/**
 * (c) 2010-2017 Torstein Honsi
 *
 * License: www.highcharts.com/license
 */

'use strict';

import Highcharts from './Globals.js';
import './Utilities.js';

var H = Highcharts,

    addEvent = H.addEvent,
    css = H.css,
    discardElement = H.discardElement,
    defined = H.defined,
    each = H.each,
    fireEvent = H.fireEvent,
    isFirefox = H.isFirefox,
    marginNames = H.marginNames,
    merge = H.merge,
    pick = H.pick,
    setAnimation = H.setAnimation,
    stableSort = H.stableSort,
    win = H.win,
    wrap = H.wrap;

/**
 * The overview of the chart's series. The legend object is instanciated
 * internally in the chart constructor, and is available from the `chart.legend`
 * property. Each chart has only one legend.
 *
 * @class
 * @name Highcharts.Legend
 *
 * @param {Highcharts.Chart} chart
 *        The chart instance.
 *
 * @param {Highcharts.LegendOptions} options
 *        Legend options.
 */
Highcharts.Legend = function (chart, options) {
    this.init(chart, options);
};

Highcharts.Legend.prototype = {

    /**
     * Initialize the legend.
     *
     * @private
     * @function Highcharts.Legend#init
     *
     * @param {Highcharts.Chart} chart
     *        The chart instance.
     *
     * @param {Highcharts.LegendOptions} options
     *        Legend options.
     */
    init: function (chart, options) {

        /**
         * Chart of this legend.
         *
         * @readonly
         * @name Highcharts.Legend#chart
         * @type {Highcharts.Chart}
         */
        this.chart = chart;

        this.setOptions(options);

        if (options.enabled) {

            // Render it
            this.render();

            // move checkboxes
            addEvent(this.chart, 'endResize', function () {
                this.legend.positionCheckboxes();
            });

            if (this.proximate) {
                this.unchartrender = addEvent(
                    this.chart,
                    'render',
                    function () {
                        this.legend.proximatePositions();
                        this.legend.positionItems();
                    }
                );
            } else if (this.unchartrender) {
                this.unchartrender();
            }
        }
    },

    /**
     * @private
     * @function Highcharts.Legend#setOptions
     *
     * @param {Highcharts.LegendOptions} options
     */
    setOptions: function (options) {

        var padding = pick(options.padding, 8);

        /**
         * Legend options.
         *
         * @readonly
         * @name Highcharts.Legend#options
         * @type {Highcharts.LegendOptions}
         */
        this.options = options;

        
        this.itemStyle = options.itemStyle;
        this.itemHiddenStyle = merge(this.itemStyle, options.itemHiddenStyle);
        
        this.itemMarginTop = options.itemMarginTop || 0;
        this.padding = padding;
        this.initialItemY = padding - 5; // 5 is pixels above the text
        this.symbolWidth = pick(options.symbolWidth, 16);
        this.pages = [];
        this.proximate = options.layout === 'proximate' && !this.chart.inverted;

    },

    /**
     * Update the legend with new options. Equivalent to running `chart.update`
     * with a legend configuration option.
     *
     * @sample highcharts/legend/legend-update/
     *         Legend update
     *
     * @function Highcharts.Legend#update
     *
     * @param {Highcharts.LegendOptions} options
     *        Legend options.
     *
     * @param {boolean} [redraw=true]
     *        Whether to redraw the chart.
     *
     * @todo
     * Make events official: Fires the event `afterUpdate`.
     */
    update: function (options, redraw) {
        var chart = this.chart;

        this.setOptions(merge(true, this.options, options));
        this.destroy();
        chart.isDirtyLegend = chart.isDirtyBox = true;
        if (pick(redraw, true)) {
            chart.redraw();
        }

        fireEvent(this, 'afterUpdate');
    },

    /**
     * Set the colors for the legend item.
     *
     * @private
     * @function Highcharts.Legend#colorizeItem
     *
     * @param {Highcharts.Point|Highcharts.Series} item
     *        A Series or Point instance
     *
     * @param {boolean} [visible=false]
     *        Dimmed or colored
     *
     * @todo
     * Make events official: Fires the event `afterColorizeItem`.
     */
    colorizeItem: function (item, visible) {
        item.legendGroup[visible ? 'removeClass' : 'addClass'](
            'highcharts-legend-item-hidden'
        );

