import type { XMLBuilder } from 'xmlbuilder2/lib/interfaces';
import { create as create_xml } from 'xmlbuilder2';
import { BuildState } from './state';
import { write_text } from '../fs';
import { AuthorConfig, app_version } from '../conf';
import { map_output_file_to_url } from './helpers';
import { DateTime } from 'luxon';
import { FileMetadata } from '../metadata';

export interface RSSEntry {
	url: string;
	in_file: string;
	title?: string;
	description?: string;
	authors?: AuthorConfig[];
	html_content?: string;
	tags?: string[];
}

export async function write_rss_if_needed(state: BuildState) {
	if (! state.conf.rss) {
		return;
	}

	for (let index = 0; index < state.conf.rss.length; index++) {
		const rss_conf = state.conf.rss[index];
		const doc = create_xml({ version: '1.0', encoding: 'UTF-8' });
		const { abs_url: self_url } = map_output_file_to_url(state, rss_conf.out_file);
	
		if (rss_conf.xsl) {
			for (const url of rss_conf.xsl) {
				doc.ins('xml-stylesheet', `href="${url}" type="text/xsl"`);
			}
		}
		
		const rss = doc.ele('rss', {
			version: '2.0',
			'xmlns:dc': 'http://purl.org/dc/elements/1.1/',
			'xmlns:content': 'http://purl.org/rss/1.0/modules/content/',
			'xmlns:atom': 'http://www.w3.org/2005/Atom',
			// 'xmlns:docs2website': 'urn:uuid:7fc4e5d4-f68e-11ed-b0d0-00155ddef564',
		});

		const channel = rss.ele('channel');
		channel.ele('generator').txt(`docs2website ${app_version}`);

		if (rss_conf.title) {
			channel.ele('title').txt(rss_conf.title);
		}

		if (rss_conf.link) {
			channel.ele('link').txt(rss_conf.link);
		}
	
		link(channel, 'application/rss+xml', 'self', self_url);

		if (rss_conf.alternates?.length) {
			for (const alt of rss_conf.alternates) {
				link(channel, alt.type, 'alternate', alt.href);
			}
		}
	
		if (rss_conf.description) {
			channel.ele('description').txt(rss_conf.description);
		}
		
		if (rss_conf.language) {
			channel.ele('language').txt(rss_conf.language);
		}
		
		if (rss_conf.copyright) {
			channel.ele('copyright').txt(rss_conf.copyright);
		}
	
		channel.ele('lastBuildDate').txt(state.build_time.rfc2822);

		// channel.ele('rating').txt('');  // see: https://www.w3.org/PICS/
		// channel.ele('pubDate').txt(publish_date.toUTCString());
		// channel.ele('categories').txt('');
		// channel.ele('docs').txt('');
		// channel.ele('managingEditor').txt('james@jbrumond.me');
		// channel.ele('webMaster').txt('james@jbrumond.me');
		// channel.ele('ttl').txt('');
		// channel.ele('image').txt('');
		// channel.ele('skipHours').txt('');
		// channel.ele('skipDays').txt('');

		let entries: (RSSEntry & { metadata: FileMetadata, first_seen: number })[] = [ ];
	
		for (const entry of state.rss[index] || [ ]) {
			const in_file = entry.in_file.slice(state.conf.input.root.length);
			const metadata = state.new_metadata.files[in_file];
			entries.push({ ...entry, metadata, first_seen: DateTime.fromISO(metadata.first_seen_time).toUnixInteger() });
		}

		entries = entries.sort((a, b) => {
			return b.first_seen - a.first_seen;
		});

		for (const entry of entries) {
			const item = channel.ele('item');
	
			item.ele('link').txt(entry.url);

			if (entry.title) {
				item.ele('title').txt(entry.title);
			}
	
			if (entry.description) {
				item.ele('description').txt(entry.description);
			}
			
			if (entry.authors) {
				for (const author of entry.authors) {
					item.ele('dc:creator').ele({ $: author.name || author.url || author.email });
				}
			}
	
			if (entry.tags) {
				entry.tags.forEach((tag) => item.ele('category').txt(tag));
			}
	
			item.ele('guid').txt(entry.url);
			item.ele('pubDate').txt(DateTime.fromISO(entry.metadata.first_seen_time).toRFC2822());

			if (entry.html_content) {
				item.ele('content:encoded').ele({ $: entry.html_content });
			}
		}
	
		const xml = doc.toString({
			indent: '  ',
			prettyPrint: true,
		});
	
		await write_text(rss_conf.out_file, xml);
	}
}
	
function link(channel: XMLBuilder, type: string, rel: string, href: string) {
	// channel.ele('link', { href, rel, type, });
	channel.ele('atom:link', { type, rel, href, });
}