/*
 * SPDX-FileCopyrightText: syuilo and misskey-project
 * SPDX-License-Identifier: AGPL-3.0-only
 */

import { Inject, Injectable } from '@nestjs/common';
import { In } from 'typeorm';
import { ModuleRef } from '@nestjs/core';
import { DI } from '@/di-symbols.js';
import type { Packed } from '@/misc/json-schema.js';
import { awaitAll } from '@/misc/prelude/await-all.js';
import type { MiUser } from '@/models/User.js';
import type { MiNote } from '@/models/Note.js';
import type { UsersRepository, NotesRepository, FollowingsRepository, PollsRepository, PollVotesRepository, NoteReactionsRepository, ChannelsRepository, MiMeta } from '@/models/_.js';
import { bindThis } from '@/decorators.js';
import { DebounceLoader } from '@/misc/loader.js';
import { IdService } from '@/core/IdService.js';
import { ReactionsBufferingService } from '@/core/ReactionsBufferingService.js';
import type { OnModuleInit } from '@nestjs/common';
import type { CustomEmojiService } from '../CustomEmojiService.js';
import type { ReactionService } from '../ReactionService.js';
import type { UserEntityService } from './UserEntityService.js';
import type { DriveFileEntityService } from './DriveFileEntityService.js';

// is-renote.tsとよしなにリンク
function isPureRenote(note: MiNote): note is MiNote & { renoteId: MiNote['id']; renote: MiNote } {
	return (
		note.renote != null &&
		note.reply == null &&
		note.text == null &&
		note.cw == null &&
		(note.fileIds == null || note.fileIds.length === 0) &&
		!note.hasPoll
	);
}

function getAppearNoteIds(notes: MiNote[]): Set<string> {
	const appearNoteIds = new Set<string>();
	for (const note of notes) {
		if (isPureRenote(note)) {
			appearNoteIds.add(note.renoteId);
		} else {
			appearNoteIds.add(note.id);
		}
	}
	return appearNoteIds;
}

@Injectable()
export class NoteEntityService implements OnModuleInit {
	private userEntityService: UserEntityService;
	private driveFileEntityService: DriveFileEntityService;
	private customEmojiService: CustomEmojiService;
	private reactionService: ReactionService;
	private reactionsBufferingService: ReactionsBufferingService;
	private idService: IdService;
	private noteLoader = new DebounceLoader(this.findNoteOrFail);

	constructor(
		private moduleRef: ModuleRef,

		@Inject(DI.meta)
		private meta: MiMeta,

		@Inject(DI.usersRepository)
		private usersRepository: UsersRepository,

		@Inject(DI.notesRepository)
		private notesRepository: NotesRepository,

		@Inject(DI.followingsRepository)
		private followingsRepository: FollowingsRepository,

		@Inject(DI.pollsRepository)
		private pollsRepository: PollsRepository,

		@Inject(DI.pollVotesRepository)
		private pollVotesRepository: PollVotesRepository,

		@Inject(DI.noteReactionsRepository)
		private noteReactionsRepository: NoteReactionsRepository,

		@Inject(DI.channelsRepository)
		private channelsRepository: ChannelsRepository,

		//private userEntityService: UserEntityService,
		//private driveFileEntityService: DriveFileEntityService,
		//private customEmojiService: CustomEmojiService,
		//private reactionService: ReactionService,
		//private reactionsBufferingService: ReactionsBufferingService,
		//private idService: IdService,
	) {
	}

	onModuleInit() {
		this.userEntityService = this.moduleRef.get('UserEntityService');
		this.driveFileEntityService = this.moduleRef.get('DriveFileEntityService');
		this.customEmojiService = this.moduleRef.get('CustomEmojiService');
		this.reactionService = this.moduleRef.get('ReactionService');
		this.reactionsBufferingService = this.moduleRef.get('ReactionsBufferingService');
		this.idService = this.moduleRef.get('IdService');
	}

	@bindThis
	private async hideNote(packedNote: Packed<'Note'>, meId: MiUser['id'] | null): Promise<void> {
		// FIXME: このvisibility変更処理が当関数にあるのは若干不自然かもしれない(関数名を treatVisibility とかに変える手もある)
		if (packedNote.visibility === 'public' || packedNote.visibility === 'home') {
			const followersOnlyBefore = packedNote.user.makeNotesFollowersOnlyBefore;
			if ((followersOnlyBefore != null)
				&& (
					(followersOnlyBefore <= 0 && (Date.now() - new Date(packedNote.createdAt).getTime() > 0 - (followersOnlyBefore * 1000)))
					|| (followersOnlyBefore > 0 && (new Date(packedNote.createdAt).getTime() < followersOnlyBefore * 1000))
				)
			) {
				packedNote.visibility = 'followers';
			}
		}

		if (meId === packedNote.userId) return;

