from typing import Any, List

from fastapi import APIRouter, Depends, HTTPException, status
from sqlalchemy import and_
from sqlalchemy.orm import Session

from app.core.deps import get_current_user, get_db
from app.models.task import Task
from app.models.user import User
from app.schemas.user import User as UserSchema

router = APIRouter()


@router.get("/{task_id}/assignees", response_model=List[UserSchema])
def read_task_assignees(
    *,
    db: Session = Depends(get_db),
    task_id: int,
    current_user: User = Depends(get_current_user),
) -> Any:
    """
    Get all assignees for a specific task.
    """
    task = db.query(Task).filter(
        and_(
            Task.id == task_id,
            not Task.is_deleted
        )
    ).first()

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

    # Check if user has access to task
    if task.owner_id != current_user.id and current_user not in task.assignees:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="You don't have access to this task"
        )

    return task.assignees


@router.post("/{task_id}/assignees/{user_id}", status_code=status.HTTP_201_CREATED)
def assign_user_to_task(
    *,
    db: Session = Depends(get_db),
    task_id: int,
    user_id: int,
    current_user: User = Depends(get_current_user),
) -> Any:
    """
    Assign a user to a task.
    """
    # Get task
    task = db.query(Task).filter(
        and_(
            Task.id == task_id,
            not Task.is_deleted
        )
    ).first()

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

    # Only task owner can assign users
    if task.owner_id != current_user.id:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Only the task owner can assign users"
        )

    # Get user to assign
    user = db.query(User).filter(User.id == user_id).first()

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

    # Check if user is already assigned
    if user in task.assignees:
        return {"message": "User is already assigned to this task"}

    # Assign user to task
    task.assignees.append(user)
    db.commit()

    return {"message": "User assigned to task successfully"}


@router.delete("/{task_id}/assignees/{user_id}", status_code=status.HTTP_200_OK)
def remove_user_from_task(
    *,
    db: Session = Depends(get_db),
    task_id: int,
    user_id: int,
    current_user: User = Depends(get_current_user),
) -> Any:
    """
    Remove a user from a task.
    """
    # Get task
    task = db.query(Task).filter(
        and_(
            Task.id == task_id,
            not Task.is_deleted
        )
    ).first()

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

    # Only task owner can remove assignments
    if task.owner_id != current_user.id:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Only the task owner can remove assignments"
        )

    # Get user to remove
    user = db.query(User).filter(User.id == user_id).first()

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

    # Check if user is assigned
    if user not in task.assignees:
        return {"message": "User is not assigned to this task"}

    # Remove user from task
    task.assignees.remove(user)
    db.commit()

    return {"message": "User removed from task successfully"}