/*
 * Copyright (C) 2026 Fluxer Contributors
 *
 * This file is part of Fluxer.
 *
 * Fluxer is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Fluxer is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with Fluxer. If not, see <https://www.gnu.org/licenses/>.
 */

import {makeAutoObservable} from 'mobx';
import {RelationshipTypes} from '~/Constants';
import type {GuildMemberRecord} from '~/records/GuildMemberRecord';
import type {GuildRecord} from '~/records/GuildRecord';
import GuildMemberStore from '~/stores/GuildMemberStore';
import GuildStore from '~/stores/GuildStore';
import RelationshipStore from '~/stores/RelationshipStore';
import UserStore from '~/stores/UserStore';

export enum MemberSearchWorkerMessageTypes {
	UPDATE_USERS = 'UPDATE_USERS',
	USER_RESULTS = 'USER_RESULTS',
	QUERY_SET = 'QUERY_SET',
	QUERY_CLEAR = 'QUERY_CLEAR',
}

export interface MemberSearchFilters {
	friends?: boolean;
	guild?: string;
}

export interface TransformedMember {
	id: string;
	username: string;
	isBot?: boolean;
	isFriend?: boolean;
	guildIds?: Array<string>;
	_delete?: boolean;
	_removeGuild?: string;
	[key: string]: string | boolean | undefined | Array<string>;
}

export type QueryBlacklist = Set<string>;
export type QueryWhitelist = Set<string>;
export type QueryBoosters = Record<string, number>;

interface QueryData {
	query: string;
	filters?: MemberSearchFilters;
	blacklist: Array<string>;
	whitelist: Array<string>;
	boosters: QueryBoosters;
	limit: number;
}

interface WorkerMessage {
	type: MemberSearchWorkerMessageTypes;
	payload?: unknown;
	uuid?: string;
}

interface MemberResultsMessage extends WorkerMessage {
	type: MemberSearchWorkerMessageTypes.USER_RESULTS;
	uuid: string;
	payload: Array<TransformedMember>;
}

interface UpdateMembersMessage extends WorkerMessage {
	type: MemberSearchWorkerMessageTypes.UPDATE_USERS;
	payload: {users: Array<TransformedMember>};
}

interface QuerySetMessage extends WorkerMessage {
	type: MemberSearchWorkerMessageTypes.QUERY_SET;
	uuid: string;
	payload: QueryData;
}

interface QueryClearMessage extends WorkerMessage {
	type: MemberSearchWorkerMessageTypes.QUERY_CLEAR;
	uuid: string;
}

const DEFAULT_LIMIT = 10;

let worker: Worker | null = null;

function updateMembers(members: Array<TransformedMember>): void {
	if (!worker) {
		return;
	}

	const filtered = members.filter((member) => member != null);
	if (filtered.length === 0) {
		return;
	}

	worker.postMessage({
		type: MemberSearchWorkerMessageTypes.UPDATE_USERS,
		payload: {users: filtered},
	} as UpdateMembersMessage);
}

function isFriendRelationship(userId: string): boolean {
	const relationship = RelationshipStore.getRelationship(userId);
	return relationship?.type === RelationshipTypes.FRIEND;
}

function applyFriendFlag(member: TransformedMember): void {
	member.isFriend = isFriendRelationship(member.id);
}

function getTransformedMember(memberRecord: GuildMemberRecord, guildId?: string): TransformedMember | null {
	const user = memberRecord.user;

	const member: TransformedMember = {
		id: user.id,
		username: user.discriminator === '0' ? user.username : `${user.username}#${user.discriminator}`,
		guildIds: [],
	};

	if (user.bot) {
		member.isBot = true;
	}

	if (guildId) {
		member[guildId] = true;
		member.guildIds = [guildId];
	}

	applyFriendFlag(member);

	return member;
}

function updateMembersList(members: Array<GuildMemberRecord>, guildId?: string): Array<TransformedMember> {
	const transformedMembers: Array<TransformedMember> = [];

	for (const memberRecord of members) {
		const member = getTransformedMember(memberRecord, guildId);
		if (member) {
			transformedMembers.push(member);
		}
	}

