如何使用telethon在电报中更快地下载大文件？

import os
import asyncio
from telethon import TelegramClient
from telethon.tl.types import InputFileLocation
from telethon.tl.functions.upload import GetFileRequest

# 替换为你的 API ID 和 API Hash
api_id = 'YOUR_API_ID'
api_hash = 'YOUR_API_HASH'
phone_number = 'YOUR_PHONE_NUMBER'

# 替换为你要下载的文件的消息 ID 和对话 ID
chat_id = 'CHAT_ID'
message_id = 'MESSAGE_ID'

# 替换为你要保存的文件路径
output_file = 'output_file.dat'

# 每个块的大小（字节）
chunk_size = 1024 * 1024  # 1 MB

async def download_chunk(client, location, offset, limit):
    result = await client(GetFileRequest(location, offset=offset, limit=limit))
    return result.bytes

async def download_file(client, location, file_size, output_file):
    tasks = []
    with open(output_file, 'wb') as f:
        for offset in range(0, file_size, chunk_size):
            limit = min(chunk_size, file_size - offset)
            tasks.append(download_chunk(client, location, offset, limit))
        
        for task in asyncio.as_completed(tasks):
            chunk = await task
            f.write(chunk)

async def main():
    client = TelegramClient('session_name', api_id, api_hash)
    await client.start(phone_number)

    # 获取消息
    message = await client.get_messages(chat_id, ids=message_id)
    if not message or not message.media:
        print("Message or media not found")
        return

    # 获取文件位置和大小
    file_location = message.media.document
    file_size = message.media.document.size

    # 下载文件
    await download_file(client, file_location, file_size, output_file)
    print(f"File downloaded to {output_file}")

    await client.disconnect()

if __name__ == '__main__':
    asyncio.run(main())