import uuid
import asyncio
from pathlib import Path
from typing import Any

import httpx
from fastapi import APIRouter, Depends, HTTPException, Query, Request, status
from fastapi.responses import Response
from fastapi.security.utils import get_authorization_scheme_param
from sqlalchemy.ext.asyncio import AsyncSession

from rehearsalhub.db.engine import get_session
from rehearsalhub.db.models import Member
from rehearsalhub.dependencies import get_current_member
from rehearsalhub.repositories.audio_version import AudioVersionRepository
from rehearsalhub.repositories.member import MemberRepository
from rehearsalhub.repositories.song import SongRepository
from rehearsalhub.schemas.audio_version import AudioVersionCreate, AudioVersionRead
from rehearsalhub.services.auth import decode_token
from rehearsalhub.services.band import BandService
from rehearsalhub.services.song import SongService
from rehearsalhub.storage.nextcloud import NextcloudClient

router = APIRouter(tags=["versions"])

_AUDIO_CONTENT_TYPES: dict[str, str] = {
    ".mp3": "audio/mpeg",
    ".wav": "audio/wav",
    ".flac": "audio/flac",
    ".ogg": "audio/ogg",
    ".m4a": "audio/mp4",
    ".aac": "audio/aac",
    ".opus": "audio/ogg",
    ".m3u8": "application/vnd.apple.mpegurl",
}


async def _download_with_retry(storage: NextcloudClient, file_path: str, max_retries: int = 3) -> bytes:
    """Download file from Nextcloud with retry logic for transient errors."""
    last_error = None
    
    for attempt in range(max_retries):
        try:
            data = await storage.download(file_path)
            return data
        except httpx.ConnectError as e:
            last_error = e
            if attempt < max_retries - 1:
                # Exponential backoff: 1s, 2s, 4s
                wait_time = 2 ** attempt
                await asyncio.sleep(wait_time)
            continue
        except httpx.HTTPStatusError as e:
            # Don't retry on 4xx errors (client errors)
            if e.response.status_code >= 500:
                last_error = e
                if attempt < max_retries - 1:
                    wait_time = 2 ** attempt
                    await asyncio.sleep(wait_time)
                continue
            else:
                raise
        except Exception as e:
            last_error = e
            break
    
    # If we exhausted retries, raise the last error
    if last_error:
        raise last_error
    else:
        raise HTTPException(
            status_code=status.HTTP_503_SERVICE_UNAVAILABLE,
            detail="Failed to download file from storage"
        )


async def _member_from_request(
    request: Request,
    token: str | None = Query(None),
    session: AsyncSession = Depends(get_session),
) -> Member:
    """Resolve member from Authorization header, ?token= query param, or httpOnly cookie.

    The cookie fallback allows fetch()-based callers (which send credentials:include)
    to use the same endpoint as EventSource callers (which must use ?token=).
    """
    auth_header = request.headers.get("Authorization")
    if auth_header:
        scheme, param = get_authorization_scheme_param(auth_header)
        if scheme.lower() == "bearer":
            token = param
    if not token:
        token = request.cookies.get("rh_token")
    if not token:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Token required")
    try:
        payload = decode_token(token)
        member_id = uuid.UUID(payload["sub"])
    except Exception:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid token")
    member = await MemberRepository(session).get_by_id(member_id)
    if member is None:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Member not found")
    return member


async def _get_version_and_assert_band_membership(
    version_id: uuid.UUID,
    session: AsyncSession,
    current_member: Member,
) -> tuple:
    version_repo = AudioVersionRepository(session)
    version = await version_repo.get_by_id(version_id)
    if version is None:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Version not found")

    song_repo = SongRepository(session)
    song = await song_repo.get_by_id(version.song_id)
    if song is None:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Song not found")

    band_svc = BandService(session)
    try:
        await band_svc.assert_membership(song.band_id, current_member.id)
    except PermissionError:
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Not a member")

    return version, song


@router.get("/songs/{song_id}/versions", response_model=list[AudioVersionRead])
async def list_versions(
    song_id: uuid.UUID,
    session: AsyncSession = Depends(get_session),
    current_member: Member = Depends(get_current_member),
):
    song_repo = SongRepository(session)
    song = await song_repo.get_by_id(song_id)
    if song is None:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Song not found")

    band_svc = BandService(session)
    try:
        await band_svc.assert_membership(song.band_id, current_member.id)
    except PermissionError:
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Not a member")

    version_repo = AudioVersionRepository(session)
    return [AudioVersionRead.model_validate(v) for v in await version_repo.list_for_song(song_id)]