	return transformedMembers;
}

export class SearchContext {
	private readonly _uuid: string;
	private readonly _callback: (results: Array<TransformedMember>) => void;
	private readonly _limit: number;
	private _currentQuery: QueryData | false | null;
	private _nextQuery: QueryData | null;
	private readonly _handleMessages: (event: MessageEvent<WorkerMessage>) => void;

	constructor(callback: (results: Array<TransformedMember>) => void, limit: number = DEFAULT_LIMIT) {
		this._uuid = crypto.randomUUID();
		this._callback = callback;
		this._limit = limit;
		this._currentQuery = null;
		this._nextQuery = null;

		this._handleMessages = (event: MessageEvent<WorkerMessage>) => {
			const data = event.data;
			if (!data || data.type !== MemberSearchWorkerMessageTypes.USER_RESULTS) {
				return;
			}
			const resultsMessage = data as MemberResultsMessage;
			if (resultsMessage.uuid !== this._uuid) {
				return;
			}
			if (this._currentQuery !== false) {
				this._callback(resultsMessage.payload);
			}
			if (this._currentQuery != null) {
				this._currentQuery = null;
			}
			this._setNextQuery();
		};

		if (worker) {
			worker.addEventListener('message', this._handleMessages);
		}
	}

	destroy(): void {
		if (worker) {
			worker.removeEventListener('message', this._handleMessages);
		}
		this.clearQuery();
	}

	clearQuery(): void {
		this._currentQuery = false;
		this._nextQuery = null;

		if (worker) {
			worker.postMessage({
				uuid: this._uuid,
				type: MemberSearchWorkerMessageTypes.QUERY_CLEAR,
			} as QueryClearMessage);
		}
	}

	setQuery(
		query: string,
		filters: MemberSearchFilters = {},
		blacklist: QueryBlacklist = new Set(),
		whitelist: QueryWhitelist = new Set(),
		boosters: QueryBoosters = {},
	): void {
		if (query == null) {
			return;
		}

		this._nextQuery = {
			query,
			filters,
			blacklist: Array.from(blacklist),
			whitelist: Array.from(whitelist),
			boosters,
			limit: this._limit,
		};

		this._setNextQuery();
	}

	private _setNextQuery(): void {
		if (this._currentQuery || !this._nextQuery) {
			return;
		}

		this._currentQuery = this._nextQuery;
		this._nextQuery = null;

		if (worker) {
			worker.postMessage({
				uuid: this._uuid,
				type: MemberSearchWorkerMessageTypes.QUERY_SET,
				payload: this._currentQuery,
			} as QuerySetMessage);
		}
	}
}

class MemberSearchStore {
	private initialized: boolean = false;
	private readonly inFlightFetches = new Map<string, Promise<void>>();

	constructor() {
		makeAutoObservable(this);
	}

	initialize(): void {
		if (this.initialized || worker) {
			return;
		}

		this.initialized = true;

		try {
			worker = new Worker(new URL('../workers/MemberSearch.worker.ts', import.meta.url), {
				type: 'module',
			});

			this.sendInitialMembers();
		} catch (err) {
			console.error('[MemberSearchStore] Failed to initialize worker:', err);
		}
	}

	private sendInitialMembers(): void {
		if (!worker) {
			return;
		}

		const allMembers: Array<TransformedMember> = [];

		const guilds = GuildStore.getGuilds();
		for (const guild of guilds) {
			const members = GuildMemberStore.getMembers(guild.id);
			const transformedMembers = updateMembersList(members, guild.id);
			allMembers.push(...transformedMembers);
		}

		updateMembers(allMembers);
	}

	handleConnectionOpen(): void {
		if (worker) {
			this.terminate();
		}

		this.initialize();
	}

	handleLogout(): void {
		this.terminate();
		this.initialized = false;
	}

	handleGuildCreate(guildId: string): void {
		if (!worker) return;

		const members = GuildMemberStore.getMembers(guildId);
		const transformedMembers = updateMembersList(members, guildId);
		updateMembers(transformedMembers);
	}

	handleGuildDelete(guildId: string): void {
		if (!worker) return;

		const members = GuildMemberStore.getMembers(guildId);
		const transformedMembers = updateMembersList(members, guildId);

