"""Extracted questions, before they are questions.

A batch is one run of extraction. It is read, edited and decided here, and
nothing reaches the question bank — or takes a question id — until somebody
accepts it.
"""
from fastapi import APIRouter, Depends, HTTPException, Query
from pydantic import BaseModel, Field
from sqlalchemy import func
from sqlalchemy.orm import Session

from app.database import get_db
from app.models.draft_question import DraftBatch, DraftQuestion
from app.models.question_category import QuestionCategory
from app.models.user import User
from app.services import draft_questions as drafts
from app.utils.auth import get_current_user, require_moderator
from app.utils.quiz_questions import validate_key_points, validate_option_explanations

router = APIRouter()


def _counts(db: Session, batch_ids: list[int]) -> dict[int, dict[str, int]]:
    if not batch_ids:
        return {}
    rows = (db.query(DraftQuestion.batch_id, DraftQuestion.status, func.count(DraftQuestion.id))
            .filter(DraftQuestion.batch_id.in_(batch_ids))
            .group_by(DraftQuestion.batch_id, DraftQuestion.status).all())
    out: dict[int, dict[str, int]] = {}
    for batch_id, status, count in rows:
        out.setdefault(batch_id, {})[status] = count
    return out


def _get_batch(db: Session, batch_id: int) -> DraftBatch:
    batch = db.get(DraftBatch, batch_id)
    if not batch:
        raise HTTPException(404, "Batch not found")
    return batch


def _get_draft(db: Session, draft_id: int) -> tuple[DraftQuestion, DraftBatch]:
    draft = db.get(DraftQuestion, draft_id)
    if not draft:
        raise HTTPException(404, "Draft not found")
    return draft, _get_batch(db, draft.batch_id)


@router.get("/batches")
def list_batches(
    status: str | None = Query(None),
    db: Session = Depends(get_db),
    current_user: User = Depends(require_moderator),
):
    query = db.query(DraftBatch)
    if status:
        query = query.filter(DraftBatch.status == status)
    batches = query.order_by(DraftBatch.created_at.desc()).limit(200).all()
    counts = _counts(db, [b.id for b in batches])
    return [drafts.batch_json(db, b, counts.get(b.id, {})) for b in batches]


@router.get("/batches/{batch_id}")
def read_batch(
    batch_id: int,
    status: str | None = Query(None),
    db: Session = Depends(get_db),
    current_user: User = Depends(require_moderator),
):
    batch = _get_batch(db, batch_id)
    query = db.query(DraftQuestion).filter(DraftQuestion.batch_id == batch_id)
    if status:
        query = query.filter(DraftQuestion.status == status)
    rows = query.order_by(DraftQuestion.position, DraftQuestion.id).all()
    body = drafts.batch_json(db, batch, _counts(db, [batch_id]).get(batch_id, {}))
    body["drafts"] = [drafts.as_json(d) for d in rows]
    return body


class BatchEdit(BaseModel):
    title: str | None = None
    category_id: int | None = None
    status: str | None = None


@router.patch("/batches/{batch_id}")
def update_batch(
    batch_id: int,
    data: BatchEdit,
    db: Session = Depends(get_db),
    current_user: User = Depends(require_moderator),
):
    batch = _get_batch(db, batch_id)
    fields = data.model_dump(exclude_unset=True)
    if fields.get("status") and fields["status"] not in ("open", "closed"):
        raise HTTPException(400, "A batch is open or closed")
    if fields.get("category_id") is not None and not db.get(QuestionCategory, fields["category_id"]):
        raise HTTPException(400, "Category not found")
    for key, value in fields.items():
        setattr(batch, key, value)
    db.commit()
    return drafts.batch_json(db, batch, _counts(db, [batch_id]).get(batch_id, {}))


@router.delete("/batches/{batch_id}", status_code=204)
def delete_batch(
    batch_id: int,
    db: Session = Depends(get_db),
    current_user: User = Depends(require_moderator),
):
    """Throw a whole run away. Questions already accepted from it stay — they
    are in the bank now and are nothing to do with the batch any more."""
    db.delete(_get_batch(db, batch_id))
    db.commit()


class DraftEdit(BaseModel):
    question_text: str | None = None
    question_type: str | None = None
    options: list[str] | None = None
    correct_answer: str | None = None
    explanation: str | None = None
    option_explanations: dict | None = None
    key_points: list[dict] | None = None
    attending_tip: str | None = None
    difficulty: str | None = None
    category_id: int | None = None


