from sqlalchemy import Column, String, Text, Integer, ForeignKey, DateTime, Enum
from sqlalchemy.orm import relationship
from datetime import datetime
from enum import Enum as PyEnum
from app.models.base import BaseModel


class TaskStatus(str, PyEnum):
    TODO = "todo"
    IN_PROGRESS = "in_progress"
    DONE = "done"
    CANCELLED = "cancelled"


class TaskPriority(str, PyEnum):
    LOW = "low"
    MEDIUM = "medium"
    HIGH = "high"
    URGENT = "urgent"


class Task(BaseModel):
    __tablename__ = "tasks"

    user_id = Column(String(36), ForeignKey("users.id"), nullable=False, index=True)
    title = Column(String(500), nullable=False)
    description = Column(Text, nullable=True)
    status = Column(Enum(TaskStatus), default=TaskStatus.TODO, nullable=False, index=True)
    priority = Column(Enum(TaskPriority), default=TaskPriority.MEDIUM, nullable=False)
    due_date = Column(DateTime, nullable=True)
    completed_at = Column(DateTime, nullable=True)
    tags = Column(String(1000), nullable=True)  # JSON 数组

    history = relationship("TaskHistory", back_populates="task", cascade="all, delete-orphan")


class TaskHistory(BaseModel):
    __tablename__ = "task_histories"

    task_id = Column(String(36), ForeignKey("tasks.id"), nullable=False, index=True)
    action = Column(String(100), nullable=False)  # created, status_changed, updated, deleted
    old_value = Column(Text, nullable=True)
    new_value = Column(Text, nullable=True)

    task = relationship("Task", back_populates="history")