import { IsNull } from 'typeorm';
import { Inject, Injectable } from '@nestjs/common';
import type { UsersRepository, FollowingsRepository, UserProfilesRepository } from '@/models/index.js';
import { Endpoint } from '@/server/api/endpoint-base.js';
import { QueryService } from '@/core/QueryService.js';
import { FollowingEntityService } from '@/core/entities/FollowingEntityService.js';
import { UtilityService } from '@/core/UtilityService.js';
import { DI } from '@/di-symbols.js';
import { ApiError } from '../../error.js';

export const meta = {
	tags: ['users'],

	requireCredential: false,

	description: 'Show everyone that follows this user.',

	res: {
		type: 'array',
		optional: false, nullable: false,
		items: {
			type: 'object',
			optional: false, nullable: false,
			ref: 'Following',
		},
	},

	errors: {
		noSuchUser: {
			message: 'No such user.',
			code: 'NO_SUCH_USER',
			id: '27fa5435-88ab-43de-9360-387de88727cd',
		},

		forbidden: {
			message: 'Forbidden.',
			code: 'FORBIDDEN',
			id: '3c6a84db-d619-26af-ca14-06232a21df8a',
		},
	},
} as const;

export const paramDef = {
	type: 'object',
	properties: {
		sinceId: { type: 'string', format: 'misskey:id' },
		untilId: { type: 'string', format: 'misskey:id' },
		limit: { type: 'integer', minimum: 1, maximum: 100, default: 10 },

		userId: { type: 'string', format: 'misskey:id' },
		username: { type: 'string' },
		host: {
			type: 'string',
			nullable: true,
			description: 'The local host is represented with `null`.',
		},
	},
	anyOf: [
		{ required: ['userId'] },
		{ required: ['username', 'host'] },
	],
} as const;

// eslint-disable-next-line import/no-default-export
@Injectable()
export default class extends Endpoint<typeof meta, typeof paramDef> {
	constructor(
		@Inject(DI.usersRepository)
		private usersRepository: UsersRepository,

		@Inject(DI.userProfilesRepository)
		private userProfilesRepository: UserProfilesRepository,

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

		private utilityService: UtilityService,
		private followingEntityService: FollowingEntityService,
		private queryService: QueryService,
	) {
		super(meta, paramDef, async (ps, me) => {
			const user = await this.usersRepository.findOneBy(ps.userId != null
				? { id: ps.userId }
				: { usernameLower: ps.username!.toLowerCase(), host: this.utilityService.toPunyNullable(ps.host) ?? IsNull() });

			if (user == null) {
				throw new ApiError(meta.errors.noSuchUser);
			}

			const profile = await this.userProfilesRepository.findOneByOrFail({ userId: user.id });

			if (profile.ffVisibility === 'private') {
				if (me == null || (me.id !== user.id)) {
					throw new ApiError(meta.errors.forbidden);
				}
			} else if (profile.ffVisibility === 'followers') {
				if (me == null) {
					throw new ApiError(meta.errors.forbidden);
				} else if (me.id !== user.id) {
					const following = await this.followingsRepository.findOneBy({
						followeeId: user.id,
						followerId: me.id,
					});
					if (following == null) {
						throw new ApiError(meta.errors.forbidden);
					}
				}
			}

			const query = this.queryService.makePaginationQuery(this.followingsRepository.createQueryBuilder('following'), ps.sinceId, ps.untilId)
				.andWhere('following.followeeId = :userId', { userId: user.id })
				.innerJoinAndSelect('following.follower', 'follower');

			const followings = await query
				.take(ps.limit)
				.getMany();

			return await this.followingEntityService.packMany(followings, me, { populateFollower: true });
		});
	}
}