        
        var legend = this,
            options = legend.options,
            legendItem = item.legendItem,
            legendLine = item.legendLine,
            legendSymbol = item.legendSymbol,
            hiddenColor = legend.itemHiddenStyle.color,
            textColor = visible ? options.itemStyle.color : hiddenColor,
            symbolColor = visible ? (item.color || hiddenColor) : hiddenColor,
            markerOptions = item.options && item.options.marker,
            symbolAttr = { fill: symbolColor };

        if (legendItem) {
            legendItem.css({
                fill: textColor,
                color: textColor // #1553, oldIE
            });
        }
        if (legendLine) {
            legendLine.attr({ stroke: symbolColor });
        }

        if (legendSymbol) {

            // Apply marker options
            if (markerOptions && legendSymbol.isMarker) { // #585
                symbolAttr = item.pointAttribs();
                if (!visible) {
                    symbolAttr.stroke = symbolAttr.fill = hiddenColor; // #6769
                }
            }

            legendSymbol.attr(symbolAttr);
        }
        

        fireEvent(this, 'afterColorizeItem', { item: item, visible: visible });
    },

    /**
     * @private
     * @function Highcharts.Legend#positionItems
     */
    positionItems: function () {

        // Now that the legend width and height are established, put the items
        // in the final position
        each(this.allItems, this.positionItem, this);

        if (!this.chart.isResizing) {
            this.positionCheckboxes();
        }
    },

    /**
     * Position the legend item.
     *
     * @private
     * @function Highcharts.Legend#positionItem
     *
     * @param {Highcharts.Point|Highcharts.Series} item
     *        The item to position
     */
    positionItem: function (item) {
        var legend = this,
            options = legend.options,
            symbolPadding = options.symbolPadding,
            ltr = !options.rtl,
            legendItemPos = item._legendItemPos,
            itemX = legendItemPos[0],
            itemY = legendItemPos[1],
            checkbox = item.checkbox,
            legendGroup = item.legendGroup;

        if (legendGroup && legendGroup.element) {
            legendGroup[defined(legendGroup.translateY) ? 'animate' : 'attr']({
                translateX: ltr ?
                    itemX :
                    legend.legendWidth - itemX - 2 * symbolPadding - 4,
                translateY: itemY
            });
        }

        if (checkbox) {
            checkbox.x = itemX;
            checkbox.y = itemY;
        }
    },

    /**
     * Destroy a single legend item, used internally on removing series items.
     *
     * @private
     * @function Highcharts.Legend#destroyItem
     *
     * @param {Highcharts.Point|Highcharts.Series} item
     *        The item to remove
     */
    destroyItem: function (item) {
        var checkbox = item.checkbox;

        // destroy SVG elements
        each(
            ['legendItem', 'legendLine', 'legendSymbol', 'legendGroup'],
            function (key) {
                if (item[key]) {
                    item[key] = item[key].destroy();
                }
            }
        );

        if (checkbox) {
            discardElement(item.checkbox);
        }
    },

    /**
     * Destroy the legend. Used internally. To reflow objects, `chart.redraw`
     * must be called after destruction.
     *
     * @private
     * @function Highcharts.Legend#destroy
     */
    destroy: function () {
        function destroyItems(key) {
            if (this[key]) {
                this[key] = this[key].destroy();
            }
        }

        // Destroy items
        each(this.getAllItems(), function (item) {
            each(['legendItem', 'legendGroup'], destroyItems, item);
        });

        // Destroy legend elements
        each([
            'clipRect',
            'up',
            'down',
            'pager',
            'nav',
            'box',
            'title',
            'group'
        ], destroyItems, this);
        this.display = null; // Reset in .render on update.
    },

    /**
     * Position the checkboxes after the width is determined.
     *
     * @private
     * @function Highcharts.Legend#positionCheckboxes
     */
    positionCheckboxes: function () {
        var alignAttr = this.group && this.group.alignAttr,
            translateY,
            clipHeight = this.clipHeight || this.legendHeight,
            titleHeight = this.titleHeight;

        if (alignAttr) {
            translateY = alignAttr.translateY;
            each(this.allItems, function (item) {
                var checkbox = item.checkbox,
                    top;

                if (checkbox) {
                    top = translateY + titleHeight + checkbox.y +
                        (this.scrollOffset || 0) + 3;
                    css(checkbox, {
                        left: (alignAttr.translateX + item.checkboxOffset +
                            checkbox.x - 20) + 'px',
                        top: top + 'px',
                        display: top > translateY - 6 && top < translateY +
                            clipHeight - 6 ? '' : 'none'
                    });
                }
            }, this);
        }
    },

