wikimedia/mediawiki-extensions-UniversalLanguageSelector

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lib/jquery.uls/src/jquery.uls.languagefilter.js

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/**
 * jQuery language filter plugin.
 *
 * Copyright (C) 2012 Alolita Sharma, Amir Aharoni, Arun Ganesh, Brandon Harris,
 * Niklas Laxström, Pau Giner, Santhosh Thottingal, Siebrand Mazeland and other
 * contributors. See CREDITS for a list.
 *
 * UniversalLanguageSelector is dual licensed GPLv2 or later and MIT. You don't
 * have to do anything special to choose one license or the other and you don't
 * have to notify anyone which license you are using. You are free to use
 * UniversalLanguageSelector in commercial projects as long as the copyright
 * header is left intact. See files GPL-LICENSE and MIT-LICENSE for details.
 *
 * @file
 * @license GNU General Public Licence 2.0 or later
 * @license MIT License
 */

/**
 * Usage: $( 'inputbox' ).languagefilter();
 * The values for autocompletion is from the options.languages or options.searchAPI.
 *
 * @param {jQuery} $
 */
( function ( $ ) {
    'use strict';

    var LanguageFilter;

    /**
     * Check if a prefix is visually prefix of a string
     *
     * @param {string} prefix
     * @param {string} string
     * @return {boolean}
     */
    function isVisualPrefix( prefix, string ) {
        // Pre-base vowel signs of Indic languages. A vowel sign is called pre-base if
        // consonant + vowel becomes [vowel][consonant] when rendered. Eg: ക + െ => കെ
        var prebases = 'െേൈൊോൌெேைொோௌେୈୋୌિਿिিেৈোৌෙේෛොෝෞ';
        return prebases.indexOf( string[ prefix.length ] ) <= 0;
    }

    LanguageFilter = function ( element, options ) {
        this.$element = $( element );
        this.options = $.extend( {}, $.fn.languagefilter.defaults, options );
        this.$element.addClass( 'languagefilter' );
        this.resultCount = 0;
        this.$suggestion = this.$element.siblings( '.' + this.$element.data( 'suggestion' ) );
        this.$clear = this.$element.siblings( '.' + this.$element.data( 'clear' ) );
        this.selectedLanguage = null;
        this.init();
        this.listen();
    };

    LanguageFilter.prototype = {
        init: function () {
            this.search();
        },

        listen: function () {
            this.$element.on( 'keydown', this.keypress.bind( this ) );
            this.$element.on( 'input', $.fn.uls.debounce( this.onInputChange.bind( this ), 300 ) );

            if ( this.$clear.length ) {
                this.$clear.on( 'click', this.clear.bind( this ) );
            }

            this.toggleClear();
        },

        onInputChange: function () {
            this.selectedLanguage = null;

            if ( !this.$element.val() ) {
                this.clear();
            } else {
                this.options.lcd.empty();
                this.search();
            }

            this.toggleClear();
        },

        keypress: function ( e ) {
            var suggestion, query;

            switch ( e.keyCode ) {
                case 9: // Tab -> Autocomplete
                    suggestion = this.$suggestion.val();

                    if ( suggestion && suggestion !== this.$element.val() ) {
                        this.$element.val( suggestion );
                        e.preventDefault();
                        e.stopPropagation();
                    }
                    break;
                case 13: // Enter
                    if ( !this.options.onSelect ) {
                        break;
                    }

                    // Avoid bubbling this 'enter' to background page elements
                    e.preventDefault();
                    e.stopPropagation();

                    query = ( this.$element.val() || '' ).trim().toLowerCase();

                    // Check if a language is currently highlighted, and if so select that
                    // if user presses enter.
                    var highlightedLanguage = this.options.lcd.getHighlightedLanguageCode();
                    if ( highlightedLanguage ) {
                        this.options.onSelect( highlightedLanguage, e );
                    } else if ( this.selectedLanguage ) {
                        // this.selectLanguage will be populated from a matching search
                        this.options.onSelect( this.selectedLanguage, e );
                    } else if ( this.options.languages[ query ] ) {
                        // Search is yet to happen (in timeout delay),
                        // but we have a matching language code.
                        this.options.onSelect( query, e );
                    }

                    break;
                case 38: // arrow up
                    this.options.lcd.navigateUp();
                    e.preventDefault();

                    break;
                case 40: // arrow down
                    this.options.lcd.navigateDown();
                    e.preventDefault();

                    break;
            }
        },

        /**
         * Clears the current search removing
         * clear buttons and suggestions.
         */
        deactivate: function () {
            this.$element.val( '' );

            if ( !$.fn.uls.Constructor.prototype.isMobile() ) {
                this.$element.trigger( 'focus' );
            }

            this.toggleClear();
            this.autofill();
        },

        /**
         * Clears the search and shows all languages
         */
        clear: function () {
            this.deactivate();
            this.search();
        },

        /**
         * Toggles the visibility of clear icon depending
         * on whether there is anything to clear.
         */
        toggleClear: function () {
            if ( !this.$clear.length ) {
                return;
            }

            if ( this.$element.val() ) {
                this.$clear.show();
            } else {
                this.$clear.hide();
            }
        },

        search: function () {
            var languages = Object.keys( this.options.languages ),
                results = [],
                query = ( this.$element.val() || '' ).trim().toLowerCase();

            // Reset the keyboard navigation index inside LanguageCategoryDisplay (lcd)
            // before re-rendering the language options
            this.options.lcd.resetNavigationIndex();

            if ( query === '' ) {
                this.options.lcd.setGroupByRegionOverride( null );
                this.resultHandler( query, languages );
                return;
            }

            this.options.lcd.setGroupByRegionOverride( false );
            // Local search results
            results = languages.filter( function ( langCode ) {
                return this.filter( langCode, query );
            }.bind( this ) );

