import uuid
import re
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

COLLECTION = "comments"
NOTIFICATIONS = "notifications"
ACTIVITY = "activity"


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


def _serialize(comment: dict[str, Any]) -> dict[str, Any]:
    return {
        "id": comment["_id"],
        "document_id": comment["document_id"],
        "body": comment["body"],
        "parent_id": comment.get("parent_id"),
        "author_id": comment["author_id"],
        "author_name": comment["author_name"],
        "created_at": comment["created_at"],
        "updated_at": comment["updated_at"],
        "resolved": comment.get("resolved", False),
    }


async def list_comments(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)
    return [_serialize(comment) async for comment in cursor]


async def create_comment(
    db: AsyncIOMotorDatabase,
    document_id: str,
    user_id: int,
    author_name: str,
    body: str,
    parent_id: str | None,
    mentioned_users: list[dict[str, Any]] | None = None,
) -> dict[str, Any] | None:
    document = await db["documents"].find_one({"_id": document_id, **access_query(user_id)})
    if document is None:
        return None
    if parent_id:
        parent = await db[COLLECTION].find_one({"_id": parent_id, "document_id": document_id})
        if parent is None:
            return None
    now = datetime.now(UTC)
    comment = {
        "_id": str(uuid.uuid4()),
        "document_id": document_id,
        "body": body.strip(),
        "parent_id": parent_id,
        "author_id": user_id,
        "author_name": author_name,
        "created_at": now,
        "updated_at": now,
        "resolved": False,
    }
    await db[COLLECTION].insert_one(comment)
    await db[ACTIVITY].insert_one({
        "_id": str(uuid.uuid4()),
        "document_id": document_id,
        "kind": "comment_created",
        "message": f"{author_name} commented on the page",
        "actor_name": author_name,
        "created_at": now,
    })
    for mentioned in mentioned_users or []:
        await db[NOTIFICATIONS].insert_one({
            "_id": str(uuid.uuid4()),
            "user_id": mentioned["id"],
            "kind": "mention",
            "message": f"{author_name} mentioned you in a comment",
            "document_id": document_id,
            "comment_id": comment["_id"],
            "actor_name": author_name,
            "read": False,
            "created_at": now,
        })
    return _serialize(comment)


async def delete_comment(db: AsyncIOMotorDatabase, comment_id: str, user_id: int) -> bool:
    comment = await db[COLLECTION].find_one({"_id": comment_id, "author_id": user_id})
    if comment is None:
        return False
    result = await db[COLLECTION].delete_one({"_id": comment_id, "author_id": user_id})
    return result.deleted_count == 1


async def resolve_comment(
    db: AsyncIOMotorDatabase,
    document_id: str,
    comment_id: str,
    user_id: int,
    resolved: bool,
    actor_name: str,
) -> dict[str, Any] | None:
    document = await db["documents"].find_one({"_id": document_id, **access_query(user_id)})
    if document is None:
        return None
    now = datetime.now(UTC)
    comment = await db[COLLECTION].find_one_and_update(
        {"_id": comment_id, "document_id": document_id},
        {"$set": {"resolved": resolved, "updated_at": now}},
        return_document=ReturnDocument.AFTER,
    )
    if comment is None:
        return None
    await db[ACTIVITY].insert_one({
        "_id": str(uuid.uuid4()),
        "document_id": document_id,
        "kind": "comment_resolved" if resolved else "comment_reopened",
        "message": f"{actor_name} {'resolved' if resolved else 'reopened'} a comment",
        "actor_name": actor_name,
        "created_at": now,
    })
    return _serialize(comment)


async def list_notifications(db: AsyncIOMotorDatabase, user_id: int) -> list[dict[str, Any]]:
    cursor = db[NOTIFICATIONS].find({"user_id": user_id}).sort("created_at", -1).limit(50)
    return [{
        "id": item["_id"],
        "kind": item["kind"],
        "message": item["message"],
        "document_id": item.get("document_id"),
        "comment_id": item.get("comment_id"),
        "actor_name": item["actor_name"],
        "read": item.get("read", False),
        "created_at": item["created_at"],
    } async for item in cursor]


async def mark_notifications_read(db: AsyncIOMotorDatabase, user_id: int) -> None:
    await db[NOTIFICATIONS].update_many({"user_id": user_id, "read": False}, {"$set": {"read": True}})


async def list_activity(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[ACTIVITY].find({"document_id": document_id}).sort("created_at", -1).limit(100)
    return [{
        "id": item["_id"],
        "document_id": item["document_id"],
        "kind": item["kind"],
        "message": item["message"],
        "actor_name": item["actor_name"],
        "created_at": item["created_at"],
    } async for item in cursor]


def mention_names(body: str) -> list[str]:
    return list(dict.fromkeys(re.findall(r"(?<![\w@])@([A-Za-z0-9_.-]{2,50})", body)))