/**
 * @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 { logging, tags } from '@angular-devkit/core';
import { Rule, SchematicContext, SchematicsException, Tree } from '@angular-devkit/schematics';
import * as npa from 'npm-package-arg';
import * as semver from 'semver';
import { Dependency, JsonSchemaForNpmPackageJsonFiles } from '../../../utilities/package-json';
import { NpmRepositoryPackageJson, getNpmPackageJson } from '../../../utilities/package-metadata';
import { Schema as UpdateSchema } from './schema';

type VersionRange = string & { __VERSION_RANGE: void };
type PeerVersionTransform = string | ((range: string) => string);

// Angular guarantees that a major is compatible with its following major (so packages that depend
// on Angular 5 are also compatible with Angular 6). This is, in code, represented by verifying
// that all other packages that have a peer dependency of `"@angular/core": "^5.0.0"` actually
// supports 6.0, by adding that compatibility to the range, so it is `^5.0.0 || ^6.0.0`.
// We export it to allow for testing.
export function angularMajorCompatGuarantee(range: string) {
  let newRange = semver.validRange(range);
  if (!newRange) {
    return range;
  }
  let major = 1;
  while (!semver.gtr(major + '.0.0', newRange)) {
    major++;
    if (major >= 99) {
      // Use original range if it supports a major this high
      // Range is most likely unbounded (e.g., >=5.0.0)
      return newRange;
    }
  }

  // Add the major version as compatible with the angular compatible, with all minors. This is
  // already one major above the greatest supported, because we increment `major` before checking.
  // We add minors like this because a minor beta is still compatible with a minor non-beta.
  newRange = range;
  for (let minor = 0; minor < 20; minor++) {
    newRange += ` || ^${major}.${minor}.0-alpha.0 `;
  }

  return semver.validRange(newRange) || range;
}

// This is a map of packageGroupName to range extending function. If it isn't found, the range is
// kept the same.
const knownPeerCompatibleList: { [name: string]: PeerVersionTransform } = {
  '@angular/core': angularMajorCompatGuarantee,
};

interface PackageVersionInfo {
  version: VersionRange;
  packageJson: JsonSchemaForNpmPackageJsonFiles;
  updateMetadata: UpdateMetadata;
}

interface PackageInfo {
  name: string;
  npmPackageJson: NpmRepositoryPackageJson;
  installed: PackageVersionInfo;
  target?: PackageVersionInfo;
  packageJsonRange: string;
}

interface UpdateMetadata {
  packageGroupName?: string;
  packageGroup: { [packageName: string]: string };
  requirements: { [packageName: string]: string };
  migrations?: string;
}

function _updatePeerVersion(infoMap: Map<string, PackageInfo>, name: string, range: string) {
  // Resolve packageGroupName.
  const maybePackageInfo = infoMap.get(name);
  if (!maybePackageInfo) {
    return range;
  }
  if (maybePackageInfo.target) {
    name = maybePackageInfo.target.updateMetadata.packageGroupName || name;
  } else {
    name = maybePackageInfo.installed.updateMetadata.packageGroupName || name;
  }

  const maybeTransform = knownPeerCompatibleList[name];
  if (maybeTransform) {
    if (typeof maybeTransform == 'function') {
      return maybeTransform(range);
    } else {
      return maybeTransform;
    }
  }

  return range;
}

function _validateForwardPeerDependencies(
  name: string,
  infoMap: Map<string, PackageInfo>,
  peers: { [name: string]: string },
  peersMeta: { [name: string]: { optional?: boolean } },
  logger: logging.LoggerApi,
  next: boolean,
): boolean {
  let validationFailed = false;
  for (const [peer, range] of Object.entries(peers)) {
    logger.debug(`Checking forward peer ${peer}...`);
    const maybePeerInfo = infoMap.get(peer);
    const isOptional = peersMeta[peer] && !!peersMeta[peer].optional;
    if (!maybePeerInfo) {
      if (!isOptional) {
        logger.warn(
          [
            `Package ${JSON.stringify(name)} has a missing peer dependency of`,
            `${JSON.stringify(peer)} @ ${JSON.stringify(range)}.`,
          ].join(' '),
        );
      }

