"""文档文件 (document_file) 业务层 — MongoDB 版本

upsert 策略：(doc_id, file_type) 唯一索引 → update_one / insert_one
"""
from pymongo.errors import DuplicateKeyError

from db import get_collection, COL_FILE, next_id, DocumentFile
from db.models import _now


def upsert_file(doc_id: str, file_type: str, object_key: str, object_bucket: str,
                size: int = 0, checksum: str | None = None, url: str | None = None,
                meta: dict | None = None) -> dict:
    """插入或更新 (doc_id, file_type) 唯一键"""
    col = get_collection(COL_FILE)
    filt = {'doc_id': doc_id, 'file_type': file_type}
    upd = {'$set': {
        'object_key': object_key, 'object_bucket': object_bucket,
        'size': size, 'checksum': checksum, 'url': url, 'meta': meta,
    }}
    r = col.update_one(filt, upd)
    if r.matched_count > 0:
        f = col.find_one(filt)
        return {'id': f['_id'], 'updated': True}
    f = DocumentFile(
        id=next_id('file_id'),
        doc_id=doc_id, file_type=file_type, object_key=object_key,
        object_bucket=object_bucket, size=size, checksum=checksum,
        url=url, meta=meta,
    )
    try:
        col.insert_one(f.to_mongo())
    except DuplicateKeyError:
        # 极小概率竞争，重试
        f2 = col.find_one(filt)
        col.update_one(filt, upd)
        return {'id': f2['_id'], 'updated': True}
    return {'id': f.id, 'updated': False}


def get_files(doc_id: str) -> list[dict]:
    col = get_collection(COL_FILE)
    return [DocumentFile.from_mongo(d).to_dict()
            for d in col.find({'doc_id': doc_id})]


def get_file_by_type(doc_id: str, file_type: str) -> dict | None:
    col = get_collection(COL_FILE)
    d = col.find_one({'doc_id': doc_id, 'file_type': file_type})
    return DocumentFile.from_mongo(d).to_dict() if d else None