    /**
     * Render the legend title on top of the legend.
     *
     * @private
     * @function Highcharts.Legend#renderTitle
     */
    renderTitle: function () {
        var options = this.options,
            padding = this.padding,
            titleOptions = options.title,
            titleHeight = 0,
            bBox;

        if (titleOptions.text) {
            if (!this.title) {
                /**
                 * SVG element of the legend title.
                 *
                 * @readonly
                 * @name Highcharts.Legend#title
                 * @type {Highcharts.SVGElement}
                 */
                this.title = this.chart.renderer.label(
                        titleOptions.text,
                        padding - 3,
                        padding - 4,
                        null,
                        null,
                        null,
                        options.useHTML,
                        null,
                        'legend-title'
                    )
                    .attr({ zIndex: 1 })
                    
                    .css(titleOptions.style)
                    
                    .add(this.group);
            }
            bBox = this.title.getBBox();
            titleHeight = bBox.height;
            this.offsetWidth = bBox.width; // #1717
            this.contentGroup.attr({ translateY: titleHeight });
        }
        this.titleHeight = titleHeight;
    },

    /**
     * Set the legend item text.
     *
     * @function Highcharts.Legend#setText
     *
     * @param {Highcharts.Point|Highcharts.Series} item
     *        The item for which to update the text in the legend.
     */
    setText: function (item) {
        var options = this.options;
        item.legendItem.attr({
            text: options.labelFormat ?
                H.format(options.labelFormat, item, this.chart.time) :
                options.labelFormatter.call(item)
        });
    },

    /**
     * Render a single specific legend item. Called internally from the `render`
     * function.
     *
     * @private
     * @function Highcharts.Legend#renderItem
     *
     * @param {Highcharts.Point|Highcharts.Series} item
     *        The item to render.
     */
    renderItem: function (item) {
        var legend = this,
            chart = legend.chart,
            renderer = chart.renderer,
            options = legend.options,
            horizontal = options.layout === 'horizontal',
            symbolWidth = legend.symbolWidth,
            symbolPadding = options.symbolPadding,
            
            itemStyle = legend.itemStyle,
            itemHiddenStyle = legend.itemHiddenStyle,
            
            itemDistance = horizontal ? pick(options.itemDistance, 20) : 0,
            ltr = !options.rtl,
            bBox,
            li = item.legendItem,
            isSeries = !item.series,
            series = !isSeries && item.series.drawLegendSymbol ?
                item.series :
                item,
            seriesOptions = series.options,
            showCheckbox = legend.createCheckboxForItem &&
                seriesOptions &&
                seriesOptions.showCheckbox,
            // full width minus text width
            itemExtraWidth = symbolWidth + symbolPadding + itemDistance +
                (showCheckbox ? 20 : 0),
            useHTML = options.useHTML,
            fontSize = 12,
            itemClassName = item.options.className;

        if (!li) { // generate it once, later move it

            // Generate the group box, a group to hold the symbol and text. Text
            // is to be appended in Legend class.
            item.legendGroup = renderer.g('legend-item')
                .addClass(
                    'highcharts-' + series.type + '-series ' +
                    'highcharts-color-' + item.colorIndex +
                    (itemClassName ? ' ' + itemClassName : '') +
                    (isSeries ? ' highcharts-series-' + item.index : '')
                )
                .attr({ zIndex: 1 })
                .add(legend.scrollGroup);

            // Generate the list item text and add it to the group
            item.legendItem = li = renderer.text(
                    '',
                    ltr ? symbolWidth + symbolPadding : -symbolPadding,
                    legend.baseline || 0,
                    useHTML
                )
                
                // merge to prevent modifying original (#1021)
                .css(merge(item.visible ? itemStyle : itemHiddenStyle))
                
                .attr({
                    align: ltr ? 'left' : 'right',
                    zIndex: 2
                })
                .add(item.legendGroup);

            // Get the baseline for the first item - the font size is equal for
            // all
            if (!legend.baseline) {
                
                fontSize = itemStyle.fontSize;
                
                legend.fontMetrics = renderer.fontMetrics(
                    fontSize,
                    li
                );
                legend.baseline =
                    legend.fontMetrics.f + 3 + legend.itemMarginTop;
                li.attr('y', legend.baseline);
            }

            // Draw the legend symbol inside the group box
            legend.symbolHeight = options.symbolHeight || legend.fontMetrics.f;
            series.drawLegendSymbol(legend, item);

            if (legend.setItemEvents) {
                legend.setItemEvents(item, li, useHTML);
            }