      continue;
    }

    const peerVersion =
      maybePeerInfo.target && maybePeerInfo.target.packageJson.version
        ? maybePeerInfo.target.packageJson.version
        : maybePeerInfo.installed.version;

    logger.debug(`  Range intersects(${range}, ${peerVersion})...`);
    if (!semver.satisfies(peerVersion, range, { includePrerelease: next || undefined })) {
      logger.error(
        [
          `Package ${JSON.stringify(name)} has an incompatible peer dependency to`,
          `${JSON.stringify(peer)} (requires ${JSON.stringify(range)},`,
          `would install ${JSON.stringify(peerVersion)})`,
        ].join(' '),
      );

      validationFailed = true;
      continue;
    }
  }

  return validationFailed;
}

function _validateReversePeerDependencies(
  name: string,
  version: string,
  infoMap: Map<string, PackageInfo>,
  logger: logging.LoggerApi,
  next: boolean,
) {
  for (const [installed, installedInfo] of infoMap.entries()) {
    const installedLogger = logger.createChild(installed);
    installedLogger.debug(`${installed}...`);
    const peers = (installedInfo.target || installedInfo.installed).packageJson.peerDependencies;

    for (const [peer, range] of Object.entries(peers || {})) {
      if (peer != name) {
        // Only check peers to the packages we're updating. We don't care about peers
        // that are unmet but we have no effect on.
        continue;
      }

      // Ignore peerDependency mismatches for these packages.
      // They are deprecated and removed via a migration.
      const ignoredPackages = [
        'codelyzer',
        '@schematics/update',
        '@angular-devkit/build-ng-packagr',
        'tsickle',
      ];
      if (ignoredPackages.includes(installed)) {
        continue;
      }

      // Override the peer version range if it's known as a compatible.
      const extendedRange = _updatePeerVersion(infoMap, peer, range);

      if (!semver.satisfies(version, extendedRange, { includePrerelease: next || undefined })) {
        logger.error(
          [
            `Package ${JSON.stringify(installed)} has an incompatible peer dependency to`,
            `${JSON.stringify(name)} (requires`,
            `${JSON.stringify(range)}${extendedRange == range ? '' : ' (extended)'},`,
            `would install ${JSON.stringify(version)}).`,
          ].join(' '),
        );

        return true;
      }
    }
  }

  return false;
}

function _validateUpdatePackages(
  infoMap: Map<string, PackageInfo>,
  force: boolean,
  next: boolean,
  logger: logging.LoggerApi,
): void {
  logger.debug('Updating the following packages:');
  infoMap.forEach((info) => {
    if (info.target) {
      logger.debug(`  ${info.name} => ${info.target.version}`);
    }
  });

  let peerErrors = false;
  infoMap.forEach((info) => {
    const { name, target } = info;
    if (!target) {
      return;
    }

    const pkgLogger = logger.createChild(name);
    logger.debug(`${name}...`);

    const { peerDependencies = {}, peerDependenciesMeta = {} } = target.packageJson;
    peerErrors =
      _validateForwardPeerDependencies(
        name,
        infoMap,
        peerDependencies,
        peerDependenciesMeta,
        pkgLogger,
        next,
      ) || peerErrors;
    peerErrors =
      _validateReversePeerDependencies(name, target.version, infoMap, pkgLogger, next) ||
      peerErrors;
  });

  if (!force && peerErrors) {
    throw new SchematicsException(tags.stripIndents`Incompatible peer dependencies found.
      Peer dependency warnings when installing dependencies means that those dependencies might not work correctly together.
      You can use the '--force' option to ignore incompatible peer dependencies and instead address these warnings later.`);
  }
}

function _performUpdate(
  tree: Tree,
  context: SchematicContext,
  infoMap: Map<string, PackageInfo>,
  logger: logging.LoggerApi,
  migrateOnly: boolean,
): void {
  const packageJsonContent = tree.read('/package.json');
  if (!packageJsonContent) {
    throw new SchematicsException('Could not find a package.json. Are you in a Node project?');
  }

  let packageJson: JsonSchemaForNpmPackageJsonFiles;
  try {
    packageJson = JSON.parse(packageJsonContent.toString()) as JsonSchemaForNpmPackageJsonFiles;
  } catch (e) {
    throw new SchematicsException('package.json could not be parsed: ' + e.message);
  }

