from sqlalchemy import Boolean, Column, Integer, String, Text, DateTime, Enum, Table, ForeignKey
from sqlalchemy.orm import relationship
from sqlalchemy.sql import func
import enum

from .database import Base

# Association table for the many-to-many relationship between Todo and Tag
todo_tag = Table(
    "todo_tag",
    Base.metadata,
    Column("todo_id", Integer, ForeignKey("todos.id"), primary_key=True),
    Column("tag_id", Integer, ForeignKey("tags.id"), primary_key=True)
)

class PriorityLevel(str, enum.Enum):
    LOW = "low"
    MEDIUM = "medium"
    HIGH = "high"

class Tag(Base):
    __tablename__ = "tags"

    id = Column(Integer, primary_key=True, index=True)
    name = Column(String(50), nullable=False, unique=True, index=True)
    created_at = Column(DateTime(timezone=True), server_default=func.now())

    # Relationship to todos
    todos = relationship("Todo", secondary=todo_tag, back_populates="tags")

class Todo(Base):
    __tablename__ = "todos"

    id = Column(Integer, primary_key=True, index=True)
    title = Column(String(100), nullable=False)
    description = Column(Text, nullable=True)
    completed = Column(Boolean, default=False)
    priority = Column(Enum(PriorityLevel), default=PriorityLevel.MEDIUM)
    due_date = Column(DateTime(timezone=True), nullable=True)
    created_at = Column(DateTime(timezone=True), server_default=func.now())
    updated_at = Column(DateTime(timezone=True), onupdate=func.now())

    # Relationship to tags
    tags = relationship("Tag", secondary=todo_tag, back_populates="todos")