/**
 * REST API search client implementation
 *
 * @module MwRestSearchClient
 */

const { CitizenCommandPaletteSearchClient, CommandPaletteSearchResponse, AbortableSearchFetch } = require( '../types.js' );
const fetchJson = require( '../utils/fetch.js' );
const { cdxIconArticle, cdxIconArticleRedirect, cdxIconEdit } = require( '../icons.json' );

/**
 * @typedef {Object} RestResponse
 * @property {RestResult[]} pages
 */

/**
 * @typedef {Object} RestResult
 * @property {number} id
 * @property {string} key
 * @property {string} title
 * @property {string | null } matched_title
 * @property {string} [description]
 * @property {RestThumbnail | null} [thumbnail]
 */

/**
 * @typedef {Object} RestThumbnail
 * @property {string} url
 * @property {number | null} [width]
 * @property {number | null} [height]
 */

/**
 * @class
 * @implements {CitizenCommandPaletteSearchClient}
 */
class MwRestSearchClient {

	constructor() {
		this.editMessage = mw.msg( 'action-edit' );
		this.searchApiUrl = mw.config.get( 'wgScriptPath' ) + '/rest.php';
	}

	/**
	 * Processes the query
	 *
	 * @param {string} query The original search query
	 * @return {string} The processed query
	 */
	processQuery( query ) {
		// Template syntax: {{Template}} -> Template:Template
		const templateMatch = /^{{(.*?)(}})?$/.exec( query );
		if ( templateMatch ) {
			return `Template:${ templateMatch[ 1 ] }`;
		}

		// Wikilink syntax: [[Article]] -> Article
		const wikilinkMatch = /^\[\[(.*?)(]]?)?$/.exec( query );
		if ( wikilinkMatch ) {
			return wikilinkMatch[ 1 ];
		}

		return query;
	}

	/**
	 * Adapts the REST API response to the SearchResponse format
	 *
	 * @private
	 * @param {string} query
	 * @param {RestResponse} response
	 * @param {boolean} showDescription
	 * @return {CommandPaletteSearchResponse}
	 */
	adaptApiResponse( query, response, showDescription ) {
		return {
			query,
			results: response.pages.map( ( page ) => {
				const thumbnail = page.thumbnail;
				return {
					id: `citizen-command-palette-item-page-${ page.key }`,
					type: 'page',
					label: page.title,
					description: showDescription ? page.description : undefined,
					url: mw.util.getUrl( page.matched_title ?? page.title ), // #1065, revisit when REST API has anchor field (T306150)
					thumbnail: thumbnail ? {
						url: thumbnail.url,
						width: thumbnail.width ?? undefined,
						height: thumbnail.height ?? undefined
					} : undefined,
					thumbnailIcon: cdxIconArticle,
					metadata: page.matched_title ? [
						{
							icon: cdxIconArticleRedirect,
							label: page.matched_title,
							highlightQuery: true
						}
					] : undefined,
					actions: [
						{
							id: 'edit',
							label: this.editMessage,
							icon: cdxIconEdit,
							url: mw.util.getUrl( page.title, { action: 'edit' } )
						}
					],
					highlightQuery: true
				};
			} )
		};
	}

	/**
	 * @override
	 * @param {string} query The search term
	 * @param {number} [limit=10] Maximum number of results
	 * @param {boolean} [showDescription=true] Whether to show descriptions
	 * @return {AbortableSearchFetch}
	 */
	fetchByQuery( query, limit = 10, showDescription = true ) {
		const processedQuery = this.processQuery( query );

		const params = { q: processedQuery, limit: limit.toString() };
		const search = new URLSearchParams( params );
		const url = `${ this.searchApiUrl }/v1/search/title?${ search.toString() }`;
		const result = fetchJson( url, {
			headers: {
				accept: 'application/json'
			}
		} );

		const searchResponsePromise = result.fetch.then( ( /** @type {RestResponse} */ res ) => this.adaptApiResponse( query, res, showDescription ) );

		return {
			abort: result.abort,
			fetch: searchResponsePromise
		};
	}

	/**
	 * TODO: MediaWiki upstream does not support load more yet
	 *
	 * @override
	 * @param {string} query The search term
	 * @param {number} offset The number of search results that were already loaded
	 * @param {number} [limit=10] How many further search results to load
	 * @return {AbortableSearchFetch}
	 */
	loadMore( query, offset, limit = 10 ) {
		const params = { q: query, limit: limit.toString(), offset: offset.toString() };
		const search = new URLSearchParams( params );
		const url = `${ this.searchApiUrl }/v1/search/title?${ search.toString() }`;
		const result = fetchJson( url, {
			headers: {
				accept: 'application/json'
			}
		} );

		const searchResponsePromise = result.fetch.then( ( /** @type {RestResponse} */ res ) => this.adaptApiResponse( query, res, true ) );

		return {
			abort: result.abort,
			fetch: searchResponsePromise
		};
	}
}

module.exports = MwRestSearchClient;