/*!

* Stickyfill – `position: sticky` polyfill
* v. 2.0.5 | https://github.com/wilddeer/stickyfill
* MIT License
*/

'use strict';

/*

* 1. Check if the browser supports `position: sticky` natively or is too old to run the polyfill.
*    If either of these is the case set `seppuku` flag. It will be checked later to disable key features
*    of the polyfill, but the API will remain functional to avoid breaking things.
*/

let seppuku = false;

// The polyfill cant’t function properly without `getComputedStyle`. if (!window.getComputedStyle) seppuku = true; // Dont’t get in a way if the browser supports `position: sticky` natively. else {

const testNode = document.createElement('div');
if (
    ['', '-webkit-', '-moz-', '-ms-'].some(prefix => {
        try {
            testNode.style.position = prefix + 'sticky';
        }
        catch(e) {}
        return testNode.style.position != '';
    })
) seppuku = true;

}

/*

* 2. “Global” vars used across the polyfill
*/

// Check if Shadow Root constructor exists to make further checks simpler const shadowRootExists = typeof ShadowRoot !== 'undefined';

// Last saved scroll position const scroll = {

top: null,
left: null

};

// Array of created Sticky instances const stickies = [];

/*

* 3. Utility functions
*/

function extend (targetObj, sourceObject) {

for (var key in sourceObject) {
    if (sourceObject.hasOwnProperty(key)) {
        targetObj[key] = sourceObject[key];
    }
}

}

function parseNumeric (val) {

return parseFloat(val) || 0;

}

function getDocOffsetTop (node) {

let docOffsetTop = 0;
while (node) {
    docOffsetTop += node.offsetTop;
    node = node.offsetParent;
}
return docOffsetTop;

