from sqlalchemy import create_engine, Column, String, Boolean, DateTime, ForeignKey
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker, relationship
from datetime import datetime
import os

# PostgreSQL connection string
# Format: postgresql://username:password@localhost:5432/database_name
DATABASE_URL = os.getenv(
    "DATABASE_URL",
    "postgresql://tasko_user:tasko_password@localhost:5432/tasko_db"
)

engine = create_engine(DATABASE_URL)
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

Base = declarative_base()

class User(Base):
    __tablename__ = "users"
    
    id = Column(String, primary_key=True, index=True)
    username = Column(String, unique=True, index=True, nullable=False)
    email = Column(String, unique=True, index=True, nullable=False)
    password_hash = Column(String, nullable=False)
    created_at = Column(DateTime, default=datetime.utcnow)
    
    # Relationships
    lists = relationship("TaskList", back_populates="user", cascade="all, delete-orphan")
    tasks = relationship("Task", back_populates="user", cascade="all, delete-orphan")
    tokens = relationship("Token", back_populates="user", cascade="all, delete-orphan")


class Token(Base):
    __tablename__ = "tokens"
    
    token = Column(String, primary_key=True, index=True)
    user_id = Column(String, ForeignKey("users.id"), nullable=False)
    created_at = Column(DateTime, default=datetime.utcnow)
    
    # Relationships
    user = relationship("User", back_populates="tokens")


class TaskList(Base):
    __tablename__ = "task_lists"
    
    id = Column(String, primary_key=True, index=True)
    user_id = Column(String, ForeignKey("users.id"), nullable=False)
    name = Column(String, nullable=False)
    icon = Column(String, default="📝")
    color = Column(String, default="#667eea")
    created_at = Column(DateTime, default=datetime.utcnow)
    
    # Relationships
    user = relationship("User", back_populates="lists")
    tasks = relationship("Task", back_populates="task_list", cascade="all, delete-orphan")


class Task(Base):
    __tablename__ = "tasks"
    
    id = Column(String, primary_key=True, index=True)
    list_id = Column(String, ForeignKey("task_lists.id"), nullable=False)
    user_id = Column(String, ForeignKey("users.id"), nullable=False)
    title = Column(String, nullable=False)
    description = Column(String, nullable=True)
    completed = Column(Boolean, default=False)
    priority = Column(String, default="medium")
    created_at = Column(DateTime, default=datetime.utcnow)
    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
    
    # Relationships
    user = relationship("User", back_populates="tasks")
    task_list = relationship("TaskList", back_populates="tasks")


def init_db():
    """Initialize the database"""
    Base.metadata.create_all(bind=engine)


def get_db():
    """Dependency for getting database session"""
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()