/** Search Engine
 * ---------------------------------------------------------------------------
 * 
 * TODO:
 * CRITICAL: (optimization)
 * Search initialization uses quite a lot of network sources;
 * thus it should be started in a later time;
 * lets say ...  after `x` seconds
 * or... when document/core-ui-elements are ready
 * 
 * @parametres (json) : options
 * ---
 * @var {string} products_json  : endpoint od product descriptions
 * @var {string} search_tag     : selector of field that shall act as typeahead-suggestions
 * @var {string} visualize_search_results_url : url that will visualize the sended "results-page"
 * @var {int} max_list  : max-size of (rated) results expected
 * @var {int} tolerance
 * @var {boolean} debug : if true sends several debug console messages; if false mesagges are eliminated
 */

retrosearch_module({
    products_json: 'https://storage.googleapis.com/pythia-files/uploads/json/emarket-products.json',
    search_tag: '#tagsInput',
    visualize_search_results_url: '/product_list',
    max_list: 24,
    tolerance: 42,
    debug: ((location.hostname == 'localhost') || (location.hostname == '127.0.0.1'))
});


  
function retrosearch_module(options) {
  
    /** CONTENTS
     * 
     * +1: Variables
     * 
     * +2: Purify string functions
     *      + keyboardize
     *      + sanitize_GR
     *      + clean
     * 
     * +3: Supplementary function (vanilla js)
     *      + ajax_get(url, callback)
     *      + createNgram (fuzzy)
     *      + checkSimilarity (fuzzy)
     *      + check_match
     *      + is_exact_match
     *      + match_one
     * 
     * +4: Actual data loading (async)
     * 
     * +5: Suggestions Engine (jQuery)
     *      + suggestions_engine
     * 
     */

    if (options.debug) console.log(`preparing retrosearch... (${+ new Date()})`);
    
    
    /** 1. VARIABLES 
     * -------------------------------------------------------------------------
     *//////////////////////////////////////////////////////////////////////////
    
    var _kwlinks;           // keyword links (word-connections; imported via ajax-get)
    var _products = [];     // all products (imported via ajax-get)
    
    // setup options
    var _maxResults = options.max_list;     // limit suggestions
    var _blendProds = 4;      // minimum final-produncts to blend with next-word suggestions
    var _timeout_ms = 100;    // time (in ms) for the search engine to find matches (before rendering)
    var _allowFuzzy = true;   // enable|disable fuzzy search
    var _fuzzyLimit = .5;     // minimum bigram score for being considered a match
    var _Ngram_base = 2;      // number of N in Ngram spliting algorithm
    var _isReady = false;     // whether the searchbox is ready to be used
    
    // product keywords
    var keywordsURL = options.keywords_json;
    
    var cursor_on = { none: true };     // what product is highlighted; if not on product then { none: true }
    
    


 
  
    /** 3. SUPPLEMENTARY FUNCTIONS
     * -------------------------------------------------------------------------
     *//////////////////////////////////////////////////////////////////////////


    // TODO:
    // exclude some generic non-critial words when proccessing user's query
    // ** example code to work with:
    // var ignoredKeys_kb = [];    // keywords to ignore (in kb-format)
    // 'μας με σε για του της των από στο στον &'.split(' ').forEach(w => { ignoredKeys_kb.push(keyboardize(w)); });
    
    // pure JS ajax GET request; return data as JSON
    // no fancy things like UTF8; if needed use base64
    function ajax_get(url, callback) {
        var xmlhttp = new XMLHttpRequest();
        xmlhttp.onreadystatechange = function() {
            if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
                try {
                    var data = JSON.parse(xmlhttp.responseText);
                } catch(err) {
                    if (options.debug) console.log(err.message + " in " + xmlhttp.responseText);
                    return;
                }
                callback(data);
            }
        };
        xmlhttp.open("GET", url, true);
        xmlhttp.send();
    }


