Add i18n support with French as first translation

README.md

@@ -50,9 +50,45 @@ Anything [yt-dlp supports](https://github.com/yt-dlp/yt-dlp/blob/master/supporte
 
 YouTube, TikTok, Instagram, Twitter/X, Reddit, Facebook, Vimeo, Twitch, Dailymotion, SoundCloud, Loom, Streamable, Pinterest, Tumblr, Threads, LinkedIn, and many more.
 
+## Internationalisation (i18n)
+
+All user-facing strings are externalised into JSON files under `translations/`.
+
+| File | Language |
+|------|----------|
+| `translations/en.json` | English (default) |
+| `translations/fr.json` | French |
+
+**How it works**
+
+The active language is resolved in this order:
+1. `RECLIP_LANG` environment variable (e.g. `RECLIP_LANG=fr`)
+2. The browser's `Accept-Language` header (first locale whose file exists)
+3. Fallback: `en`
+
+The server loads the matching JSON file, merges it on top of the English base (so missing keys always fall back to English), and injects the full strings object into the page as `window.i18n`. All HTML strings use Jinja2 `{{ t('key') }}` and all JavaScript strings use `i18n['key']`.
+
+**Adding a new language**
+
+1. Copy `translations/en.json` to `translations/<lang_code>.json` (e.g. `translations/de.json`).
+2. Translate all the values — keep the keys unchanged.
+3. Set `RECLIP_LANG=de` (or rely on the browser header) — no code changes needed.
+
+**Setting the default language**
+
+```bash
+RECLIP_LANG=fr ./reclip.sh
+```
+
+Or in Docker:
+
+```bash
+docker run -e RECLIP_LANG=fr -p 8899:8899 reclip
+```
+
 ## Stack
 
-- **Backend:** Python + Flask (~150 lines)
+- **Backend:** Python + Flask (~170 lines)
 - **Frontend:** Vanilla HTML/CSS/JS (single file, no build step)
 - **Download engine:** [yt-dlp](https://github.com/yt-dlp/yt-dlp) + [ffmpeg](https://ffmpeg.org/)
 - **Dependencies:** 2 (Flask, yt-dlp)

app.py

@@ -6,14 +6,16 @@
 import threading
 from flask import Flask, request, jsonify, send_file, render_template
 
+from i18n import detect_lang, get_translator
+
 app = Flask(__name__)
 DOWNLOAD_DIR = os.path.join(os.path.dirname(__file__), "downloads")
 os.makedirs(DOWNLOAD_DIR, exist_ok=True)
 
 jobs = {}
 
 
-def run_download(job_id, url, format_choice, format_id):
+def run_download(job_id, url, format_choice, format_id, t):
     job = jobs[job_id]
     out_template = os.path.join(DOWNLOAD_DIR, f"{job_id}.%(ext)s")
 
@@ -38,7 +40,7 @@ def run_download(job_id, url, format_choice, format_id):
         files = glob.glob(os.path.join(DOWNLOAD_DIR, f"{job_id}.*"))
         if not files:
             job["status"] = "error"
-            job["error"] = "Download completed but no file was found"
+            job["error"] = t("error.file_not_found")
             return
 
         if format_choice == "audio":
@@ -67,23 +69,28 @@ def run_download(job_id, url, format_choice, format_id):
             job["filename"] = os.path.basename(chosen)
     except subprocess.TimeoutExpired:
         job["status"] = "error"
-        job["error"] = "Download timed out (5 min limit)"
+        job["error"] = t("error.download_timeout")
     except Exception as e:
         job["status"] = "error"
         job["error"] = str(e)
 
 
 @app.route("/")
 def index():
-    return render_template("index.html")
+    lang = detect_lang(request.headers.get("Accept-Language", ""))
+    t, strings = get_translator(lang)
+    return render_template("index.html", t=t, strings=strings, lang=lang)
 
 
 @app.route("/api/info", methods=["POST"])
 def get_info():
+    lang = detect_lang(request.headers.get("Accept-Language", ""))
+    t, _ = get_translator(lang)
+
     data = request.json
     url = data.get("url", "").strip()
     if not url:
-        return jsonify({"error": "No URL provided"}), 400
+        return jsonify({"error": t("error.no_url")}), 400
 
     cmd = ["yt-dlp", "--no-playlist", "-j", url]
     try:
@@ -119,26 +126,29 @@ def get_info():
             "formats": formats,
         })
     except subprocess.TimeoutExpired:
-        return jsonify({"error": "Timed out fetching video info"}), 400
+        return jsonify({"error": t("error.info_timeout")}), 400
     except Exception as e:
         return jsonify({"error": str(e)}), 400
 
