"""
Files API - Upload and download files
"""

from fastapi import APIRouter, Depends, HTTPException, UploadFile, File as FastAPIFile
from fastapi.responses import StreamingResponse
from sqlalchemy.orm import Session
from pydantic import BaseModel
from typing import List, Optional
import os
import uuid
from pathlib import Path
import aiofiles
import mimetypes

from core.database import get_db
from core.models import File, User
from api.auth import get_current_user

router = APIRouter()

# File storage configuration
UPLOAD_DIR = os.getenv("UPLOAD_DIR", "/tmp/uploads")
Path(UPLOAD_DIR).mkdir(parents=True, exist_ok=True)

class FileResponse(BaseModel):
    id: int
    filename: str
    original_filename: str
    file_size: int
    mime_type: str
    uploaded_by: int
    channel_id: Optional[int]
    created_at: str
    download_url: str
    
    class Config:
        from_attributes = True

@router.post("/upload", response_model=FileResponse)
async def upload_file(
    file: UploadFile = FastAPIFile(...),
    channel_id: Optional[int] = None,
    current_user: User = Depends(get_current_user),
    db: Session = Depends(get_db)
):
    """Upload a file"""
    
    # Generate unique filename
    file_ext = os.path.splitext(file.filename)[1]
    unique_filename = f"{uuid.uuid4()}{file_ext}"
    file_path = os.path.join(UPLOAD_DIR, unique_filename)
    
    # Save file
    try:
        async with aiofiles.open(file_path, 'wb') as f:
            content = await file.read()
            await f.write(content)
        
        file_size = len(content)
        mime_type = file.content_type or mimetypes.guess_type(file.filename)[0] or "application/octet-stream"
        
    except Exception as e:
        raise HTTPException(status_code=500, detail=f"Failed to save file: {str(e)}")
    
    # Create file record
    file_record = File(
        filename=unique_filename,
        original_filename=file.filename,
        file_path=file_path,
        file_size=file_size,
        mime_type=mime_type,
        uploaded_by=current_user.id,
        channel_id=channel_id
    )
    
    db.add(file_record)
    db.commit()
    db.refresh(file_record)
    
    return {
        **file_record.__dict__,
        "created_at": file_record.created_at.isoformat(),
        "download_url": f"/api/files/{file_record.id}/download"
    }

@router.get("/{file_id}/download")
async def download_file(
    file_id: int,
    current_user: User = Depends(get_current_user),
    db: Session = Depends(get_db)
):
    """Download a file"""
    
    # Get file record
    file_record = db.query(File).filter(File.id == file_id).first()
    if not file_record:
        raise HTTPException(status_code=404, detail="File not found")
    
    # Check file exists
    if not os.path.exists(file_record.file_path):
        raise HTTPException(status_code=404, detail="File not found on disk")
    
    # Stream file
    def iterfile():
        with open(file_record.file_path, mode="rb") as f:
            yield from f
    
    return StreamingResponse(
        iterfile(),
        media_type=file_record.mime_type,
        headers={
            "Content-Disposition": f"attachment; filename={file_record.original_filename}"
        }
    )

@router.get("/", response_model=List[FileResponse])
async def list_files(
    channel_id: Optional[int] = None,
    limit: int = 50,
    current_user: User = Depends(get_current_user),
    db: Session = Depends(get_db)
):
    """List files (optionally filtered by channel)"""
    
    query = db.query(File)
    
    if channel_id:
        query = query.filter(File.channel_id == channel_id)
    
    files = query.order_by(File.id.desc()).limit(limit).all()
    
    return [
        {
            **f.__dict__,
            "created_at": f.created_at.isoformat(),
            "download_url": f"/api/files/{f.id}/download"
        }
        for f in files
    ]

@router.delete("/{file_id}")
async def delete_file(
    file_id: int,
    current_user: User = Depends(get_current_user),
    db: Session = Depends(get_db)
):
    """Delete a file"""
    
    file_record = db.query(File).filter(File.id == file_id).first()
    if not file_record:
        raise HTTPException(status_code=404, detail="File not found")
    
    # Check permissions (owner or admin)
    if file_record.uploaded_by != current_user.id and current_user.role.value != "admin":
        raise HTTPException(status_code=403, detail="Not authorized to delete this file")
    
    # Delete from disk
    try:
        if os.path.exists(file_record.file_path):
            os.remove(file_record.file_path)
    except Exception as e:
        pass  # Continue even if disk delete fails
    
    # Delete record
    db.delete(file_record)
    db.commit()
    
    return {"message": "File deleted"}