    // callback function for sorting resulrs per r (=rating) property
    function compare_rate(a,b) {
        return (a.r < b.r);
    }


    /** vwOverUnder
     * vertical-wise over/under
     * 
     * @param {document.element} el : element to check
     * @param {document.element} container : container element (compairing)
     * @return {int} .. [-1|0|+1]
     * ..:  0 if element's heignt is completely into container's viewport
     * ..: -1 if element's heignt is over container's viewport
     * ..: +1 if element's heignt is under container's veiwport
     */
    function vwOverUnder(el, container) {
        let eR = el.getBoundingClientRect();
        let cR = container.getBoundingClientRect();
        console.log('er|cr', eR, cR);
        
        let result = -1;    // default: element is under container's viewport
        
        if (eR.y >= cR.y  && eR.y + eR.height <= cR.y + cR.height - options.tolerance) {
            result = 0      // fully inside

        } else if (eR.y < cR.y) {
            result = -1
        }
        
        return result;
    }



  
    /** 4. ACTUAL DATA LOADING
     * -------------------------------------------------------------------------
     *//////////////////////////////////////////////////////////////////////////



    // TODO:
    // control completion of async loads via .then() rather by this custom structrure
    // Need to rewrite the folllowing code ............................. from here
    // ...........................................................................
    // ...........................................................................
    

    /** workline
     * -------------------------------------------------------------------------
     * custom object/data-structure
     * to track status/completion of async svents
     * (it does the job using a special set method)
     */
    var workline = {
    
        trackerJL : 0,
        set jsonLoaded(x) {
            this.trackerJL = x;
    
            // fire event on certain values
            if (x == 2) {
                if (options.debug) console.info('suggestion-engine requirements fulfilled');
                _isReady = true;
                // code to execute
                // ...
            }
        },
        get jsonLoaded() { return this.trackerJL; }
    };
  
      
    /** LOAD DATA (from endoints)
     * ---------------------------------------------------------------------------
     */

    
    function load_store_products(storeID) {
        let prData = getSessionObj('prd');
        if (prData !== null) {
            _products = prData;
            if (options.debug) console.log(`...products fetched from cache (${+ new Date()})`);
            workline.jsonLoaded++;

        } else {
            ajax_get(options.products_json, function(data) {    // get stor's _products
                _products = data;
                _products.forEach(p => {p.kb = keyboardize(p.w).toLowerCase()} );
                setSessionObj('prd', _products);
                if (options.debug) console.log(`...products loaded; (${+ new Date()})`);
                workline.jsonLoaded++;
                CURRENT_STOREs_CATALOG = storeID;
            });
        }
    }
    
    var STORE = { id: 904 };
    
    if (STORE.id != 0) load_store_products(STORE.id);
      
    // ...........................................................................
    // ...........................................................................
    // ................................................................ up to here


  
      
  
    /** 5. SEARCH ENGINE
     * -------------------------------------------------------------------------
     *//////////////////////////////////////////////////////////////////////////
   
    workline.jsonLoaded++;      // notify workline that jQuery is ready!!

    // suggestions engine //////////////////////////////////////////////////
    // ---
    function suggestions_engine(qOrig) {
        var results = [];       // suggestions to respond
        var pot = [];   pot.length = 0;

        var space_ended = (qOrig.slice(-1) == ' ') ? true : false;

        // clean and sanitize and mark links onto q(uery) string
        var q = keyboardize( sanitize_GR( clean_text(qOrig.trim()) ) ).trim();
        
