"""study_cards API — 암기카드 검수 (공부 암기노트 Phase 1 검수 UI).

needs_review=true 카드를 '출처 문제별 그룹'으로 보고 채택(approve)/수정(edit)/폐기(delete).
별 라우터(prefix=/api/study-cards)라 /api/study-questions/{id} 와 경로 충돌 없음.
정적 경로(/needs-review/count, /approve-batch)는 /{card_id} 보다 먼저 정의.

결정(2026-06-07):
  - 수정(cue/fact/cloze 편집) 시 dedup_hash 재계산 + needs_review=false(사용자 확정본). flagged 클리어.
  - 전체 일괄승인 버튼 없음 — approve-batch 는 source_question_id 단위(그 문제의 카드만).
"""

from __future__ import annotations

from datetime import datetime, timezone
from typing import Annotated

from fastapi import APIRouter, Depends, HTTPException, Query
from pydantic import BaseModel
from sqlalchemy import func, select, update
from sqlalchemy.exc import IntegrityError
from sqlalchemy.ext.asyncio import AsyncSession

from core.auth import get_current_user
from core.database import get_session
from models.study_memo_card import StudyMemoCard, StudyMemoCardEvidence
from models.study_question import StudyQuestion
from models.user import User
from services.study.card_normalize import compute_dedup_hash

router = APIRouter()


class CardEvidence(BaseModel):
    source_type: str
    source_id: int | None = None
    snippet: str | None = None


class CardItem(BaseModel):
    id: int
    source_kind: str = "question"
    format: str
    cue: str
    fact: str
    cloze_text: str | None = None
    needs_review: bool
    flagged_by: str | None = None
    evidence: list[CardEvidence] = []


class CardQuestionGroup(BaseModel):
    source_question_id: int | None = None
    question_text: str | None = None
    correct_choice: int | None = None
    cards: list[CardItem] = []


class CardUpdate(BaseModel):
    needs_review: bool | None = None
    cue: str | None = None
    fact: str | None = None
    cloze_text: str | None = None


class ApproveBatch(BaseModel):
    source_question_id: int


def _verify_card(card: StudyMemoCard | None, user: User) -> StudyMemoCard:
    if card is None or card.user_id != user.id or card.deleted_at is not None:
        raise HTTPException(status_code=404, detail="카드를 찾을 수 없습니다")
    return card


@router.get("/needs-review/count")
async def count_needs_review_cards(
    user: Annotated[User, Depends(get_current_user)],
    session: Annotated[AsyncSession, Depends(get_session)],
):
    """검수 대기 카드 수 (배지용)."""
    n = (
        await session.execute(
            select(func.count())
            .select_from(StudyMemoCard)
            .where(
                StudyMemoCard.user_id == user.id,
                StudyMemoCard.deleted_at.is_(None),
                StudyMemoCard.needs_review,
            )
        )
    ).scalar_one()
    return {"count": n}


@router.get("", response_model=list[CardQuestionGroup])
async def list_cards(
    user: Annotated[User, Depends(get_current_user)],
    session: Annotated[AsyncSession, Depends(get_session)],
    needs_review: Annotated[bool, Query()] = True,
    format: Annotated[str | None, Query()] = None,
    limit: Annotated[int, Query(ge=1, le=2000)] = 600,
):
    """카드 목록 — 출처 문제별 그룹. 기본 needs_review=true 검수 큐."""
    conds = [StudyMemoCard.user_id == user.id, StudyMemoCard.deleted_at.is_(None)]
    if needs_review:
        conds.append(StudyMemoCard.needs_review)
    if format in ("qa", "cloze"):
        conds.append(StudyMemoCard.format == format)

    rows = (
        await session.execute(
            select(StudyMemoCard)
            .where(*conds)
            .order_by(StudyMemoCard.source_question_id.asc().nulls_last(), StudyMemoCard.id.asc())
            .limit(limit)
        )
    ).scalars().all()
    if not rows:
        return []

    # evidence 일괄 조회
    card_ids = [c.id for c in rows]
    ev_rows = (
        await session.execute(
            select(StudyMemoCardEvidence).where(StudyMemoCardEvidence.card_id.in_(card_ids))
        )
    ).scalars().all()
    ev_by_card: dict[int, list[CardEvidence]] = {}
    for e in ev_rows:
        ev_by_card.setdefault(e.card_id, []).append(
            CardEvidence(source_type=e.source_type, source_id=e.source_id, snippet=e.snippet)
        )