 
 @app.route("/api/download", methods=["POST"])
 def start_download():
+    lang = detect_lang(request.headers.get("Accept-Language", ""))
+    t, _ = get_translator(lang)
+
     data = request.json
     url = data.get("url", "").strip()
     format_choice = data.get("format", "video")
     format_id = data.get("format_id")
     title = data.get("title", "")
 
     if not url:
-        return jsonify({"error": "No URL provided"}), 400
+        return jsonify({"error": t("error.no_url")}), 400
 
     job_id = uuid.uuid4().hex[:10]
     jobs[job_id] = {"status": "downloading", "url": url, "title": title}
 
-    thread = threading.Thread(target=run_download, args=(job_id, url, format_choice, format_id))
+    thread = threading.Thread(target=run_download, args=(job_id, url, format_choice, format_id, t))
     thread.daemon = True
     thread.start()
 
@@ -147,9 +157,12 @@ def start_download():
 
 @app.route("/api/status/<job_id>")
 def check_status(job_id):
+    lang = detect_lang(request.headers.get("Accept-Language", ""))
+    t, _ = get_translator(lang)
+
     job = jobs.get(job_id)
     if not job:
-        return jsonify({"error": "Job not found"}), 404
+        return jsonify({"error": t("error.job_not_found")}), 404
     return jsonify({
         "status": job["status"],
         "error": job.get("error"),
@@ -159,9 +172,12 @@ def check_status(job_id):
 
 @app.route("/api/file/<job_id>")
 def download_file(job_id):
+    lang = detect_lang(request.headers.get("Accept-Language", ""))
+    t, _ = get_translator(lang)
+
     job = jobs.get(job_id)
     if not job or job["status"] != "done":
-        return jsonify({"error": "File not ready"}), 404
+        return jsonify({"error": t("error.file_not_ready")}), 404
     return send_file(job["file"], as_attachment=True, download_name=job["filename"])
 
 

i18n.py

@@ -0,0 +1,71 @@
+"""
+Lightweight i18n module for ReClip.
+
+Language resolution order:
+  1. RECLIP_LANG environment variable  (e.g. RECLIP_LANG=fr)
+  2. Accept-Language HTTP header       (first locale whose .json file exists)
+  3. Default: "en"
+
+To add a new language:
+  - Copy translations/en.json to translations/<lang_code>.json
+  - Translate the values (keep the keys unchanged)
+  - That's it — no code changes required.
+"""
+
+import json
+import os
+from pathlib import Path
+
+TRANSLATIONS_DIR = Path(__file__).parent / "translations"
+DEFAULT_LANG = "en"
+
+_cache: dict = {}
+
+
+def _load(lang: str) -> dict:
+    """Load and cache a translation file. Returns {} if not found."""
+    if lang in _cache:
+        return _cache[lang]
+    path = TRANSLATIONS_DIR / f"{lang}.json"
+    if not path.exists():
+        return {}
+    with open(path, encoding="utf-8") as fh:
+        _cache[lang] = json.load(fh)
+    return _cache[lang]
+
+
+def detect_lang(accept_language: str = "") -> str:
+    """
+    Return the best supported language code.
+
+    Checks RECLIP_LANG env var first, then the Accept-Language header,
+    then falls back to DEFAULT_LANG.
+    """
+    forced = os.environ.get("RECLIP_LANG", "").strip().lower()
+    if forced and (TRANSLATIONS_DIR / f"{forced}.json").exists():
+        return forced
+
+    for token in accept_language.split(","):
+        lang = token.split(";")[0].strip().split("-")[0].lower()
+        if lang and (TRANSLATIONS_DIR / f"{lang}.json").exists():
+            return lang
+
+    return DEFAULT_LANG
+
+
+def get_translator(lang: str):
+    """
+    Return (t, strings) for the given language.
+
+    - t(key) returns the translated string; falls back to English,
+      then to the key itself if still not found.
+    - strings is the complete merged dict exposed as window.i18n in JS.
+    """
+    base = _load(DEFAULT_LANG)
+    overlay = _load(lang) if lang != DEFAULT_LANG else {}
+    strings = {**base, **overlay}
+
+    def t(key: str) -> str:
+        return strings.get(key, key)
+
+    return t, strings