"""
HEVC video is transcoded to H264 for streaming, never copied — unlike the
codecs media_probe.py's BROWSER_INCOMPATIBLE_VIDEO_CODECS excludes.

Found live: a real HEVC/EAC3 WEB-DL streamed fine over MNP (ffprobe/VLC play
it) but the browser reported "Codec not supported for streaming:
hev1.1.6.L93.B0,mp4a.40.2" from MediaSource.isTypeSupported — Chrome has no
HEVC decoder on most non-Apple platforms. "-c:v copy" on an incompatible
codec is not a mux failure the way EAC3 audio is (test_stream_audio_
transcode.py); ffmpeg happily remuxes it, and the browser is the one that
then refuses it, silently, at playback rather than at stream_init.

These tests spawn real ffmpeg/ffprobe against small synthetic files (lavfi
test sources, ~1s), the same style as test_stream_audio_transcode.py.
"""

import shutil
import subprocess
from pathlib import Path

import pytest
from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey

from meshbay_common.crypto import generate_gek
from meshbay_common.webcrypto import chunk_key_aes, decrypt_chunk_aes
from meshbay_node.indexer.group_index import GroupIndex
from meshbay_node.transport.webrtc_server import WebRTCPeerSession, _probe_video

from conftest import needs_subprocess, one_root

_HAVE_FFMPEG = shutil.which("ffmpeg") and shutil.which("ffprobe")
_HAVE_HEVC_ENCODER = _HAVE_FFMPEG and b"libx265" in subprocess.run(
    ["ffmpeg", "-hide_banner", "-encoders"], capture_output=True).stdout
pytestmark = [
    pytest.mark.asyncio,
    pytest.mark.skipif(not _HAVE_HEVC_ENCODER, reason="ffmpeg/libx265 not installed"),
    needs_subprocess,
]


def _make_hevc_clip(path: Path) -> None:
    """~1s of HEVC video + AAC audio — a minimal stand-in for a real HEVC WEB-DL."""
    subprocess.run(
        ["ffmpeg", "-hide_banner", "-loglevel", "error", "-y",
         "-f", "lavfi", "-i", "testsrc=size=320x240:rate=25:duration=1",
         "-f", "lavfi", "-i", "sine=frequency=440:duration=1:sample_rate=48000",
         "-c:v", "libx265", "-preset", "ultrafast", "-c:a", "aac",
         str(path)],
        check=True, capture_output=True,
    )


def _session(video_path: Path, gek: bytes, *, transcode_incompatible_video: bool = True):
    import blake3
    file_bytes = video_path.read_bytes()
    file_id = blake3.blake3(file_bytes).hexdigest()

    sk_node = Ed25519PrivateKey.generate()
    index = GroupIndex(group_id="g" * 32, sk_node=sk_node, gek=gek)
    from meshbay_common.protocol import IndexEntry
    index.add_entry(IndexEntry(
        id=file_id, name=video_path.name, path=video_path.parent.name,
        size=len(file_bytes), type="video", added_at=0))

    session = WebRTCPeerSession.__new__(WebRTCPeerSession)
    session._ctx = {
        "roots": one_root(video_path.parent),
        "index": index,
        "gek": gek,
        "sk_node": sk_node,
        "max_concurrent_streams": 4,
        "transcode_incompatible_video": transcode_incompatible_video,
    }
    session._group_id = None
    session._user_id = "tester"
    session._stream_stopped = False
    session._stream_keepalives = 0
    session.sent = []
    session._send = session.sent.append
    session._audit = lambda *a, **k: None
    return session, file_id


def _reassemble(sent: list[dict], gek: bytes, file_id: str) -> bytes:
    file_hash = bytes.fromhex(file_id)
    segments = sorted(
        (m for m in sent if m.get("type") == "stream_data"),
        key=lambda m: m["segment_index"])
    out = b""
    for m in segments:
        key = chunk_key_aes(gek, file_hash, m["segment_index"])
        out += decrypt_chunk_aes(key, m["nonce"], m["ct"])
    return out


def _output_video_codec(path: Path) -> str:
    probe = subprocess.run(
        ["ffprobe", "-v", "error", "-select_streams", "v:0",
         "-show_entries", "stream=codec_name", "-of", "csv=p=0", str(path)],
        check=True, capture_output=True, text=True)
    return probe.stdout.strip()


async def test_hevc_video_is_transcoded_to_h264_by_default(tmp_path):
    clip = tmp_path / "clip.mkv"
    _make_hevc_clip(clip)
    gek = generate_gek()
    session, file_id = _session(clip, gek)

    await session._stream_video_inner({"file_id": file_id, "start": 0, "credits": 0})

    errors = [m for m in session.sent if m.get("type") == "error"]
    assert not errors, f"streaming must not fail: {errors}"

    init = next(m for m in session.sent if m.get("type") == "stream_init")
    assert init["codec"].startswith("avc1."), (
        "the reported codec must be the transcoded H264 string, never the "
        f"source's hev1 string a browser cannot decode: {init['codec']}")

    remuxed = _reassemble(session.sent, gek, file_id)
    out_path = tmp_path / "out.mp4"
    out_path.write_bytes(remuxed)
    assert _output_video_codec(out_path) == "h264", \
        "the bytes on the wire must actually be H264, not just the reported label"


async def test_hevc_transcode_can_be_disabled_by_the_operator(tmp_path):
    clip = tmp_path / "clip.mkv"
    _make_hevc_clip(clip)
    gek = generate_gek()
    session, file_id = _session(clip, gek, transcode_incompatible_video=False)

    await session._stream_video_inner({"file_id": file_id, "start": 0, "credits": 0})

    assert not [m for m in session.sent if m.get("type") == "error"]
    init = next(m for m in session.sent if m.get("type") == "stream_init")
    assert init["codec"].startswith("hev1."), (
        "with the fallback disabled, the source is copied as-is and the "
        f"original HEVC codec string must be reported unchanged: {init['codec']}")

    remuxed = _reassemble(session.sent, gek, file_id)
    out_path = tmp_path / "out.mp4"
    out_path.write_bytes(remuxed)
    assert _output_video_codec(out_path) == "hevc", \
        "with the fallback disabled, the wire bytes must still be copied HEVC"


async def test_probe_video_reports_raw_codec_name_for_hevc(tmp_path):
    clip = tmp_path / "clip.mkv"
    _make_hevc_clip(clip)

    codec, duration, has_audio, width, height, raw_codec = await _probe_video(str(clip))

    assert raw_codec == "hevc"
    assert codec is not None and codec.startswith("hev1.")