import { URL } from 'node:url';
import { Inject, Injectable } from '@nestjs/common';
import chalk from 'chalk';
import { IsNull } from 'typeorm';
import { DI } from '@/di-symbols.js';
import type { UsersRepository } from '@/models/index.js';
import type { LocalUser, RemoteUser } from '@/models/entities/User.js';
import type { Config } from '@/config.js';
import type Logger from '@/logger.js';
import { UtilityService } from '@/core/UtilityService.js';
import { WebfingerService } from '@/core/WebfingerService.js';
import { RemoteLoggerService } from '@/core/RemoteLoggerService.js';
import { ApPersonService } from '@/core/activitypub/models/ApPersonService.js';
import { bindThis } from '@/decorators.js';

@Injectable()
export class RemoteUserResolveService {
	private logger: Logger;

	constructor(
		@Inject(DI.config)
		private config: Config,

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

		private utilityService: UtilityService,
		private webfingerService: WebfingerService,
		private remoteLoggerService: RemoteLoggerService,
		private apPersonService: ApPersonService,
	) {
		this.logger = this.remoteLoggerService.logger.createSubLogger('resolve-user');
	}

	@bindThis
	public async resolveUser(username: string, host: string | null): Promise<LocalUser | RemoteUser> {
		const usernameLower = username.toLowerCase();
	
		if (host == null) {
			this.logger.info(`return local user: ${usernameLower}`);
			return await this.usersRepository.findOneBy({ usernameLower, host: IsNull() }).then(u => {
				if (u == null) {
					throw new Error('user not found');
				} else {
					return u;
				}
			}) as LocalUser;
		}
	
		host = this.utilityService.toPuny(host);
	
		if (this.config.host === host) {
			this.logger.info(`return local user: ${usernameLower}`);
			return await this.usersRepository.findOneBy({ usernameLower, host: IsNull() }).then(u => {
				if (u == null) {
					throw new Error('user not found');
				} else {
					return u;
				}
			}) as LocalUser;
		}
	
		const user = await this.usersRepository.findOneBy({ usernameLower, host }) as RemoteUser | null;
	
		const acctLower = `${usernameLower}@${host}`;
	
		if (user == null) {
			const self = await this.resolveSelf(acctLower);
	
			this.logger.succ(`return new remote user: ${chalk.magenta(acctLower)}`);
			return await this.apPersonService.createPerson(self.href);
		}
	
		// ユーザー情報が古い場合は、WebFilgerからやりなおして返す
		if (user.lastFetchedAt == null || Date.now() - user.lastFetchedAt.getTime() > 1000 * 60 * 60 * 24) {
			// 繋がらないインスタンスに何回も試行するのを防ぐ, 後続の同様処理の連続試行を防ぐ ため 試行前にも更新する
			await this.usersRepository.update(user.id, {
				lastFetchedAt: new Date(),
			});
	
			this.logger.info(`try resync: ${acctLower}`);
			const self = await this.resolveSelf(acctLower);
	
			if (user.uri !== self.href) {
				// if uri mismatch, Fix (user@host <=> AP's Person id(RemoteUser.uri)) mapping.
				this.logger.info(`uri missmatch: ${acctLower}`);
				this.logger.info(`recovery missmatch uri for (username=${username}, host=${host}) from ${user.uri} to ${self.href}`);
	
				// validate uri
				const uri = new URL(self.href);
				if (uri.hostname !== host) {
					throw new Error('Invalid uri');
				}
	
				await this.usersRepository.update({
					usernameLower,
					host: host,
				}, {
					uri: self.href,
				});
			} else {
				this.logger.info(`uri is fine: ${acctLower}`);
			}
	
			await this.apPersonService.updatePerson(self.href);
	
			this.logger.info(`return resynced remote user: ${acctLower}`);
			return await this.usersRepository.findOneBy({ uri: self.href }).then(u => {
				if (u == null) {
					throw new Error('user not found');
				} else {
					return u as LocalUser | RemoteUser;
				}
			});
		}
	
		this.logger.info(`return existing remote user: ${acctLower}`);
		return user;
	}

	@bindThis
	private async resolveSelf(acctLower: string) {
		this.logger.info(`WebFinger for ${chalk.yellow(acctLower)}`);
		const finger = await this.webfingerService.webfinger(acctLower).catch(err => {
			this.logger.error(`Failed to WebFinger for ${chalk.yellow(acctLower)}: ${ err.statusCode ?? err.message }`);
			throw new Error(`Failed to WebFinger for ${acctLower}: ${ err.statusCode ?? err.message }`);
		});
		const self = finger.links.find(link => link.rel != null && link.rel.toLowerCase() === 'self');
		if (!self) {
			this.logger.error(`Failed to WebFinger for ${chalk.yellow(acctLower)}: self link not found`);
			throw new Error('self link not found');
		}
		return self;
	}
}