(function() {
    /**
     * Levenshtein function courtesy of https://github.com/tad-lispy/node-damerau-levenshtein / https://www.npmjs.com/package/damerau-levenshtein
     */
    function levenshtein(__this, that, limit) {
    
        var thisLength = __this.length,
                thatLength = that.length,
                matrix = [];
    
        // If the limit is not defined it will be calculate from this and that args.
        limit = (limit || ((thatLength > thisLength ? thatLength : thisLength)))+1;
    
        for (var i = 0; i < limit; i++) {
            matrix[i] = [i];
            matrix[i].length = limit;
        }
        for (i = 0; i < limit; i++) {
            matrix[0][i] = i;
        }
    
        if (Math.abs(thisLength - thatLength) > (limit || 100)){
            return prepare (limit || 100);
        }
        if (thisLength === 0){
            return prepare (thatLength);
        }
        if (thatLength === 0){
            return prepare (thisLength);
        }
    
        // Calculate matrix.
        var j, this_i, that_j, cost, min, t;
        for (i = 1; i <= thisLength; ++i) {
            this_i = __this[i-1];
    
            // Step 4
            for (j = 1; j <= thatLength; ++j) {
                // Check the jagged ld total so far
                if (i === j && matrix[i][j] > 4) return prepare (thisLength);
    
                that_j = that[j-1];
                cost = (this_i === that_j) ? 0 : 1; // Step 5
                // Calculate the minimum (much faster than Math.min(...)).
                min    = matrix[i - 1][j    ] + 1; // Deletion.
                if ((t = matrix[i    ][j - 1] + 1   ) < min) min = t;   // Insertion.
                if ((t = matrix[i - 1][j - 1] + cost) < min) min = t;   // Substitution.
    
                // Update matrix.
                matrix[i][j] = (i > 1 && j > 1 && this_i === that[j-2] && __this[i-2] === that_j && (t = matrix[i-2][j-2]+cost) < min) ? t : min; // Transposition.
            }
        }
    
        return prepare (matrix[thisLength][thatLength]);
    
        /**
         *
         */
        function prepare(steps) {
            var length = Math.max(thisLength, thatLength)
            var relative = length === 0
                ? 0
                : (steps / length);
            var similarity = 1 - relative
            return {
                steps: steps,
                relative: relative,
                similarity: similarity
            };
        }
    }
    
    function fuzzySearch(searchVal, data, initial) {
        // If no searchVal has been defined then return all rows.
        if(searchVal === undefined || searchVal.length === 0) {
            return {
                pass: true,
                score: ''
            }
        }
    
        var threshold = initial.threshold !== undefined ? initial.threshold : 0.5;
    
        // Split the searchVal into individual words.
        var splitSearch = searchVal.split(/[^(a-z|A-Z|0-9)]/g);
    
        // Array to keep scores in
        var highestCollated = [];
    
        // Remove any empty words or spaces
        for(var x = 0; x < splitSearch.length; x++) {
            if (splitSearch[x].length === 0 || splitSearch[x] === ' ') {
                splitSearch.splice(x, 1);
                x--;
            }
            // Aside - Add to the score collection if not done so yet for this search word
            else if (highestCollated.length < splitSearch.length) {
                highestCollated.push({pass: false, score: 0});
            }
        }
    
        // Going to check each cell for potential matches
        for(var i = 0; i < data.length; i++) {
            // Convert all data points to lower case fo insensitive sorting
            data[i] = data[i].toLowerCase();
    
            // Split the data into individual words
            var splitData = data[i].split(/[^(a-z|A-Z|0-9)]/g);
    
            // Remove any empty words or spaces
            for (var y = 0; y < splitData.length; y++){
                if(splitData[y].length === 0 || splitData[y] === ' ') {
                    splitData.splice(y, 1);
                    x--;
                }
            }
    
            // Check each search term word
            for(var x = 0; x < splitSearch.length; x++) {
                // Reset highest score
                var highest = {
                    pass: undefined,
                    score: 0
                };
    
                // Against each word in the cell
                for (var y = 0; y < splitData.length; y++){
                    // If this search Term word is the beginning of the word in the cell we want to pass this word
                    if(splitData[y].indexOf(splitSearch[x]) === 0){
                        highest = {
                            pass: true,
                            score: splitSearch[x].length / splitData[y].length
                        };
                    }
    
