/**
 * --------------------------------------------------------------------------
 * Bootstrap (v5.2.0-beta1): util/scrollBar.js
 * Licensed under MIT (https://github.com/twbs/bootstrap/blob/main/LICENSE)
 * --------------------------------------------------------------------------
 */

import SelectorEngine from '../dom/selector-engine'
import Manipulator from '../dom/manipulator'
import {
    isElement
} from './index'

/**
 * Constants
 */

const SELECTOR_FIXED_CONTENT = '.fixed-top, .fixed-bottom, .is-fixed, .sticky-top'
const SELECTOR_STICKY_CONTENT = '.sticky-top'
const PROPERTY_PADDING = 'padding-right'
const PROPERTY_MARGIN = 'margin-right'

/**
 * Class definition
 */

class ScrollBarHelper {
    constructor() {
        this._element = document.body
    }

    // Public
    getWidth() {
        // https://developer.mozilla.org/en-US/docs/Web/API/Window/innerWidth#usage_notes
        const documentWidth = document.documentElement.clientWidth
        return Math.abs(window.innerWidth - documentWidth)
    }

    hide() {
        const width = this.getWidth()
        this._disableOverFlow()
        // give padding to element to balance the hidden scrollbar width
        this._setElementAttributes(this._element, PROPERTY_PADDING, calculatedValue => calculatedValue + width)
        // trick: We adjust positive paddingRight and negative marginRight to sticky-top elements to keep showing fullwidth
        this._setElementAttributes(SELECTOR_FIXED_CONTENT, PROPERTY_PADDING, calculatedValue => calculatedValue + width)
        this._setElementAttributes(SELECTOR_STICKY_CONTENT, PROPERTY_MARGIN, calculatedValue => calculatedValue - width)
    }

    reset() {
        this._resetElementAttributes(this._element, 'overflow')
        this._resetElementAttributes(this._element, PROPERTY_PADDING)
        this._resetElementAttributes(SELECTOR_FIXED_CONTENT, PROPERTY_PADDING)
        this._resetElementAttributes(SELECTOR_STICKY_CONTENT, PROPERTY_MARGIN)
    }

    isOverflowing() {
        return this.getWidth() > 0
    }

    // Private
    _disableOverFlow() {
        this._saveInitialAttribute(this._element, 'overflow')
        this._element.style.overflow = 'hidden'
    }

    _setElementAttributes(selector, styleProperty, callback) {
        const scrollbarWidth = this.getWidth()
        const manipulationCallBack = element => {
            if (element !== this._element && window.innerWidth > element.clientWidth + scrollbarWidth) {
                return
            }

            this._saveInitialAttribute(element, styleProperty)
            const calculatedValue = window.getComputedStyle(element).getPropertyValue(styleProperty)
            element.style.setProperty(styleProperty, `${callback(Number.parseFloat(calculatedValue))}px`)
        }

        this._applyManipulationCallback(selector, manipulationCallBack)
    }

    _saveInitialAttribute(element, styleProperty) {
        const actualValue = element.style.getPropertyValue(styleProperty)
        if (actualValue) {
            Manipulator.setDataAttribute(element, styleProperty, actualValue)
        }
    }

    _resetElementAttributes(selector, styleProperty) {
        const manipulationCallBack = element => {
            const value = Manipulator.getDataAttribute(element, styleProperty)
            // We only want to remove the property if the value is `null`; the value can also be zero
            if (value === null) {
                element.style.removeProperty(styleProperty)
                return
            }

            Manipulator.removeDataAttribute(element, styleProperty)
            element.style.setProperty(styleProperty, value)
        }

        this._applyManipulationCallback(selector, manipulationCallBack)
    }

    _applyManipulationCallback(selector, callBack) {
        if (isElement(selector)) {
            callBack(selector)
            return
        }

        for (const sel of SelectorEngine.find(selector, this._element)) {
            callBack(sel)
        }
    }
}

export default ScrollBarHelper