/**
 * Menu.js
 *
 * @author realor
 */

import { I18N } from '../i18n/I18N.js'

class AbstractMenuItem {
    constructor(menuBar, label) {
        this.label = label
        this.menuBar = menuBar
        this.parentMenu = null

        this.itemElement = document.createElement('li')
        this.anchorElement = document.createElement('a')
        this.anchorElement.href = '#'
        this.labelElement = document.createElement('div')
        this.labelElement.className = 'label'
        this.anchorElement.appendChild(this.labelElement)
        I18N.set(this.labelElement, 'innerHTML', label || 'menuitem')
        this.itemElement.appendChild(this.anchorElement)

        this.anchorElement.addEventListener('pointerenter', () => this.anchorElement.focus())
    }
}

class MenuItem extends AbstractMenuItem {
    constructor(menuBar, tool) {
        super(menuBar, tool.label)

        this.anchorElement.addEventListener('click', () => {
            if (this.menuBar.isVertical()) {
                this.menuBar.hide()
            } else {
                this.menuBar.focusMenuItem(null)
            }
            this.menuBar.application.useTool(tool)
        })

        this.anchorElement.addEventListener('focusin', () => {
            this.menuBar.focusMenuItem(this)
        })

        const keyShortcut = tool.keyShortcut
        if (keyShortcut) {
            this.menuBar.keyShortcuts.set(keyShortcut, tool)
            this.anchorElement.setAttribute('aria-keyshortcuts', keyShortcut)
            this.keyElement = document.createElement('div')
            this.keyElement.innerHTML = keyShortcut
            this.keyElement.className = 'shortcut'
            this.anchorElement.appendChild(this.keyElement)
        }
    }
}

class Menu extends AbstractMenuItem {
    constructor(menuBar, label) {
        super(menuBar, label)
        this.menuItems = [] // child menuItems

        this.listElement = document.createElement('ul')
        this.itemElement.appendChild(this.listElement)
        this.anchorElement.className = 'menu'

        this.anchorElement.addEventListener('click', event => {
            event.preventDefault()
            if (this.isVisible() && this.menuBar.isVertical()) {
                this.hide()
            } else {
                this.menuBar.armed = true
                this.drop()
            }
        })

        this.anchorElement.addEventListener('contextmenu', event => event.preventDefault())

        this.anchorElement.addEventListener('focusin', () => {
            menuBar.focusMenuItem(this)
            if (menuBar.armed && !menuBar.isVertical()) {
                this.drop()
            }
        })
    }

    isVisible() {
        return this.itemElement.className === 'drop'
    }

    drop() {
        this.itemElement.className = 'drop'
    }

    hide(recursive) {
        this.itemElement.className = 'hide'
        if (recursive) {
            for (let menuItem of this.menuItems) {
                if (menuItem instanceof Menu) {
                    menuItem.hide(recursive)
                }
            }
        }
    }

    addMenuItem(tool) {
        let menuItem = new MenuItem(this.menuBar, tool)
        menuItem.parentMenu = this
        this.menuItems.push(menuItem)
        this.listElement.appendChild(menuItem.itemElement)
        return menuItem
    }

    addMenu(label, index) {
        let menu = new Menu(this.menuBar, label)
        menu.parentMenu = this

        const children = this.listElement.children
        if (typeof index === 'number' && index < children.length) {
            if (index < 0) index = 0
            let oldElem = children[index]
            this.listElement.insertBefore(menu.itemElement, oldElem)
            this.menuItems.splice(index, 0, menu)
        } else {
            this.menuItems.push(menu)
            this.listElement.appendChild(menu.itemElement)
        }
        return menu
    }
}

