"""A sidecar subtitle in a legacy code page must render its accents, not U+FFFD.

Found live on Arrow S03E15 (a Hungarian .srt beside the .mp4): the served WebVTT held 1391 U+FFFD and
not one accented letter, because `_sidecar_vtt` decoded the bytes as UTF-8 with `errors="replace"`
while the file was Windows-1250 (ő = 0xF5, ű = 0xFB). Legacy-code-page .srt files are the norm for
Hungarian releases, and SubRip carries no charset of its own, so the stream's language is the only hint.
No Postgres: Plex and ffmpeg are stubbed.
"""

from pathlib import Path
from typing import cast

import pytest
from sqlalchemy.orm import Session

from app.plex import subtitles

HU = "1\r\n00:00:01,000 --> 00:00:02,000\r\nMiért nem szóltál? Ősz, űr.\r\n"
FR = "1\r\n00:00:01,000 --> 00:00:02,000\r\nDéjà vu, garçon.\r\n"
RU = "1\r\n00:00:01,000 --> 00:00:02,000\r\nПривет, мир.\r\n"


class _Plex:
    def __init__(self, raw: bytes):
        self.raw = raw

    def __enter__(self):
        return self

    def __exit__(self, *exc):
        return False

    def raw_get(self, key: str) -> bytes:
        return self.raw


def _sidecar(monkeypatch, raw: bytes, lang: str | None, codec: str = "srt") -> str:
    monkeypatch.setattr(subtitles, "PlexClient", lambda db: _Plex(raw))
    stream = {"key": "/library/streams/1", "codec": codec, "languageCode": lang}
    return subtitles._sidecar_vtt(cast(Session, None), stream)


@pytest.mark.parametrize(
    ("text", "encoding", "lang"),
    [
        (HU, "cp1250", "hun"),  # the file that was found broken
        (FR, "cp1252", "fre"),  # a Western legacy file
        (RU, "cp1251", "rus"),  # a Cyrillic one
        (HU, "utf-8", "hun"),  # already UTF-8: untouched
        (HU, "utf-8-sig", "hun"),  # UTF-8 with a BOM
        (HU, "utf-16", "hun"),  # UTF-16 (carries its BOM)
    ],
    ids=["cp1250-hu", "cp1252-fr", "cp1251-ru", "utf8", "utf8-bom", "utf16"],
)
def test_a_sidecar_srt_is_decoded_in_its_own_encoding(monkeypatch, text, encoding, lang):
    vtt = _sidecar(monkeypatch, text.encode(encoding), lang)
    assert "\ufffd" not in vtt
    assert vtt.startswith("WEBVTT\n\n")
    assert text.splitlines()[2] in vtt


def test_a_non_srt_sidecar_reaches_ffmpeg_as_utf8(monkeypatch):
    seen: dict[str, bytes] = {}

    def fake_ffmpeg(src: str, sub_ord):
        seen["bytes"] = Path(src).read_bytes()
        return "WEBVTT\n"

    monkeypatch.setattr(subtitles, "ffmpeg_to_vtt", fake_ffmpeg)
    _sidecar(monkeypatch, "[Events]\nDialogue: Ősz\n".encode("cp1250"), "hun", codec="ass")
    assert seen["bytes"].decode("utf-8") == "[Events]\nDialogue: Ősz\n"


def test_a_track_cached_before_the_encoding_fix_is_not_served(tmp_path, monkeypatch):
    """The cache has no eviction, so a mis-decoded track would have stayed broken for good: the key
    is versioned, and a track cached under the old one is read again (once) instead of served."""
    monkeypatch.setattr(subtitles, "CACHE_DIR", tmp_path)
    (tmp_path / "sub_14881_1.vtt").write_text(
        "WEBVTT\n\n1\n00:00:01.000 --> 00:00:02.000\nAz�rt\n", "utf-8"
    )
    assert subtitles.cached_track("14881", 1)[0] is None