                    // Get the levenshtein similarity score for the two words
                    var steps = levenshtein(splitSearch[x], splitData[y]).similarity;
                    
                    // If the levenshtein similarity score is better than a previous one for the search word then let's store it
                    if(steps > highest.score) {
                        highest.score = steps;
                    }
                }
    
                // If this cell has a higher scoring word than previously found to the search term in the row, store it
                if(highestCollated[x].score < highest.score || highest.pass) {
                    highestCollated[x] = {
                        pass: highest.pass || highestCollated.pass ? true : highest.score > threshold,
                        score: highest.score
                    };
                }
            }
        }
        
        // Check that all of the rows have a score greater than 0.5
        for(var i = 0; i < highestCollated.length; i++) {
            if(!highestCollated[i].pass) {
                return {
                    pass: false,
                    score: Math.round(((highestCollated.reduce((a,b) => a+b.score, 0) / highestCollated.length) * 100)) + "%"
                };
            }
        }
    
        // If we get to here, all scores greater than 0.5 so display the row
        return {
            pass: true,
            score: Math.round(((highestCollated.reduce((a,b) => a+b.score, 0) / highestCollated.length) * 100)) + "%"
        };
    }
    
    $.fn.dataTable.ext.search.push(
        function( settings, data, dataIndex ) {
            var initial = settings.oInit.fuzzySearch;
            // If fuzzy searching has not been implemented then pass all rows for this function
            if (settings.aoData[dataIndex]._fuzzySearch !== undefined) {
                // Read score to set the cell content and sort data
                var score = settings.aoData[dataIndex]._fuzzySearch.score;
                settings.aoData[dataIndex].anCells[initial.rankColumn].innerHTML = score;
    
                // Remove '%' from the end of the score so can sort on a number
                settings.aoData[dataIndex]._aSortData[initial.rankColumn] = +score.substring(0, score.length - 1);
    
                // Return the value for the pass as decided by the fuzzySearch function
                return settings.aoData[dataIndex]._fuzzySearch.pass;
            }
            else {
                settings.aoData[dataIndex].anCells[initial.rankColumn].innerHTML = '';
                settings.aoData[dataIndex]._aSortData[initial.rankColumn] = '';
            }
            return true;
        }
    );
    
    $(document).on('init.dt', function(e, settings) {
        let api = new $.fn.dataTable.Api(settings);
        var initial = api.init().fuzzySearch;

        // If this is not set then fuzzy searching is not enabled on the table so return.
        if(!initial) {
            return;
        }
    
        // Find the input element
        let input = $('div.dataTables_filter input', api.table().container())

        let fontBold = {
            'font-weight': '600',
            'background-color': 'rgba(255,255,255,0.1)'
        };
        let fontNormal = {
            'font-weight': '500',
            'background-color': 'transparent'
        };
        let toggleCSS = {
            'border': 'none',
            'background': 'none',
            'font-size': '100%',
            'width': '50%',
            'display': 'inline-block',
            'color': 'white',
            'cursor': 'pointer',
            'padding': '0.5em'
        }
        
        // Only going to set the toggle if it is enabled
        let toggle, tooltip, exact, fuzzy, label;
        if(initial.toggleSmart) {
            toggle =$('<button class="toggleSearch">Abc</button>')
                .insertAfter(input)
                .css({
                    'border': 'none',
                    'background': 'none',
                    'position': 'absolute',
                    'right': '0px',
                    'top': '4px',
                    'cursor': 'pointer',
                    'color': '#3b5e99',
                    'margin-top': '1px'
                });
            exact =$('<button class="toggleSearch">Exact</button>')
                .insertAfter(input)
                .css(toggleCSS)
                .css(fontBold)
                .attr('highlighted', true);
            fuzzy =$('<button class="toggleSearch">Fuzzy</button>')
                .insertAfter(input)
                .css(toggleCSS);
            input.css({
                'padding-right': '30px'
            });
            label = $('<div>Search Type<div>').css({'padding-bottom': '0.5em', 'font-size': '0.8em'})
            tooltip = $('<div class="fuzzyToolTip"></div>')
                .css({
                    'position': 'absolute',
                    'right': '0px',
                    'top': '2em',
                    'background': 'white',
                    'border-radius': '4px',
                    'text-align': 'center',
                    'padding': '0.5em',
                    'background-color': '#16232a',
                    'box-shadow': '4px 4px 4px rgba(0, 0, 0, 0.5)',
                    'color': 'white',
                    'transition': 'opacity 0.25s',					
                    'z-index': '30001'
                })
                .width(input.outerWidth() - 3)
                .append(label).append(exact).append(fuzzy);
        }