    # 출처 문제 메타 일괄 조회
    qids = sorted({c.source_question_id for c in rows if c.source_question_id is not None})
    q_meta: dict[int, tuple[str, int]] = {}
    if qids:
        q_rows = (
            await session.execute(
                select(StudyQuestion.id, StudyQuestion.question_text, StudyQuestion.correct_choice)
                .where(StudyQuestion.id.in_(qids))
            )
        ).all()
        q_meta = {r.id: (r.question_text, r.correct_choice) for r in q_rows}

    # 그룹핑 (출제순서=rows 순서 유지). question 카드는 출처 문제별,
    # manual(직접 추가) 카드는 extra.material 별로 묶는다.
    groups: dict[str, CardQuestionGroup] = {}
    order: list[str] = []
    for c in rows:
        if c.source_question_id is not None:
            gkey = f"q:{c.source_question_id}"
        else:
            material = c.extra.get("material") if isinstance(c.extra, dict) else None
            gkey = f"m:{material or '직접 추가'}"
        if gkey not in groups:
            if c.source_question_id is not None:
                qt, cc = q_meta.get(c.source_question_id, (None, None))
                groups[gkey] = CardQuestionGroup(
                    source_question_id=c.source_question_id, question_text=qt, correct_choice=cc, cards=[]
                )
            else:
                material = c.extra.get("material") if isinstance(c.extra, dict) else None
                groups[gkey] = CardQuestionGroup(
                    source_question_id=None,
                    question_text=(f"[자료] {material}" if material else "직접 추가 카드"),
                    correct_choice=None, cards=[],
                )
            order.append(gkey)
        groups[gkey].cards.append(
            CardItem(
                id=c.id, source_kind=c.source_kind, format=c.format, cue=c.cue, fact=c.fact,
                cloze_text=c.cloze_text, needs_review=c.needs_review, flagged_by=c.flagged_by,
                evidence=ev_by_card.get(c.id, []),
            )
        )
    return [groups[k] for k in order]


@router.post("/approve-batch")
async def approve_batch(
    body: ApproveBatch,
    user: Annotated[User, Depends(get_current_user)],
    session: Annotated[AsyncSession, Depends(get_session)],
):
    """한 출처 문제의 검수 대기 카드를 일괄 승인(needs_review=false). 전체 일괄승인은 없음."""
    result = await session.execute(
        update(StudyMemoCard)
        .where(
            StudyMemoCard.user_id == user.id,
            StudyMemoCard.source_question_id == body.source_question_id,
            StudyMemoCard.deleted_at.is_(None),
            StudyMemoCard.needs_review,
        )
        .values(needs_review=False, flagged_by=None, flagged_at=None)
    )
    await session.commit()
    return {"approved": result.rowcount or 0}


@router.patch("/{card_id}", response_model=CardItem)
async def update_card(
    card_id: int,
    body: CardUpdate,
    user: Annotated[User, Depends(get_current_user)],
    session: Annotated[AsyncSession, Depends(get_session)],
):
    """승인(needs_review=false) 또는 수정(cue/fact/cloze). 내용 수정 시 dedup_hash 재계산 + 검수완료."""
    card = await session.get(StudyMemoCard, card_id)
    card = _verify_card(card, user)
    fields_set = body.model_fields_set

    content_changed = False
    for fname in {"cue", "fact", "cloze_text"} & fields_set:
        setattr(card, fname, getattr(body, fname))
        content_changed = True

    if content_changed:
        # 정답 토큰(fact) 기준 dedup_hash 재계산 + 사용자 확정본 → 검수 완료.
        card.dedup_hash = compute_dedup_hash(card.source_question_id, card.format, card.fact)
        card.needs_review = False
        card.flagged_by = None
        card.flagged_at = None
    elif "needs_review" in fields_set:
        card.needs_review = bool(body.needs_review)
        if card.needs_review:
            card.flagged_by = "user"
            card.flagged_at = datetime.now(timezone.utc)
        else:
            card.flagged_by = None
            card.flagged_at = None

    try:
        await session.commit()
    except IntegrityError:
        await session.rollback()
        raise HTTPException(status_code=409, detail="같은 정답의 중복 카드가 이미 있습니다")

    return CardItem(
        id=card.id, source_kind=card.source_kind, format=card.format, cue=card.cue, fact=card.fact,
        cloze_text=card.cloze_text, needs_review=card.needs_review, flagged_by=card.flagged_by, evidence=[],
    )


@router.delete("/{card_id}", status_code=204)
async def delete_card(
    card_id: int,
    user: Annotated[User, Depends(get_current_user)],
    session: Annotated[AsyncSession, Depends(get_session)],
):
    """저품질 카드 soft-delete. partial unique(WHERE deleted_at IS NULL)가 자연 정합."""
    card = await session.get(StudyMemoCard, card_id)
    card = _verify_card(card, user)
    card.deleted_at = datetime.now(timezone.utc)
    await session.commit()