"""Flashcard decks and cards — generate, browse, edit, delete."""
from fastapi import APIRouter, Depends, HTTPException, Query
from pydantic import BaseModel
from sqlalchemy import or_, text as sa_text
from sqlalchemy.orm import Session

from app.database import get_db
from app.models.flashcard import FlashcardDeck, Flashcard
from app.models.section import Section
from app.models.user import User
from app.utils.auth import get_current_user, require_moderator

router = APIRouter()


# ── Schemas ──────────────────────────────────────────────────────────

class FlashcardDeckCreate(BaseModel):
    section_id: int
    title: str
    model_id: str | None = None


class FlashcardDeckResponse(BaseModel):
    id: int
    title: str
    section_id: int | None
    user_id: int
    card_count: int
    created_at: object

    class Config:
        from_attributes = True


class FlashcardCardResponse(BaseModel):
    id: int
    deck_id: int
    front: str
    back: str
    page_reference: int | None = None
    image_path: str | None = None
    created_at: object

    class Config:
        from_attributes = True


class FlashcardDeckDetail(BaseModel):
    id: int
    title: str
    section_id: int | None
    user_id: int
    card_count: int
    created_at: object
    cards: list[FlashcardCardResponse]

    class Config:
        from_attributes = True


class CardEdit(BaseModel):
    front: str | None = None
    back: str | None = None


# ── Deck endpoints ───────────────────────────────────────────────────

@router.post("/")
def create_flashcard_deck(
    data: FlashcardDeckCreate,
    db: Session = Depends(get_db),
    current_user: User = Depends(require_moderator),
):
    """Start async flashcard generation from a section. Returns {job_id} immediately."""
    import uuid

    section = db.query(Section).filter(Section.id == data.section_id).first()
    if not section:
        raise HTTPException(status_code=404, detail="Section not found")
    if not current_user.is_admin and section.document.user_id != current_user.id:
        raise HTTPException(status_code=403, detail="Not your document")

    job_id = str(uuid.uuid4())

    try:
        from app.tasks.quiz_tasks import generate_flashcard_deck
        import redis as redis_lib
        from app.config import settings

        r = redis_lib.from_url(settings.REDIS_URL, decode_responses=True)
        r.set(f"extraction:status:{job_id}", "pending", ex=3600)
        r.lpush(f"extraction:user_jobs:{current_user.id}", job_id)
        r.expire(f"extraction:user_jobs:{current_user.id}", 86400)
        r.set(f"extraction:job_title:{job_id}", data.title, ex=3600)

        generate_flashcard_deck.delay(
            job_id=job_id,
            user_id=current_user.id,
            section_id=data.section_id,
            title=data.title,
            model_id=data.model_id,
        )
    except Exception:
        raise HTTPException(status_code=503, detail="Task queue unavailable")

    return {"job_id": job_id, "status": "pending"}


@router.get("/", response_model=list[FlashcardDeckResponse])
def list_flashcard_decks(
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """List flashcard decks. Moderators see all; regular users see own."""
    q = db.query(FlashcardDeck)
    if not current_user.is_moderator:
        q = q.filter(FlashcardDeck.user_id == current_user.id)
    return q.order_by(FlashcardDeck.created_at.desc()).all()


@router.get("/{deck_id}", response_model=FlashcardDeckDetail)
def get_flashcard_deck(
    deck_id: int,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """Get a deck with all its cards."""
    deck = db.query(FlashcardDeck).filter(FlashcardDeck.id == deck_id).first()
    if not deck:
        raise HTTPException(status_code=404, detail="Deck not found")
    if not current_user.is_moderator and deck.user_id != current_user.id:
        raise HTTPException(status_code=403, detail="Not your deck")
    return deck


@router.delete("/{deck_id}", status_code=204)
def delete_flashcard_deck(
    deck_id: int,
    db: Session = Depends(get_db),
    current_user: User = Depends(require_moderator),
):
    """Delete a deck and all its cards."""
    deck = db.query(FlashcardDeck).filter(FlashcardDeck.id == deck_id).first()
    if not deck:
        raise HTTPException(status_code=404, detail="Deck not found")
    db.delete(deck)
    db.commit()


# ── Card browse endpoints ────────────────────────────────────────────

@router.get("/cards/browse")
def browse_flashcards(
    q: str | None = Query(None),
    deck_id: int | None = Query(None),
    tag_ids: str | None = Query(None, description="Comma-separated tag IDs (AND filter)"),
    limit: int = Query(50, le=200),
    offset: int = Query(0),
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """Browse ALL flashcards across all decks (like question bank)."""
    query = db.query(Flashcard)