		updateMembers(
			transformedMembers.map((m) => ({
				id: m.id,
				username: m.username,
				isBot: m.isBot,
				_removeGuild: guildId,
			})),
		);
	}

	handleMemberAdd(guildId: string, memberId: string): void {
		if (!worker) return;

		const member = GuildMemberStore.getMember(guildId, memberId);
		if (!member) return;

		const transformedMember = getTransformedMember(member, guildId);
		if (transformedMember) {
			updateMembers([transformedMember]);
		}
	}

	handleMemberUpdate(guildId: string, memberId: string): void {
		if (!worker) return;

		const member = GuildMemberStore.getMember(guildId, memberId);
		if (!member) return;

		const transformedMember = getTransformedMember(member, guildId);
		if (transformedMember) {
			updateMembers([transformedMember]);
		}
	}

	handleMembersChunk(guildId: string, members: Array<GuildMemberRecord>): void {
		if (!worker) return;

		const transformedMembers = updateMembersList(members, guildId);
		updateMembers(transformedMembers);
	}

	handleUserUpdate(userId: string): void {
		if (!worker) return;

		const guilds = GuildStore.getGuilds();
		const allMembers: Array<TransformedMember> = [];

		for (const guild of guilds) {
			const member = GuildMemberStore.getMember(guild.id, userId);
			if (member) {
				const transformedMember = getTransformedMember(member, guild.id);
				if (transformedMember) {
					allMembers.push(transformedMember);
				}
			}
		}

		if (allMembers.length > 0) {
			updateMembers(allMembers);
		}
	}

	handleFriendshipChange(userId: string, isFriend: boolean): void {
		if (!worker) return;

		const user = UserStore.getUser(userId);
		if (!user) return;

		const username = user.discriminator === '0' ? user.username : `${user.username}#${user.discriminator}`;

		updateMembers([{id: userId, username, isFriend}]);
	}

	getSearchContext(
		callback: (results: Array<TransformedMember>) => void,
		limit: number = DEFAULT_LIMIT,
	): SearchContext {
		if (!worker) {
			this.initialize();
		}

		return new SearchContext(callback, limit);
	}

	private terminate(): void {
		if (worker) {
			worker.terminate();
			worker = null;
		}
	}

	cleanup(): void {
		this.terminate();
		this.initialized = false;
		this.inFlightFetches.clear();
	}

	async fetchMembersInBackground(query: string, guildIds: Array<string>, priorityGuildId?: string): Promise<void> {
		const trimmed = query.trim();
		if (!trimmed) {
			return;
		}

		if (!guildIds || guildIds.length === 0) {
			return;
		}

		const sortedGuildIds = priorityGuildId
			? [...guildIds].sort((a, b) => (a === priorityGuildId ? -1 : b === priorityGuildId ? 1 : 0))
			: guildIds;

		const promises = sortedGuildIds.map(async (guildId) => {
			if (!guildId) {
				return;
			}

			const guild = GuildStore.getGuild(guildId);
			if (!guild) {
				return;
			}

			if (GuildMemberStore.isGuildFullyLoaded(guildId)) {
				return;
			}

			const key = `${guildId}:${trimmed.toLowerCase()}`;
			const existing = this.inFlightFetches.get(key);
			if (existing) {
				await existing;
				return;
			}

			const promise = this.fetchFromGuild(guild, trimmed).finally(() => {
				this.inFlightFetches.delete(key);
			});

			this.inFlightFetches.set(key, promise);
			await promise;
		});

		await Promise.all(promises);
	}

	private async fetchFromGuild(guild: GuildRecord, query: string): Promise<void> {
		if (GuildMemberStore.isGuildFullyLoaded(guild.id)) {
			return;
		}

		try {
			const members = (await GuildMemberStore.fetchMembers(guild.id, {query, limit: 25})) as Array<GuildMemberRecord>;
			if (members.length > 0) {
				const transformedMembers = updateMembersList(members, guild.id);
				updateMembers(transformedMembers);
			}
		} catch (error) {
			console.error('[MemberSearchStore] fetchFromGuild failed:', error);
		}
	}
}

export default new MemberSearchStore();