		// TODO: isVisibleForMe を使うようにしても良さそう(型違うけど)
		let hide = false;

		if (packedNote.user.requireSigninToViewContents && meId == null) {
			hide = true;
		}

		if (!hide) {
			const hiddenBefore = packedNote.user.makeNotesHiddenBefore;
			if ((hiddenBefore != null)
				&& (
					(hiddenBefore <= 0 && (Date.now() - new Date(packedNote.createdAt).getTime() > 0 - (hiddenBefore * 1000)))
					|| (hiddenBefore > 0 && (new Date(packedNote.createdAt).getTime() < hiddenBefore * 1000))
				)
			) {
				hide = true;
			}
		}

		// visibility が specified かつ自分が指定されていなかったら非表示
		if (!hide) {
			if (packedNote.visibility === 'specified') {
				if (meId == null) {
					hide = true;
				} else {
					// 指定されているかどうか
					const specified = packedNote.visibleUserIds!.some(id => meId === id);

					if (!specified) {
						hide = true;
					}
				}
			}
		}

		// visibility が followers かつ自分が投稿者のフォロワーでなかったら非表示
		if (!hide) {
			if (packedNote.visibility === 'followers') {
				if (meId == null) {
					hide = true;
				} else if (packedNote.reply && (meId === packedNote.reply.userId)) {
					// 自分の投稿に対するリプライ
					hide = false;
				} else if (packedNote.mentions && packedNote.mentions.some(id => meId === id)) {
					// 自分へのメンション
					hide = false;
				} else {
					// フォロワーかどうか
					// TODO: 当関数呼び出しごとにクエリが走るのは重そうだからなんとかする
					const isFollowing = await this.followingsRepository.exists({
						where: {
							followeeId: packedNote.userId,
							followerId: meId,
						},
					});

					hide = !isFollowing;
				}
			}
		}

		if (hide) {
			packedNote.visibleUserIds = undefined;
			packedNote.fileIds = [];
			packedNote.files = [];
			packedNote.text = null;
			packedNote.poll = undefined;
			packedNote.cw = null;
			packedNote.isHidden = true;
			// TODO: hiddenReason みたいなのを提供しても良さそう
		}
	}

	@bindThis
	private async populatePoll(note: MiNote, meId: MiUser['id'] | null) {
		const poll = await this.pollsRepository.findOneByOrFail({ noteId: note.id });
		const choices = poll.choices.map(c => ({
			text: c,
			votes: poll.votes[poll.choices.indexOf(c)],
			isVoted: false,
		}));

		if (meId) {
			if (poll.multiple) {
				const votes = await this.pollVotesRepository.findBy({
					userId: meId,
					noteId: note.id,
				});

				const myChoices = votes.map(v => v.choice);
				for (const myChoice of myChoices) {
					choices[myChoice].isVoted = true;
				}
			} else {
				const vote = await this.pollVotesRepository.findOneBy({
					userId: meId,
					noteId: note.id,
				});

				if (vote) {
					choices[vote.choice].isVoted = true;
				}
			}
		}

		return {
			multiple: poll.multiple,
			expiresAt: poll.expiresAt?.toISOString() ?? null,
			choices,
		};
	}

	@bindThis
	public async populateMyReaction(note: { id: MiNote['id']; reactions: MiNote['reactions']; reactionAndUserPairCache?: MiNote['reactionAndUserPairCache']; }, meId: MiUser['id'], _hint_?: {
		myReactions: Map<MiNote['id'], string | null>;
	}) {
		if (_hint_?.myReactions) {
			const reaction = _hint_.myReactions.get(note.id);
			if (reaction) {
				return this.reactionService.convertLegacyReaction(reaction);
			} else {
				return undefined;
			}
		}

		const reactionsCount = Object.values(note.reactions).reduce((a, b) => a + b, 0);
		if (reactionsCount === 0) return undefined;
		if (note.reactionAndUserPairCache && reactionsCount <= note.reactionAndUserPairCache.length) {
			const pair = note.reactionAndUserPairCache.find(p => p.startsWith(meId));
			if (pair) {
				return this.reactionService.convertLegacyReaction(pair.split('/')[1]);
			} else {
				return undefined;
			}
		}

