import './emby-textarea.scss';
import 'webcomponents.js/webcomponents-lite';
import '../emby-input/emby-input';

/**
 * Calculates the vertical padding of the element
 * @param textarea
 * @returns {number}
 */

function calculateOffset(textarea) {
    const style = window.getComputedStyle(textarea, null);
    const props = ['paddingTop', 'paddingBottom'];
    let offset = 0;

    for (let i = 0; i < props.length; i++) {
        offset += parseInt(style[props[i]], 10);
    }
    return offset;
}

/* eslint-disable indent */
    function autoGrow(textarea, maxLines) {
        const self = this;

        if (maxLines === undefined) {
            maxLines = 999;
        }

        let offset;
        function reset() {
            textarea.rows = 1;
            offset = calculateOffset(textarea);
            self.rows = textarea.rows || 1;
            self.lineHeight = (textarea.scrollHeight / self.rows) - (offset / self.rows);
            self.maxAllowedHeight = (self.lineHeight * maxLines) - offset;
        }

        function autogrowFn() {
            if (!self.lineHeight || self.lineHeight <= 0) {
                reset();
            }
            if (self.lineHeight <= 0) {
                textarea.style.overflowY = 'scroll';
                textarea.style.height = 'auto';
                textarea.rows = 3;
                return;
            }
            let newHeight = 0;

            if ((textarea.scrollHeight - offset) > self.maxAllowedHeight) {
                textarea.style.overflowY = 'scroll';
                newHeight = self.maxAllowedHeight;
            } else {
                textarea.style.overflowY = 'hidden';
                textarea.style.height = 'auto';
                newHeight = textarea.scrollHeight/* - offset*/;
            }
            textarea.style.height = newHeight + 'px';
        }

        // Call autogrowFn() when textarea's value is changed
        textarea.addEventListener('input', autogrowFn);
        textarea.addEventListener('focus', autogrowFn);
        textarea.addEventListener('valueset', autogrowFn);

        autogrowFn();
    }

    const EmbyTextAreaPrototype = Object.create(HTMLTextAreaElement.prototype);

    let elementId = 0;

    if (Object.getOwnPropertyDescriptor && Object.defineProperty) {
        const descriptor = Object.getOwnPropertyDescriptor(HTMLTextAreaElement.prototype, 'value');

        // descriptor returning null in webos
        if (descriptor && descriptor.configurable) {
            const baseSetMethod = descriptor.set;
            descriptor.set = function (value) {
                baseSetMethod.call(this, value);

                this.dispatchEvent(new CustomEvent('valueset', {
                    bubbles: false,
                    cancelable: false
                }));
            };

            Object.defineProperty(HTMLTextAreaElement.prototype, 'value', descriptor);
        }
    }

    EmbyTextAreaPrototype.createdCallback = function () {
        if (!this.id) {
            this.id = 'embytextarea' + elementId;
            elementId++;
        }
    };

    EmbyTextAreaPrototype.attachedCallback = function () {
        if (this.classList.contains('emby-textarea')) {
            return;
        }

        this.rows = 1;
        this.classList.add('emby-textarea');

        const parentNode = this.parentNode;
        const label = this.ownerDocument.createElement('label');
        label.innerText = this.getAttribute('label') || '';
        label.classList.add('textareaLabel');

        label.htmlFor = this.id;
        parentNode.insertBefore(label, this);

        this.addEventListener('focus', function () {
            label.classList.add('textareaLabelFocused');
            label.classList.remove('textareaLabelUnfocused');
        });
        this.addEventListener('blur', function () {
            label.classList.remove('textareaLabelFocused');
            label.classList.add('textareaLabelUnfocused');
        });

        this.label = function (text) {
            label.innerText = text;
        };

        new autoGrow(this);
    };

    document.registerElement('emby-textarea', {
        prototype: EmbyTextAreaPrototype,
        extends: 'textarea'
    });

/* eslint-enable indent */