#!/usr/bin/env python3
"""
magnet_dl.py - 命令行 Magnet/Torrent 下载工具（aria2c 包装）
支持选择性下载种子中的部分文件

用法:
  magnet_dl "magnet:?xt=urn:btih:xxxxx"
  magnet_dl "magnet:?xt=urn:btih:xxxxx" -d ./downloads
  magnet_dl "magnet:?xt=urn:btih:xxxxx" -s 1,3,5
  magnet_dl "magnet:?xt=urn:btih:xxxxx" --list
  magnet_dl file.torrent -s 1-3,5
"""
import subprocess, sys, os, argparse, tempfile, glob, re

ARIA2C = os.path.join(os.path.dirname(os.path.abspath(__file__)), "aria2c.exe")
if not os.path.exists(ARIA2C):
    ARIA2C = "aria2c"

TRACKERS = ",".join([
    "udp://tracker.opentrackr.org:1337/announce",
    "udp://open.stealth.si:80/announce",
    "udp://tracker.torrent.eu.org:451/announce",
    "udp://public.popcorn-tracker.org:6969/announce",
    "udp://tracker.dler.org:6969/announce",
    "udp://exodus.desync.com:6969/announce",
    "udp://open.demonii.com:1337/announce",
    "udp://tracker.openbittorrent.com:6969/announce",
    "udp://tracker.moeking.me:6969/announce",
    "udp://tracker.bittor.pw:1337/announce",
    "udp://opentracker.i2p.rocks:6969/announce",
    "udp://tracker.tiny-vps.com:6969/announce",
    "udp://p4p.arenabg.com:1337/announce",
    "http://tracker.openbittorrent.com:80/announce",
    "https://opentracker.i2p.rocks:443/announce",
])

COMMON_ARGS = [
    "--enable-dht=true",
    "--enable-peer-exchange=true",
    "--dht-listen-port=6881",
    "--listen-port=6881",
    "--bt-enable-lpd=true",
    "--seed-time=0",
    "--max-connection-per-server=16",
    "--split=16",
    "--min-split-size=1M",
    "--bt-max-peers=100",
    "--bt-request-peer-speed-limit=10M",
    f"--bt-tracker={TRACKERS}",
    "--dht-entry-point=router.bittorrent.com:6881",
    "--dht-entry-point=router.utorrent.com:6881",
    "--dht-entry-point=dht.transmissionbt.com:6881",
    "--summary-interval=5",
    "--file-allocation=falloc",
    "--check-integrity=true",
    "--bt-remove-unselected-file=true",
]

def is_magnet(s):
    return s.startswith("magnet:")

def get_torrent_from_magnet(magnet, tmpdir):
    print("[*] 获取元数据中 (加载了15个tracker + DHT)...")
    cmd = [ARIA2C, "--bt-metadata-only=true", "--bt-save-metadata=true",
           f"--dir={tmpdir}", *COMMON_ARGS, magnet]
    try:
        subprocess.run(cmd, timeout=120)
    except subprocess.TimeoutExpired:
        print("[!] 元数据获取超时(120s)")
    except KeyboardInterrupt:
        print("[!] 用户中断")
    torrents = glob.glob(os.path.join(tmpdir, "*.torrent"))
    return torrents[0] if torrents else None

def show_files(torrent_path):
    r = subprocess.run([ARIA2C, "--show-files", torrent_path], capture_output=True, text=True, encoding='utf-8', errors='replace')
    print(r.stdout)
    return r.stdout

def parse_selection(s, max_n):
    sel = set()
    for part in s.split(','):
        part = part.strip()
        if not part: continue
        if '-' in part:
            a, b = part.split('-', 1)
            sel.update(range(int(a), int(b) + 1))
        else:
            sel.add(int(part))
    return sorted(x for x in sel if 1 <= x <= max_n)

def download(target, save_path, select=None):
    cmd = [ARIA2C, f"--dir={save_path}", *COMMON_ARGS]
    if select:
        cmd.append(f"--select-file={','.join(str(x) for x in select)}")
    cmd.append(target)
    print(f"\n[*] 下载到: {save_path}")
    if select: print(f"[*] 已选文件: {select}")
    print("=" * 60)
    try:
        subprocess.run(cmd)
    except KeyboardInterrupt:
        print("\n[!] 用户中断")

def main():
    ap = argparse.ArgumentParser(description='命令行 Magnet/Torrent 下载 (aria2c)')
    ap.add_argument('target', help='Magnet 链接或 .torrent 文件')
    ap.add_argument('-d', '--dir', default='.', help='下载目录 (默认.)')
    ap.add_argument('-s', '--select', default='', help='文件编号: 1,3,5 或 1-3,5')
    ap.add_argument('--list', action='store_true', help='仅列出文件')
    ap.add_argument('-i', '--interactive', action='store_true', help='交互选择文件')
    args = ap.parse_args()

    save_path = os.path.abspath(args.dir)
    os.makedirs(save_path, exist_ok=True)
    target = args.target

    # magnet + 需要文件信息 → 先获取元数据
    if is_magnet(target) and (args.list or args.interactive or args.select):
        tmpdir = tempfile.mkdtemp(prefix="magnet_dl_")
        torrent = get_torrent_from_magnet(target, tmpdir)
        if not torrent:
            print("[!] 无法获取元数据" + ("" if args.list else "，尝试直接下载..."))
            if not args.list: download(target, save_path)
            return
        print(f"[OK] 元数据: {torrent}")
        target = torrent

    if args.list or args.interactive:
        output = show_files(target)
        if args.list: return
        indices = re.findall(r'^\s*(\d+)\|', output, re.MULTILINE)
        max_n = max(int(x) for x in indices) if indices else 0
        if max_n > 0:
            print("输入编号 (1-3,5,7)  回车=全部  q=退出")
            try:
                c = input("> ").strip()
            except (EOFError, KeyboardInterrupt):
                return
            if c.lower() == 'q': return
            if c:
                download(target, save_path, parse_selection(c, max_n))
                return
        download(target, save_path)
        return

    if args.select:
        download(target, save_path, parse_selection(args.select, 9999))
    elif is_magnet(target):
        download(target, save_path)
    else:
        download(target, save_path)

if __name__ == '__main__':
    main()