// set up javascript listeners
window.onload = function() {
    // buttons that display or hide content
    document.querySelectorAll('[data-controls]')
        .forEach(t => t.onclick = toggleAction);

    // javascript interactions (boost/fav)
    Array.from(document.getElementsByClassName('interaction'))
        .forEach(t => t.onsubmit = interact);

    // Toggle all checkboxes.
    document
        .querySelectorAll('[data-action="toggle-all"]')
        .forEach(input => {
            input.addEventListener('change', toggleAllCheckboxes);
        });

    // tab groups
    Array.from(document.getElementsByClassName('tab-group'))
        .forEach(t => new TabGroup(t));

    // handle aria settings on menus
    Array.from(document.getElementsByClassName('pulldown-menu'))
        .forEach(t => t.onclick = toggleMenu);

    // display based on localstorage vars
    document.querySelectorAll('[data-hide]')
        .forEach(t => setDisplay(t));

    // update localstorage
    Array.from(document.getElementsByClassName('set-display'))
        .forEach(t => t.onclick = updateDisplay);

    // hidden submit button in a form
    document.querySelectorAll('.hidden-form input')
        .forEach(t => t.onchange = revealForm);

    // polling
    document.querySelectorAll('[data-poll]')
        .forEach(el => polling(el));

    // browser back behavior
    document.querySelectorAll('[data-back]')
        .forEach(t => t.onclick = back);
};

function back(e) {
    e.preventDefault();
    history.back();
}

function polling(el, delay) {
    delay = delay || 10000;
    delay += (Math.random() * 1000);
    setTimeout(function() {
        fetch('/api/updates/' + el.getAttribute('data-poll'))
            .then(response => response.json())
            .then(data => updateCountElement(el, data));
        polling(el, delay * 1.25);
    }, delay, el);
}

function updateCountElement(el, data) {
    const currentCount = el.innerText;
    const count = data[el.getAttribute('data-poll')];
    if (count != currentCount) {
        addRemoveClass(el, 'hidden', count < 1);
        el.innerText = count;
    }
}


function revealForm(e) {
    var hidden = e.currentTarget.closest('.hidden-form').getElementsByClassName('hidden')[0];
    if (hidden) {
        removeClass(hidden, 'hidden');
    }
}


function updateDisplay(e) {
    // used in set reading goal
    var key = e.target.getAttribute('data-id');
    var value = e.target.getAttribute('data-value');
    window.localStorage.setItem(key, value);

    document.querySelectorAll('[data-hide="' + key + '"]')
        .forEach(t => setDisplay(t));
}

function setDisplay(el) {
    // used in set reading goal
    var key = el.getAttribute('data-hide');
    var value = window.localStorage.getItem(key);
    addRemoveClass(el, 'hidden', value);
}


function toggleAction(e) {
    var el = e.currentTarget;
    var pressed = el.getAttribute('aria-pressed') == 'false';

    var targetId = el.getAttribute('data-controls');
    document.querySelectorAll('[data-controls="' + targetId + '"]')
        .forEach(t => t.setAttribute('aria-pressed', (t.getAttribute('aria-pressed') == 'false')));

    if (targetId) {
        var target = document.getElementById(targetId);
        addRemoveClass(target, 'hidden', !pressed);
        addRemoveClass(target, 'is-active', pressed);
    }

    // show/hide container
    var container = document.getElementById('hide-' + targetId);
    if (!!container) {
        addRemoveClass(container, 'hidden', pressed);
    }

    // set checkbox, if appropriate
    var checkbox = el.getAttribute('data-controls-checkbox');
    if (checkbox) {
        document.getElementById(checkbox).checked = !!pressed;
    }

    // set focus, if appropriate
    var focus = el.getAttribute('data-focus-target');
    if (focus) {
        var focusEl = document.getElementById(focus);
        focusEl.focus();
        setTimeout(function(){ focusEl.selectionStart = focusEl.selectionEnd = 10000; }, 0);
    }
}

function interact(e) {
    e.preventDefault();
    ajaxPost(e.target);
    var identifier = e.target.getAttribute('data-id');
    Array.from(document.getElementsByClassName(identifier))
        .forEach(t => addRemoveClass(t, 'hidden', t.className.indexOf('hidden') == -1));
}