            // add the HTML checkbox on top
            if (showCheckbox) {
                legend.createCheckboxForItem(item);
            }
        }

        // Colorize the items
        legend.colorizeItem(item, item.visible);

        // Take care of max width and text overflow (#6659)
        
        if (!itemStyle.width) {
        
            li.css({
                width: (
                    options.itemWidth ||
                    options.width ||
                    chart.spacingBox.width
                ) - itemExtraWidth
            });
        
        }
        

        // Always update the text
        legend.setText(item);

        // calculate the positions for the next line
        bBox = li.getBBox();

        item.itemWidth = item.checkboxOffset =
            options.itemWidth ||
            item.legendItemWidth ||
            bBox.width + itemExtraWidth;
        legend.maxItemWidth = Math.max(legend.maxItemWidth, item.itemWidth);
        legend.totalItemWidth += item.itemWidth;
        legend.itemHeight = item.itemHeight = Math.round(
            item.legendItemHeight || bBox.height || legend.symbolHeight
        );
    },

    /**
     * Get the position of the item in the layout. We now know the
     * maxItemWidth from the previous loop.
     *
     * @private
     * @function Highcharts.Legend#layoutItem
     *
     * @param {Highcharts.Point|Highcharts.Series} item
     */
    layoutItem: function (item) {

        var options = this.options,
            padding = this.padding,
            horizontal = options.layout === 'horizontal',
            itemHeight = item.itemHeight,
            itemMarginBottom = options.itemMarginBottom || 0,
            itemMarginTop = this.itemMarginTop,
            itemDistance = horizontal ? pick(options.itemDistance, 20) : 0,
            widthOption = options.width,
            maxLegendWidth = widthOption || (
                this.chart.spacingBox.width - 2 * padding - options.x
            ),
            itemWidth = (
                    options.alignColumns &&
                    this.totalItemWidth > maxLegendWidth
                ) ?
                this.maxItemWidth :
                item.itemWidth;

        // If the item exceeds the width, start a new line
        if (
            horizontal &&
            this.itemX - padding + itemWidth > maxLegendWidth
        ) {
            this.itemX = padding;
            this.itemY += itemMarginTop + this.lastLineHeight +
                itemMarginBottom;
            this.lastLineHeight = 0; // reset for next line (#915, #3976)
        }

        // Set the edge positions
        this.lastItemY = itemMarginTop + this.itemY + itemMarginBottom;
        this.lastLineHeight = Math.max( // #915
            itemHeight,
            this.lastLineHeight
        );

        // cache the position of the newly generated or reordered items
        item._legendItemPos = [this.itemX, this.itemY];

        // advance
        if (horizontal) {
            this.itemX += itemWidth;

        } else {
            this.itemY += itemMarginTop + itemHeight + itemMarginBottom;
            this.lastLineHeight = itemHeight;
        }

        // the width of the widest item
        this.offsetWidth = widthOption || Math.max(
            (
                horizontal ? this.itemX - padding - (item.checkbox ?
                    // decrease by itemDistance only when no checkbox #4853
                    0 :
                    itemDistance
                ) : itemWidth
            ) + padding,
            this.offsetWidth
        );
    },

    /**
     * Get all items, which is one item per series for most series and one
     * item per point for pie series and its derivatives.
     *
     * @private
     * @function Highcharts.Legend#getAllItems
     *
     * @return {Array<Highcharts.Point|Highcharts.Series>}
     *         The current items in the legend.
     *
     * @fires Highcharts.Legend#event:afterGetAllItems
     *
     * @todo
     * Make events official: Fires the event `afterGetAllItems`.
     */
    getAllItems: function () {
        var allItems = [];
        each(this.chart.series, function (series) {
            var seriesOptions = series && series.options;

            // Handle showInLegend. If the series is linked to another series,
            // defaults to false.
            if (series && pick(
                seriesOptions.showInLegend,
                !defined(seriesOptions.linkedTo) ? undefined : false, true
            )) {

                // Use points or series for the legend item depending on
                // legendType
                allItems = allItems.concat(
                    series.legendItems ||
                    (
                        seriesOptions.legendType === 'point' ?
                            series.data :
                            series
                    )
                );
            }
        });

        fireEvent(this, 'afterGetAllItems', { allItems: allItems });

        return allItems;
    },

    /**
     * Get a short, three letter string reflecting the alignment and layout.
     *
     * @private
     * @function Highcharts.Legend#getAlignment
     *
     * @return {string}
     *         The alignment, empty string if floating
     */
    getAlignment: function () {
        var options = this.options;

