from fastapi import APIRouter, HTTPException, status, UploadFile, File
from sqlalchemy import select

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
from app.services.storage import storage_service

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}",
        )

    # Delete old avatar if exists
    if current_user.avatar_path:
        await storage_service.delete_file(current_user.avatar_path)

    # Upload file
    filename = storage_service.generate_filename(current_user.id, file.filename)
    file_path = await storage_service.upload_file(
        content=contents,
        folder="avatars",
        filename=filename,
        content_type=file.content_type or "image/jpeg",
    )

    # Update user
    current_user.avatar_path = file_path
    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")