import * as mongo from 'mongodb';
import * as promiseLimit from 'promise-limit';

import config from '../../../config';
import Resolver from '../resolver';
import Note, { INote } from '../../../models/note';
import post from '../../../services/note/create';
import { INote as INoteActivityStreamsObject, IObject } from '../type';
import { resolvePerson, updatePerson } from './person';
import { resolveImage } from './image';
import { IRemoteUser, IUser } from '../../../models/user';
import { fromHtml } from '../../../mfm/fromHtml';
import Emoji, { IEmoji } from '../../../models/emoji';
import { ITag, extractHashtags } from './tag';
import { toUnicode } from 'punycode';
import { unique, concat, difference } from '../../../prelude/array';
import { extractPollFromQuestion } from './question';
import vote from '../../../services/note/polls/vote';
import { apLogger } from '../logger';
import { IDriveFile } from '../../../models/drive-file';
import { deliverQuestionUpdate } from '../../../services/note/polls/update';

const logger = apLogger;

/**
 * Noteをフェッチします。
 *
 * Misskeyに対象のNoteが登録されていればそれを返します。
 */
export async function fetchNote(value: string | IObject, resolver?: Resolver): Promise<INote> {
	const uri = typeof value == 'string' ? value : value.id;

	// URIがこのサーバーを指しているならデータベースからフェッチ
	if (uri.startsWith(config.url + '/')) {
		const id = new mongo.ObjectID(uri.split('/').pop());
		return await Note.findOne({ _id: id });
	}

	//#region このサーバーに既に登録されていたらそれを返す
	const exist = await Note.findOne({ uri });

	if (exist) {
		return exist;
	}
	//#endregion

	return null;
}

/**
 * Noteを作成します。
 */
export async function createNote(value: any, resolver?: Resolver, silent = false): Promise<INote> {
	if (resolver == null) resolver = new Resolver();

	const object: any = await resolver.resolve(value);

	if (!object || !['Note', 'Question'].includes(object.type)) {
		logger.error(`invalid note: ${value}`, {
			resolver: {
				history: resolver.getHistory()
			},
			value: value,
			object: object
		});
		return null;
	}

	const note: INoteActivityStreamsObject = object;

	logger.debug(`Note fetched: ${JSON.stringify(note, null, 2)}`);

	logger.info(`Creating the Note: ${note.id}`);

	// 投稿者をフェッチ
	const actor = await resolvePerson(note.attributedTo, null, resolver) as IRemoteUser;

	// 投稿者が凍結されていたらスキップ
	if (actor.isSuspended) {
		return null;
	}

	//#region Visibility
	note.to = note.to == null ? [] : typeof note.to == 'string' ? [note.to] : note.to;
	note.cc = note.cc == null ? [] : typeof note.cc == 'string' ? [note.cc] : note.cc;

	let visibility = 'public';
	let visibleUsers: IUser[] = [];
	if (!note.to.includes('https://www.w3.org/ns/activitystreams#Public')) {
		if (note.cc.includes('https://www.w3.org/ns/activitystreams#Public')) {
			visibility = 'home';
		} else if (note.to.includes(`${actor.uri}/followers`)) {	// TODO: person.followerと照合するべき？
			visibility = 'followers';
		} else {
			visibility = 'specified';
			visibleUsers = await Promise.all(note.to.map(uri => resolvePerson(uri, null, resolver)));
		}
}
	//#endergion

	const apMentions = await extractMentionedUsers(actor, note.to, note.cc, resolver);

	const apHashtags = await extractHashtags(note.tag);

	// 添付ファイル
	// TODO: attachmentは必ずしもImageではない
	// TODO: attachmentは必ずしも配列ではない
	// Noteがsensitiveなら添付もsensitiveにする
	const limit = promiseLimit(2);

	note.attachment = Array.isArray(note.attachment) ? note.attachment : note.attachment ? [note.attachment] : [];
	const files = note.attachment
		.map(attach => attach.sensitive = note.sensitive)
		? await Promise.all(note.attachment.map(x => limit(() => resolveImage(actor, x)) as Promise<IDriveFile>))
		: [];

	// リプライ
	const reply = note.inReplyTo ? await resolveNote(note.inReplyTo, resolver) : null;

	// 引用
	let quote: INote;

	if (note._misskey_quote && typeof note._misskey_quote == 'string') {
		quote = await resolveNote(note._misskey_quote).catch(() => null);
	}

	const cw = note.summary === '' ? null : note.summary;

	// テキストのパース
	const text = note._misskey_content || fromHtml(note.content);

