import os
import json
import uuid
import re
import unicodedata
import subprocess
from urllib.parse import urlparse, parse_qs, urlencode, urlunparse

from flask import Flask, request, jsonify, render_template, session, send_from_directory
from werkzeug.exceptions import BadRequest
from yt_dlp import YoutubeDL, DownloadError
from dotenv import load_dotenv

load_dotenv()

FLASK_SECRET_KEY = os.getenv('FLASK_SECRET_KEY', 'default_secret_key')
OUTPUT_FOLDER = os.path.join(os.path.expanduser("~"), "Desktop", "myUniqSong")
os.makedirs(OUTPUT_FOLDER, exist_ok=True)
USER_DATA_FILE = 'users.json'

app = Flask(__name__)
app.secret_key = FLASK_SECRET_KEY

def load_users():
    if os.path.isfile(USER_DATA_FILE):
        with open(USER_DATA_FILE, 'r', encoding='utf-8') as f:
            return json.load(f)
    return {}

def save_users(data):
    with open(USER_DATA_FILE, 'w', encoding='utf-8') as f:
        json.dump(data, f, indent=2, ensure_ascii=False)

def sanitize_title(title):
    title = unicodedata.normalize('NFC', title.strip())
    title = re.sub(r'[\\/:"*?<>|]', '_', title)
    title = re.sub(r'\s+', '_', title)
    title = re.sub(r'_+', '_', title)
    return title.strip('_')

def clean_youtube_url(url):
    parsed = urlparse(url)
    qs = parse_qs(parsed.query)
    v = qs.get('v')
    if v:
        new_qs = {'v': v[0]}
        cleaned = urlunparse((
            parsed.scheme if parsed.scheme else 'https',
            parsed.netloc,
            parsed.path,
            parsed.params,
            urlencode(new_qs),
            parsed.fragment
        ))
        return cleaned
    return url

def download_youtube_audio(url, quality='192'):
    ydl_opts = {
        'format': 'bestaudio/best',
        'postprocessors': [{
            'key': 'FFmpegExtractAudio',
            'preferredcodec': 'mp3',
            'preferredquality': quality,
        }],
        'outtmpl': os.path.join(OUTPUT_FOLDER, '%(title)s.%(ext)s'),
        'quiet': True,
        'noplaylist': True,
    }
    with YoutubeDL(ydl_opts) as ydl:
        info = ydl.extract_info(url, download=True)

    raw_title = info.get('title', 'audio')
    title = sanitize_title(raw_title)

    if 'requested_downloads' in info and info['requested_downloads']:
        for download in info['requested_downloads']:
            filepath = download.get('filepath')
            if filepath and filepath.lower().endswith('.mp3') and os.path.exists(filepath):
                return filepath, title

    mp3_files = [f for f in os.listdir(OUTPUT_FOLDER) if f.lower().endswith('.mp3')]
    cleaned_title = title.lower().replace('_', '').replace(' ', '')
    for f in mp3_files:
        cleaned_f = f.lower().replace('_', '').replace(' ', '')
        if cleaned_title in cleaned_f:
            return os.path.join(OUTPUT_FOLDER, f), title

    raise FileNotFoundError(f"MP3 file not found after download: {os.path.join(OUTPUT_FOLDER, title + '.mp3')}")

def convert_to_m4a(mp3_path):
    m4a_path = mp3_path.rsplit('.', 1)[0] + '.m4a'
    subprocess.run(['ffmpeg', '-y', '-i', mp3_path, '-c:a', 'aac', m4a_path], check=True)
    return m4a_path

def download_tiktok_audio(url, quality='192'):
    # TikTok video audio download, similar options to YouTube audio
    ydl_opts = {
        'format': 'bestaudio/best',
        'postprocessors': [{
            'key': 'FFmpegExtractAudio',
            'preferredcodec': 'mp3',
            'preferredquality': quality,
        }],
        'outtmpl': os.path.join(OUTPUT_FOLDER, '%(title)s.%(ext)s'),
        'quiet': True,
        'noplaylist': True,
        # To avoid common TikTok issues
        'merge_output_format': 'mp4',
        'nocheckcertificate': True,
    }
    with YoutubeDL(ydl_opts) as ydl:
        info = ydl.extract_info(url, download=True)

