import { URL } from 'node:url';
import { Inject, Injectable } from '@nestjs/common';
import { JSDOM } from 'jsdom';
import fetch from 'node-fetch';
import tinycolor from 'tinycolor2';
import type { Instance } from '@/models/entities/Instance.js';
import type { InstancesRepository } from '@/models/index.js';
import { AppLockService } from '@/core/AppLockService.js';
import type Logger from '@/logger.js';
import { DI } from '@/di-symbols.js';
import { LoggerService } from '@/core/LoggerService.js';
import { HttpRequestService } from '@/core/HttpRequestService.js';
import type { DOMWindow } from 'jsdom';

type NodeInfo = {
	openRegistrations?: unknown;
	software?: {
		name?: unknown;
		version?: unknown;
	};
	metadata?: {
		name?: unknown;
		nodeName?: unknown;
		nodeDescription?: unknown;
		description?: unknown;
		maintainer?: {
			name?: unknown;
			email?: unknown;
		};
		themeColor?: unknown;
	};
};

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

	constructor(
		@Inject(DI.instancesRepository)
		private instancesRepository: InstancesRepository,

		private appLockService: AppLockService,
		private httpRequestService: HttpRequestService,
		private loggerService: LoggerService,
	) {
		this.logger = this.loggerService.getLogger('metadata', 'cyan');
	}

	public async fetchInstanceMetadata(instance: Instance, force = false): Promise<void> {
		const unlock = await this.appLockService.getFetchInstanceMetadataLock(instance.host);
	
		if (!force) {
			const _instance = await this.instancesRepository.findOneBy({ host: instance.host });
			const now = Date.now();
			if (_instance && _instance.infoUpdatedAt && (now - _instance.infoUpdatedAt.getTime() < 1000 * 60 * 60 * 24)) {
				unlock();
				return;
			}
		}
	
		this.logger.info(`Fetching metadata of ${instance.host} ...`);
	
		try {
			const [info, dom, manifest] = await Promise.all([
				this.fetchNodeinfo(instance).catch(() => null),
				this.fetchDom(instance).catch(() => null),
				this.fetchManifest(instance).catch(() => null),
			]);
	
			const [favicon, icon, themeColor, name, description] = await Promise.all([
				this.fetchFaviconUrl(instance, dom).catch(() => null),
				this.fetchIconUrl(instance, dom, manifest).catch(() => null),
				this.getThemeColor(info, dom, manifest).catch(() => null),
				this.getSiteName(info, dom, manifest).catch(() => null),
				this.getDescription(info, dom, manifest).catch(() => null),
			]);
	
			this.logger.succ(`Successfuly fetched metadata of ${instance.host}`);
	
			const updates = {
				infoUpdatedAt: new Date(),
			} as Record<string, any>;
	
			if (info) {
				updates.softwareName = typeof info.software?.name === 'string' ? info.software.name.toLowerCase() : '?';
				updates.softwareVersion = info.software?.version;
				updates.openRegistrations = info.openRegistrations;
				updates.maintainerName = info.metadata ? info.metadata.maintainer ? (info.metadata.maintainer.name ?? null) : null : null;
				updates.maintainerEmail = info.metadata ? info.metadata.maintainer ? (info.metadata.maintainer.email ?? null) : null : null;
			}
	
			if (name) updates.name = name;
			if (description) updates.description = description;
			if (icon || favicon) updates.iconUrl = icon ?? favicon;
			if (favicon) updates.faviconUrl = favicon;
			if (themeColor) updates.themeColor = themeColor;
	
			await this.instancesRepository.update(instance.id, updates);
	
			this.logger.succ(`Successfuly updated metadata of ${instance.host}`);
		} catch (e) {
			this.logger.error(`Failed to update metadata of ${instance.host}: ${e}`);
		} finally {
			unlock();
		}
	}

	private async fetchNodeinfo(instance: Instance): Promise<NodeInfo> {
		this.logger.info(`Fetching nodeinfo of ${instance.host} ...`);
	
		try {
			const wellknown = await this.httpRequestService.getJson('https://' + instance.host + '/.well-known/nodeinfo')
				.catch(err => {
					if (err.statusCode === 404) {
						throw 'No nodeinfo provided';
					} else {
						throw err.statusCode ?? err.message;
					}
				}) as Record<string, unknown>;
	
			if (wellknown.links == null || !Array.isArray(wellknown.links)) {
				throw 'No wellknown links';
			}
	
			const links = wellknown.links as any[];
	
			const lnik1_0 = links.find(link => link.rel === 'http://nodeinfo.diaspora.software/ns/schema/1.0');
			const lnik2_0 = links.find(link => link.rel === 'http://nodeinfo.diaspora.software/ns/schema/2.0');
			const lnik2_1 = links.find(link => link.rel === 'http://nodeinfo.diaspora.software/ns/schema/2.1');
			const link = lnik2_1 ?? lnik2_0 ?? lnik1_0;
	
