zeropod/src/menu/console.ts

import { MenuConfig, MenuPrinter, MenuType } from './interface';
import * as readline from 'readline';

type Key = {name: string, ctrl: boolean};

export class ConsolePrinter implements MenuPrinter {
  private _path: number[] = [];
  private _selectedIndex: number = 0;
  private _config: MenuConfig[];
  private _curMenu: MenuConfig[];

  constructor(config: MenuConfig[]) {
    this._config = config;
    this._curMenu = config;
    readline.emitKeypressEvents(process.stdin);
    process.stdin.setRawMode(true);
  }

  private async keypress(): Promise<Key> {
    return new Promise((resolve) => {
      const listener = (_letter: string, key: Key): void => {
        process.stdin.removeListener('keypress', listener);
        resolve(key);
      }
      process.stdin.on('keypress', listener);
    });
  }

  private printMenu(): void {
    console.clear();
    for (let i = 0; i < this._curMenu.length; i++) {
      const line = (i === this._selectedIndex
        ? "> "
        : "  ") + this._curMenu[i].display;
      console.log(line);
    }
  }

  public async getSelection(): Promise<MenuConfig> {
    return new Promise(async (resolve) => {
      while (true) {
        // print menu
        this.printMenu();

        // get user input
        const key = await this.keypress();

        if (key.ctrl && key.name === 'c') {
          process.exit();
        } else if (key.name === 'up') {
          this._selectedIndex--;
          if (this._selectedIndex < 0) {
            this._selectedIndex = 0;
          }
        } else if (key.name ==='down') {
          this._selectedIndex++
          if (this._selectedIndex > this._curMenu.length - 1) {
            this._selectedIndex = this._curMenu.length - 1;
          }
        } else if (key.name === 'left') {
          if (this._path.length > 0) {
            this._path.pop();
            this._selectedIndex = 0;
          }
        } else if (key.name === 'right' || key.name === 'return') {
          this._path.push(this._selectedIndex);
        }
        this._curMenu = this._config;
        for (let i = 0; i < this._path.length; i++) {
          if (this._curMenu[this._path[i]].type === MenuType.SubMenu) {
            this._curMenu = this._curMenu[this._path[i]].subMenu!;
            this._selectedIndex = 0;
          } else {
            resolve(this._curMenu[this._path[i]]);
            this._path.pop();
            return;
          }
        }
      }
    });
  }
}