		// パフォーマンスのためノートが作成されてから2秒以上経っていない場合はリアクションを取得しない
		if (this.idService.parse(note.id).date.getTime() + 2000 > Date.now()) {
			return undefined;
		}

		const reaction = await this.noteReactionsRepository.findOneBy({
			userId: meId,
			noteId: note.id,
		});

		if (reaction) {
			return this.reactionService.convertLegacyReaction(reaction.reaction);
		}

		return undefined;
	}

	@bindThis
	public async isVisibleForMe(note: MiNote, meId: MiUser['id'] | null): Promise<boolean> {
		// This code must always be synchronized with the checks in generateVisibilityQuery.
		// visibility が specified かつ自分が指定されていなかったら非表示
		if (note.visibility === 'specified') {
			if (meId == null) {
				return false;
			} else if (meId === note.userId) {
				return true;
			} else {
				// 指定されているかどうか
				return note.visibleUserIds.some(id => meId === id);
			}
		}

		// visibility が followers かつ自分が投稿者のフォロワーでなかったら非表示
		if (note.visibility === 'followers') {
			if (meId == null) {
				return false;
			} else if (meId === note.userId) {
				return true;
			} else if (note.reply && (meId === note.reply.userId)) {
				// 自分の投稿に対するリプライ
				return true;
			} else if (note.mentions && note.mentions.some(id => meId === id)) {
				// 自分へのメンション
				return true;
			} else {
				// フォロワーかどうか
				const [following, user] = await Promise.all([
					this.followingsRepository.count({
						where: {
							followeeId: note.userId,
							followerId: meId,
						},
						take: 1,
					}),
					this.usersRepository.findOneByOrFail({ id: meId }),
				]);

				/* If we know the following, everyhting is fine.

				But if we do not know the following, it might be that both the
				author of the note and the author of the like are remote users,
				in which case we can never know the following. Instead we have
				to assume that the users are following each other.
				*/
				return following > 0 || (note.userHost != null && user.host != null);
			}
		}

		return true;
	}

	@bindThis
	public async packAttachedFiles(fileIds: MiNote['fileIds'], packedFiles: Map<MiNote['fileIds'][number], Packed<'DriveFile'> | null>): Promise<Packed<'DriveFile'>[]> {
		const missingIds = [];
		for (const id of fileIds) {
			if (!packedFiles.has(id)) missingIds.push(id);
		}
		if (missingIds.length) {
			const additionalMap = await this.driveFileEntityService.packManyByIdsMap(missingIds);
			for (const [k, v] of additionalMap) {
				packedFiles.set(k, v);
			}
		}
		return fileIds.map(id => packedFiles.get(id)).filter(x => x != null);
	}

	@bindThis
	public async pack(
		src: MiNote['id'] | MiNote,
		me?: { id: MiUser['id'] } | null | undefined,
		options?: {
			detail?: boolean;
			skipHide?: boolean;
			withReactionAndUserPairCache?: boolean;
			_hint_?: {
				bufferedReactions: Map<MiNote['id'], { deltas: Record<string, number>; pairs: ([MiUser['id'], string])[] }> | null;
				myReactions: Map<MiNote['id'], string | null>;
				packedFiles: Map<MiNote['fileIds'][number], Packed<'DriveFile'> | null>;
				packedUsers: Map<MiUser['id'], Packed<'UserLite'>>
			};
		},
	): Promise<Packed<'Note'>> {
		const opts = Object.assign({
			detail: true,
			skipHide: false,
			withReactionAndUserPairCache: false,
		}, options);

		const meId = me ? me.id : null;
		const note = typeof src === 'object' ? src : await this.noteLoader.load(src);
		const host = note.userHost;

		const bufferedReactions = opts._hint_?.bufferedReactions != null
			? (opts._hint_.bufferedReactions.get(note.id) ?? { deltas: {}, pairs: [] })
			: this.meta.enableReactionsBuffering
				? await this.reactionsBufferingService.get(note.id)
				: { deltas: {}, pairs: [] };
		const reactions = this.reactionService.convertLegacyReactions(this.reactionsBufferingService.mergeReactions(note.reactions, bufferedReactions.deltas ?? {}));

		const reactionAndUserPairCache = note.reactionAndUserPairCache.concat(bufferedReactions.pairs.map(x => x.join('/')));

		let text = note.text;

		if (note.name && (note.url ?? note.uri)) {
			text = `【${note.name}】\n${(note.text ?? '').trim()}\n\n${note.url ?? note.uri}`;
		}

		const channel = note.channelId
			? note.channel
				? note.channel
				: await this.channelsRepository.findOneBy({ id: note.channelId })
			: null;