        // TODO:
        // construct direct-linked words
        // = do unequivocally replaces
        // steps:
        // 1. replace accented vowels with non accented ones
        // 2. replace `/some pattern/gi , 'SOME-REPLACE-PATTERN'`

        var qAr = q.split(' ');     // split to words
        /// if (space_ended) qAr.push(' ');     // if space-end existed, push a space to query array
        /// 
        /// if (qAr.slice(-1) == "") {
        ///     qAr.pop();
        /// }

        if (options.debug) console.log('*** init SEARCH QUERY:', qOrig, 'search:', qAr);
    
        pot = _products;      // potential results // NOTE: CRITICAL: BY REFERENCE

        var wi = 0;           // word index (from list)
        var wc = qAr.length;

        qAr.forEach( w => {
            if (options.debug) console.log('...testing', w);

            let sf = [];      // (matches) so far
            let mi;           // position of match
            wi++;

            pot.forEach( it => {
                let matched = false;
                let tester = ' '+ it.kb + ' ';

                // reset previous history and ratings
                if (wi == 1) {
                    it.r = 0;
                    it.history = [];
                }


                // rate word-match > start-match > simple-match
                // ... up to 8 points

                if (tester.indexOf(' '+ w +' ') != -1) {
                    it.r += 9;
                    it.history.push({ w: w, rate: 9 });
                    matched = true;
                }
                else if (tester.indexOf(' '+ w) != -1) {
                    it.r += 5;
                    it.history.push({ w: w, rate: 5 });
                    matched = true;
                }
                else if (tester.indexOf(w) != -1) {
                    it.r += 2;
                    it.history.push({ w: w, rate: 2 });
                    matched = true;
                }
                
                // rate `near-to-start` matching .. up to 7p
                // rate `earlyness` of word in query .. up to 7p

                if ((mi = tester.indexOf(' '+w)) != -1) {
                    let fc1 = 100 - ((mi < 99) ? mi : 99);    // near-to-start factor
                    let fc2 = wc - wi + 1;                    // query earlyness factor
                    let r1 = Math.floor(7*fc1/100);
                    let r2 = Math.floor(7*fc2/wc);

                    it.r += (r1 + r2);
                    it.history.push({ w: w, left: [fc1, r1], early: [fc2, r2] });
                }
                if (matched) sf.push(it);
            });

            if ((sf.length > (_maxResults + Math.floor(_maxResults/2)))
            || (wi == 1) ) {
                // ..if pot has a fair amount (= max + 50%) of results
                // ..or these are results of '1st-query-word'
                // set sf as new source
                pot.lenght = 0; pot = [];
                pot = JSON.parse(JSON.stringify(sf));   // copy by value

            } else {
                // else.. keep the source list and increase of 'so-far rating'
                // console.log('found small list', sf, pot)
                pot.forEach( it => {
                    sf.forEach( si => {
                        if (it.id == si.id) {
                            it.r += 10;
                            it.history.push({ w: w, plus: '+10'});
                        }
                    });
                });
            }
        });

        // sort results, get max-list of best rated
        results = (pot.length > _maxResults)
            ? pot.sort(compare_rate).slice(0, _maxResults)
            : pot.sort(compare_rate)

        if (options.debug) console.log(results);
    
        return results;
    }
    
    // suggestions caller (router function)
    // arguments:
    // * qOrig : original query string
    // ** list : callback array structure to host results
    // ---
    var isuggest = function(qOrig, list) {
        var results;

        qSanit = sanitize_GR(qOrig);  // sanitize greek accended chars

        // TODO:
        // check if all source-lists are ready
        // if not you need to wait ...
        // via async promishes or synced timouts

        /// // DEPRECATED: Suppport for eys-code search
        /// // if query seems to be some king of 'code/id'
        /// if (qSanit.length>2 && qSanit.match(/^[0-9]+$/) != null) {
        ///     results = search_by_code(qOrig);
        /// 
        /// } else {
        ///     // string match procedure with suggestions engine
        results = suggestions_engine(qOrig);
        /// }

        list(results);
    }

        // var rsfoot = document.createElement('div');
        // rsfoot.setAttribute("id", "retrosearch-footer");
        // $('#retrosearch-footer').html('Multi Search');

    /*
      jQuery(function() {     // on document ready code //////////////////////////

