#!/usr/bin/env python3
# coding:utf-8

"""delarte.

Retrieve video stream in a local file, including sub-titles

Licence: GNU AGPL v3: http://www.gnu.org/licenses/

This file is part of [`delarte`](https://git.afpy.org/fcode/delarte)
"""


import json
import sys
import re
import io
import subprocess

from http import HTTPStatus
from os import environ
from typing import cast
from urllib.parse import urlparse
from urllib.request import urlopen

import m3u8
import webvtt

FFMPEG = environ.get("PATH_FFMPEG", "ffmpeg path not found")


def call_api(api_url):
    """Retrieve subtitles versions available for a given URL."""
    http_response = urlopen(api_url)

    if http_response.status != HTTPStatus.OK:
        raise RuntimeError("API request failed")

    config = json.load(http_response)["data"]["attributes"]

    title = config["metadata"]["title"]

    versions = {
        s["versions"][0]["eStat"]["ml5"]: (s["url"], s["versions"][0]["label"])
        for s in config["streams"]
    }

    return (title, versions)


def write_subtitles(m3u8_url, base_name):
    """Convert distant vtt subtitles to local srt."""
    main = m3u8.load(m3u8_url)

    sub_m3u8_urls = [
        (m.base_uri + "/" + m.uri, m.language)
        for m in main.media
        if m.type == "SUBTITLES"
    ]

    for sub_m3u8_url, sub_lang in sub_m3u8_urls:

        sub_m3u8 = m3u8.load(sub_m3u8_url)
        sub_urls = [cast(str, sub_m3u8.base_uri) + "/" + f for f in sub_m3u8.files]

        if not sub_urls:
            raise ValueError("No subtitle files")

        if len(sub_urls) > 1:
            raise ValueError("Multiple subtitle files")

        http_response = urlopen(sub_urls[0])
        if http_response.status != HTTPStatus.OK:
            raise RuntimeError("Subtitle request failed")

        buffer = io.StringIO(http_response.read().decode("utf8"))

        with open(f"{base_name}.{sub_lang}.srt", "w", encoding="utf8") as f:
            for i, caption in enumerate(webvtt.read_buffer(buffer), 1):
                print(i, file=f)
                print(
                    re.sub(r"\.", ",", caption.start)
                    + " --> "
                    + re.sub(r"\.", ",", caption.end),
                    file=f,
                )
                print(caption.text + "\n", file=f)
            return f.name


# command line arguments
(UI_LANG, _, STREAM_ID, SLUG) = urlparse(sys.argv[1]).path[1:-1].split("/")
VERSION = " ".join(sys.argv[2:])

if UI_LANG not in ("fr", "de", "en", "es", "pl", "it") or _ != "videos":
    raise ValueError("Invalid URL")

TITLE, VERSIONS = call_api(
    f"https://api.arte.tv/api/player/v2/config/{UI_LANG}/{STREAM_ID}"
)

FILENAME = TITLE.replace("/", "-")

if VERSION not in VERSIONS:
    print(TITLE)
    for v, (_, l) in VERSIONS.items():
        print(f"\t{v} : {l}")
    exit(1)

M3U8_URL, VERSION_NAME = VERSIONS[VERSION]

write_subtitles(M3U8_URL, FILENAME)

subprocess.run(
    [FFMPEG, "-i", M3U8_URL, "-c", "copy", "-bsf:a", "aac_adtstoasc", f"{FILENAME}.mp4"]
)