	// vote
	if (reply && reply.poll) {
		const tryCreateVote = async (name: string, index: number): Promise<null> => {
			if (reply.poll.expiresAt && Date.now() > new Date(reply.poll.expiresAt).getTime()) {
				logger.warn(`vote to expired poll from AP: actor=${actor.username}@${actor.host}, note=${note.id}, choice=${name}`);
			} else if (index >= 0) {
				logger.info(`vote from AP: actor=${actor.username}@${actor.host}, note=${note.id}, choice=${name}`);
				await vote(actor, reply, index);

				// リモートフォロワーにUpdate配信
				deliverQuestionUpdate(reply._id);
			}
			return null;
		};

		if (note.name) {
			return await tryCreateVote(note.name, reply.poll.choices.findIndex(x => x.text === note.name));
		}

		// 後方互換性のため
		if (text) {
			const m = text.match(/(\d+)$/);

			if (m) {
				return await tryCreateVote(m[0], Number(m[1]));
			}
		}
	}

	const emojis = await extractEmojis(note.tag, actor.host).catch(e => {
		logger.info(`extractEmojis: ${e}`);
		return [] as IEmoji[];
	});

	const apEmojis = emojis.map(emoji => emoji.name);

	const questionUri = note._misskey_question;
	const poll = await extractPollFromQuestion(note._misskey_question || note).catch(() => undefined);

	// ユーザーの情報が古かったらついでに更新しておく
	if (actor.lastFetchedAt == null || Date.now() - actor.lastFetchedAt.getTime() > 1000 * 60 * 60 * 24) {
		updatePerson(note.attributedTo);
	}

	return await post(actor, {
		createdAt: new Date(note.published),
		files,
		reply,
		renote: quote,
		cw,
		text,
		viaMobile: false,
		localOnly: false,
		geo: undefined,
		visibility,
		visibleUsers,
		apMentions,
		apHashtags,
		apEmojis,
		questionUri,
		poll,
		uri: note.id
	}, silent);
}

/**
 * Noteを解決します。
 *
 * Misskeyに対象のNoteが登録されていればそれを返し、そうでなければ
 * リモートサーバーからフェッチしてMisskeyに登録しそれを返します。
 */
export async function resolveNote(value: string | IObject, resolver?: Resolver): Promise<INote> {
	const uri = typeof value == 'string' ? value : value.id;

	//#region このサーバーに既に登録されていたらそれを返す
	const exist = await fetchNote(uri);

	if (exist) {
		return exist;
	}
	//#endregion

	// リモートサーバーからフェッチしてきて登録
	// ここでuriの代わりに添付されてきたNote Objectが指定されていると、サーバーフェッチを経ずにノートが生成されるが
	// 添付されてきたNote Objectは偽装されている可能性があるため、常にuriを指定してサーバーフェッチを行う。
	return await createNote(uri, resolver);
}

export async function extractEmojis(tags: ITag[], host_: string) {
	const host = toUnicode(host_.toLowerCase());

	if (!tags) return [];

	const eomjiTags = tags.filter(tag => tag.type === 'Emoji' && tag.icon && tag.icon.url);

	return await Promise.all(
		eomjiTags.map(async tag => {
			const name = tag.name.replace(/^:/, '').replace(/:$/, '');

			const exists = await Emoji.findOne({
				host,
				name
			});

			if (exists) {
				if ((tag.updated != null && exists.updatedAt == null)
					|| (tag.id != null && exists.uri == null)
					|| (tag.updated != null && exists.updatedAt != null && new Date(tag.updated) > exists.updatedAt)) {
						return await Emoji.findOneAndUpdate({
							host,
							name,
						}, {
							$set: {
								uri: tag.id,
								url: tag.icon.url,
								updatedAt: new Date(tag.updated),
							}
						});
				}
				return exists;
			}

			logger.info(`register emoji host=${host}, name=${name}`);

			return await Emoji.insert({
				host,
				name,
				uri: tag.id,
				url: tag.icon.url,
				updatedAt: tag.updated ? new Date(tag.updated) : undefined,
				aliases: []
			});
		})
	);
}

async function extractMentionedUsers(actor: IRemoteUser, to: string[], cc: string[], resolver: Resolver) {
	const ignoreUris = ['https://www.w3.org/ns/activitystreams#Public', `${actor.uri}/followers`];
	const uris = difference(unique(concat([to || [], cc || []])), ignoreUris);

	const limit = promiseLimit(2);
	const users = await Promise.all(
		uris.map(uri => limit(() => resolvePerson(uri, null, resolver).catch(() => null)) as Promise<IUser>)
	);

	return users.filter(x => x != null);
}
