from datetime import UTC, date, datetime

from fastapi import APIRouter, Depends, HTTPException, Query
from sqlalchemy import desc, select
from sqlalchemy.ext.asyncio import AsyncSession
from app.database import get_db
from app.models.task import Task, TaskStatus
from app.models.user import User
from app.routers.auth import get_current_user
from app.schemas.task import TaskCreate, TaskUpdate, TaskOut

router = APIRouter(prefix="/api/tasks", tags=["看板"])


@router.get("", response_model=list[TaskOut])
async def list_tasks(
    status: TaskStatus | None = None,
    due_date: date | None = Query(default=None),
    date_from: date | None = Query(default=None),
    date_to: date | None = Query(default=None),
    current_user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    query = select(Task).where(Task.user_id == current_user.id)
    if status:
        query = query.where(Task.status == status)
    if due_date:
        start = datetime.combine(due_date, datetime.min.time())
        end = datetime.combine(due_date, datetime.max.time())
        query = query.where(Task.due_date.is_not(None), Task.due_date >= start, Task.due_date <= end)
    else:
        start = datetime.combine(date_from, datetime.min.time()) if date_from else None
        end = datetime.combine(date_to, datetime.max.time()) if date_to else None
        if start and end and start > end:
            raise HTTPException(status_code=400, detail="开始日期不能晚于结束日期")
        if start is not None:
            query = query.where(Task.due_date.is_not(None), Task.due_date >= start)
        if end is not None:
            query = query.where(Task.due_date.is_not(None), Task.due_date <= end)
    query = query.order_by(desc(Task.created_at))
    result = await db.execute(query)
    return result.scalars().all()


@router.post("", response_model=TaskOut, status_code=201)
async def create_task(
    data: TaskCreate,
    current_user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    import json
    task = Task(
        user_id=current_user.id,
        title=data.title,
        description=data.description,
        priority=data.priority,
        due_date=data.due_date,
        tags=json.dumps(data.tags) if data.tags else None,
    )
    db.add(task)
    await db.commit()
    await db.refresh(task)
    return task


@router.patch("/{task_id}", response_model=TaskOut)
async def update_task(
    task_id: str,
    data: TaskUpdate,
    current_user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    import json
    result = await db.execute(
        select(Task).where(Task.id == task_id, Task.user_id == current_user.id)
    )
    task = result.scalar_one_or_none()
    if not task:
        raise HTTPException(status_code=404, detail="任务不存在")

    for field, value in data.model_dump(exclude_none=True).items():
        if field == "tags":
            setattr(task, field, json.dumps(value))
        elif field == "status" and value == TaskStatus.DONE:
            task.completed_at = datetime.now(UTC)
            setattr(task, field, value)
        elif field == "status":
            task.completed_at = None
            setattr(task, field, value)

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


@router.delete("/{task_id}", status_code=204)
async def delete_task(
    task_id: str,
    current_user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    result = await db.execute(
        select(Task).where(Task.id == task_id, Task.user_id == current_user.id)
    )
    task = result.scalar_one_or_none()
    if not task:
        raise HTTPException(status_code=404, detail="任务不存在")
    await db.delete(task)
    await db.commit()