        // UI-dependent code
        // uses reference to specific document element (passed via options)
        // -----------------------------------------------------------------------
        const searchBox = $(options.search_tag);
        searchBox.typeahead(
            {
                hint: true,
                highlight: true,
                minLength: 1
            },
            {
                limit: _maxResults,   // +1 for extra button
                // name: 'kwlinks',
                displayKey: 'w',
                source: isuggest,
                templates: {
                    suggestion: function(data) {
                    return `<div data-id="${data.id}">${data.w}<span>Alfa, Beta and Gamma</span></div>`;
                    },

                    footer: '<div class="tt-suggestion tt-selectable call-multi-search">Multi Searh</div>',

                    empty: '<div class="-empty-">Δεν υπάρχει στο κωδικολόγιο του καταστήματος</div>'
                }
            }
        )
        .bind("typeahead:selected", function(obj, datum, name) {
            if (datum.hasOwnProperty('id')) {   // ** selected: PRODUCT
    
                // $('#js-add-product-to-order').attr('disabled', false);
                // fill_fields(datum.id, datum.sc, datum.x, datum.w, 1, datum.bc, datum.eu, datum.stk, datum.img);
                if (options.debug) console.log('selected: ', datum.id, datum.w);

                // GOTO product page
                window.location.href = 'product_list?product=id-' + datum.id;
    
                // $("#product-quantity").trigger('focus');  

            }
            else {      // selected: SUGGESTION
    
                $('.typeahead').typeahead('val','').trigger('blur');
                $('.typeahead').typeahead('val', datum.w +' ')
                    .trigger("query");
                // give some time to the engine to calculate results
                // then fire focus again...
                setTimeout(() => { $('.typeahead').trigger('focus'); }, _timeout_ms);
            }
    
        })
        .bind("typeahead:cursorchange", function( event, obj) {
            // track cursor-chane to handle special keys after a final product is selected

            if (typeof obj  === 'object'
            && !Array.isArray(obj) &&  obj !== null) {


                // console.log(obj);
                // var liObj = $(`.tt-menu .tt-dataset .tt-suggestion[data-id="${obj.id}"]`)
                // var c = liObj.html();
                // liObj.html = c + '\n\n_';
                // liObj.html = c;

                var y = $('.tt-menu').scrollTop();
                let ou = vwOverUnder(
                    document.querySelector(`.tt-menu .tt-suggestion[data-id="${obj.id}"]`),
                    document.querySelector('.tt-menu')
                );
                console.log('y:',y, 'obj:', obj, 'o/u:', ou);
                $('.tt-menu').scrollTop( y - ou * options.tolerance);

                // TODO:
                // need to park the cursorChanged-div into tt-menu veiwport (??)
                // check: https://stackoverflow.com/questions/75002332/check-if-child-element-is-100-visible-inside-a-parent-div-that-has-overflow-hid
                
            }
            

            // TODO:
            // handle exception where obj is undefined;
            // this occures...
            // when cusror returns from suggestions list back to the search field

            if (typeof obj === 'undefined')         cursor_on = { none: true };
            else if (obj.hasOwnProperty('id'))    cursor_on = obj;
            else                                cursor_on = { none: true };
        })
        .bind('typeahead:opened', function(e) {
        console.log('attach multisearch option if not exist');
        });
    
        // TRACK user search attempt ///////////////////////////////////////////////


        // $('.typeahead').on('typeahead:opened', function(e) {
        //       console.log('attach multisearch option if not exist');
        // });

        $('.typeahead').on('keyup', function(e) {
            if (_isReady) {
                // console.log('on:', cursor_on);
                // console.log('key:', e.key);
                if ((e.key == ' ') && cursor_on.hasOwnProperty('id')) {

                    // product is actually selected
                    var datum = cursor_on;

                    // fill_fields(datum.id, datum.sc, datum.x, datum.w, 1, datum.bc, datum.eu, datum.stk, datum.img);
                    $("#product-quantity").trigger('focus');
                    e.preventDefault();