    # Restrict non-moderators to own decks
    if not current_user.is_moderator:
        own_deck_ids = [d.id for d in db.query(FlashcardDeck.id).filter(
            FlashcardDeck.user_id == current_user.id
        ).all()]
        if not own_deck_ids:
            return {"total": 0, "cards": []}
        query = query.filter(Flashcard.deck_id.in_(own_deck_ids))

    if deck_id:
        query = query.filter(Flashcard.deck_id == deck_id)

    if q and q.strip():
        phrase = q.strip()
        query = query.filter(
            or_(
                Flashcard.front.ilike(f"%{phrase}%"),
                Flashcard.back.ilike(f"%{phrase}%"),
            )
        )

    # Tag filter: cards must have ALL specified tags
    if tag_ids:
        tag_id_list = [int(t.strip()) for t in tag_ids.split(",") if t.strip().isdigit()]
        if tag_id_list:
            matching_ids = list(db.execute(sa_text("""
                SELECT flashcard_id FROM flashcard_tag_links
                WHERE tag_id = ANY(:tag_ids)
                GROUP BY flashcard_id
                HAVING COUNT(DISTINCT tag_id) = :cnt
            """), {"tag_ids": tag_id_list, "cnt": len(tag_id_list)}).scalars())
            if matching_ids:
                query = query.filter(Flashcard.id.in_(matching_ids))
            else:
                return {"total": 0, "cards": []}

    total = query.count()
    cards = query.order_by(Flashcard.deck_id, Flashcard.id).offset(offset).limit(limit).all()

    deck_cache: dict[int, str] = {}
    result = []
    for card in cards:
        if card.deck_id not in deck_cache:
            deck = db.query(FlashcardDeck).filter(FlashcardDeck.id == card.deck_id).first()
            deck_cache[card.deck_id] = deck.title if deck else f"Deck {card.deck_id}"
        result.append({
            "id": card.id,
            "deck_id": card.deck_id,
            "deck_title": deck_cache[card.deck_id],
            "front": card.front,
            "back": card.back,
            "page_reference": card.page_reference,
            "image_path": card.image_path,
            "created_at": card.created_at,
        })

    return {"total": total, "cards": result}


@router.get("/cards/browse/ids")
def browse_flashcard_ids(
    q: str | None = Query(None),
    deck_id: int | None = Query(None),
    tag_ids: str | None = Query(None, description="Comma-separated tag IDs (AND filter)"),
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """Return just IDs for matching cards (for select-all)."""
    query = db.query(Flashcard.id)

    if not current_user.is_moderator:
        own_deck_ids = [d.id for d in db.query(FlashcardDeck.id).filter(
            FlashcardDeck.user_id == current_user.id
        ).all()]
        if not own_deck_ids:
            return []
        query = query.filter(Flashcard.deck_id.in_(own_deck_ids))

    if deck_id:
        query = query.filter(Flashcard.deck_id == deck_id)

    if q and q.strip():
        phrase = q.strip()
        query = query.filter(
            or_(
                Flashcard.front.ilike(f"%{phrase}%"),
                Flashcard.back.ilike(f"%{phrase}%"),
            )
        )

    if tag_ids:
        tag_id_list = [int(t.strip()) for t in tag_ids.split(",") if t.strip().isdigit()]
        if tag_id_list:
            matching_ids = list(db.execute(sa_text("""
                SELECT flashcard_id FROM flashcard_tag_links
                WHERE tag_id = ANY(:tag_ids)
                GROUP BY flashcard_id
                HAVING COUNT(DISTINCT tag_id) = :cnt
            """), {"tag_ids": tag_id_list, "cnt": len(tag_id_list)}).scalars())
            if matching_ids:
                query = query.filter(Flashcard.id.in_(matching_ids))
            else:
                return []

    return [row[0] for row in query.all()]


# ── Single card endpoints ────────────────────────────────────────────

@router.put("/cards/{card_id}")
def update_flashcard(
    card_id: int,
    data: CardEdit,
    db: Session = Depends(get_db),
    current_user: User = Depends(require_moderator),
):
    """Edit a single flashcard (front, back). Requires moderator."""
    card = db.query(Flashcard).filter(Flashcard.id == card_id).first()
    if not card:
        raise HTTPException(status_code=404, detail="Card not found")
    if data.front is not None:
        card.front = data.front
    if data.back is not None:
        card.back = data.back
    db.commit()
    db.refresh(card)
    return {
        "id": card.id,
        "deck_id": card.deck_id,
        "front": card.front,
        "back": card.back,
        "page_reference": card.page_reference,
        "image_path": card.image_path,
    }


@router.delete("/cards/{card_id}", status_code=204)
def delete_flashcard(
    card_id: int,
    db: Session = Depends(get_db),
    current_user: User = Depends(require_moderator),
):
    """Delete a single flashcard. Requires moderator."""
    card = db.query(Flashcard).filter(Flashcard.id == card_id).first()
    if not card:
        raise HTTPException(status_code=404, detail="Card not found")
    deck = db.query(FlashcardDeck).filter(FlashcardDeck.id == card.deck_id).first()
    db.delete(card)
    if deck and deck.card_count > 0:
        deck.card_count -= 1
    db.commit()