@router.post(
    "/songs/{song_id}/versions",
    response_model=AudioVersionRead,
    status_code=status.HTTP_201_CREATED,
)
async def create_version(
    song_id: uuid.UUID,
    data: AudioVersionCreate,
    session: AsyncSession = Depends(get_session),
    current_member: Member = Depends(get_current_member),
):
    song_repo = SongRepository(session)
    song = await song_repo.get_by_id(song_id)
    if song is None:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Song not found")

    band_svc = BandService(session)
    try:
        await band_svc.assert_membership(song.band_id, current_member.id)
    except PermissionError:
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Not a member")

    storage = NextcloudClient.for_member(current_member)
    song_svc = SongService(session, storage=storage)
    version = await song_svc.register_version(song_id, data, current_member.id)
    return AudioVersionRead.model_validate(version)


@router.get("/versions/{version_id}/waveform")
async def get_waveform(
    version_id: uuid.UUID,
    session: AsyncSession = Depends(get_session),
    current_member: Member = Depends(get_current_member),
) -> Any:
    version, _ = await _get_version_and_assert_band_membership(version_id, session, current_member)
    if not version.waveform_url:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Waveform not ready")
    
    storage = NextcloudClient.for_member(current_member)
    if storage is None:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="No storage provider configured for this account"
        )
    try:
        data = await _download_with_retry(storage, version.waveform_url)
    except httpx.ConnectError:
        raise HTTPException(
            status_code=status.HTTP_503_SERVICE_UNAVAILABLE,
            detail="Storage service unavailable."
        )
    except httpx.HTTPStatusError as e:
        if e.response.status_code == 404:
            raise HTTPException(
                status_code=status.HTTP_404_NOT_FOUND,
                detail="Waveform file not found in storage."
            )
        else:
            raise HTTPException(
                status_code=status.HTTP_502_BAD_GATEWAY,
                detail="Storage returned an error."
            )
    except Exception:
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail="Failed to fetch waveform."
        )
    import json

    return json.loads(data)


@router.get("/versions/{version_id}/stream")
async def stream_version(
    version_id: uuid.UUID,
    session: AsyncSession = Depends(get_session),
    current_member: Member = Depends(_member_from_request),
):
    version, song = await _get_version_and_assert_band_membership(version_id, session, current_member)
    role = await BandRepository(session).get_member_role(song.band_id, current_member.id)

    # Debug logging for permission issues
    import logging
    log = logging.getLogger(__name__)
    log.info(f"User {current_member.id} accessing version {version_id}")
    log.info(f"Song band: {song.band_id}")
    log.info(f"User role in band: {role if role else 'NOT A MEMBER'}")

    # Prefer HLS playlist if transcoding finished, otherwise serve the raw file
    if version.cdn_hls_base:
        file_path = f"{version.cdn_hls_base}/playlist.m3u8"
    elif version.nc_file_path:
        file_path = version.nc_file_path
    else:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="No audio file")

    storage = NextcloudClient.for_member(current_member)
    if storage is None:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="No storage provider configured for this account"
        )
    try:
        data = await _download_with_retry(storage, file_path)
    except httpx.ConnectError:
        raise HTTPException(
            status_code=status.HTTP_503_SERVICE_UNAVAILABLE,
            detail="Storage service unavailable."
        )
    except httpx.HTTPStatusError as e:
        if e.response.status_code == 404:
            raise HTTPException(
                status_code=status.HTTP_404_NOT_FOUND,
                detail="File not found in storage."
            )
        else:
            raise HTTPException(
                status_code=status.HTTP_502_BAD_GATEWAY,
                detail="Storage returned an error."
            )
    except Exception:
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail="Failed to stream file."
        )
    
    content_type = _AUDIO_CONTENT_TYPES.get(Path(file_path).suffix.lower(), "application/octet-stream")
    return Response(content=data, media_type=content_type)