import * as fs from 'fs';
import * as jsYaml from 'js-yaml';
import * as path from 'path';

export interface AppContext {
  appId?: string;
  displayName?: string;
  version?: string;
  vendor?: string;
  runtime?: string;
}

export function appContext(appId?: string, vendor?: string, runtime?: string): AppContext {
  if (appId) {
    if (appId.includes('@')) {
      const [id, version] = appId.split('@');
      return {
        appId: id,
        version,
        vendor,
        runtime
      };
    } else {
      return {appId, vendor, runtime};
    }
  }

  const yaml = readAppYaml();
  if (yaml && yaml.meta) {
    return {
      appId: yaml.meta.app_id,
      displayName: yaml.meta.display_name,
      version: yaml.meta.version,
      vendor: yaml.meta.vendor,
      runtime: yaml.runtime
    };
  }
  return {};
}

export function readAppYaml(): any {
  const file = path.join(process.cwd(), 'app.yml');
  if (!fs.existsSync(file)) {
    throw new Error(
      `Can not find app manifest (app.yaml) in working directory. Please run this command from the root of your app.`
    );
  }

  return jsYaml.safeLoad(fs.readFileSync(file, 'utf8'));
}