from sqlalchemy import Column, Integer, String, Text, DateTime, ForeignKey, JSON, Boolean, Table
from sqlalchemy.orm import relationship
from datetime import datetime
from .database import Base


# Default statuses for new projects
DEFAULT_STATUSES = ["backlog", "in_progress", "on_hold", "done"]


# Association table for task blocker relationships (many-to-many)
task_blockers = Table(
    "task_blockers",
    Base.metadata,
    Column("task_id", Integer, ForeignKey("tasks.id", ondelete="CASCADE"), primary_key=True),
    Column("blocked_by_id", Integer, ForeignKey("tasks.id", ondelete="CASCADE"), primary_key=True),
)


class Project(Base):
    __tablename__ = "projects"

    id = Column(Integer, primary_key=True, index=True)
    name = Column(String(255), nullable=False)
    description = Column(Text, nullable=True)
    statuses = Column(JSON, nullable=False, default=DEFAULT_STATUSES)
    is_archived = Column(Boolean, default=False, nullable=False)
    created_at = Column(DateTime, default=datetime.utcnow)
    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)

    tasks = relationship("Task", back_populates="project", cascade="all, delete-orphan")


class Task(Base):
    __tablename__ = "tasks"

    id = Column(Integer, primary_key=True, index=True)
    project_id = Column(Integer, ForeignKey("projects.id"), nullable=False)
    parent_task_id = Column(Integer, ForeignKey("tasks.id"), nullable=True)
    title = Column(String(500), nullable=False)
    description = Column(Text, nullable=True)
    status = Column(String(50), default="backlog", nullable=False)
    sort_order = Column(Integer, default=0)
    estimated_minutes = Column(Integer, nullable=True)
    tags = Column(JSON, nullable=True)
    flag_color = Column(String(50), nullable=True)
    created_at = Column(DateTime, default=datetime.utcnow)
    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)

    project = relationship("Project", back_populates="tasks")
    parent = relationship("Task", remote_side=[id], backref="subtasks")

    # blockers: tasks that must be done before this task can start
    # blocking: tasks that this task is holding up
    blockers = relationship(
        "Task",
        secondary=task_blockers,
        primaryjoin=lambda: Task.id == task_blockers.c.task_id,
        secondaryjoin=lambda: Task.id == task_blockers.c.blocked_by_id,
        backref="blocking",
    )