import {Command, UsageError}                                  from 'clipanion';
import path                                                   from 'path';
import tar                                                    from 'tar';

import * as folderUtils                                       from '../folderUtils';
import {Context}                                              from '../main';
import {SupportedPackageManagerSet, SupportedPackageManagers} from '../types';

export class HydrateCommand extends Command<Context> {
  static usage = Command.Usage({
    description: `Import a package manager into the cache`,
    details: `
      This command unpacks a package manager archive into the cache. The archive must have been generated by the \`corepack pack\` command - no other will work.
    `,
    examples: [[
      `Import a package manager in the cache`,
      `$0 hydrate corepack-yarn-2.2.2.tgz`,
    ]],
  });

  @Command.String()
  fileName!: string;

  @Command.Boolean(`--activate`)
  activate: boolean = false;

  @Command.Path(`hydrate`)
  async execute() {
    const installFolder = folderUtils.getInstallFolder();
    const fileName = path.resolve(this.context.cwd, this.fileName);

    const firstLevel = new Set();
    const secondLevel = new Set();

    let hasShortEntries = false;

    await tar.t({file: fileName, onentry: entry => {
      const segments = entry.header.path.split(/\//g);

      if (segments.length < 3) {
        hasShortEntries = true;
      } else {
        firstLevel.add(segments[0]);
        secondLevel.add(segments[1]);
      }
    }});

    if (hasShortEntries || firstLevel.size !== 1 || secondLevel.size !== 1)
      throw new UsageError(`Invalid archive format; did it get generated by 'corepack prepare'?`);

    const name = [...firstLevel][0] as SupportedPackageManagers;
    const reference = [...secondLevel][0] as string;

    if (!SupportedPackageManagerSet.has(name))
      throw new UsageError(`Unsupported package manager '${name}'`);

    await tar.x({file: fileName, cwd: installFolder});

    if (this.activate)
      await this.context.engine.activatePackageManager({name, reference});

    this.context.stdout.write(`Hydrated ${name}@${reference}\n`);
  }
}