            // Use the searchAPI if available, assuming that it has superior search results.
            if ( this.options.searchAPI ) {
                this.searchAPI( query )
                    .done( this.resultHandler.bind( this ) )
                    .fail( this.resultHandler.bind( this, query, results, undefined ) );
            } else {
                this.resultHandler( query, results );
            }
        },

        searchAPI: function ( query ) {
            return $.get( this.options.searchAPI, { search: query } ).then( function ( result ) {
                var autofillLabel,
                    results = [];

                // eslint-disable-next-line no-jquery/no-each-util
                $.each( result.languagesearch, function ( apiCode, name ) {
                    var code, redirect;

                    if ( this.options.languages[ apiCode ] ) {
                        code = apiCode;
                    } else {
                        redirect = $.uls.data.isRedirect( apiCode );
                        if ( !redirect || !this.options.languages[ redirect ] ) {
                            return;
                        }
                        code = redirect;
                    }

                    // Because of the redirect checking above, we might get duplicates.
                    // For example if API returns both `sr` and `sr-cyrl`, the former
                    // could get mapped to `sr-cyrl` and then we would have it twice.
                    // The exact cases when this happens of course depends on what is in
                    // options.languages, which might contain redirects such as `sr`. In
                    // this case we only show `sr` if no other variants are there.
                    // This also protects against broken search APIs returning duplicate
                    // results, although that is not happening in practice.
                    if ( results.indexOf( code ) === -1 ) {
                        autofillLabel = autofillLabel || name;
                        results.push( code );
                    }
                }.bind( this ) );

                return $.Deferred().resolve( query, results, autofillLabel );
            }.bind( this ) );
        },

        /**
         * Handler method to be called once search is over.
         * Based on search result triggers resultsfound or noresults events
         *
         * @param {string} query
         * @param {string[]} results
         * @param {string} [autofillLabel]
         */
        resultHandler: function ( query, results, autofillLabel ) {
            if ( results.length === 0 ) {
                this.$suggestion.val( '' );
                this.$element.trigger(
                    'noresults.uls',
                    {
                        query: query,
                        ulsPurpose: this.options.ulsPurpose
                    }
                );
                return;
            }

            if ( query ) {
                this.selectedLanguage = results[ 0 ];
                this.autofill( results[ 0 ], autofillLabel );
            }

            results.map( this.render.bind( this ) );
            this.$element.trigger( 'resultsfound.uls', [ query, results.length ] );
        },

        autofill: function ( langCode, languageName ) {
            var autonym, userInput, suggestion;

            if ( !this.$suggestion.length ) {
                return;
            }

            if ( !this.$element.val() ) {
                this.$suggestion.val( '' );
                return;
            }

            languageName = languageName || this.options.languages[ langCode ];

            if ( !languageName ) {
                return;
            }

            userInput = this.$element.val();
            suggestion = userInput +
                languageName.slice( userInput.length, languageName.length );

            if ( suggestion.toLowerCase() !== languageName.toLowerCase() ) {
                // see if it was autonym match
                autonym = $.uls.data.getAutonym( langCode ) || '';
                suggestion = userInput + autonym.slice( userInput.length, autonym.length );

                if ( suggestion !== autonym ) {
                    // Give up. It may be an ISO/script code match.
                    suggestion = '';
                }
            }

            // Make sure that it is a visual prefix.
            if ( !isVisualPrefix( userInput, suggestion ) ) {
                suggestion = '';
            }

            this.$suggestion.val( suggestion );
        },

        render: function ( langCode ) {
            return this.options.lcd.append( langCode );
        },

        escapeRegex: function ( value ) {
            return value.replace( /[-[\]{}()*+?.,\\^$|#\s]/g, '\\$&' );
        },

        /**
         * A search match happens if any of the following passes:
         * a) Language name in current user interface language
         * 'starts with' search string.
         * b) Language autonym 'starts with' search string.
         * c) ISO 639 code match with search string.
         * d) ISO 15924 code for the script match the search string.
         *
         * @param {string} langCode
         * @param {string} searchTerm
         * @return {boolean}
         */
        filter: function ( langCode, searchTerm ) {
            // FIXME script is ISO 15924 code. We might need actual name of script.
            var matcher = new RegExp( '^' + this.escapeRegex( searchTerm ), 'i' ),
                languageName = this.options.languages[ langCode ];

            return matcher.test( languageName ) ||
                matcher.test( $.uls.data.getAutonym( langCode ) ) ||
                matcher.test( langCode ) ||
                matcher.test( $.uls.data.getScript( langCode ) );
        }
    };

    $.fn.languagefilter = function ( option ) {
        return this.each( function () {
            var $this = $( this ),
                data = $this.data( 'languagefilter' ),
                options = typeof option === 'object' && option;

            if ( !data ) {
                $this.data( 'languagefilter', ( data = new LanguageFilter( this, options ) ) );
            }

            if ( typeof option === 'string' ) {
                data[ option ]();
            }
        } );
    };

    $.fn.languagefilter.defaults = {
        // LanguageCategoryDisplay
        lcd: undefined,
        // URL to which we append query parameter with the query value
        searchAPI: undefined,
        // What is this ULS used for.
        // Should be set for distinguishing between different instances of ULS
        // in the same application.
        ulsPurpose: '',
        // Object of language tags to language names
        languages: [],
        // Callback function when language is selected
        onSelect: undefined
    };

    $.fn.languagefilter.Constructor = LanguageFilter;

}( jQuery ) );