from __future__ import annotations

from datetime import datetime

from sqlalchemy import DateTime, ForeignKey, Index, String, func
from sqlalchemy.orm import Mapped, mapped_column

from app.core.database import Base
from app.utils.ids import prefixed_id


class PasswordResetToken(Base):
    """One-time password recovery token.

    Only the SHA-256 digest is persisted. The raw token exists only in the
    recovery link sent to the student and can therefore never be recovered
    from a database dump or application log.
    """

    __tablename__ = "password_reset_tokens"
    __table_args__ = (
        Index("ix_password_reset_tokens_user_created", "user_id", "created_at"),
        Index("ix_password_reset_tokens_hash", "token_hash", unique=True),
    )

    id: Mapped[str] = mapped_column(
        String(40),
        primary_key=True,
        default=lambda: prefixed_id("pwreset"),
    )
    user_id: Mapped[str] = mapped_column(
        String(40),
        ForeignKey("users.id", ondelete="CASCADE"),
        nullable=False,
        index=True,
    )
    token_hash: Mapped[str] = mapped_column(String(64), nullable=False)
    expires_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)
    used_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        server_default=func.now(),
        nullable=False,
    )