"""Asset management router."""

import os
from pathlib import Path
from typing import Optional

from fastapi import APIRouter, Depends, HTTPException, UploadFile, File, Query
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.config import settings
from app.database import get_db
from app.dependencies import CurrentUser
from app.models.asset import Asset, AssetType
from app.models.world import World
from pydantic import BaseModel, Field

router = APIRouter()


# --- Pydantic schemas ---

class AssetCreate(BaseModel):
    """Schema for creating an asset reference."""
    name: str = Field(..., min_length=1, max_length=255)
    description: Optional[str] = None
    asset_type: AssetType
    world_id: Optional[int] = None


class AssetResponse(BaseModel):
    """Schema for asset responses."""
    id: int
    name: str
    description: Optional[str]
    asset_type: AssetType
    file_path: str
    file_size: Optional[int]
    mime_type: Optional[str]
    world_id: Optional[int]
    owner_id: int
    is_public: bool
    created_at: str
    updated_at: str

    model_config = {"from_attributes": True}


class AssetUpdate(BaseModel):
    """Schema for updating an asset."""
    name: Optional[str] = None
    description: Optional[str] = None
    is_public: Optional[bool] = None


# --- Helpers ---

def _sanitize_filename(filename: str) -> str:
    """Strip path components and unsafe characters from a filename."""
    # Remove any directory components (path traversal protection).
    base = os.path.basename(filename.replace("\\", "/"))
    # Keep only safe characters.
    safe = "".join(c for c in base if c.isalnum() or c in "._-")
    return safe or "file"


# --- Endpoints ---

@router.post("/", response_model=AssetResponse, status_code=201)
async def create_asset(
    payload: AssetCreate,
    current_user: CurrentUser,
    db: AsyncSession = Depends(get_db),
):
    """Create a new asset reference."""
    # Verify world ownership if world_id is provided
    if payload.world_id is not None:
        world = await db.get(World, payload.world_id)
        if world is None:
            raise HTTPException(status_code=404, detail="World not found")
        if world.owner_id != current_user.id:
            raise HTTPException(status_code=403, detail="Not owner of this world")

    asset = Asset(
        name=payload.name,
        description=payload.description,
        asset_type=payload.asset_type,
        file_path="",  # Will be set after upload
        owner_id=current_user.id,
        world_id=payload.world_id,
        is_public=False,
    )
    db.add(asset)
    await db.commit()
    await db.refresh(asset)
    return asset


@router.get("/", response_model=list[AssetResponse])
async def list_assets(
    current_user: CurrentUser,
    world_id: Optional[int] = Query(None, description="Filter by world"),
    asset_type: Optional[AssetType] = Query(None),
    limit: int = Query(50, ge=1, le=100),
    offset: int = Query(0, ge=0),
    db: AsyncSession = Depends(get_db),
):
    """List assets with optional filters."""
    stmt = select(Asset).where(Asset.owner_id == current_user.id)

    if world_id is not None:
        stmt = stmt.where(Asset.world_id == world_id)
    if asset_type is not None:
        stmt = stmt.where(Asset.asset_type == asset_type)

    stmt = stmt.order_by(Asset.created_at.desc()).limit(limit).offset(offset)
    result = await db.execute(stmt)
    assets = result.scalars().all()
    return assets


@router.get("/{asset_id}", response_model=AssetResponse)
async def get_asset(
    asset_id: int,
    current_user: CurrentUser,
    db: AsyncSession = Depends(get_db),
):
    """Get a single asset by ID."""
    asset = await db.get(Asset, asset_id)
    if asset is None or asset.owner_id != current_user.id:
        raise HTTPException(status_code=404, detail="Asset not found")
    return asset


@router.patch("/{asset_id}", response_model=AssetResponse)
async def update_asset(
    asset_id: int,
    payload: AssetUpdate,
    current_user: CurrentUser,
    db: AsyncSession = Depends(get_db),
):
    """Update an asset."""
    asset = await db.get(Asset, asset_id)
    if asset is None or asset.owner_id != current_user.id:
        raise HTTPException(status_code=404, detail="Asset not found")

    update_data = payload.model_dump(exclude_unset=True)
    for field, value in update_data.items():
        setattr(asset, field, value)

    await db.commit()
    await db.refresh(asset)
    return asset


@router.delete("/{asset_id}", status_code=204)
async def delete_asset(
    asset_id: int,
    current_user: CurrentUser,
    db: AsyncSession = Depends(get_db),
):
    """Delete an asset."""
    asset = await db.get(Asset, asset_id)
    if asset is None or asset.owner_id != current_user.id:
        raise HTTPException(status_code=404, detail="Asset not found")

    await db.delete(asset)
    await db.commit()


@router.post("/{asset_id}/upload", response_model=AssetResponse)
async def upload_asset_file(
    asset_id: int,
    file: UploadFile = File(...),
    current_user: CurrentUser = Depends(),
    db: AsyncSession = Depends(get_db),
):
    """Upload a file for an existing asset."""
    asset = await db.get(Asset, asset_id)
    if asset is None or asset.owner_id != current_user.id:
        raise HTTPException(status_code=404, detail="Asset not found")

    # Sanitize filename to prevent path traversal.
    safe_filename = _sanitize_filename(file.filename or f"asset_{asset_id}")

    # Validate file size against configured maximum.
    max_bytes = settings.MAX_UPLOAD_SIZE_MB * 1024 * 1024
    content = await file.read()
    file_size = len(content)
    if file_size > max_bytes:
        raise HTTPException(
            status_code=413,
            detail=f"File size {file_size} exceeds maximum allowed size {max_bytes} bytes",
        )

    # Write the file to the upload directory.
    upload_dir = Path(settings.UPLOAD_DIR)
    upload_dir.mkdir(parents=True, exist_ok=True)
    stored_name = f"{asset_id}_{safe_filename}"
    file_path = upload_dir / stored_name
    file_path.write_bytes(content)

    asset.file_path = str(file_path)
    asset.mime_type = file.content_type
    asset.file_size = file_size

    await db.commit()
    await db.refresh(asset)
    return asset