		const reactionEmojiNames = Object.keys(reactions)
			.filter(x => x.startsWith(':') && x.includes('@') && !x.includes('@.')) // リモートカスタム絵文字のみ
			.map(x => this.reactionService.decodeReaction(x).reaction.replaceAll(':', ''));
		const packedFiles = options?._hint_?.packedFiles;
		const packedUsers = options?._hint_?.packedUsers;

		const packed: Packed<'Note'> = await awaitAll({
			id: note.id,
			createdAt: this.idService.parse(note.id).date.toISOString(),
			userId: note.userId,
			user: packedUsers?.get(note.userId) ?? this.userEntityService.pack(note.user ?? note.userId, me),
			text: text,
			cw: note.cw,
			visibility: note.visibility,
			localOnly: note.localOnly,
			reactionAcceptance: note.reactionAcceptance,
			visibleUserIds: note.visibility === 'specified' ? note.visibleUserIds : undefined,
			renoteCount: note.renoteCount,
			repliesCount: note.repliesCount,
			reactionCount: Object.values(reactions).reduce((a, b) => a + b, 0),
			reactions: reactions,
			reactionEmojis: this.customEmojiService.populateEmojis(reactionEmojiNames, host),
			reactionAndUserPairCache: opts.withReactionAndUserPairCache ? reactionAndUserPairCache : undefined,
			emojis: host != null ? this.customEmojiService.populateEmojis(note.emojis, host) : undefined,
			tags: note.tags.length > 0 ? note.tags : undefined,
			fileIds: note.fileIds,
			files: packedFiles != null ? this.packAttachedFiles(note.fileIds, packedFiles) : this.driveFileEntityService.packManyByIds(note.fileIds),
			replyId: note.replyId,
			renoteId: note.renoteId,
			channelId: note.channelId ?? undefined,
			channel: channel ? {
				id: channel.id,
				name: channel.name,
				color: channel.color,
				isSensitive: channel.isSensitive,
				allowRenoteToExternal: channel.allowRenoteToExternal,
				userId: channel.userId,
			} : undefined,
			mentions: note.mentions.length > 0 ? note.mentions : undefined,
			uri: note.uri ?? undefined,
			url: note.url ?? undefined,

			...(opts.detail ? {
				clippedCount: note.clippedCount,

				reply: note.replyId ? this.pack(note.reply ?? note.replyId, me, {
					detail: false,
					skipHide: opts.skipHide,
					withReactionAndUserPairCache: opts.withReactionAndUserPairCache,
					_hint_: options?._hint_,
				}) : undefined,

				renote: note.renoteId ? this.pack(note.renote ?? note.renoteId, me, {
					detail: true,
					skipHide: opts.skipHide,
					withReactionAndUserPairCache: opts.withReactionAndUserPairCache,
					_hint_: options?._hint_,
				}) : undefined,

				poll: note.hasPoll ? this.populatePoll(note, meId) : undefined,

				...(meId && Object.keys(reactions).length > 0 ? {
					myReaction: this.populateMyReaction({
						id: note.id,
						reactions: reactions,
						reactionAndUserPairCache: reactionAndUserPairCache,
					}, meId, options?._hint_),
				} : {}),
			} : {}),
		});

		if (!opts.skipHide) {
			await this.hideNote(packed, meId);
		}

		return packed;
	}

	@bindThis
	public async packMany(
		notes: MiNote[],
		me?: { id: MiUser['id'] } | null | undefined,
		options?: {
			detail?: boolean;
			skipHide?: boolean;
		},
	) {
		if (notes.length === 0) return [];

		const bufferedReactions = this.meta.enableReactionsBuffering ? await this.reactionsBufferingService.getMany([...getAppearNoteIds(notes)]) : null;

		const meId = me ? me.id : null;
		const myReactionsMap = new Map<MiNote['id'], string | null>();
		if (meId) {
			const idsNeedFetchMyReaction = new Set<MiNote['id']>();

