"""Task service: CRUD + assignment + status management."""
from sqlalchemy.orm import Session
from typing import List, Optional
from datetime import datetime
from app.models.task import Task
from app.schemas.task import TaskCreate, TaskUpdate, TaskAssign


class TaskService:
    @staticmethod
    def list_tasks(
        db: Session,
        tenant_id: int,
        project_id: Optional[int] = None,
        status: Optional[str] = None,
        assignee_id: Optional[int] = None,
        skip: int = 0,
        limit: int = 100,
    ) -> List[Task]:
        q = db.query(Task).filter(Task.tenant_id == tenant_id)
        if project_id:
            q = q.filter(Task.project_id == project_id)
        if status:
            q = q.filter(Task.status == status)
        if assignee_id:
            q = q.filter(Task.assignee_id == assignee_id)
        return q.order_by(Task.created_at.desc()).offset(skip).limit(limit).all()

    @staticmethod
    def get_task(db: Session, tenant_id: int, task_id: int) -> Optional[Task]:
        return (
            db.query(Task)
            .filter(Task.id == task_id, Task.tenant_id == tenant_id)
            .first()
        )

    @staticmethod
    def create_task(
        db: Session, tenant_id: int, project_id: int, req: TaskCreate
    ) -> Task:
        task = Task(
            tenant_id=tenant_id,
            project_id=project_id,
            title=req.title,
            description=req.description,
            status="pending",
            priority=req.priority,
            task_type=req.task_type,
            input_data=req.input_data,
            requires_review=req.requires_review,
            assignee_id=req.assignee_id,
            worker_id=req.worker_id,
            due_date=req.due_date,
            depends_on=req.depends_on,
        )
        db.add(task)
        db.commit()
        db.refresh(task)
        return task

    @staticmethod
    def update_task(
        db: Session, tenant_id: int, task_id: int, req: TaskUpdate
    ) -> Task:
        task = TaskService.get_task(db, tenant_id, task_id)
        if not task:
            raise ValueError(f"Task #{task_id} not found")
        for field, value in req.model_dump(exclude_unset=True).items():
            setattr(task, field, value)
        db.commit()
        db.refresh(task)
        return task

    @staticmethod
    def delete_task(db: Session, tenant_id: int, task_id: int) -> bool:
        task = TaskService.get_task(db, tenant_id, task_id)
        if not task:
            return False
        db.delete(task)
        db.commit()
        return True

    @staticmethod
    def assign_task(
        db: Session, tenant_id: int, task_id: int, req: TaskAssign
    ) -> Task:
        task = TaskService.get_task(db, tenant_id, task_id)
        if not task:
            raise ValueError(f"Task #{task_id} not found")
        if req.assignee_id is not None:
            task.assignee_id = req.assignee_id
        if req.worker_id is not None:
            task.worker_id = req.worker_id
        if task.status == "pending":
            task.status = "assigned"
        db.commit()
        db.refresh(task)
        return task

    @staticmethod
    def mark_status(
        db: Session, tenant_id: int, task_id: int, status: str, output: str = ""
    ) -> Task:
        task = TaskService.get_task(db, tenant_id, task_id)
        if not task:
            raise ValueError(f"Task #{task_id} not found")
        task.status = status
        if output:
            task.output_data = output
        if status == "in_progress":
            task.started_at = datetime.utcnow()
        elif status in ("done", "review", "rejected", "cancelled"):
            task.completed_at = datetime.utcnow()
        db.commit()
        db.refresh(task)
        return task