enigFM/backend/app/routers/tracks.py

import uuid
from urllib.parse import quote
from fastapi import APIRouter, Depends, HTTPException, status, UploadFile, File, Form, Request
from fastapi.responses import StreamingResponse
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select, func
from mutagen.mp3 import MP3
from io import BytesIO
from ..database import get_db
from ..models.user import User
from ..models.track import Track
from ..schemas.track import TrackResponse, TrackWithUrl
from ..services.auth import get_current_user
from ..services.s3 import upload_file, delete_file, generate_presigned_url, can_upload_file, get_file_size, stream_file_chunks
from ..config import get_settings

settings = get_settings()
router = APIRouter(prefix="/api/tracks", tags=["tracks"])


@router.get("", response_model=list[TrackResponse])
async def get_tracks(
    my: bool = False,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    query = select(Track)
    if my:
        query = query.where(Track.uploaded_by == current_user.id)
    query = query.order_by(Track.created_at.desc())
    result = await db.execute(query)
    return result.scalars().all()


async def _process_single_track(
    file: UploadFile,
    title: str,
    artist: str,
    current_user: User,
) -> tuple[Track, Exception | None]:
    """Process a single track upload. Returns (track, error)."""
    try:
        # Check file type
        if not file.content_type or not file.content_type.startswith("audio/"):
            return None, Exception("File must be an audio file")

        # Read file content
        content = await file.read()
        file_size = len(content)

        # Check file size
        max_size = settings.max_file_size_mb * 1024 * 1024
        if file_size > max_size:
            return None, Exception(f"File size exceeds {settings.max_file_size_mb}MB limit")

        # Check storage limit
        if not await can_upload_file(file_size):
            return None, Exception("Storage limit exceeded")

        # Get duration and metadata from MP3
        try:
            audio = MP3(BytesIO(content))
            duration = int(audio.info.length * 1000)  # Convert to milliseconds

            # Extract ID3 tags if title/artist not provided
            if not title or not artist:
                tags = audio.tags
                if tags:
                    # TIT2 = Title, TPE1 = Artist
                    if not title and tags.get("TIT2"):
                        title = str(tags.get("TIT2"))
                    if not artist and tags.get("TPE1"):
                        artist = str(tags.get("TPE1"))

            # Fallback to filename if still no title
            if not title:
                title = file.filename.rsplit(".", 1)[0] if file.filename else "Unknown"
            if not artist:
                artist = "Unknown"

        except Exception as e:
            return None, Exception("Could not read audio file")

        # Upload to S3
        s3_key = f"tracks/{uuid.uuid4()}.mp3"
        await upload_file(content, s3_key)

        # Create track record
        track = Track(
            title=title,
            artist=artist,
            duration=duration,
            s3_key=s3_key,
            file_size=file_size,
            uploaded_by=current_user.id,
        )
        return track, None

    except Exception as e:
        return None, e


@router.post("/upload", response_model=TrackResponse)
async def upload_track(
    file: UploadFile = File(...),
    title: str = Form(None),
    artist: str = Form(None),
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    track, error = await _process_single_track(file, title, artist, current_user)

    if error:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail=str(error),
        )

    db.add(track)
    await db.flush()
    return track


@router.post("/upload-multiple", response_model=list[TrackResponse])
async def upload_multiple_tracks(
    files: list[UploadFile] = File(...),
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """Upload multiple tracks at once. Each file's metadata is auto-detected from ID3 tags."""
    if not files:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="No files provided",
        )

    # Process all files
    results = []
    for file in files:
        track, error = await _process_single_track(file, None, None, current_user)
        if track:
            db.add(track)
            results.append(track)

    # Commit all at once
    await db.flush()

    return results


@router.get("/{track_id}", response_model=TrackWithUrl)
async def get_track(track_id: uuid.UUID, db: AsyncSession = Depends(get_db)):
    result = await db.execute(select(Track).where(Track.id == track_id))
    track = result.scalar_one_or_none()

    if not track:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Track not found")

    url = generate_presigned_url(track.s3_key)
    return TrackWithUrl(
        id=track.id,
        title=track.title,
        artist=track.artist,
        duration=track.duration,
        file_size=track.file_size,
        uploaded_by=track.uploaded_by,
        created_at=track.created_at,
        url=url,
    )


@router.delete("/{track_id}")
async def delete_track(
    track_id: uuid.UUID,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    result = await db.execute(select(Track).where(Track.id == track_id))
    track = result.scalar_one_or_none()

    if not track:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Track not found")

    if track.uploaded_by != current_user.id:
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Not track owner")

    # Delete from S3
    await delete_file(track.s3_key)

    # Delete from DB
    await db.delete(track)

    return {"status": "deleted"}


@router.get("/storage/info")
async def get_storage_info(db: AsyncSession = Depends(get_db)):
    result = await db.execute(select(func.sum(Track.file_size)))
    total_size = result.scalar() or 0
    max_size = settings.max_storage_gb * 1024 * 1024 * 1024

    return {
        "used_bytes": total_size,
        "max_bytes": max_size,
        "used_gb": round(total_size / (1024 * 1024 * 1024), 2),
        "max_gb": settings.max_storage_gb,
    }


@router.get("/{track_id}/stream")
async def stream_track(track_id: uuid.UUID, request: Request, db: AsyncSession = Depends(get_db)):
    """Stream audio file through backend with Range support (bypasses S3 SSL issues)"""
    result = await db.execute(select(Track).where(Track.id == track_id))
    track = result.scalar_one_or_none()

    if not track:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Track not found")

    # Get file size from S3 (without downloading)
    file_size = get_file_size(track.s3_key)
    if file_size is None:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Track file not found in storage")

    # Encode filename for non-ASCII characters
    encoded_filename = quote(f"{track.title}.mp3")

    # Parse Range header
    range_header = request.headers.get("range")

    if range_header:
        # Parse "bytes=start-end"
        range_match = range_header.replace("bytes=", "").split("-")
        start = int(range_match[0]) if range_match[0] else 0
        end = int(range_match[1]) if range_match[1] else file_size - 1

        # Ensure valid range
        if start >= file_size:
            raise HTTPException(status_code=416, detail="Range not satisfiable")

        end = min(end, file_size - 1)
        content_length = end - start + 1

        return StreamingResponse(
            stream_file_chunks(track.s3_key, start, end),
            status_code=206,
            media_type="audio/mpeg",
            headers={
                "Content-Range": f"bytes {start}-{end}/{file_size}",
                "Accept-Ranges": "bytes",
                "Content-Length": str(content_length),
                "Content-Disposition": f"inline; filename*=UTF-8''{encoded_filename}",
                "X-Accel-Buffering": "no",
                "Cache-Control": "no-cache",
            }
        )

    # No range - stream full file
    return StreamingResponse(
        stream_file_chunks(track.s3_key),
        media_type="audio/mpeg",
        headers={
            "Accept-Ranges": "bytes",
            "Content-Length": str(file_size),
            "Content-Disposition": f"inline; filename*=UTF-8''{encoded_filename}",
            "X-Accel-Buffering": "no",
            "Cache-Control": "no-cache",
        }
    )