}

/*

* 4. Sticky class
*/

class Sticky {

constructor (node) {
    if (!(node instanceof HTMLElement))
        throw new Error('First argument must be HTMLElement');
    if (stickies.some(sticky => sticky._node === node))
        throw new Error('Stickyfill is already applied to this node');
    this._node = node;
    this._stickyMode = null;
    this._active = false;
    stickies.push(this);
    this.refresh();
}
refresh () {
    if (seppuku || this._removed) return;
    if (this._active) this._deactivate();
    const node = this._node;
    /*
     * 1. Save node computed props
     */
    const nodeComputedStyle = getComputedStyle(node);
    const nodeComputedProps = {
        top: nodeComputedStyle.top,
        display: nodeComputedStyle.display,
        marginTop: nodeComputedStyle.marginTop,
        marginBottom: nodeComputedStyle.marginBottom,
        marginLeft: nodeComputedStyle.marginLeft,
        marginRight: nodeComputedStyle.marginRight,
        cssFloat: nodeComputedStyle.cssFloat
    };
    /*
     * 2. Check if the node can be activated
     */
    if (
        isNaN(parseFloat(nodeComputedProps.top)) ||
        nodeComputedProps.display == 'table-cell' ||
        nodeComputedProps.display == 'none'
    ) return;
    this._active = true;
    /*
     * 3. Get necessary node parameters
     */
    const referenceNode = node.parentNode;
    const parentNode = shadowRootExists && referenceNode instanceof ShadowRoot? referenceNode.host: referenceNode;
    const nodeWinOffset = node.getBoundingClientRect();
    const parentWinOffset = parentNode.getBoundingClientRect();
    const parentComputedStyle = getComputedStyle(parentNode);
    this._parent = {
        node: parentNode,
        styles: {
            position: parentNode.style.position
        },
        offsetHeight: parentNode.offsetHeight
    };
    this._offsetToWindow = {
        left: nodeWinOffset.left,
        right: document.documentElement.clientWidth - nodeWinOffset.right
    };
    this._offsetToParent = {
        top: nodeWinOffset.top - parentWinOffset.top - parseNumeric(parentComputedStyle.borderTopWidth),
        left: nodeWinOffset.left - parentWinOffset.left - parseNumeric(parentComputedStyle.borderLeftWidth),
        right: -nodeWinOffset.right + parentWinOffset.right - parseNumeric(parentComputedStyle.borderRightWidth)
    };
    this._styles = {
        position: node.style.position,
        top: node.style.top,
        bottom: node.style.bottom,
        left: node.style.left,
        right: node.style.right,
        width: node.style.width,
        marginTop: node.style.marginTop,
        marginLeft: node.style.marginLeft,
        marginRight: node.style.marginRight
    };
    const nodeTopValue = parseNumeric(nodeComputedProps.top);
    this._limits = {
        start: nodeWinOffset.top + window.pageYOffset - nodeTopValue,
        end: parentWinOffset.top + window.pageYOffset + parentNode.offsetHeight -
            parseNumeric(parentComputedStyle.borderBottomWidth) - node.offsetHeight -
            nodeTopValue - parseNumeric(nodeComputedProps.marginBottom)
    };
    /*
     * 4. Ensure that the node will be positioned relatively to the parent node
     */
    const parentPosition = parentComputedStyle.position;
    if (
        parentPosition != 'absolute' &&
        parentPosition != 'relative'
    ) {
        parentNode.style.position = 'relative';
    }
    /*
     * 5. Recalc node position.
     *    It’s important to do this before clone injection to avoid scrolling bug in Chrome.
     */
    this._recalcPosition();
    /*
     * 6. Create a clone
     */
    const clone = this._clone = {};
    clone.node = document.createElement('div');
    // Apply styles to the clone
    extend(clone.node.style, {
        width: nodeWinOffset.right - nodeWinOffset.left + 'px',
        height: nodeWinOffset.bottom - nodeWinOffset.top + 'px',
        marginTop: nodeComputedProps.marginTop,
        marginBottom: nodeComputedProps.marginBottom,
        marginLeft: nodeComputedProps.marginLeft,
        marginRight: nodeComputedProps.marginRight,
        cssFloat: nodeComputedProps.cssFloat,
        padding: 0,
        border: 0,
        borderSpacing: 0,
        fontSize: '1em',
        position: 'static'
    });
    referenceNode.insertBefore(clone.node, node);
    clone.docOffsetTop = getDocOffsetTop(clone.node);
}
_recalcPosition () {
    if (!this._active || this._removed) return;
    const stickyMode = scroll.top <= this._limits.start? 'start': scroll.top >= this._limits.end? 'end': 'middle';
    if (this._stickyMode == stickyMode) return;
    switch (stickyMode) {
        case 'start':
            extend(this._node.style, {
                position: 'absolute',
                left: this._offsetToParent.left + 'px',
                right: this._offsetToParent.right + 'px',
                top: this._offsetToParent.top + 'px',
                bottom: 'auto',
                width: 'auto',
                marginLeft: 0,
                marginRight: 0,
                marginTop: 0
            });
            break;
        case 'middle':
            extend(this._node.style, {
                position: 'fixed',
                left: this._offsetToWindow.left + 'px',
                right: this._offsetToWindow.right + 'px',
                top: this._styles.top,
                bottom: 'auto',
                width: 'auto',
                marginLeft: 0,
                marginRight: 0,
                marginTop: 0
            });
            break;
        case 'end':
            extend(this._node.style, {
                position: 'absolute',
                left: this._offsetToParent.left + 'px',
                right: this._offsetToParent.right + 'px',
                top: 'auto',
                bottom: 0,
                width: 'auto',
                marginLeft: 0,
                marginRight: 0
            });
            break;
    }
    this._stickyMode = stickyMode;
}
_fastCheck () {
    if (!this._active || this._removed) return;
    if (
        Math.abs(getDocOffsetTop(this._clone.node) - this._clone.docOffsetTop) > 1 ||
        Math.abs(this._parent.node.offsetHeight - this._parent.offsetHeight) > 1
    ) this.refresh();
}
_deactivate () {
    if (!this._active || this._removed) return;
    this._clone.node.parentNode.removeChild(this._clone.node);
    delete this._clone;
    extend(this._node.style, this._styles);
    delete this._styles;
    // Check whether element’s parent node is used by other stickies.
    // If not, restore parent node’s styles.
    if (!stickies.some(sticky => sticky !== this && sticky._parent && sticky._parent.node === this._parent.node)) {
        extend(this._parent.node.style, this._parent.styles);
    }
    delete this._parent;
    this._stickyMode = null;
    this._active = false;
    delete this._offsetToWindow;
    delete this._offsetToParent;
    delete this._limits;
}
remove () {
    this._deactivate();
    stickies.some((sticky, index) => {
        if (sticky._node === this._node) {
            stickies.splice(index, 1);
            return true;
        }
    });
    this._removed = true;
}

