/**
 * @license
 * Copyright Google LLC All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */

import { Rule, SchematicContext } from '@angular-devkit/schematics';
import { NodePackageInstallTask } from '@angular-devkit/schematics/tasks';
import * as path from 'path';

const installTasks = new WeakMap<SchematicContext, Set<string>>();

interface MinimalPackageManifest {
  dependencies?: Record<string, string>;
  devDependencies?: Record<string, string>;
  peerDependencies?: Record<string, string>;
}

/**
 * An enum used to specify the type of a dependency found within a package manifest
 * file (`package.json`).
 */
export enum DependencyType {
  Default = 'dependencies',
  Dev = 'devDependencies',
  Peer = 'peerDependencies',
}

/**
 * Adds a package as a dependency to a `package.json`. By default the `package.json` located
 * at the schematic's root will be used. The `manifestPath` option can be used to explicitly specify
 * a `package.json` in different location. The type of the dependency can also be specified instead
 * of the default of the `dependencies` section by using the `type` option for either `devDependencies`
 * or `peerDependencies`.
 *
 * When using this rule, {@link NodePackageInstallTask} does not need to be included directly by
 * a schematic. A package manager install task will be automatically scheduled as needed.
 *
 * @param name The name of the package to add.
 * @param specifier The package specifier for the package to add. Typically a SemVer range.
 * @param options An optional object that can contain the `type` of the dependency
 * and/or a path (`packageJsonPath`) of a manifest file (`package.json`) to modify.
 * @returns A Schematics {@link Rule}
 */
export function addDependency(
  name: string,
  specifier: string,
  options: {
    /**
     * The type of the dependency determines the section of the `package.json` to which the
     * dependency will be added. Defaults to {@link DependencyType.Default} (`dependencies`).
     */
    type?: DependencyType;
    /**
     * The path of the package manifest file (`package.json`) that will be modified.
     * Defaults to `/package.json`.
     */
    packageJsonPath?: string;
  } = {},
): Rule {
  const { type = DependencyType.Default, packageJsonPath = '/package.json' } = options;

  return (tree, context) => {
    const manifest = tree.readJson(packageJsonPath) as MinimalPackageManifest;
    const dependencySection = manifest[type];

    if (!dependencySection) {
      // Section is not present. The dependency can be added to a new object literal for the section.
      manifest[type] = { [name]: specifier };
    } else if (dependencySection[name] === specifier) {
      // Already present with same specifier
      return;
    } else if (dependencySection[name]) {
      // Already present but different specifier
      throw new Error(`Package dependency "${name}" already exists with a different specifier.`);
    } else {
      // Add new dependency in alphabetical order
      const entries = Object.entries(dependencySection);
      entries.push([name, specifier]);
      entries.sort((a, b) => a[0].localeCompare(b[0]));
      manifest[type] = Object.fromEntries(entries);
    }

    tree.overwrite(packageJsonPath, JSON.stringify(manifest, null, 2));

    const installPaths = installTasks.get(context) ?? new Set<string>();
    if (!installPaths.has(packageJsonPath)) {
      context.addTask(
        new NodePackageInstallTask({ workingDirectory: path.dirname(packageJsonPath) }),
      );
      installPaths.add(packageJsonPath);
      installTasks.set(context, installPaths);
    }
  };
}