"""Pydantic schemas for Task CRUD operations."""
from datetime import datetime
from typing import Optional
from pydantic import BaseModel, Field, ConfigDict


class TaskCreate(BaseModel):
    """Schema for creating a new task."""
    title: str = Field(..., min_length=1, max_length=200, description="Task title")
    description: Optional[str] = Field(None, max_length=1000, description="Task description")

    model_config = ConfigDict(
        json_schema_extra={
            "example": {
                "title": "Buy groceries",
                "description": "Milk, eggs, bread"
            }
        }
    )


class TaskResponse(BaseModel):
    """Schema for task response."""
    id: int = Field(..., description="Task ID")
    user_id: int = Field(..., description="User ID who owns the task")
    title: str = Field(..., description="Task title")
    description: Optional[str] = Field(None, description="Task description")
    completed: bool = Field(..., description="Task completion status")
    created_at: datetime = Field(..., description="Task creation timestamp")
    updated_at: datetime = Field(..., description="Task last update timestamp")

    model_config = ConfigDict(
        from_attributes=True,
        json_schema_extra={
            "example": {
                "id": 1,
                "user_id": 1,
                "title": "Buy groceries",
                "description": "Milk, eggs, bread",
                "completed": False,
                "created_at": "2026-01-08T10:00:00Z",
                "updated_at": "2026-01-08T10:00:00Z"
            }
        }
    )


class TaskUpdate(BaseModel):
    """Schema for updating a task (PUT - replaces all fields)."""
    title: str = Field(..., min_length=1, max_length=200, description="Task title")
    description: Optional[str] = Field(None, max_length=1000, description="Task description")
    completed: bool = Field(..., description="Task completion status")

    model_config = ConfigDict(
        json_schema_extra={
            "example": {
                "title": "Buy groceries",
                "description": "Milk, eggs, bread, cheese",
                "completed": False
            }
        }
    )


class TaskPatch(BaseModel):
    """Schema for partially updating a task (PATCH - updates only provided fields)."""
    title: Optional[str] = Field(None, min_length=1, max_length=200, description="Task title")
    description: Optional[str] = Field(None, max_length=1000, description="Task description")
    completed: Optional[bool] = Field(None, description="Task completion status")

    model_config = ConfigDict(
        json_schema_extra={
            "example": {
                "completed": True
            }
        }
    )


class TaskListResponse(BaseModel):
    """Schema for list of tasks response."""
    tasks: list[TaskResponse] = Field(..., description="List of tasks")
    total: int = Field(..., description="Total number of tasks")

    model_config = ConfigDict(
        json_schema_extra={
            "example": {
                "tasks": [
                    {
                        "id": 1,
                        "user_id": 1,
                        "title": "Buy groceries",
                        "description": "Milk, eggs, bread",
                        "completed": False,
                        "created_at": "2026-01-08T10:00:00Z",
                        "updated_at": "2026-01-08T10:00:00Z"
                    }
                ],
                "total": 1
            }
        }
    )