}

/*

* 5. Stickyfill API
*/

const Stickyfill = {

stickies,
Sticky,
addOne (node) {
    // Check whether it’s a node
    if (!(node instanceof HTMLElement)) {
        // Maybe it’s a node list of some sort?
        // Take first node from the list then
        if (node.length && node[0]) node = node[0];
        else return;
    }
    // Check if Stickyfill is already applied to the node
    // and return existing sticky
    for (var i = 0; i < stickies.length; i++) {
        if (stickies[i]._node === node) return stickies[i];
    }
    // Create and return new sticky
    return new Sticky(node);
},
add (nodeList) {
    // If it’s a node make an array of one node
    if (nodeList instanceof HTMLElement) nodeList = [nodeList];
    // Check if the argument is an iterable of some sort
    if (!nodeList.length) return;
    // Add every element as a sticky and return an array of created Sticky instances
    const addedStickies = [];
    for (let i = 0; i < nodeList.length; i++) {
        const node = nodeList[i];
        // If it’s not an HTMLElement – create an empty element to preserve 1-to-1
        // correlation with input list
        if (!(node instanceof HTMLElement)) {
            addedStickies.push(void 0);
            continue;
        }
        // If Stickyfill is already applied to the node
        // add existing sticky
        if (stickies.some(sticky => {
            if (sticky._node === node) {
                addedStickies.push(sticky);
                return true;
            }
        })) continue;
        // Create and add new sticky
        addedStickies.push(new Sticky(node));
    }
    return addedStickies;
},
refreshAll () {
    stickies.forEach(sticky => sticky.refresh());
},
removeOne (node) {
    // Check whether it’s a node
    if (!(node instanceof HTMLElement)) {
        // Maybe it’s a node list of some sort?
        // Take first node from the list then
        if (node.length && node[0]) node = node[0];
        else return;
    }
    // Remove the stickies bound to the nodes in the list
    stickies.some(sticky => {
        if (sticky._node === node) {
            sticky.remove();
            return true;
        }
    });
},
remove (nodeList) {
    // If it’s a node make an array of one node
    if (nodeList instanceof HTMLElement) nodeList = [nodeList];
    // Check if the argument is an iterable of some sort
    if (!nodeList.length) return;
    // Remove the stickies bound to the nodes in the list
    for (let i = 0; i < nodeList.length; i++) {
        const node = nodeList[i];
        stickies.some(sticky => {
            if (sticky._node === node) {
                sticky.remove();
                return true;
            }
        });
    }
},
removeAll () {
    while (stickies.length) stickies[0].remove();
}

};

/*

* 6. Setup events (unless the polyfill was disabled)
*/

function init () {

// Watch for scroll position changes and trigger recalc/refresh if needed
function checkScroll () {
    if (window.pageXOffset != scroll.left) {
        scroll.top = window.pageYOffset;
        scroll.left = window.pageXOffset;
        Stickyfill.refreshAll();
    }
    else if (window.pageYOffset != scroll.top) {
        scroll.top = window.pageYOffset;
        scroll.left = window.pageXOffset;
        // recalc position for all stickies
        stickies.forEach(sticky => sticky._recalcPosition());
    }
}
checkScroll();
window.addEventListener('scroll', checkScroll);
// Watch for window resizes and device orientation changes and trigger refresh
window.addEventListener('resize', Stickyfill.refreshAll);
window.addEventListener('orientationchange', Stickyfill.refreshAll);
//Fast dirty check for layout changes every 500ms
let fastCheckTimer;
function startFastCheckTimer () {
    fastCheckTimer = setInterval(function () {
        stickies.forEach(sticky => sticky._fastCheck());
    }, 500);
}
function stopFastCheckTimer () {
    clearInterval(fastCheckTimer);
}
let docHiddenKey;
let visibilityChangeEventName;
if ('hidden' in document) {
    docHiddenKey = 'hidden';
    visibilityChangeEventName = 'visibilitychange';
}
else if ('webkitHidden' in document) {
    docHiddenKey = 'webkitHidden';
    visibilityChangeEventName = 'webkitvisibilitychange';
}
if (visibilityChangeEventName) {
    if (!document[docHiddenKey]) startFastCheckTimer();
    document.addEventListener(visibilityChangeEventName, () => {
        if (document[docHiddenKey]) {
            stopFastCheckTimer();
        }
        else {
            startFastCheckTimer();
        }
    });
}
else startFastCheckTimer();

}

if (!seppuku) init();

/*

* 7. Expose Stickyfill
*/

if (typeof module != 'undefined' && module.exports) {

module.exports = Stickyfill;

} else {

window.Stickyfill = Stickyfill;

}