feat: implemented Monochrome downloading

app.py

@@ -259,6 +259,70 @@ def start_download():
     return jsonify({"job_id": job_id})
 
 
+def run_monochrome_download(job_id: str, url: str, quality: str):
+    with jobs_lock:
+        jobs[job_id]["status"] = "running"
+
+    def log(msg):
+        with jobs_lock:
+            jobs[job_id]["output"] = jobs[job_id].get("output", [])[-500:] + [msg]
+
+    def is_cancelled():
+        with jobs_lock:
+            return jobs[job_id]["status"] == "cancelled"
+
+    try:
+        from monochrome.api import download_spotify_url
+        success, total = download_spotify_url(
+            spotify_url=url,
+            quality=quality,
+            output_dir=str(DOWNLOADS_DIR),
+            log=log,
+            cancel_check=is_cancelled,
+        )
+        with jobs_lock:
+            if jobs[job_id]["status"] != "cancelled":
+                jobs[job_id]["status"] = "completed" if success > 0 else "failed"
+                jobs[job_id]["return_code"] = 0 if success > 0 else 1
+    except Exception as e:
+        with jobs_lock:
+            jobs[job_id]["status"] = "failed"
+            jobs[job_id]["output"] = jobs[job_id].get("output", []) + [f"[error] {e}"]
+            jobs[job_id]["return_code"] = 1
+
+
+@app.route("/api/monochrome/download", methods=["POST"])
+def start_monochrome_download():
+    data = request.json
+    url = data.get("url", "").strip()
+    quality = data.get("quality", "HI_RES_LOSSLESS")
+
+    if not url:
+        return jsonify({"error": "No URL provided"}), 400
+
+    valid_qualities = ["HI_RES_LOSSLESS", "LOSSLESS", "HIGH", "LOW", "MP3_320"]
+    if quality not in valid_qualities:
+        return jsonify({"error": f"Invalid quality. Choose from: {valid_qualities}"}), 400
+
+    job_id = str(uuid.uuid4())[:8]
+    with jobs_lock:
+        jobs[job_id] = {
+            "id": job_id,
+            "urls": [url],
+            "options": {"quality": quality, "source": "monochrome"},
+            "status": "queued",
+            "output": [],
+            "created_at": time.time(),
+        }
+
+    thread = threading.Thread(
+        target=run_monochrome_download, args=(job_id, url, quality), daemon=True
+    )
+    thread.start()
+
+    return jsonify({"job_id": job_id})
+
+
 def job_to_dict(job):
     return {k: v for k, v in job.items() if k != "process"}