from __future__ import annotations

from datetime import datetime
from typing import TYPE_CHECKING

from sqlalchemy import Boolean, DateTime, Float, ForeignKey, Integer, JSON, String, Text, func
from sqlalchemy.orm import Mapped, mapped_column, relationship

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

if TYPE_CHECKING:
    from app.models.previous_paper import PreviousPaper


class PreviousQuestion(Base):
    __tablename__ = "previous_questions"

    id: Mapped[str] = mapped_column(
        String(40),
        primary_key=True,
        default=lambda: prefixed_id("pq"),
    )
    previous_paper_id: Mapped[str] = mapped_column(
        String(40),
        ForeignKey("previous_papers.id", ondelete="CASCADE"),
        index=True,
        nullable=False,
    )
    question_number: Mapped[str | None] = mapped_column(String(40), nullable=True)
    question_text: Mapped[str] = mapped_column(Text, nullable=False)
    marks: Mapped[int | None] = mapped_column(Integer, nullable=True)
    subject: Mapped[str | None] = mapped_column(String(120), nullable=True)
    syllabus: Mapped[str | None] = mapped_column(String(120), nullable=True)
    year: Mapped[int | None] = mapped_column(Integer, nullable=True)
    chapter: Mapped[str | None] = mapped_column(String(180), nullable=True)
    topic: Mapped[str | None] = mapped_column(String(180), nullable=True)
    question_type: Mapped[str] = mapped_column(
        String(40),
        default="unknown",
        nullable=False,
    )
    difficulty: Mapped[str] = mapped_column(
        String(40),
        default="unknown",
        nullable=False,
    )
    keywords_json: Mapped[list[str]] = mapped_column(JSON, default=list, nullable=False)
    # ── T2: Enhanced PYQ extraction fields ──────────────────────────────────
    answer_type: Mapped[str | None] = mapped_column(String(40), nullable=True)
    formula_needed: Mapped[bool] = mapped_column(Boolean, default=False, nullable=False)
    diagram_needed: Mapped[bool] = mapped_column(Boolean, default=False, nullable=False)
    extracted_answer_if_available: Mapped[str | None] = mapped_column(Text, nullable=True)
    confidence: Mapped[float] = mapped_column(Float, default=0.0, nullable=False)
    source_origin: Mapped[str] = mapped_column(
        String(30),
        default="user_uploaded",
        nullable=False,
    )
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        server_default=func.now(),
        nullable=False,
    )

    previous_paper: Mapped["PreviousPaper"] = relationship(
        "PreviousPaper",
        back_populates="questions",
    )