			// パフォーマンスのためノートが作成されてから2秒以上経っていない場合はリアクションを取得しない
			const oldId = this.idService.gen(Date.now() - 2000);

			for (const note of notes) {
				if (isPureRenote(note)) {
					const reactionsCount = Object.values(this.reactionsBufferingService.mergeReactions(note.renote.reactions, bufferedReactions?.get(note.renote.id)?.deltas ?? {})).reduce((a, b) => a + b, 0);
					if (reactionsCount === 0) {
						myReactionsMap.set(note.renote.id, null);
					} else if (reactionsCount <= note.renote.reactionAndUserPairCache.length + (bufferedReactions?.get(note.renote.id)?.pairs.length ?? 0)) {
						const pairInBuffer = bufferedReactions?.get(note.renote.id)?.pairs.find(p => p[0] === meId);
						if (pairInBuffer) {
							myReactionsMap.set(note.renote.id, pairInBuffer[1]);
						} else {
							const pair = note.renote.reactionAndUserPairCache.find(p => p.startsWith(meId));
							myReactionsMap.set(note.renote.id, pair ? pair.split('/')[1] : null);
						}
					} else {
						idsNeedFetchMyReaction.add(note.renote.id);
					}
				} else {
					if (note.id < oldId) {
						const reactionsCount = Object.values(this.reactionsBufferingService.mergeReactions(note.reactions, bufferedReactions?.get(note.id)?.deltas ?? {})).reduce((a, b) => a + b, 0);
						if (reactionsCount === 0) {
							myReactionsMap.set(note.id, null);
						} else if (reactionsCount <= note.reactionAndUserPairCache.length + (bufferedReactions?.get(note.id)?.pairs.length ?? 0)) {
							const pairInBuffer = bufferedReactions?.get(note.id)?.pairs.find(p => p[0] === meId);
							if (pairInBuffer) {
								myReactionsMap.set(note.id, pairInBuffer[1]);
							} else {
								const pair = note.reactionAndUserPairCache.find(p => p.startsWith(meId));
								myReactionsMap.set(note.id, pair ? pair.split('/')[1] : null);
							}
						} else {
							idsNeedFetchMyReaction.add(note.id);
						}
					} else {
						myReactionsMap.set(note.id, null);
					}
				}
			}

			const myReactions = idsNeedFetchMyReaction.size > 0 ? await this.noteReactionsRepository.findBy({
				userId: meId,
				noteId: In(Array.from(idsNeedFetchMyReaction)),
			}) : [];

			for (const id of idsNeedFetchMyReaction) {
				myReactionsMap.set(id, myReactions.find(reaction => reaction.noteId === id)?.reaction ?? null);
			}
		}

		await this.customEmojiService.prefetchEmojis(this.aggregateNoteEmojis(notes));
		// TODO: 本当は renote とか reply がないのに renoteId とか replyId があったらここで解決しておく
		const fileIds = notes.map(n => [n.fileIds, n.renote?.fileIds, n.reply?.fileIds]).flat(2).filter(x => x != null);
		const packedFiles = fileIds.length > 0 ? await this.driveFileEntityService.packManyByIdsMap(fileIds) : new Map();
		const users = [
			...notes.map(({ user, userId }) => user ?? userId),
			...notes.map(({ replyUserId }) => replyUserId).filter(x => x != null),
			...notes.map(({ renoteUserId }) => renoteUserId).filter(x => x != null),
		];
		const packedUsers = await this.userEntityService.packMany(users, me)
			.then(users => new Map(users.map(u => [u.id, u])));

		return await Promise.all(notes.map(n => this.pack(n, me, {
			...options,
			_hint_: {
				bufferedReactions,
				myReactions: myReactionsMap,
				packedFiles,
				packedUsers,
			},
		})));
	}

	@bindThis
	public aggregateNoteEmojis(notes: MiNote[]) {
		let emojis: { name: string | null; host: string | null; }[] = [];
		for (const note of notes) {
			emojis = emojis.concat(note.emojis
				.map(e => this.customEmojiService.parseEmojiStr(e, note.userHost)));
			if (note.renote) {
				emojis = emojis.concat(note.renote.emojis
					.map(e => this.customEmojiService.parseEmojiStr(e, note.renote!.userHost)));
				if (note.renote.user) {
					emojis = emojis.concat(note.renote.user.emojis
						.map(e => this.customEmojiService.parseEmojiStr(e, note.renote!.userHost)));
				}
			}
			const customReactions = Object.keys(note.reactions).map(x => this.reactionService.decodeReaction(x)).filter(x => x.name != null) as typeof emojis;
			emojis = emojis.concat(customReactions);
			if (note.user) {
				emojis = emojis.concat(note.user.emojis
					.map(e => this.customEmojiService.parseEmojiStr(e, note.userHost)));
			}
		}
		return emojis.filter(x => x.name != null && x.host != null) as { name: string; host: string; }[];
	}

	@bindThis
	private findNoteOrFail(id: string): Promise<MiNote> {
		return this.notesRepository.findOneOrFail({
			where: { id },
			relations: ['user'],
		});
	}
}