@router.patch("/{draft_id}")
def update_draft(
    draft_id: int,
    data: DraftEdit,
    db: Session = Depends(get_db),
    current_user: User = Depends(require_moderator),
):
    """Fix a draft in place. This is the whole point of the staging table: it
    can be wrong, and be corrected, without anything being in the bank."""
    draft, _ = _get_draft(db, draft_id)
    if draft.status == "accepted":
        raise HTTPException(409, "That draft is in the bank; edit the question instead")
    fields = data.model_dump(exclude_unset=True)
    if "difficulty" in fields and fields["difficulty"] not in (None, "easy", "medium", "hard"):
        raise HTTPException(422, "Difficulty is easy, medium or hard")
    options = fields.get("options", draft.options)
    if "option_explanations" in fields:
        fields["option_explanations"] = validate_option_explanations(options, fields["option_explanations"])
    if "key_points" in fields:
        fields["key_points"] = validate_key_points(fields["key_points"], db)
    if fields.get("category_id") is not None and not db.get(QuestionCategory, fields["category_id"]):
        raise HTTPException(400, "Category not found")
    for key, value in fields.items():
        setattr(draft, key, value)
    # Worth knowing about a model's output: how much of it a human had to change.
    draft.edited = 1
    db.commit()
    return drafts.as_json(draft)


class Decision(BaseModel):
    ids: list[int] = Field(min_length=1, max_length=200)
    note: str | None = None


@router.post("/accept")
def accept_drafts(
    data: Decision,
    db: Session = Depends(get_db),
    current_user: User = Depends(require_moderator),
):
    """Put drafts into the bank. Each one becomes a question here and nowhere
    else, which is the only moment a question id is taken.

    All or nothing: a batch half-accepted because the twentieth draft was
    missing an answer is worse than a refusal naming it.
    """
    rows = db.query(DraftQuestion).filter(DraftQuestion.id.in_(data.ids)).all()
    missing = set(data.ids) - {row.id for row in rows}
    if missing:
        raise HTTPException(404, f"No such draft: {', '.join(str(m) for m in sorted(missing))}")

    batches = {b.id: b for b in db.query(DraftBatch).filter(
        DraftBatch.id.in_({row.batch_id for row in rows})).all()}

    # Everything is checked before anything is created. Creating as we go and
    # refusing part-way leaves questions in the bank from a call that reported
    # failure — and the caller has no way to know which.
    # Already in the bank is a different answer from not ready: one is a
    # conflict with what has happened, the other is work still to do.
    done = [row.id for row in rows if row.status == "accepted" and row.question_id]
    if done:
        raise HTTPException(409, "Already in the bank: "
                                 f"{', '.join(f'draft {i}' for i in sorted(done))}")
    faults = []
    for row in rows:
        found = drafts.problems(row)
        if found:
            faults.append(f"draft {row.id}: {', '.join(found)}")
    if faults:
        raise HTTPException(400, "; ".join(faults[:10]))

    made = []
    try:
        for row in sorted(rows, key=lambda r: (r.batch_id, r.position, r.id)):
            question = drafts.accept(db, row, batches[row.batch_id], current_user)
            made.append({"draft_id": row.id, "question_id": question.id})
        db.commit()
    except Exception:
        db.rollback()
        raise

    # A batch with nothing left to decide closes itself.
    for batch_id in {row.batch_id for row in rows}:
        left = db.query(DraftQuestion.id).filter(
            DraftQuestion.batch_id == batch_id, DraftQuestion.status == "pending").first()
        if not left:
            db.get(DraftBatch, batch_id).status = "closed"
    db.commit()
    return {"accepted": len(made), "questions": made}


@router.post("/reject")
def reject_drafts(
    data: Decision,
    db: Session = Depends(get_db),
    current_user: User = Depends(require_moderator),
):
    rows = db.query(DraftQuestion).filter(DraftQuestion.id.in_(data.ids)).all()
    for row in rows:
        drafts.reject(db, row, current_user, data.note)
    db.commit()
    return {"rejected": len(rows)}


@router.post("/{draft_id}/reopen")
def reopen_draft(
    draft_id: int,
    db: Session = Depends(get_db),
    current_user: User = Depends(require_moderator),
):
    draft, _ = _get_draft(db, draft_id)
    drafts.reopen(db, draft)
    db.commit()
    return drafts.as_json(draft)


@router.delete("/{draft_id}", status_code=204)
def delete_draft(
    draft_id: int,
    db: Session = Depends(get_db),
    current_user: User = Depends(require_moderator),
):
    """Remove a draft outright. Nothing in the bank is touched: a draft that
    was accepted has already become a question, which is its own row."""
    draft, _ = _get_draft(db, draft_id)
    db.delete(draft)
    db.commit()