    raw_title = info.get('title', 'tiktok_audio')
    title = sanitize_title(raw_title)

    if 'requested_downloads' in info and info['requested_downloads']:
        for download in info['requested_downloads']:
            filepath = download.get('filepath')
            if filepath and filepath.lower().endswith('.mp3') and os.path.exists(filepath):
                return filepath, title

    mp3_files = [f for f in os.listdir(OUTPUT_FOLDER) if f.lower().endswith('.mp3')]
    cleaned_title = title.lower().replace('_', '').replace(' ', '')
    for f in mp3_files:
        cleaned_f = f.lower().replace('_', '').replace(' ', '')
        if cleaned_title in cleaned_f:
            return os.path.join(OUTPUT_FOLDER, f), title

    raise FileNotFoundError(f"TikTok MP3 file not found after download: {os.path.join(OUTPUT_FOLDER, title + '.mp3')}")

users = load_users()

@app.route('/')
def home():
    return render_template('index.html')

@app.route('/service', methods=['POST'])
def run_service():
    try:
        if not request.is_json:
            raise BadRequest("請用 JSON 格式送出請求")

        data = request.get_json()
        url = data.get('input', '').strip()

        if not url:
            raise BadRequest("❌ 請輸入影片連結")

        # Determine platform and clean URL if needed
        if "youtube.com" in url or "youtu.be" in url:
            url = clean_youtube_url(url)
            platform = "youtube"
        elif "tiktok.com" in url:
            platform = "tiktok"
        else:
            raise BadRequest("目前只支援 YouTube 和 TikTok 影片連結！")

        fmt = data.get('format', 'mp3')
        quality = data.get('quality', '192')

        if fmt not in ['mp3', 'm4a']:
            raise BadRequest("不支援的格式，僅支援 mp3 與 m4a")

        user_id = session.setdefault('user_id', str(uuid.uuid4()))
        user = users.get(user_id, {"usage": 0})

        links = {}

        if platform == "youtube":
            mp3_path, title = download_youtube_audio(url, quality)
        else:  # tiktok
            mp3_path, title = download_tiktok_audio(url, quality)

        if fmt == 'mp3':
            links['mp3'] = f"/download/{os.path.basename(mp3_path)}"
        elif fmt == 'm4a':
            m4a_path = convert_to_m4a(mp3_path)
            links['m4a'] = f"/download/{os.path.basename(m4a_path)}"

        user["usage"] += 1
        users[user_id] = user
        save_users(users)

        return jsonify({'status': 'success', 'message': f"{title} 已完成！", 'download_links': links})

    except DownloadError as e:
        app.logger.error(f"DownloadError: {e}")
        return jsonify({'status': 'error', 'message': f"下載錯誤: {str(e)}"}), 400
    except BadRequest as e:
        app.logger.warning(f"BadRequest: {e}")
        return jsonify({'status': 'error', 'message': str(e)}), 400
    except Exception as e:
        app.logger.error(f"Exception: {e}", exc_info=True)
        return jsonify({'status': 'error', 'message': f"伺服器發生錯誤: {str(e)}"}), 500

@app.route('/download/<filename>')
def download_file(filename):
    path = os.path.join(OUTPUT_FOLDER, filename)
    if os.path.isfile(path):
        return send_from_directory(OUTPUT_FOLDER, filename, as_attachment=True)
    return jsonify({'status': 'error', 'message': '找不到檔案'}), 404

if __name__ == '__main__':
    import logging
    logging.basicConfig(level=logging.INFO,
                        format='%(asctime)s - %(levelname)s - %(message)s')
    port = int(os.getenv('PORT', 5000))
    app.logger.info(f"Flask app running on port {port}, saving files to {OUTPUT_FOLDER}")
    app.run(host='0.0.0.0', port=port, debug=False)