			if (link == null) {
				throw 'No nodeinfo link provided';
			}
	
			const info = await this.httpRequestService.getJson(link.href)
				.catch(err => {
					throw err.statusCode ?? err.message;
				});
	
			this.logger.succ(`Successfuly fetched nodeinfo of ${instance.host}`);
	
			return info as NodeInfo;
		} catch (err) {
			this.logger.error(`Failed to fetch nodeinfo of ${instance.host}: ${err}`);
	
			throw err;
		}
	}

	private async fetchDom(instance: Instance): Promise<DOMWindow['document']> {
		this.logger.info(`Fetching HTML of ${instance.host} ...`);
	
		const url = 'https://' + instance.host;
	
		const html = await this.httpRequestService.getHtml(url);
	
		const { window } = new JSDOM(html);
		const doc = window.document;
	
		return doc;
	}

	private async fetchManifest(instance: Instance): Promise<Record<string, unknown> | null> {
		const url = 'https://' + instance.host;
	
		const manifestUrl = url + '/manifest.json';
	
		const manifest = await this.httpRequestService.getJson(manifestUrl) as Record<string, unknown>;
	
		return manifest;
	}

	private async fetchFaviconUrl(instance: Instance, doc: DOMWindow['document'] | null): Promise<string | null> {
		const url = 'https://' + instance.host;
	
		if (doc) {
			// https://github.com/misskey-dev/misskey/pull/8220#issuecomment-1025104043
			const href = Array.from(doc.getElementsByTagName('link')).reverse().find(link => link.relList.contains('icon'))?.href;
	
			if (href) {
				return (new URL(href, url)).href;
			}
		}
	
		const faviconUrl = url + '/favicon.ico';
	
		const favicon = await fetch(faviconUrl, {
			// TODO
			//timeout: 10000,
			agent: url => this.httpRequestService.getAgentByUrl(url),
		});
	
		if (favicon.ok) {
			return faviconUrl;
		}
	
		return null;
	}

	private async fetchIconUrl(instance: Instance, doc: DOMWindow['document'] | null, manifest: Record<string, any> | null): Promise<string | null> {
		if (manifest && manifest.icons && manifest.icons.length > 0 && manifest.icons[0].src) {
			const url = 'https://' + instance.host;
			return (new URL(manifest.icons[0].src, url)).href;
		}
	
		if (doc) {
			const url = 'https://' + instance.host;
	
			// https://github.com/misskey-dev/misskey/pull/8220#issuecomment-1025104043
			const links = Array.from(doc.getElementsByTagName('link')).reverse();
			// https://github.com/misskey-dev/misskey/pull/8220/files/0ec4eba22a914e31b86874f12448f88b3e58dd5a#r796487559
			const href = 
				[
					links.find(link => link.relList.contains('apple-touch-icon-precomposed'))?.href,
					links.find(link => link.relList.contains('apple-touch-icon'))?.href,
					links.find(link => link.relList.contains('icon'))?.href,
				]
					.find(href => href);
	
			if (href) {
				return (new URL(href, url)).href;
			}
		}
	
		return null;
	}

	private async getThemeColor(info: NodeInfo | null, doc: DOMWindow['document'] | null, manifest: Record<string, any> | null): Promise<string | null> {
		const themeColor = info?.metadata?.themeColor ?? doc?.querySelector('meta[name="theme-color"]')?.getAttribute('content') ?? manifest?.theme_color;
	
		if (themeColor) {
			const color = new tinycolor(themeColor);
			if (color.isValid()) return color.toHexString();
		}
	
		return null;
	}

	private async getSiteName(info: NodeInfo | null, doc: DOMWindow['document'] | null, manifest: Record<string, any> | null): Promise<string | null> {
		if (info && info.metadata) {
			if (typeof info.metadata.nodeName === 'string') {
				return info.metadata.nodeName;
			} else if (typeof info.metadata.name === 'string') {
				return info.metadata.name;
			}
		}
	
		if (doc) {
			const og = doc.querySelector('meta[property="og:title"]')?.getAttribute('content');
	
			if (og) {
				return og;
			}
		}
	
		if (manifest) {
			return manifest.name ?? manifest.short_name;
		}
	
		return null;
	}

	private async getDescription(info: NodeInfo | null, doc: DOMWindow['document'] | null, manifest: Record<string, any> | null): Promise<string | null> {
		if (info && info.metadata) {
			if (typeof info.metadata.nodeDescription === 'string') {
				return info.metadata.nodeDescription;
			} else if (typeof info.metadata.description === 'string') {
				return info.metadata.description;
			}
		}
	
		if (doc) {
			const meta = doc.querySelector('meta[name="description"]')?.getAttribute('content');
			if (meta) {
				return meta;
			}
	
			const og = doc.querySelector('meta[property="og:description"]')?.getAttribute('content');
			if (og) {
				return og;
			}
		}
	
		if (manifest) {
			return manifest.name ?? manifest.short_name;
		}
	
		return null;
	}
}