/* *
 *
 *  (c) 2009-2019 Øystein Moseng
 *
 *  Main keyboard navigation handling.
 *
 *  License: www.highcharts.com/license
 *
 * */

'use strict';
import H from '../../parts/Globals.js';
import KeyboardNavigationHandler from './KeyboardNavigationHandler.js';

var merge = H.merge,
    addEvent = H.addEvent,
    win = H.win,
    doc = win.document;


/**
 * The KeyboardNavigation class, containing the overall keyboard navigation
 * logic for the chart.
 *
 * @requires module:modules/accessibility
 *
 * @private
 * @class
 * @param {Highcharts.Chart} chart
 *        Chart object
 * @param {object} components
 *        Map of component names to AccessibilityComponent objects.
 * @name Highcharts.KeyboardNavigation
 */
function KeyboardNavigation(chart, components, order) {
    this.init(chart, components, order);
}
KeyboardNavigation.prototype = {

    /**
     * Initialize the class
     * @private
     * @param {Highcharts.Chart} chart
     *        Chart object
     * @param {object} components
     *        Map of component names to AccessibilityComponent objects.
     */
    init: function (chart, components) {
        var keyboardNavigation = this;
        this.chart = chart;
        this.components = components;
        this.modules = [];
        this.currentModuleIx = 0;

        // Make chart container reachable by tab
        if (!chart.container.hasAttribute('tabIndex')) {
            chart.container.setAttribute('tabindex', '0');
        }

        // Add exit anchor for focus
        this.addExitAnchor();

        // Add keydown event
        this.unbindKeydownHandler = addEvent(
            chart.renderTo, 'keydown', function (e) {
                keyboardNavigation.onKeydown(e);
            }
        );

        // Add mouseup event on doc
        this.unbindMouseUpHandler = addEvent(doc, 'mouseup', function () {
            keyboardNavigation.onMouseUp();
        });

        // Run an update to get all modules
        this.update();

        // Init first module
        if (this.modules.length) {
            this.modules[0].init(1);
        }
    },


    /**
     * Update the modules for the keyboard navigation
     * @param {Array<string>} order
     *        Array specifying the tab order of the components.
     */
    update: function (order) {
        var a11yOptions = this.chart.options.accessibility,
            keyboardOptions = a11yOptions && a11yOptions.keyboardNavigation,
            components = this.components;

        if (
            keyboardOptions && keyboardOptions.enabled && order && order.length
        ) {
            // We (still) have keyboard navigation. Update module list
            this.modules = order.reduce(function (modules, componentName) {
                var navModules = components[componentName]
                    .getKeyboardNavigation();
                // If we didn't get back a list of modules, just push the one
                if (!navModules.length) {
                    modules.push(navModules);
                    return modules;
                }
                // Add all of the modules
                return modules.concat(navModules);
            }, [
                // Add an empty module at the start of list, to allow users to
                // tab into the chart.
                new KeyboardNavigationHandler(this.chart, {})
            ]);
        } else {
            // Clear module list and reset
            this.modules = [];
            this.currentModuleIx = 0;
        }
    },


    /**
     * Reset chart navigation state if we click outside the chart and it's
     * not already reset.
     * @private
     */
    onMouseUp: function () {
        if (
            !this.keyboardReset &&
            !(this.chart.pointer && this.chart.pointer.chartPosition)
        ) {
            var chart = this.chart,
                curMod = this.modules &&
                    this.modules[this.currentModuleIx || 0];

            if (curMod && curMod.terminate) {
                curMod.terminate();
            }
            if (chart.focusElement) {
                chart.focusElement.removeFocusBorder();
            }
            this.currentModuleIx = 0;
            this.keyboardReset = true;
        }
    },


    /**
     * Function to run on keydown
     * @private
     * @param {global.Event} ev
     *        Browser keydown event
     */
    onKeydown: function (ev) {
        var e = ev || win.event,
            preventDefault,
            curNavModule = this.modules && this.modules.length &&
                this.modules[this.currentModuleIx];

        // Used for resetting nav state when clicking outside chart
        this.keyboardReset = false;

        // If there is a nav module for the current index, run it.
        // Otherwise, we are outside of the chart in some direction.
        if (curNavModule) {
            var response = curNavModule.run(e);
            if (response === curNavModule.response.success) {
                preventDefault = true;
            } else if (response === curNavModule.response.prev) {
                preventDefault = this.prev();
            } else if (response === curNavModule.response.next) {
                preventDefault = this.next();
            }
            if (preventDefault) {
                e.preventDefault();
            }
        }
    },


    /**
     * Go to previous module.
     * @private
     */
    prev: function () {
        return this.move(-1);
    },


