app.py

import streamlit as st
import aria2p  # 改用更稳定的 aria2p 库
import time
import threading
import os
from pathlib import Path

# Aria2 配置
ARIA2_RPC_HOST = "http://localhost"
ARIA2_RPC_PORT = 6800
ARIA2_SECRET = "SECRET_KEY"

# 初始化 aria2 连接
def init_aria2():
    try:
        # 自动启动 aria2 后台进程
        if not os.popen("pgrep aria2c").read():
            download_dir = os.path.abspath("./downloads")
            os.makedirs(download_dir, exist_ok=True)
            
            cmd = [
                "aria2c",
                "--enable-rpc",
                f"--rpc-listen-port={ARIA2_RPC_PORT}",
                f"--rpc-secret={ARIA2_SECRET}",
                f"--dir={download_dir}",
                "--daemon=true",
                "--max-concurrent-downloads=5",
                "--split=16",
                "--max-connection-per-server=16",
                "--file-allocation=prealloc"
            ]
            threading.Thread(target=lambda: os.system(" ".join(cmd))).start()
            time.sleep(2)
        
        # 初始化 API 客户端
        return aria2p.Client(
            host=ARIA2_RPC_HOST,
            port=ARIA2_RPC_PORT,
            secret=ARIA2_SECRET
        )
    except Exception as e:
        st.error(f"初始化失败: {str(e)}")
        raise

# Session 状态初始化
if 'aria_client' not in st.session_state:
    st.session_state.aria_client = init_aria2()
if 'aria_api' not in st.session_state:
    st.session_state.aria_api = aria2p.API(st.session_state.aria_client)
if 'download_progress' not in st.session_state:
    st.session_state.download_progress = 0
if 'downloading' not in st.session_state:
    st.session_state.downloading = False
if 'download_complete' not in st.session_state:
    st.session_state.download_complete = False
if 'download_filename' not in st.session_state:
    st.session_state.download_filename = None
if 'error_message' not in st.session_state:
    st.session_state.error_message = None

def download_torrent(magnet_link):
    try:
        # 添加下载任务
        download = st.session_state.aria_api.add_magnet(
            magnet_link,
            options={
                "max-download-limit": "0",
                "seed-time": "0",
                "bt-detach-seed-only": "true"
            }
        )
        
        st.session_state.error_message = None
        st.session_state.downloading = True
        
        # 进度监控
        while download.is_active:
            download.update()
            st.session_state.download_progress = download.progress * 100
            
            # 自动刷新间隔
            time.sleep(1)
            
        if download.is_complete:
            st.session_state.download_complete = True
            st.session_state.download_filename = download.files[0].path
        else:
            raise Exception(download.error_message)

    except Exception as e:
        st.session_state.error_message = f"下载失败: {str(e)}"
    finally:
        st.session_state.downloading = False


# 界面布局
st.title("磁力链接下载器 🧲 (Aria2版)")

with st.form("magnet_form"):
    magnet_link = st.text_input("输入磁力链接：", placeholder="magnet:?xt=urn:btih:...")
    submitted = st.form_submit_button("开始下载")

    if submitted and magnet_link:
        if st.session_state.downloading:
            st.warning("当前已有下载任务在进行中")
        else:
            # 重置状态
            st.session_state.download_progress = 0
            st.session_state.download_complete = False
            st.session_state.download_filename = None
            st.session_state.error_message = None
            st.session_state.downloading = True
            start_download_thread(magnet_link)

if st.session_state.downloading:
    st.info("下载状态")
    progress_col, control_col = st.columns([4, 1])
    
    with progress_col:
        progress_bar = st.progress(int(st.session_state.download_progress))
        st.write(f"当前进度：{st.session_state.download_progress:.1f}%")
    
    with control_col:
        if st.button("取消下载"):
            st.session_state.downloading = False
            st.session_state.download_complete = False
            st.session_state.error_message = "下载已取消"
            st.experimental_rerun()

if st.session_state.error_message:
    st.error(st.session_state.error_message)

if st.session_state.download_complete:
    st.success("下载完成！✅")
    if st.session_state.download_filename and Path(st.session_state.download_filename).exists():
        file_path = Path(st.session_state.download_filename)
        file_size = file_path.stat().st_size
        st.write(f"文件大小：{file_size/1024/1024:.2f} MB")
        
        with open(file_path, "rb") as f:
            st.download_button(
                label="下载文件",
                data=f,
                file_name=file_path.name,
                mime="application/octet-stream"
            )
    else:
        st.error("文件不存在，可能下载失败")

# 注意事项
st.markdown("---")
st.info("""
**使用说明：**
1. 确保已安装 aria2：`brew install aria2` (macOS) 或 `sudo apt install aria2` (Linux)
2. 首次运行会自动启动 aria2 后台服务
3. 下载文件将保存到当前目录的 downloads 文件夹
""")