#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# vim:fenc=utf-8 et ts=4 sts=4 sw=4
#
# Copyright © 2022 Maxime “pep” Buquet <pep@bouah.net>
#
# This file is licensed under AGPL-3.0-or-later

"""
    AESGCM URIs downloader
"""

import sys
import asyncio
from io import BytesIO
from pathlib import Path

from aiohttp import ClientSession
from slixmpp.version import __version__ as slixmpp_version
from slixmpp.plugins.xep_0454 import XEP_0454


class InvalidURI(Exception):
    """Raised when an invalid aesgcm URI is specified"""

    def __init__(self, url) -> None:
        self.url = url


async def handle_file(uri: str) -> None:
    """Downloads, decrypts, and writes specified URI"""

    try:
        aesurl, fragment = uri.rsplit('#', 1)
    except ValueError as exn:
        raise InvalidURI(uri) from exn

    url = aesurl.replace('aesgcm://', 'https://')
    filename = Path(url.rsplit('/', 1)[1])

    async with ClientSession(headers={'User-Agent': 'slixmpp ' + slixmpp_version}) as session:
        async with session.get(url) as response:
            print(f'Got response for {url}')
            input_file = BytesIO(await response.read())

    with filename.open('wb') as file:
        print(f'Writing to {filename}')
        file.write(XEP_0454.decrypt(input_file, fragment))


if __name__ == '__main__':
    if len(sys.argv) != 2:
        print('usage: aesgcm-dl <URI>', file=sys.stderr)
        sys.exit(1)

    try:
        asyncio.run(handle_file(sys.argv[1]))
    except InvalidURI as exn:
        print(f'Invalid aesgcm URI: {exn.url}', file=sys.stderr)
        sys.exit(2)