"""知识点关系：全局 Knowledge + 章节/题目多对多 + 用户掌握度。"""
from __future__ import annotations

from sqlalchemy.orm import Session

from models import (
    ChapterKnowledge,
    Knowledge,
    KnowledgeRelation,
    KnowledgeResource,
    Question,
    QuestionKnowledge,
    UserKnowledge,
)


def ensure_knowledge(db: Session, name: str) -> Knowledge:
    clean = name.strip()
    row = db.query(Knowledge).filter(Knowledge.name == clean).first()
    if row is None:
        row = Knowledge(name=clean)
        db.add(row)
        db.flush()
    return row


def ensure_knowledge_relation(
    db: Session,
    source: Knowledge,
    target: Knowledge,
    relation_type: str = "前置",
) -> KnowledgeRelation:
    row = (
        db.query(KnowledgeRelation)
        .filter(
            KnowledgeRelation.source_id == source.id,
            KnowledgeRelation.target_id == target.id,
            KnowledgeRelation.relation_type == relation_type,
        )
        .first()
    )
    if row is None:
        row = KnowledgeRelation(
            source_id=source.id,
            target_id=target.id,
            relation_type=relation_type,
        )
        db.add(row)
        db.flush()
    return row


def chapter_knowledge_names(db: Session, chapter_id: int) -> list[str]:
    rows = (
        db.query(Knowledge.name)
        .join(ChapterKnowledge, ChapterKnowledge.knowledge_id == Knowledge.id)
        .filter(ChapterKnowledge.chapter_id == chapter_id)
        .order_by(ChapterKnowledge.id.asc())
        .all()
    )
    return [name for (name,) in rows]


def knowledge_resources(db: Session, knowledge_id: int) -> list[KnowledgeResource]:
    return (
        db.query(KnowledgeResource)
        .filter(KnowledgeResource.knowledge_id == knowledge_id)
        .order_by(KnowledgeResource.position.asc(), KnowledgeResource.id.asc())
        .all()
    )


def ensure_knowledge_resource(
    db: Session,
    knowledge_id: int,
    *,
    kind: str,
    title: str,
    url: str,
    textbook_id: int | None = None,
    course_id: int | None = None,
) -> KnowledgeResource:
    row = (
        db.query(KnowledgeResource)
        .filter(
            KnowledgeResource.knowledge_id == knowledge_id,
            KnowledgeResource.kind == kind,
            KnowledgeResource.url == url,
        )
        .first()
    )
    if row is None:
        row = KnowledgeResource(
            knowledge_id=knowledge_id,
            kind=kind,
            title=title,
            url=url,
            textbook_id=textbook_id,
            course_id=course_id,
        )
        db.add(row)
        db.flush()
    return row


def set_chapter_knowledge_names(
    db: Session, chapter_id: int, names: list[str]
) -> list[Knowledge]:
    cleaned = list(dict.fromkeys(name.strip() for name in names if name.strip()))
    db.query(ChapterKnowledge).filter(
        ChapterKnowledge.chapter_id == chapter_id
    ).delete(synchronize_session=False)
    db.flush()
    ordered: list[Knowledge] = []
    for name in cleaned:
        knowledge = ensure_knowledge(db, name)
        db.add(ChapterKnowledge(chapter_id=chapter_id, knowledge_id=knowledge.id))
        ordered.append(knowledge)
    db.flush()
    return ordered


def set_chapter_knowledge_ids(
    db: Session, chapter_id: int, knowledge_ids: list[int]
) -> list[Knowledge]:
    ids = list(dict.fromkeys(int(kid) for kid in knowledge_ids))
    rows = (
        db.query(Knowledge).filter(Knowledge.id.in_(ids)).all()
        if ids
        else []
    )
    by_id = {row.id: row for row in rows}
    if len(by_id) != len(ids):
        raise ValueError("部分知识点不存在")
    db.query(ChapterKnowledge).filter(
        ChapterKnowledge.chapter_id == chapter_id
    ).delete(synchronize_session=False)
    db.flush()
    ordered = [by_id[kid] for kid in ids]
    for knowledge in ordered:
        db.add(ChapterKnowledge(chapter_id=chapter_id, knowledge_id=knowledge.id))
    db.flush()
    return ordered


def question_knowledge_names(db: Session, question: Question) -> list[str]:
    rows = (
        db.query(Knowledge.name)
        .join(QuestionKnowledge, QuestionKnowledge.knowledge_id == Knowledge.id)
        .filter(QuestionKnowledge.question_id == question.id)
        .order_by(QuestionKnowledge.id.asc())
        .all()
    )
    names = [name for (name,) in rows]
    return names or ([question.knowledge_name] if question.knowledge_name else [])


def set_question_knowledge_names(
    db: Session,
    question: Question,
    names: list[str],
    *,
    attach_to_chapter: bool = False,
) -> list[Knowledge]:
    cleaned = list(dict.fromkeys(name.strip() for name in names if name.strip()))
    if not cleaned and question.knowledge_name:
        cleaned = [question.knowledge_name]
    db.query(QuestionKnowledge).filter(
        QuestionKnowledge.question_id == question.id
    ).delete(synchronize_session=False)
    db.flush()
    ordered: list[Knowledge] = []
    for name in cleaned:
        knowledge = ensure_knowledge(db, name)
        db.add(
            QuestionKnowledge(question_id=question.id, knowledge_id=knowledge.id)
        )
        ordered.append(knowledge)
        if attach_to_chapter and question.chapter_id is not None:
            exists = (
                db.query(ChapterKnowledge)
                .filter(
                    ChapterKnowledge.chapter_id == question.chapter_id,
                    ChapterKnowledge.knowledge_id == knowledge.id,
                )
                .first()
            )
            if exists is None:
                db.add(
                    ChapterKnowledge(
                        chapter_id=question.chapter_id,
                        knowledge_id=knowledge.id,
                    )
                )
    db.flush()
    if cleaned:
        question.knowledge_name = cleaned[0]
    return ordered


def ensure_user_knowledge(
    db: Session, user_id: int, knowledge: Knowledge
) -> UserKnowledge:
    row = (
        db.query(UserKnowledge)
        .filter(
            UserKnowledge.user_id == user_id,
            UserKnowledge.knowledge_id == knowledge.id,
        )
        .first()
    )
    if row is None:
        max_position = (
            db.query(UserKnowledge.position)
            .filter(UserKnowledge.user_id == user_id)
            .count()
        )
        row = UserKnowledge(
            user_id=user_id,
            knowledge_id=knowledge.id,
            mastery=60,
            position=max_position,
        )
        db.add(row)
        db.flush()
    return row