        // Use the first letter of each alignment option in order to detect
        // the side. (#4189 - use charAt(x) notation instead of [x] for IE7)
        if (this.proximate) {
            return options.align.charAt(0) + 'tv';
        }
        return options.floating ? '' : (
            options.align.charAt(0) +
            options.verticalAlign.charAt(0) +
            options.layout.charAt(0)
        );
    },

    /**
     * Adjust the chart margins by reserving space for the legend on only one
     * side of the chart. If the position is set to a corner, top or bottom is
     * reserved for horizontal legends and left or right for vertical ones.
     *
     * @private
     * @function Highcharts.Legend#adjustMargins
     *
     * @param {Array<number>} margin
     *
     * @param {number} spacing
     */
    adjustMargins: function (margin, spacing) {
        var chart = this.chart,
            options = this.options,
            alignment = this.getAlignment();

        if (alignment) {

            each([
                /(lth|ct|rth)/,
                /(rtv|rm|rbv)/,
                /(rbh|cb|lbh)/,
                /(lbv|lm|ltv)/
            ], function (alignments, side) {
                if (alignments.test(alignment) && !defined(margin[side])) {

                    // Now we have detected on which side of the chart we should
                    // reserve space for the legend
                    chart[marginNames[side]] = Math.max(
                        chart[marginNames[side]],
                        (
                            chart.legend[
                                (side + 1) % 2 ? 'legendHeight' : 'legendWidth'
                            ] +
                            [1, -1, -1, 1][side] * options[
                                (side % 2) ? 'x' : 'y'
                            ] +
                            pick(options.margin, 12) +
                            spacing[side] +
                            (
                                side === 0 &&
                                chart.options.title.margin !== undefined ?
                                    chart.titleOffset +
                                        chart.options.title.margin :
                                    0
                            ) // #7428, #7894
                        )
                    );
                }
            });
        }
    },

    /**
     * @private
     * @function Highcharts.Legend#proximatePositions
     */
    proximatePositions: function () {
        var chart = this.chart,
            boxes = [],
            alignLeft = this.options.align === 'left';

        each(this.allItems, function (item) {
            var lastPoint,
                height,
                useFirstPoint = alignLeft;

            if (item.xAxis && item.points) {

                if (item.xAxis.options.reversed) {
                    useFirstPoint = !useFirstPoint;
                }
                lastPoint = H.find(
                    useFirstPoint ?
                        item.points :
                        item.points.slice(0).reverse(),
                    function (item) {
                        return H.isNumber(item.plotY);
                    }
                );
                height = item.legendGroup.getBBox().height;
                boxes.push({
                    target: item.visible ?
                        (lastPoint ? lastPoint.plotY : item.xAxis.height) -
                            0.3 * height :
                        chart.plotHeight,
                    size: height,
                    item: item
                });
            }
        }, this);
        H.distribute(boxes, chart.plotHeight);
        each(boxes, function (box) {
            box.item._legendItemPos[1] =
                chart.plotTop - chart.spacing[0] + box.pos;
        });

    },

    /**
     * Render the legend. This method can be called both before and after
     * `chart.render`. If called after, it will only rearrange items instead
     * of creating new ones. Called internally on initial render and after
     * redraws.
     *
     * @private
     * @function Highcharts.Legend#render
     */
    render: function () {
        var legend = this,
            chart = legend.chart,
            renderer = chart.renderer,
            legendGroup = legend.group,
            allItems,
            display,
            legendWidth,
            legendHeight,
            box = legend.box,
            options = legend.options,
            padding = legend.padding,
            alignTo;

        legend.itemX = padding;
        legend.itemY = legend.initialItemY;
        legend.offsetWidth = 0;
        legend.lastItemY = 0;

        if (!legendGroup) {
            /**
             * SVG group of the legend.
             *
             * @readonly
             * @name Highcharts.Legend#group
             * @type {Highcharts.SVGElement}
             */
            legend.group = legendGroup = renderer.g('legend')
                .attr({ zIndex: 7 })
                .add();
            legend.contentGroup = renderer.g()
                .attr({ zIndex: 1 }) // above background
                .add(legendGroup);
            legend.scrollGroup = renderer.g()
                .add(legend.contentGroup);
        }

        legend.renderTitle();

        // add each series or point
        allItems = legend.getAllItems();

        // sort by legendIndex
        stableSort(allItems, function (a, b) {
            return ((a.options && a.options.legendIndex) || 0) -
                ((b.options && b.options.legendIndex) || 0);
        });

