import uuid
from datetime import UTC, datetime
from typing import Any

from motor.motor_asyncio import AsyncIOMotorDatabase
from pymongo import ReturnDocument

from app.services.document_service import access_query, can_edit

COLLECTION = "document_versions"


async def ensure_history_indexes(db: AsyncIOMotorDatabase) -> None:
    await db[COLLECTION].create_index([("document_id", 1), ("created_at", -1)])


def serialize_version(version: dict[str, Any]) -> dict[str, Any]:
    return {
        "id": version["_id"],
        "document_id": version["document_id"],
        "title": version["title"],
        "content": version.get("content", {}),
        "created_by": version["created_by"],
        "created_at": version["created_at"],
        "reason": version.get("reason", "Updated"),
    }


async def create_version(
    db: AsyncIOMotorDatabase,
    document: dict[str, Any],
    actor_id: int,
    actor_name: str,
    reason: str,
) -> None:
    if not can_edit(document, actor_id):
        return
    await db[COLLECTION].insert_one({
        "_id": str(uuid.uuid4()),
        "document_id": document["_id"],
        "title": document["title"],
        "content": document.get("content", {}),
        "created_by": actor_name,
        "created_at": datetime.now(UTC),
        "reason": reason,
    })


async def list_versions(
    db: AsyncIOMotorDatabase,
    document_id: str,
    user_id: int,
) -> list[dict[str, Any]] | None:
    document = await db["documents"].find_one({"_id": document_id, **access_query(user_id)})
    if document is None:
        return None
    cursor = db[COLLECTION].find({"document_id": document_id}).sort("created_at", -1).limit(50)
    return [serialize_version(version) async for version in cursor]


async def restore_version(
    db: AsyncIOMotorDatabase,
    document_id: str,
    version_id: str,
    user_id: int,
    actor_name: str,
) -> dict[str, Any] | None:
    document = await db["documents"].find_one({"_id": document_id, **access_query(user_id)})
    if document is None or not can_edit(document, user_id):
        return None
    version = await db[COLLECTION].find_one({"_id": version_id, "document_id": document_id})
    if version is None:
        return None
    await create_version(db, document, user_id, actor_name, "Before restore")
    now = datetime.now(UTC)
    updated = await db["documents"].find_one_and_update(
        {"_id": document_id},
        {"$set": {"title": version["title"], "content": version.get("content", {}), "updated_at": now}},
        return_document=ReturnDocument.AFTER,
    )
    return updated