from datetime import datetime, timezone
from sqlalchemy import String, Text, Boolean, DateTime, ForeignKey, Integer, UniqueConstraint
from sqlalchemy.orm import Mapped, mapped_column, relationship

from app.database import Base


def utcnow() -> datetime:
    return datetime.now(timezone.utc)


class Contest(Base):
    __tablename__ = "contests"

    id: Mapped[int] = mapped_column(primary_key=True)
    title: Mapped[str] = mapped_column(String(255), nullable=False)
    description: Mapped[str | None] = mapped_column(Text, nullable=True)
    start_time: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)
    end_time: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)
    is_active: Mapped[bool] = mapped_column(Boolean, default=False)
    show_leaderboard_during_contest: Mapped[bool] = mapped_column(Boolean, default=False)
    created_by: Mapped[int | None] = mapped_column(ForeignKey("users.id"), nullable=True)
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=utcnow)

    # Relationships
    creator = relationship("User", back_populates="created_contests")
    problems = relationship("Problem", back_populates="contest", cascade="all, delete-orphan")
    participants = relationship("ContestParticipant", back_populates="contest", cascade="all, delete-orphan")
    submissions = relationship("Submission", back_populates="contest", cascade="all, delete-orphan", passive_deletes=True)

    @property
    def is_running(self) -> bool:
        now = datetime.now(timezone.utc)
        start = self.start_time if self.start_time.tzinfo else self.start_time.replace(tzinfo=timezone.utc)
        end = self.end_time if self.end_time.tzinfo else self.end_time.replace(tzinfo=timezone.utc)
        return self.is_active and start <= now <= end

    @property
    def has_ended(self) -> bool:
        now = datetime.now(timezone.utc)
        end = self.end_time if self.end_time.tzinfo else self.end_time.replace(tzinfo=timezone.utc)
        return now > end


class ContestParticipant(Base):
    __tablename__ = "contest_participants"

    id: Mapped[int] = mapped_column(primary_key=True)
    contest_id: Mapped[int] = mapped_column(ForeignKey("contests.id", ondelete="CASCADE"), nullable=False)
    user_id: Mapped[int] = mapped_column(ForeignKey("users.id", ondelete="CASCADE"), nullable=False)
    joined_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=utcnow)

    # Relationships
    contest = relationship("Contest", back_populates="participants")
    user = relationship("User", back_populates="participations")

    __table_args__ = (
        UniqueConstraint("contest_id", "user_id", name="unique_contest_participant"),
    )