/*** MenuBar ***/

class MenuBar {
    constructor(application, element) {
        this.application = application
        this.menuItem = null
        this.menus = []
        this.armed = false
        this.keyShortcuts = new Map()

        this.navElement = document.createElement('nav')
        element.appendChild(this.navElement)

        this.listElement = document.createElement('ul')
        this.navElement.appendChild(this.listElement)

        const menuBar = this
        this.dropButtonElement = document.createElement('a')
        I18N.set(this.dropButtonElement, 'innerHTML', 'button.menu_show')
        this.dropButtonElement.className = 'menu_button'
        this.dropButtonElement.setAttribute('role', 'button')
        this.dropButtonElement.setAttribute('aria-pressed', 'false')
        this.dropButtonElement.addEventListener('click', () => {
            if (this.isVisible()) {
                menuBar.hide()
            } else {
                menuBar.drop()
            }
        })
        element.appendChild(this.dropButtonElement)

        document.body.addEventListener(
            'pointerdown',
            event => {
                if ((this.isVertical() && this.isVisible()) || (!this.isVertical() && this.armed)) {
                    // click outside root menu element ?
                    const rootMenuElement = this.navElement.parentElement

                    let element = event.srcElement
                    while (element !== null && element !== rootMenuElement) {
                        element = element.parentElement
                    }
                    if (element === null) {
                        // click outside menu, hide menu
                        event.preventDefault()

                        if (this.isVertical()) {
                            this.hide()
                        } else {
                            this.hideAllMenus()
                        }
                    }
                }
            },
            true
        )

        document.addEventListener('keydown', event => {
            this.processKey(event)
        })

        window.addEventListener('resize', () => this.hideAllMenus(), false)

        window.addEventListener(
            'keyup',
            event => {
                if (this.armed && event.keyCode === 27) {
                    this.hideAllMenus()
                }
            },
            false
        )
    }

    addMenu(label, index) {
        const menu = new Menu(this, label)

        const children = this.listElement.children
        if (typeof index === 'number' && index < children.length) {
            if (index < 0) index = 0
            let oldElem = children[index]
            this.listElement.insertBefore(menu.itemElement, oldElem)
            this.menus.splice(index, 0, menu)
        } else {
            this.listElement.appendChild(menu.itemElement)
            this.menus.push(menu)
        }
        return menu
    }

    isVisible() {
        return this.listElement.className === 'menu_drop'
    }

    drop() {
        this.listElement.className = 'menu_drop'
        I18N.set(this.dropButtonElement, 'innerHTML', 'button.menu_hide')
        this.application.i18n.update(this.dropButtonElement)
        this.dropButtonElement.setAttribute('aria-pressed', 'true')
    }

    hide() {
        this.listElement.className = 'menu_hide'
        I18N.set(this.dropButtonElement, 'innerHTML', 'button.menu_show')
        this.application.i18n.update(this.dropButtonElement)
        this.dropButtonElement.setAttribute('aria-pressed', 'false')
        this.armed = false
    }

    isVertical() {
        return document.body.clientWidth < 950
    }

    focusMenuItem(menuItem) {
        if (!this.isVertical()) {
            let menu

            if (this.menuItem) {
                // have previous menuItem
                menu = this.menuItem.parentMenu
                if (menu) {
                    for (let i = 0; i < menu.menuItems.length; i++) {
                        let sibling = menu.menuItems[i]
                        if (sibling instanceof Menu) {
                            sibling.hide() // hide sibling menu
                        }
                    }

                    do {
                        menu.hide() // hide parent menus
                        menu = menu.parentMenu
                    } while (menu)
                } else {
                    this.menuItem.hide()
                }
            }

            if (menuItem) {
                menu = menuItem.parentMenu
                while (menu) {
                    menu.drop() // show parent menu
                    menu = menu.parentMenu
                }
            }
        }
        this.menuItem = menuItem
        if (menuItem === null) {
            this.armed = false
        }
    }

    hideAllMenus() {
        for (var i = 0; i < this.menus.length; i++) {
            let menu = this.menus[i]
            menu.hide(true)
        }
        this.menuItem = null
        this.armed = false
    }

    processKey(event) {
        if (event.srcElement.nodeName === 'INPUT') return

        let keys = []
        if (event.altKey) keys.push('Alt')
        if (event.ctrlKey) keys.push('Control')
        if (event.shiftKey) keys.push('Shift')

        let key = event.key
        if (key !== 'Alt' && key !== 'Control' && key !== 'Shift') {
            if (key.length === 1) key = key.toUpperCase()
            keys.push(key)
        }

        let keyShortcut = keys.join('+')

        let tool = this.keyShortcuts.get(keyShortcut)
        if (tool) {
            this.application.useTool(tool)
            event.preventDefault()
        }
    }
}

export { MenuBar, Menu, MenuItem }