from fastapi import APIRouter, HTTPException, status, UploadFile, File
from sqlalchemy import select
import uuid
from pathlib import Path

from app.api.deps import DbSession, CurrentUser
from app.core.config import settings
from app.models import User
from app.schemas import UserPublic, UserUpdate, TelegramLink, MessageResponse

router = APIRouter(prefix="/users", tags=["users"])


@router.get("/{user_id}", response_model=UserPublic)
async def get_user(user_id: int, db: DbSession):
    result = await db.execute(select(User).where(User.id == user_id))
    user = result.scalar_one_or_none()

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

    return UserPublic.model_validate(user)


@router.patch("/me", response_model=UserPublic)
async def update_me(data: UserUpdate, current_user: CurrentUser, db: DbSession):
    if data.nickname is not None:
        current_user.nickname = data.nickname

    await db.commit()
    await db.refresh(current_user)

    return UserPublic.model_validate(current_user)


@router.post("/me/avatar", response_model=UserPublic)
async def upload_avatar(
    current_user: CurrentUser,
    db: DbSession,
    file: UploadFile = File(...),
):
    # Validate file
    if not file.content_type.startswith("image/"):
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="File must be an image",
        )

    contents = await file.read()
    if len(contents) > settings.MAX_UPLOAD_SIZE:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail=f"File too large. Maximum size is {settings.MAX_UPLOAD_SIZE // 1024 // 1024} MB",
        )

    # Get file extension
    ext = file.filename.split(".")[-1].lower() if file.filename else "jpg"
    if ext not in settings.ALLOWED_IMAGE_EXTENSIONS:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail=f"Invalid file type. Allowed: {settings.ALLOWED_IMAGE_EXTENSIONS}",
        )

    # Save file
    filename = f"{current_user.id}_{uuid.uuid4().hex}.{ext}"
    filepath = Path(settings.UPLOAD_DIR) / "avatars" / filename
    filepath.parent.mkdir(parents=True, exist_ok=True)

    with open(filepath, "wb") as f:
        f.write(contents)

    # Update user
    current_user.avatar_path = str(filepath)
    await db.commit()
    await db.refresh(current_user)

    return UserPublic.model_validate(current_user)


@router.post("/me/telegram", response_model=MessageResponse)
async def link_telegram(
    data: TelegramLink,
    current_user: CurrentUser,
    db: DbSession,
):
    # Check if telegram_id already linked to another user
    result = await db.execute(
        select(User).where(User.telegram_id == data.telegram_id, User.id != current_user.id)
    )
    if result.scalar_one_or_none():
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="This Telegram account is already linked to another user",
        )

    current_user.telegram_id = data.telegram_id
    current_user.telegram_username = data.telegram_username

    await db.commit()

    return MessageResponse(message="Telegram account linked successfully")