        // reversed legend
        if (options.reversed) {
            allItems.reverse();
        }

        /**
         * All items for the legend, which is an array of series for most series
         * and an array of points for pie series and its derivatives.
         *
         * @readonly
         * @name Highcharts.Legend#allItems
         * @type {Array<Highcharts.Point|Highcharts.Series>}
         */
        legend.allItems = allItems;
        legend.display = display = !!allItems.length;

        // Render the items. First we run a loop to set the text and properties
        // and read all the bounding boxes. The next loop computes the item
        // positions based on the bounding boxes.
        legend.lastLineHeight = 0;
        legend.maxItemWidth = 0;
        legend.totalItemWidth = 0;
        legend.itemHeight = 0;
        each(allItems, legend.renderItem, legend);
        each(allItems, legend.layoutItem, legend);

        // Get the box
        legendWidth = (options.width || legend.offsetWidth) + padding;
        legendHeight = legend.lastItemY + legend.lastLineHeight +
            legend.titleHeight;
        legendHeight = legend.handleOverflow(legendHeight);
        legendHeight += padding;

        // Draw the border and/or background
        if (!box) {
            /**
             * SVG element of the legend box.
             *
             * @readonly
             * @name Highcharts.Legend#box
             * @type {Highcharts.SVGElement}
             */
            legend.box = box = renderer.rect()
                .addClass('highcharts-legend-box')
                .attr({
                    r: options.borderRadius
                })
                .add(legendGroup);
            box.isNew = true;
        }

        
        // Presentational
        box
            .attr({
                stroke: options.borderColor,
                'stroke-width': options.borderWidth || 0,
                fill: options.backgroundColor || 'none'
            })
            .shadow(options.shadow);
        

        if (legendWidth > 0 && legendHeight > 0) {
            box[box.isNew ? 'attr' : 'animate'](
                box.crisp.call({}, { // #7260
                    x: 0,
                    y: 0,
                    width: legendWidth,
                    height: legendHeight
                }, box.strokeWidth())
            );
            box.isNew = false;
        }

        // hide the border if no items
        box[display ? 'show' : 'hide']();

        

        legend.legendWidth = legendWidth;
        legend.legendHeight = legendHeight;

        if (display) {
            // If aligning to the top and the layout is horizontal, adjust for
            // the title (#7428)
            alignTo = chart.spacingBox;
            if (/(lth|ct|rth)/.test(legend.getAlignment())) {
                alignTo = merge(alignTo, {
                    y: alignTo.y + chart.titleOffset +
                        chart.options.title.margin
                });
            }

            legendGroup.align(merge(options, {
                width: legendWidth,
                height: legendHeight,
                verticalAlign: this.proximate ? 'top' : options.verticalAlign
            }), true, alignTo);
        }

        if (!this.proximate) {
            this.positionItems();
        }
    },

    /**
     * Set up the overflow handling by adding navigation with up and down arrows
     * below the legend.
     *
     * @private
     * @function Highcharts.Legend#handleOverflow
     *
     * @param {number} legendHeight
     *
     * @return {number}
     */
    handleOverflow: function (legendHeight) {
        var legend = this,
            chart = this.chart,
            renderer = chart.renderer,
            options = this.options,
            optionsY = options.y,
            alignTop = options.verticalAlign === 'top',
            padding = this.padding,
            spaceHeight = chart.spacingBox.height +
                (alignTop ? -optionsY : optionsY) - padding,
            maxHeight = options.maxHeight,
            clipHeight,
            clipRect = this.clipRect,
            navOptions = options.navigation,
            animation = pick(navOptions.animation, true),
            arrowSize = navOptions.arrowSize || 12,
            nav = this.nav,
            pages = this.pages,
            lastY,
            allItems = this.allItems,
            clipToHeight = function (height) {
                if (typeof height === 'number') {
                    clipRect.attr({
                        height: height
                    });
                } else if (clipRect) { // Reset (#5912)
                    legend.clipRect = clipRect.destroy();
                    legend.contentGroup.clip();
                }

                // useHTML
                if (legend.contentGroup.div) {
                    legend.contentGroup.div.style.clip = height ?
                        'rect(' + padding + 'px,9999px,' +
                            (padding + height) + 'px,0)' :
                        'auto';
                }
            };


        // Adjust the height
        if (
            options.layout === 'horizontal' &&
            options.verticalAlign !== 'middle' &&
            !options.floating
        ) {
            spaceHeight /= 2;
        }
        if (maxHeight) {
            spaceHeight = Math.min(spaceHeight, maxHeight);
        }

