import { EventEmitter } from "events"

export class Keyboard extends EventEmitter {
    constructor() {
        super()

        document.addEventListener("keydown", (evt) => {
            const vimKey = this._convertKeyEventToVimKey(evt)
            const mappedKey = this._wrapWithBracketsAndModifiers(vimKey, evt)

            if (mappedKey) {
                this.emit("keydown", mappedKey)
            }

            // Temporary workaround to block closing Window
            // The default electron menu maps C-w to close the window,
            // so we need to stop that.
            //
            // Later, the menu should be customized to fix this.
        })
    }

    private _wrapWithBracketsAndModifiers(vimKey: null | string, evt: KeyboardEvent): null | string {
        if (vimKey === null) {
            return null
        }

        let mappedKey = vimKey

        if (mappedKey === "<") {
            mappedKey = "lt"
        }

        if (evt.ctrlKey) {
            mappedKey = "C-" + vimKey + ""
            evt.preventDefault()
        }

        if (evt.altKey) {
            mappedKey = "A-" + mappedKey
            evt.preventDefault()
        }

        if (evt.metaKey) {
            evt.preventDefault()
        }

        if (mappedKey.length > 1) {
            mappedKey = "<" + mappedKey + ">"
        }

        return mappedKey
    }

    private _convertKeyEventToVimKey(evt: KeyboardEvent): null | string {

        const keyCode: { [key: number]: string } = {
            8: "bs",      // Backspace
            9: "tab",     // Tab
            13: "enter",   // Enter
            27: "esc",     // Escape
            33: "pageup",  // Page up
            34: "pagedown", // Page down
            35: "end",
            36: "home",
            37: "left",    // ArrowLeft
            38: "up",      // ArrowUp
            39: "right",   // ArrowRight
            40: "down",    // ArrowDown
            45: "insert",
            114: "f3",
            116: "f5",
            123: "f12",
            16: null,     // Shift left
            17: null,     // Ctrl left
            18: null,     // Alt left
            19: null,     // Pause
            20: null,     // Caps lock
            145: null,     // Scroll lock
            174: null,     // Volume up
            175: null,     // Volume down
        }

        return keyCode[evt.keyCode] ? keyCode[evt.keyCode] : evt.key

    }
}