from typing import List, Optional

from sqlalchemy import or_
from sqlalchemy.orm import Session

from app.models.task import Task
from app.schemas.task import TaskCreate, TaskUpdate


def get_task(db: Session, task_id: int) -> Optional[Task]:
    """
    Get a task by ID
    """
    return db.query(Task).filter(Task.id == task_id).first()


def get_task_by_user(db: Session, task_id: int, user_id: int) -> Optional[Task]:
    """
    Get a task by ID for a specific user
    """
    return db.query(Task).filter(
        Task.id == task_id, Task.owner_id == user_id
    ).first()


def get_tasks(
    db: Session,
    user_id: int,
    skip: int = 0,
    limit: int = 100,
    completed: Optional[bool] = None,
    category_id: Optional[int] = None,
    search: Optional[str] = None,
    priority: Optional[str] = None,
) -> List[Task]:
    """
    Get all tasks for a user with optional filtering
    """
    query = db.query(Task).filter(Task.owner_id == user_id)

    # Apply filters
    if completed is not None:
        query = query.filter(Task.is_completed == completed)

    if category_id:
        query = query.filter(Task.category_id == category_id)

    if search:
        search_term = f"%{search}%"
        query = query.filter(
            or_(
                Task.title.ilike(search_term),
                Task.description.ilike(search_term)
            )
        )

    if priority:
        query = query.filter(Task.priority == priority)

    # Apply pagination and return results
    return query.order_by(Task.created_at.desc()).offset(skip).limit(limit).all()


def create_task(db: Session, task_in: TaskCreate, user_id: int) -> Task:
    """
    Create a new task for a user
    """
    db_task = Task(
        **task_in.dict(),
        owner_id=user_id,
    )
    db.add(db_task)
    db.commit()
    db.refresh(db_task)
    return db_task


def update_task(
    db: Session, task_id: int, task_in: TaskUpdate, user_id: int
) -> Optional[Task]:
    """
    Update a task
    """
    db_task = get_task_by_user(db, task_id, user_id)
    if not db_task:
        return None

    update_data = task_in.dict(exclude_unset=True)
    for field, value in update_data.items():
        setattr(db_task, field, value)

    db.add(db_task)
    db.commit()
    db.refresh(db_task)
    return db_task


def delete_task(db: Session, task_id: int, user_id: int) -> Optional[Task]:
    """
    Delete a task
    """
    db_task = get_task_by_user(db, task_id, user_id)
    if not db_task:
        return None

    db.delete(db_task)
    db.commit()
    return db_task