"""教辅 (book) 业务层 — MongoDB 版本

幂等策略：
- 同 zip_sha256 直接 return 旧 book
- 同 (name, version, is_deleted) 唯一索引保护
"""
import re
from pymongo.errors import DuplicateKeyError

from db import get_collection, COL_BOOK, COL_DOC, COL_FILE, next_id, Book, BookDocument, DocumentFile
from db.models import _now


def create_book(name: str, zip_path: str, zip_sha256: str, zip_size: int = 0,
                subject: str | None = None, grade: str | None = None,
                version: str | None = None, type_: str | None = None,
                created_by: str | None = None) -> dict:
    """创建教辅。同 zip_sha256 幂等。"""
    col = get_collection(COL_BOOK)

    # 幂等查
    existing = col.find_one({'zip_sha256': zip_sha256, 'is_deleted': 0})
    if existing:
        b = Book.from_mongo(existing)
        return {
            'ok': True, 'idempotent': True, 'book_id': b.id,
            'status': b.status, 'total_count': b.total_count,
        }

    # 自增 book_id
    book_id = next_id('book_id')
    book = Book(
        id=book_id, name=name, zip_path=zip_path, zip_sha256=zip_sha256,
        zip_size=zip_size, subject=subject, grade=grade, version=version,
        type=type_, created_by=created_by, status='pending',
    )
    try:
        col.insert_one(book.to_mongo())
    except DuplicateKeyError:
        # uk_name_version 撞了，重查
        existing = col.find_one({'zip_sha256': zip_sha256, 'is_deleted': 0})
        if existing:
            b = Book.from_mongo(existing)
            return {
                'ok': True, 'idempotent': True, 'book_id': b.id,
                'status': b.status, 'total_count': b.total_count,
            }
        return {'ok': False, 'error': 'duplicate key (name+version)'}

    return {
        'ok': True, 'idempotent': False, 'book_id': book_id,
        'status': 'pending', 'total_count': 0,
    }


def get_book(book_id: int, include_documents: bool = True) -> dict | None:
    """查教辅（含所有 doc + file）"""
    col = get_collection(COL_BOOK)
    doc = col.find_one({'_id': book_id, 'is_deleted': 0})
    if not doc:
        return None
    book = Book.from_mongo(doc).to_dict()

    if include_documents:
        docs = list(get_collection(COL_DOC).find({'book_id': book_id})
                    .sort('order_index', 1))
        book['documents'] = []
        for d in docs:
            bd = BookDocument.from_mongo(d).to_dict()
            files = list(get_collection(COL_FILE).find({'doc_id': bd['doc_id']}))
            bd['files'] = [DocumentFile.from_mongo(f).to_dict() for f in files]
            book['documents'].append(bd)

    return book


def list_books(status: str | None = None, page: int = 1, page_size: int = 20,
               keyword: str | None = None) -> dict:
    """列表查询（分页）"""
    col = get_collection(COL_BOOK)
    q: dict = {'is_deleted': 0}
    if status:
        q['status'] = status
    if keyword:
        kw = re.escape(keyword)
        q['$or'] = [
            {'name': {'$regex': kw, '$options': 'i'}},
            {'subject': {'$regex': kw, '$options': 'i'}},
            {'grade': {'$regex': kw, '$options': 'i'}},
            {'version': {'$regex': kw, '$options': 'i'}},
        ]
    total = col.count_documents(q)
    cursor = (col.find(q).sort('created_at', -1)
              .skip((page - 1) * page_size).limit(page_size))
    books = [Book.from_mongo(d).to_dict() for d in cursor]
    return {'books': books, 'total': total, 'page': page, 'page_size': page_size}


def update_book_status(book_id: int, status: str, error_msg: str | None = None) -> bool:
    col = get_collection(COL_BOOK)
    upd = {'status': status, 'updated_at': _now()}
    if error_msg is not None:
        upd['error_msg'] = error_msg
    r = col.update_one({'_id': book_id, 'is_deleted': 0}, {'$set': upd})
    return r.matched_count > 0


def recompute_book_stats(book_id: int) -> None:
    """重算 total / success / failed，并触发状态机"""
    col_book = get_collection(COL_BOOK)
    col_doc = get_collection(COL_DOC)

    docs = list(col_doc.find({'book_id': book_id}))
    total = len(docs)
    success = sum(1 for d in docs if d.get('status') in ('html_ready', 'json_ready'))
    failed = sum(1 for d in docs if d.get('status') == 'failed')

    new_status = ('pending' if total == 0 else
                   'done' if failed == 0 else
                   'failed' if success == 0 else 'partial')

    book = col_book.find_one({'_id': book_id})
    if not book:
        return
    upd = {
        'total_count': total, 'success_count': success,
        'failed_count': failed, 'updated_at': _now(),
    }
    if book.get('status') != 'processing':
        upd['status'] = new_status
    col_book.update_one({'_id': book_id}, {'$set': upd})


def soft_delete_book(book_id: int) -> bool:
    col = get_collection(COL_BOOK)
    r = col.update_one({'_id': book_id, 'is_deleted': 0},
                       {'$set': {'is_deleted': 1, 'updated_at': _now()}})
    return r.matched_count > 0