        // Reset the legend height and adjust the clipping rectangle
        pages.length = 0;
        if (legendHeight > spaceHeight && navOptions.enabled !== false) {

            this.clipHeight = clipHeight =
                Math.max(spaceHeight - 20 - this.titleHeight - padding, 0);
            this.currentPage = pick(this.currentPage, 1);
            this.fullHeight = legendHeight;

            // Fill pages with Y positions so that the top of each a legend item
            // defines the scroll top for each page (#2098)
            each(allItems, function (item, i) {
                var y = item._legendItemPos[1],
                    h = Math.round(item.legendItem.getBBox().height),
                    len = pages.length;

                if (!len || (y - pages[len - 1] > clipHeight &&
                        (lastY || y) !== pages[len - 1])) {
                    pages.push(lastY || y);
                    len++;
                }

                // Keep track of which page each item is on
                item.pageIx = len - 1;
                if (lastY) {
                    allItems[i - 1].pageIx = len - 1;
                }

                if (i === allItems.length - 1 &&
                        y + h - pages[len - 1] > clipHeight) {
                    pages.push(y);
                    item.pageIx = len;
                }
                if (y !== lastY) {
                    lastY = y;
                }
            });

            // Only apply clipping if needed. Clipping causes blurred legend in
            // PDF export (#1787)
            if (!clipRect) {
                clipRect = legend.clipRect =
                    renderer.clipRect(0, padding, 9999, 0);
                legend.contentGroup.clip(clipRect);
            }

            clipToHeight(clipHeight);

            // Add navigation elements
            if (!nav) {
                this.nav = nav = renderer.g()
                    .attr({ zIndex: 1 })
                    .add(this.group);

                this.up = renderer
                    .symbol(
                        'triangle',
                        0,
                        0,
                        arrowSize,
                        arrowSize
                    )
                    .on('click', function () {
                        legend.scroll(-1, animation);
                    })
                    .add(nav);

                this.pager = renderer.text('', 15, 10)
                    .addClass('highcharts-legend-navigation')
                    
                    .css(navOptions.style)
                    
                    .add(nav);

                this.down = renderer
                    .symbol(
                        'triangle-down',
                        0,
                        0,
                        arrowSize,
                        arrowSize
                    )
                    .on('click', function () {
                        legend.scroll(1, animation);
                    })
                    .add(nav);
            }

            // Set initial position
            legend.scroll(0);

            legendHeight = spaceHeight;

        // Reset
        } else if (nav) {
            clipToHeight();
            this.nav = nav.destroy(); // #6322
            this.scrollGroup.attr({
                translateY: 1
            });
            this.clipHeight = 0; // #1379
        }

        return legendHeight;
    },

    /**
     * Scroll the legend by a number of pages.
     *
     * @private
     * @function Highcharts.Legend#scroll
     *
     * @param {number} scrollBy
     *        The number of pages to scroll.
     *
     * @param {Highcharts.AnimationOptionsObject} animation
     *        Whether and how to apply animation.
     */
    scroll: function (scrollBy, animation) {
        var pages = this.pages,
            pageCount = pages.length,
            currentPage = this.currentPage + scrollBy,
            clipHeight = this.clipHeight,
            navOptions = this.options.navigation,
            pager = this.pager,
            padding = this.padding;

        // When resizing while looking at the last page
        if (currentPage > pageCount) {
            currentPage = pageCount;
        }

        if (currentPage > 0) {

            if (animation !== undefined) {
                setAnimation(animation, this.chart);
            }

            this.nav.attr({
                translateX: padding,
                translateY: clipHeight + this.padding + 7 + this.titleHeight,
                visibility: 'visible'
            });
            this.up.attr({
                'class': currentPage === 1 ?
                    'highcharts-legend-nav-inactive' :
                    'highcharts-legend-nav-active'
            });
            pager.attr({
                text: currentPage + '/' + pageCount
            });
            this.down.attr({
                'x': 18 + this.pager.getBBox().width, // adjust to text width
                'class': currentPage === pageCount ?
                    'highcharts-legend-nav-inactive' :
                    'highcharts-legend-nav-active'
            });

