import path from 'path';
import os from 'os';
import fs from 'fs';

export interface Config {
  credsStore?: string;
  experimental?: string;
  stackOrchestrator?: string;
  aliases?: {
    builder?: string;
  };
}

export interface Image {
  registry?: string;
  namespace?: string;
  repository: string;
  tag?: string;
}

export async function config(): Promise<Config | undefined> {
  const dockerHome: string = process.env.DOCKER_CONFIG || path.join(os.homedir(), '.docker');

  const file: string = path.join(dockerHome, 'config.json');
  if (!fs.existsSync(file)) {
    return;
  }

  return JSON.parse(fs.readFileSync(file, {encoding: 'utf-8'})) as Config;
}

export const parseImage = async (image: string): Promise<Image | undefined> => {
  const match = image.match(/^(?:([^\/]+)\/)?(?:([^\/]+)\/)?([^@:\/]+)(?:[@:](.+))?$/);
  if (!match) {
    return;
  }

  let res: Image = {
    registry: match[1],
    namespace: match[2],
    repository: match[3],
    tag: match[4]
  };

  if (!res.namespace && res.registry && !/[:.]/.test(res.registry)) {
    res.namespace = res.registry;
    res.registry = undefined;
  }

  res.registry = res.registry ? `${res.registry}/` : '';
  res.namespace = res.namespace && res.namespace !== 'library' ? `${res.namespace}/` : '';
  res.tag = res.tag && res.tag !== 'latest' ? `:${res.tag}` : '';
  return res;
};