import { Tree } from '@angular-devkit/schematics';

/**
 * Sorts the keys of the given object.
 * @returns A new object instance with sorted keys
 */
function sortObjectByKeys(obj: any) {
  return Object.keys(obj)
    .sort()
    .reduce((result, key: string) => ({ ...result, [key]: obj[key] }), {});
}

/** Adds a package to the package.json in the given host tree. */
export function addPackageToPackageJson(
  host: Tree,
  pkg: string,
  version: string
): Tree {
  if (host.exists('package.json')) {
    const sourceText = host.read('package.json')!.toString('utf-8');
    const json = JSON.parse(sourceText);

    if (!json.devDependencies) {
      json.devDependencies = {};
    }

    if (!json.devDependencies[pkg]) {
      json.devDependencies[pkg] = version;
      json.devDependencies = sortObjectByKeys(json.devDependencies);
    }

    host.overwrite('package.json', JSON.stringify(json, null, 2));
  }

  return host;
}

/** Gets the version of the specified package by looking at the package.json in the given tree. */
export function getPackageVersionFromPackageJson(
  tree: Tree,
  name: string
): string | null {
  if (!tree.exists('package.json')) {
    return null;
  }

  const packageJson = JSON.parse(tree.read('package.json')!.toString('utf8'));

  if (packageJson.dependencies && packageJson.dependencies[name]) {
    return packageJson.dependencies[name];
  }

  return null;
}