/**
 * Toggle all descendant checkboxes of a target.
 *
 * Use `data-target="ID_OF_TARGET"` on the node being listened to.
 *
 * @param  {Event} event - change Event
 * @return {undefined}
 */
function toggleAllCheckboxes(event) {
    const mainCheckbox = event.target;

    document
        .querySelectorAll(`#${mainCheckbox.dataset.target} [type="checkbox"]`)
        .forEach(checkbox => {checkbox.checked = mainCheckbox.checked;});
}

function toggleMenu(e) {
    var el = e.currentTarget;
    var expanded = el.getAttribute('aria-expanded') == 'false';
    el.setAttribute('aria-expanded', expanded);
    var targetId = el.getAttribute('data-controls');
    if (targetId) {
        var target = document.getElementById(targetId);
        addRemoveClass(target, 'is-active', expanded);
    }
}

function ajaxPost(form) {
    fetch(form.action, {
        method : "POST",
        body: new FormData(form)
    });
}

function addRemoveClass(el, classname, bool) {
    if (bool) {
        addClass(el, classname);
    } else {
        removeClass(el, classname);
    }
}

function addClass(el, classname) {
    var classes = el.className.split(' ');
    if (classes.indexOf(classname) > -1) {
        return;
    }
    el.className = classes.concat(classname).join(' ');
}

function removeClass(el, className) {
    var classes = [];
    if (el.className) {
        classes = el.className.split(' ');
    }
    const idx = classes.indexOf(className);
    if (idx > -1) {
        classes.splice(idx, 1);
    }
    el.className = classes.join(' ');
}

/*
* The content below is licensed according to the W3C Software License at
* https://www.w3.org/Consortium/Legal/2015/copyright-software-and-document
* Heavily modified to web component by Zach Leatherman
* Modified back to vanilla JavaScript with support for Bulma markup and nested tabs by Ned Zimmerman
*/
class TabGroup {
    constructor(container) {
        this.container = container;

        this.tablist = this.container.querySelector('[role="tablist"]');
        this.buttons = this.tablist.querySelectorAll('[role="tab"]');
        this.panels = this.container.querySelectorAll(':scope > [role="tabpanel"]');
        this.delay = this.determineDelay();

        if(!this.tablist || !this.buttons.length || !this.panels.length) {
            return;
        }

        this.keys = this.keys();
        this.direction = this.direction();
        this.initButtons();
        this.initPanels();
    }

    keys() {
        return {
            end: 35,
            home: 36,
            left: 37,
            up: 38,
            right: 39,
            down: 40
        };
    }

    // Add or substract depending on key pressed
    direction() {
        return {
            37: -1,
            38: -1,
            39: 1,
            40: 1
        };
    }

    initButtons() {
        let count = 0;
        for(let button of this.buttons) {
            let isSelected = button.getAttribute("aria-selected") === "true";
            button.setAttribute("tabindex", isSelected ? "0" : "-1");

            button.addEventListener('click', this.clickEventListener.bind(this));
            button.addEventListener('keydown', this.keydownEventListener.bind(this));
            button.addEventListener('keyup', this.keyupEventListener.bind(this));

            button.index = count++;
        }
    }

    initPanels() {
        let selectedPanelId = this.tablist.querySelector('[role="tab"][aria-selected="true"]').getAttribute("aria-controls");
        for(let panel of this.panels) {
            if(panel.getAttribute("id") !== selectedPanelId) {
                panel.setAttribute("hidden", "");
            }
            panel.setAttribute("tabindex", "0");
        }
    }

    clickEventListener(event) {
        let button = event.target.closest('a');

        event.preventDefault();

        this.activateTab(button, false);
    }

    // Handle keydown on tabs
    keydownEventListener(event) {
        var key = event.keyCode;

        switch (key) {
            case this.keys.end:
                event.preventDefault();
                // Activate last tab
                this.activateTab(this.buttons[this.buttons.length - 1]);
                break;
            case this.keys.home:
                event.preventDefault();
                // Activate first tab
                this.activateTab(this.buttons[0]);
                break;