    /**
     * Go to next module.
     * @private
     */
    next: function () {
        return this.move(1);
    },


    /**
     * Move to prev/next module.
     * @private
     * @param {number} direction Direction to move. +1 for next, -1 for prev.
     * @return {boolean} True if there was a valid module in direction.
     */
    move: function (direction) {
        var curModule = this.modules && this.modules[this.currentModuleIx];
        if (curModule && curModule.terminate) {
            curModule.terminate(direction);
        }

        // Remove existing focus border if any
        if (this.chart.focusElement) {
            this.chart.focusElement.removeFocusBorder();
        }

        this.currentModuleIx += direction;
        var newModule = this.modules && this.modules[this.currentModuleIx];
        if (newModule) {
            if (newModule.validate && !newModule.validate()) {
                return this.move(direction); // Invalid module, recurse
            }
            if (newModule.init) {
                newModule.init(direction); // Valid module, init it
                return true;
            }
        }

        // No module
        this.currentModuleIx = 0; // Reset counter

        // Set focus to chart or exit anchor depending on direction
        if (direction > 0) {
            this.exiting = true;
            this.exitAnchor.focus();
        } else {
            this.chart.renderTo.focus();
        }

        return false;
    },


    /**
     * Add exit anchor to the chart. We use this to move focus out of chart
     * whenever we want, by setting focus to this div and not preventing the
     * default tab action. We also use this when users come back into the chart
     * by tabbing back, in order to navigate from the end of the chart.
     * @private
     */
    addExitAnchor: function () {
        var chart = this.chart,
            exitAnchor = this.exitAnchor = doc.createElement('h6'),
            keyboardNavigation = this,
            exitAnchorLabel = chart.langFormat(
                'accessibility.svgContainerEnd', { chart: chart }
            );

        exitAnchor.setAttribute('tabindex', '0');
        exitAnchor.setAttribute('aria-label', exitAnchorLabel);
        exitAnchor.setAttribute('aria-hidden', false);

        // Hide exit anchor
        merge(true, exitAnchor.style, {
            position: 'absolute',
            width: '1px',
            height: '1px',
            zIndex: 0,
            overflow: 'hidden',
            outline: 'none'
        });

        chart.renderTo.appendChild(exitAnchor);

        // Update position on render
        this.unbindExitAnchorUpdate = addEvent(chart, 'render', function () {
            this.renderTo.appendChild(exitAnchor);
        });

        // Handle focus
        this.unbindExitAnchorFocus = addEvent(
            exitAnchor,
            'focus',
            function (ev) {
                var e = ev || win.event,
                    curModule;

                // If focusing and we are exiting, do nothing once.
                if (!keyboardNavigation.exiting) {

                    // Not exiting, means we are coming in backwards
                    chart.renderTo.focus();
                    e.preventDefault();

                    // Move to last valid keyboard nav module
                    // Note the we don't run it, just set the index
                    if (
                        keyboardNavigation.modules &&
                        keyboardNavigation.modules.length
                    ) {
                        keyboardNavigation.currentModuleIx =
                            keyboardNavigation.modules.length - 1;
                        curModule = keyboardNavigation.modules[
                            keyboardNavigation.currentModuleIx
                        ];

                        // Validate the module
                        if (
                            curModule &&
                            curModule.validate && !curModule.validate()
                        ) {
                            // Invalid. Try moving backwards to find next valid.
                            keyboardNavigation.prev();
                        } else if (curModule) {
                            // We have a valid module, init it
                            curModule.init(-1);
                        }
                    }
                } else {
                    // Don't skip the next focus, we only skip once.
                    keyboardNavigation.exiting = false;
                }
            }
        );
    },


    /**
     * Remove all traces of keyboard navigation.
     * @private
     */
    destroy: function () {
        // Remove exit anchor
        if (this.unbindExitAnchorFocus) {
            this.unbindExitAnchorFocus();
            delete this.unbindExitAnchorFocus;
        }
        if (this.unbindExitAnchorUpdate) {
            this.unbindExitAnchorUpdate();
            delete this.unbindExitAnchorUpdate;
        }
        if (this.exitAnchor && this.exitAnchor.parentNode) {
            this.exitAnchor.parentNode.removeChild(this.exitAnchor);
            delete this.exitAnchor;
        }

        // Remove keydown handler
        if (this.unbindKeydownHandler) {
            this.unbindKeydownHandler();
        }

        // Remove mouseup handler
        if (this.unbindMouseUpHandler) {
            this.unbindMouseUpHandler();
        }
    }
};

export default KeyboardNavigation;