            
            this.up
                .attr({
                    fill: currentPage === 1 ?
                        navOptions.inactiveColor :
                        navOptions.activeColor
                })
                .css({
                    cursor: currentPage === 1 ? 'default' : 'pointer'
                });
            this.down
                .attr({
                    fill: currentPage === pageCount ?
                        navOptions.inactiveColor :
                        navOptions.activeColor
                })
                .css({
                    cursor: currentPage === pageCount ? 'default' : 'pointer'
                });
            

            this.scrollOffset = -pages[currentPage - 1] + this.initialItemY;

            this.scrollGroup.animate({
                translateY: this.scrollOffset
            });

            this.currentPage = currentPage;
            this.positionCheckboxes();
        }

    }

};

/**
 * Legend symbol mixin.
 *
 * @private
 * @mixin Highcharts.LegendSymbolMixin
 */
H.LegendSymbolMixin = {

    /**
     * Get the series' symbol in the legend
     *
     * @private
     * @function Highcharts.LegendSymbolMixin.drawRectangle
     *
     * @param {Highcharts.Legend} legend
     *        The legend object
     *
     * @param {Highcharts.Point|Highcharts.Series} item
     *        The series (this) or point
     */
    drawRectangle: function (legend, item) {
        var options = legend.options,
            symbolHeight = legend.symbolHeight,
            square = options.squareSymbol,
            symbolWidth = square ? symbolHeight : legend.symbolWidth;

        item.legendSymbol = this.chart.renderer.rect(
            square ? (legend.symbolWidth - symbolHeight) / 2 : 0,
            legend.baseline - symbolHeight + 1, // #3988
            symbolWidth,
            symbolHeight,
            pick(legend.options.symbolRadius, symbolHeight / 2)
        )
        .addClass('highcharts-point')
        .attr({
            zIndex: 3
        }).add(item.legendGroup);

    },

    /**
     * Get the series' symbol in the legend. This method should be overridable
     * to create custom symbols through
     * Highcharts.seriesTypes[type].prototype.drawLegendSymbols.
     *
     * @private
     * @function Highcharts.LegendSymbolMixin.drawLineMarker
     *
     * @param {Highcharts.Legend} legend
     *        The legend object.
     */
    drawLineMarker: function (legend) {

        var options = this.options,
            markerOptions = options.marker,
            radius,
            legendSymbol,
            symbolWidth = legend.symbolWidth,
            symbolHeight = legend.symbolHeight,
            generalRadius = symbolHeight / 2,
            renderer = this.chart.renderer,
            legendItemGroup = this.legendGroup,
            verticalCenter = legend.baseline -
                Math.round(legend.fontMetrics.b * 0.3),
            attr = {};

        // Draw the line
        
        attr = {
            'stroke-width': options.lineWidth || 0
        };
        if (options.dashStyle) {
            attr.dashstyle = options.dashStyle;
        }
        

        this.legendLine = renderer.path([
            'M',
            0,
            verticalCenter,
            'L',
            symbolWidth,
            verticalCenter
        ])
        .addClass('highcharts-graph')
        .attr(attr)
        .add(legendItemGroup);

        // Draw the marker
        if (markerOptions && markerOptions.enabled !== false && symbolWidth) {

            // Do not allow the marker to be larger than the symbolHeight
            radius = Math.min(
                pick(markerOptions.radius, generalRadius),
                generalRadius
            );

            // Restrict symbol markers size
            if (this.symbol.indexOf('url') === 0) {
                markerOptions = merge(markerOptions, {
                    width: symbolHeight,
                    height: symbolHeight
                });
                radius = 0;
            }

            this.legendSymbol = legendSymbol = renderer.symbol(
                this.symbol,
                (symbolWidth / 2) - radius,
                verticalCenter - radius,
                2 * radius,
                2 * radius,
                markerOptions
            )
            .addClass('highcharts-point')
            .add(legendItemGroup);
            legendSymbol.isMarker = true;
        }
    }
};

// Workaround for #2030, horizontal legend items not displaying in IE11 Preview,
// and for #2580, a similar drawing flaw in Firefox 26.
// Explore if there's a general cause for this. The problem may be related
// to nested group elements, as the legend item texts are within 4 group
// elements.
if (/Trident\/7\.0/.test(win.navigator.userAgent) || isFirefox) {
    wrap(Highcharts.Legend.prototype, 'positionItem', function (proceed, item) {
        var legend = this,
            // If chart destroyed in sync, this is undefined (#2030)
            runPositionItem = function () {
                if (item._legendItemPos) {
                    proceed.call(legend, item);
                }
            };

        // Do it now, for export and to get checkbox placement
        runPositionItem();

        // Do it after to work around the core issue
        setTimeout(runPositionItem);
    });
}