        function toggleFuzzy() {
            if(toggle.attr('blurred')) {
                toggle.css({'filter': 'blur(0px)'}).removeAttr('blurred');
                fuzzy.removeAttr('highlighted').css(fontNormal);
                exact.attr('highlighted', true).css(fontBold);
            }
            else {
                toggle.css({'filter': 'blur(1px)'}).attr('blurred', true);
                exact.removeAttr('highlighted').css(fontNormal);
                fuzzy.attr('highlighted', true).css(fontBold);
            }
            triggerSearchFunction();
        }

        // Turn off the default datatables searching events
        $(settings.nTable).off('search.dt.DT');

        // The function that we want to run on search
        var triggerSearchFunction = function(event){
            // If the search is only to be triggered on return wait for that
            if (!initial.returnSearch || event.key === "Enter") {
                var searchVal = '';
                // If the toggle is set and isn't checkd then perform a normal search
                if(toggle && !toggle.attr('blurred')) {
                    api.rows().iterator('row', function(settings, rowIdx) {
                        settings.aoData[rowIdx]._fuzzySearch = undefined;
                    })
                    api.search(input.val())
                    api.draw();
                }
                // Otherwise perform a fuzzy search
                else {
                    // Get the value from the input element and convert to lower case
                    searchVal = input.val();
                    
                    if (searchVal !== undefined && searchVal.length === 0) {
                        searchVal = searchVal.toLowerCase();
                    }
                    
                    // For each row call the fuzzy search function to get result
                    api.rows().iterator('row', function(settings, rowIdx) {
                        settings.aoData[rowIdx]._fuzzySearch = fuzzySearch(searchVal, settings.aoData[rowIdx]._aFilterData, initial)
                    });

                    // Empty the datatables search and replace it with our own
                    api.search("");
                    input.val(searchVal);
                    api.draw();
                }
            }
        }

        input.off();
        // Set listeners to occur on toggle and typing
        if(toggle) {
            // Highlights one of the buttons in the tooltip and un-highlights the other
            function highlightButton(toHighlight, noHighlight) {
                if(!toHighlight.attr('highlighted')){
                    toHighlight.attr('highlighted', true);
                    toHighlight.css(fontBold);
                    noHighlight.css(fontNormal);
                    noHighlight.removeAttr('highlighted');
                    toggleFuzzy()
                }
            }

            // Removes the tooltip element
            function removeToolTip() {
                tooltip.remove();
            }

            // Actions for the toggle button
            toggle
                .on('click', toggleFuzzy)
                .on('mouseenter', function() {
                    tooltip
                        .insertAfter(toggle)
                        .on('mouseleave', removeToolTip);
                    exact.on('click',  () => highlightButton(exact, fuzzy));
                    fuzzy.on('click', () => highlightButton(fuzzy, exact));
                })
                .on('mouseleave', removeToolTip);

            // Actions for the input element
            input
                .on('mouseenter', function() {
                    tooltip
                        .insertAfter(toggle)
                        .on('mouseleave', removeToolTip);
                    exact.on('click',  () => highlightButton(exact, fuzzy))
                    fuzzy.on('click', () => highlightButton(fuzzy, exact))
                })
                .on('mouseleave', function() {
                    var inToolTip = false;
                    tooltip.on('mouseenter', () => inToolTip = true);
                    toggle.on('mouseenter', () => inToolTip = true);
                    setTimeout(function(){
                        if(!inToolTip) {
                            removeToolTip();
                        }
                    }, 50)
                });
            
            var state = api.state.loaded();


            if(state !== null && state._fuzzySearch === 'true') {
                toggle.click();
            }

            api.on('stateSaveParams', function(e, settings, data) {
                data._fuzzySearch = toggle.attr('blurred');
            })

            api.state.save();
        }

        // Always add this event no matter if toggling is enabled
        input.on('input keydown', triggerSearchFunction);
    })
}());