            // Up and down are in keydown
            // because we need to prevent page scroll >:)
            case this.keys.up:
            case this.keys.down:
                this.determineOrientation(event);
                break;
        }
    }

    // Handle keyup on tabs
    keyupEventListener(event) {
        var key = event.keyCode;

        switch (key) {
            case this.keys.left:
            case this.keys.right:
                this.determineOrientation(event);
                break;
        }
    }

    // When a tablist’s aria-orientation is set to vertical,
    // only up and down arrow should function.
    // In all other cases only left and right arrow function.
    determineOrientation(event) {
        var key = event.keyCode;
        var vertical = this.tablist.getAttribute('aria-orientation') == 'vertical';
        var proceed = false;

        if (vertical) {
            if (key === this.keys.up || key === this.keys.down) {
                event.preventDefault();
                proceed = true;
            }
        }
        else {
            if (key === this.keys.left || key === this.keys.right) {
                proceed = true;
            }
        }

        if (proceed) {
            this.switchTabOnArrowPress(event);
        }
    }

    // Either focus the next, previous, first, or last tab
    // depending on key pressed
    switchTabOnArrowPress(event) {
        var pressed = event.keyCode;

        for (let button of this.buttons) {
            button.addEventListener('focus', this.focusEventHandler.bind(this));
        }

        if (this.direction[pressed]) {
            var target = event.target;
            if (target.index !== undefined) {
                if (this.buttons[target.index + this.direction[pressed]]) {
                    this.buttons[target.index + this.direction[pressed]].focus();
                }
                else if (pressed === this.keys.left || pressed === this.keys.up) {
                    this.focusLastTab();
                }
                else if (pressed === this.keys.right || pressed == this.keys.down) {
                    this.focusFirstTab();
                }
            }
        }
    }

    // Activates any given tab panel
    activateTab (tab, setFocus) {
        if(tab.getAttribute("role") !== "tab") {
            tab = tab.closest('[role="tab"]');
        }

        setFocus = setFocus || true;

        // Deactivate all other tabs
        this.deactivateTabs();

        // Remove tabindex attribute
        tab.removeAttribute('tabindex');

        // Set the tab as selected
        tab.setAttribute('aria-selected', 'true');

        // Give the tab parent an is-active class
        tab.parentNode.classList.add('is-active');

        // Get the value of aria-controls (which is an ID)
        var controls = tab.getAttribute('aria-controls');

        // Remove hidden attribute from tab panel to make it visible
        document.getElementById(controls).removeAttribute('hidden');

        // Set focus when required
        if (setFocus) {
            tab.focus();
        }
    }

    // Deactivate all tabs and tab panels
    deactivateTabs() {
        for (let button of this.buttons) {
            button.parentNode.classList.remove('is-active');
            button.setAttribute('tabindex', '-1');
            button.setAttribute('aria-selected', 'false');
            button.removeEventListener('focus', this.focusEventHandler.bind(this));
        }

        for (let panel of this.panels) {
            panel.setAttribute('hidden', 'hidden');
        }
    }

    focusFirstTab() {
        this.buttons[0].focus();
    }

    focusLastTab() {
        this.buttons[this.buttons.length - 1].focus();
    }

    // Determine whether there should be a delay
    // when user navigates with the arrow keys
    determineDelay() {
        var hasDelay = this.tablist.hasAttribute('data-delay');
        var delay = 0;

        if (hasDelay) {
            var delayValue = this.tablist.getAttribute('data-delay');
            if (delayValue) {
                delay = delayValue;
            }
            else {
                // If no value is specified, default to 300ms
                delay = 300;
            }
        }

        return delay;
    }

    focusEventHandler(event) {
        var target = event.target;

        setTimeout(this.checkTabFocus.bind(this), this.delay, target);
    }

    // Only activate tab on focus if it still has focus after the delay
    checkTabFocus(target) {
        let focused = document.activeElement;

        if (target === focused) {
            this.activateTab(target, false);
        }
    }
}