                } else { 
                    if (e.key === "Enter") {

                        // if curson is not on some option
                        if ((typeof curson_on === 'undefined') || (curson_on.none == true)) {

                            // do a common search
                            if (options.debug) console.log('Do a Non-Suggestions search', searchBox.val());

                            // DEPRICATED: var location = encodeURI('/product_list?productSearch=%'+ searchBox.val() +'%');

                            // search_results = common_search(searchBox.val());
                            // TODO:
                            console.log('DO A COMMON_SEARCH');


                        } else {
                            // launch a product page
                            var location = '/product_list?product=id-'+ cursor_on.id;
                            if (options.debug) console.log('product', cursor_on.id, cursor_on.w);

                            // TODO:
                            console.log('GO TO PRODUCT PAGE', location)
                        }
                        // window.location.href = location;
                    }
                }
            }
        });
    
      });
    */

    // sub-module (start)
    ////////////////////////////////////////////////////////////////////////////

    function update_common_search_results(q, results) {
        let queries = getSessionObj('sr');
        let newSRlist = [];
        let isnewQ = true;
        if (queries === null) {
            setSessionObj('sr', [{
                q: q,
                result: result,
                t: + new Date()
            }]);
            return true;

        } else {

            queries.forEach(it => {
                if (it.q == q) {
                    newSRlist.push({
                        q:q,
                        result: result,
                        t: + new Date()
                    });
                    isnewQ = false;
                } else { newSRlist.push(it); }
            });

            if (isnewQ) {
                newSRlist.push({
                    q:q,
                    result: result,
                    t: + new Date()
                });
            }

            return true;
        }
    }

  

    ////////////////////////////////////////////////////////////////////////////
    // sub-module (end)
  
  
    function common_search(query) {
        // clear ; sanitize ; split
        var qAr = keyboardize( sanitize_GR( clean_text(query) ) ).toLowerCase().split(' ');

        // if last item is empty, remove it
        if ((qAr.slice(-1) == ' ') || (qAr.slice(-1) == '')) qAr.pop()

        var results = _products;

        // for each key fitler results
        qAr.forEach( key => {
            results = key_sublist(key, results)
        });

        // echo products (and prepare list to POST)
        var list_ = [];
        results.forEach( item => {
            if (options.debug) console.log(item.id, ':', item.w);
            list_.push(item.id)
        })

        // *** TODO: keep results in local storage (or on session storage)

        // update_common_search_results(query, list_);

        let l = list_.join(',');
        var url = encodeURI(`${options.visualize_search_results_url}?search=${query}&eys_code=${l}`);

        console.log('common search: search query > location = search')
        window.location.href = encodeURI(`${options.visualize_search_results_url}?search=${query}`);

    }

    /** return from list only items that include 'key'
     */
    function key_sublist(key, list) {
        var result = [];
        list.forEach( item => {
            if (item.kb.includes(key)) {
                result.push(item);
            }
        });
        
        return result;
    }
  
}
  

/** test script
 * ---
 *  pl = getSessionObj('prd'); wl = ['coca', 'xvris', 'zaxarh', '2x1'];
 *  pot = pl;
 *  console.log(+ new Date());
 *  wl.forEach( w => {
 *      let sf = [];
 *      for(i=0 ; i < pot.length; i++) { if (pot[i].kb.includes(w)) sf.push(pot[i]); }
 *      pot.lenght = 0; pot = sf;
 *  });
 *  console.log(+ new Date(), pot);
 *  
 *  
 ** test performance for vs foreach
 *  ---
 *  pl = getSessionObj('prd'); console.log('started', + new Date());
 *  for(j=0; j<50; j++) { for(i=0; i<pl.length; i++) { let x = pl[i].kb; } }
 *  console.log('ended', + new Date());
 * 
 *  pl = getSessionObj('prd'); console.log('started', + new Date());
 *  for(j=0; j<50; j++) { pl.forEach( it => { let x = it.kb; }); }
 *  console.log('ended', + new Date());
**/