import { OperatingSystem } from '@/domain/OperatingSystem';
import { BrowserOsDetector } from './BrowserOs/BrowserOsDetector';
import { IBrowserOsDetector } from './BrowserOs/IBrowserOsDetector';
import { IEnvironment } from './IEnvironment';

export interface IEnvironmentVariables {
  readonly window: Window & typeof globalThis;
  readonly process: NodeJS.Process;
  readonly navigator: Navigator;
}

export class Environment implements IEnvironment {
  public static readonly CurrentEnvironment: IEnvironment = new Environment({
    window,
    process: typeof process !== 'undefined' ? process /* electron only */ : undefined,
    navigator,
  });

  public readonly isDesktop: boolean;

  public readonly os: OperatingSystem;

  protected constructor(
    variables: IEnvironmentVariables,
    browserOsDetector: IBrowserOsDetector = new BrowserOsDetector(),
  ) {
    if (!variables) {
      throw new Error('variables is null or empty');
    }
    this.isDesktop = isDesktop(variables);
    if (this.isDesktop) {
      this.os = getDesktopOsType(getProcessPlatform(variables));
    } else {
      const userAgent = getUserAgent(variables);
      this.os = !userAgent ? undefined : browserOsDetector.detect(userAgent);
    }
  }
}

function getUserAgent(variables: IEnvironmentVariables): string {
  if (!variables.window || !variables.window.navigator) {
    return undefined;
  }
  return variables.window.navigator.userAgent;
}

function getProcessPlatform(variables: IEnvironmentVariables): string {
  if (!variables.process || !variables.process.platform) {
    return undefined;
  }
  return variables.process.platform;
}

function getDesktopOsType(processPlatform: string): OperatingSystem | undefined {
  // https://nodejs.org/api/process.html#process_process_platform
  switch (processPlatform) {
    case 'darwin':
      return OperatingSystem.macOS;
    case 'win32':
      return OperatingSystem.Windows;
    case 'linux':
      return OperatingSystem.Linux;
    default:
      return undefined;
  }
}

function isDesktop(variables: IEnvironmentVariables): boolean {
  // More: https://github.com/electron/electron/issues/2288
  // Renderer process
  if (variables.window
    && variables.window.process
    && variables.window.process.type === 'renderer') {
    return true;
  }
  // Main process
  if (variables.process
    && variables.process.versions
    && Boolean(variables.process.versions.electron)) {
    return true;
  }
  // Detect the user agent when the `nodeIntegration` option is set to true
  if (variables.navigator
    && variables.navigator.userAgent
    && variables.navigator.userAgent.includes('Electron')) {
    return true;
  }
  return false;
}