanguageCode = "en"
+
+var ErrUnsupportedLanguage = errors.New("unsupported language")
+
+// Language describes one shipped UI locale. DisplayName is in the locale's
+// own script (a Hungarian entry reads "Magyar" regardless of UI language).
+type Language struct {
+	Code        LanguageCode `json:"code"`
+	DisplayName string       `json:"displayName"`
+	EnglishName string       `json:"englishName"`
+}
+
+type localeIndex struct {
+	Languages []Language `json:"languages"`
+}
+
+// Bundle holds the parsed translation bundles. Loaded once at construction
+// and never mutated.
+type Bundle struct {
+	mu        sync.RWMutex
+	languages []Language
+	bundles   map[LanguageCode]map[string]string
+}
+
+// NewBundle parses _index.json plus every <code>/common.json in the locale
+// tree. Hard-fails only when the default language is missing; other locales
+// without a bundle are dropped with a warning.
+func NewBundle(localesFS fs.FS) (*Bundle, error) {
+	idx, err := loadLocaleIndex(localesFS)
+	if err != nil {
+		return nil, fmt.Errorf("load locale index: %w", err)
+	}
+
+	bundles := make(map[LanguageCode]map[string]string, len(idx.Languages))
+	available := make([]Language, 0, len(idx.Languages))
+	for _, l := range idx.Languages {
+		b, err := loadBundle(localesFS, l.Code)
+		if err != nil {
+			log.Warnf("skip language %q: %v", l.Code, err)
+			continue
+		}
+		bundles[l.Code] = b
+		available = append(available, l)
+	}
+
+	if _, ok := bundles[DefaultLanguage]; !ok {
+		return nil, fmt.Errorf("default language %q bundle missing", DefaultLanguage)
+	}
+
+	sort.Slice(available, func(i, j int) bool { return available[i].Code < available[j].Code })
+
+	return &Bundle{
+		languages: available,
+		bundles:   bundles,
+	}, nil
+}
+
+// Languages returns a copy of the available locales.
+func (b *Bundle) Languages() []Language {
+	b.mu.RLock()
+	defer b.mu.RUnlock()
+	out := make([]Language, len(b.languages))
+	copy(out, b.languages)
+	return out
+}
+
+func (b *Bundle) HasLanguage(code LanguageCode) bool {
+	b.mu.RLock()
+	defer b.mu.RUnlock()
+	_, ok := b.bundles[code]
+	return ok
+}
+
+// BundleFor returns a copy of the full key->text map for one language.
+func (b *Bundle) BundleFor(code LanguageCode) (map[string]string, error) {
+	b.mu.RLock()
+	defer b.mu.RUnlock()
+
+	bundle, ok := b.bundles[code]
+	if !ok {
+		return nil, fmt.Errorf("%w: %q", ErrUnsupportedLanguage, code)
+	}
+	out := make(map[string]string, len(bundle))
+	for k, v := range bundle {
+		out[k] = v
+	}
+	return out, nil
+}
+
+// Translate resolves key for lang, substituting args given as name/value
+// pairs ("version", "1.2.3" replaces "{version}"). Unknown keys fall back to
+// the default language, then to the key itself so a miss is visible in the UI.
+func (b *Bundle) Translate(lang LanguageCode, key string, args ...string) string {
+	b.mu.RLock()
+	defer b.mu.RUnlock()
+
+	if v, ok := b.bundles[lang][key]; ok {
+		return applyPlaceholders(v, args)
+	}
+	if lang != DefaultLanguage {
+		if v, ok := b.bundles[DefaultLanguage][key]; ok {
+			return applyPlaceholders(v, args)
+		}
+	}
+	return key
+}
+
+// applyPlaceholders substitutes {name} in s using args as flat name/value
+// pairs. An odd-length args drops the trailing item.
+func applyPlaceholders(s string, args []string) string {
+	if len(args) == 0 {
+		return s
+	}
+	if len(args)%2 != 0 {
+		log.Debugf("i18n placeholder args not paired: %d items, last dropped", len(args))
+		args = args[:len(args)-1]
+	}
+	for j := 0; j < len(args); j += 2 {
+		s = strings.ReplaceAll(s, "{"+args[j]+"}", args[j+1])
+	}
+	return s
+}
+
+func loadLocaleIndex(localesFS fs.FS) (*localeIndex, error) {
+	data, err := fs.ReadFile(localesFS, localeIndexFile)
+	if err != nil {
+		return nil, err
+	}
+	var idx localeIndex
+	if err := json.Unmarshal(data, &idx); err != nil {
+		return nil, fmt.Errorf("parse %s: %w", localeIndexFile, err)
+	}
+	if len(idx.Languages) == 0 {
+		return nil, errors.New("no languages declared")
+	}
+	return &idx, nil
+}
+
+// bundleEntry is one translation key on disk; Description is Crowdin context,
+// ignored at runtime.
+type bundleEntry struct {
+	Message     string `json:"message"`
+	Description string `json:"description,omitempty"`
+}
+
+func loadBundle(localesFS fs.FS, code LanguageCode) (map[string]string, error) {
+	p := path.Join(string(code), commonBundleFile)
+	data, err := fs.ReadFile(localesFS, p)
+	if err != nil {
+		return nil, err
+	}
+	var entries map[string]bundleEntry
+	if err := json.Unmarshal(data, &entries); err != nil {
+		return nil, fmt.Errorf("parse %s: %w", p, err)
+	}
+	bundle := make(map[string]string, len(entries))
+	for k, e := range entries {
+		bundle[k] = e.Message
+	}
+	return bundle, nil
+}