  const updateDependency = (deps: Dependency, name: string, newVersion: string) => {
    const oldVersion = deps[name];
    // We only respect caret and tilde ranges on update.
    const execResult = /^[\^~]/.exec(oldVersion);
    deps[name] = `${execResult ? execResult[0] : ''}${newVersion}`;
  };

  const toInstall = [...infoMap.values()]
    .map((x) => [x.name, x.target, x.installed])
    .filter(([name, target, installed]) => {
      return !!name && !!target && !!installed;
    }) as [string, PackageVersionInfo, PackageVersionInfo][];

  toInstall.forEach(([name, target, installed]) => {
    logger.info(
      `Updating package.json with dependency ${name} ` +
        `@ ${JSON.stringify(target.version)} (was ${JSON.stringify(installed.version)})...`,
    );

    if (packageJson.dependencies && packageJson.dependencies[name]) {
      updateDependency(packageJson.dependencies, name, target.version);

      if (packageJson.devDependencies && packageJson.devDependencies[name]) {
        delete packageJson.devDependencies[name];
      }
      if (packageJson.peerDependencies && packageJson.peerDependencies[name]) {
        delete packageJson.peerDependencies[name];
      }
    } else if (packageJson.devDependencies && packageJson.devDependencies[name]) {
      updateDependency(packageJson.devDependencies, name, target.version);

      if (packageJson.peerDependencies && packageJson.peerDependencies[name]) {
        delete packageJson.peerDependencies[name];
      }
    } else if (packageJson.peerDependencies && packageJson.peerDependencies[name]) {
      updateDependency(packageJson.peerDependencies, name, target.version);
    } else {
      logger.warn(`Package ${name} was not found in dependencies.`);
    }
  });

  const newContent = JSON.stringify(packageJson, null, 2);
  if (packageJsonContent.toString() != newContent || migrateOnly) {
    if (!migrateOnly) {
      tree.overwrite('/package.json', JSON.stringify(packageJson, null, 2));
    }

    const externalMigrations: {}[] = [];

    // Run the migrate schematics with the list of packages to use. The collection contains
    // version information and we need to do this post installation. Please note that the
    // migration COULD fail and leave side effects on disk.
    // Run the schematics task of those packages.
    toInstall.forEach(([name, target, installed]) => {
      if (!target.updateMetadata.migrations) {
        return;
      }

      externalMigrations.push({
        package: name,
        collection: target.updateMetadata.migrations,
        from: installed.version,
        to: target.version,
      });

      return;
    });

    if (externalMigrations.length > 0) {
      // eslint-disable-next-line @typescript-eslint/no-explicit-any
      (global as any).externalMigrations = externalMigrations;
    }
  }
}

function _getUpdateMetadata(
  packageJson: JsonSchemaForNpmPackageJsonFiles,
  logger: logging.LoggerApi,
): UpdateMetadata {
  const metadata = packageJson['ng-update'];

  const result: UpdateMetadata = {
    packageGroup: {},
    requirements: {},
  };

  if (!metadata || typeof metadata != 'object' || Array.isArray(metadata)) {
    return result;
  }

  if (metadata['packageGroup']) {
    const packageGroup = metadata['packageGroup'];
    // Verify that packageGroup is an array of strings or an map of versions. This is not an error
    // but we still warn the user and ignore the packageGroup keys.
    if (Array.isArray(packageGroup) && packageGroup.every((x) => typeof x == 'string')) {
      result.packageGroup = packageGroup.reduce((group, name) => {
        group[name] = packageJson.version;

        return group;
      }, result.packageGroup);
    } else if (
      typeof packageGroup == 'object' &&
      packageGroup &&
      Object.values(packageGroup).every((x) => typeof x == 'string')
    ) {
      result.packageGroup = packageGroup;
    } else {
      logger.warn(`packageGroup metadata of package ${packageJson.name} is malformed. Ignoring.`);
    }

    result.packageGroupName = Object.keys(result.packageGroup)[0];
  }

  if (typeof metadata['packageGroupName'] == 'string') {
    result.packageGroupName = metadata['packageGroupName'];
  }

  if (metadata['requirements']) {
    const requirements = metadata['requirements'];
    // Verify that requirements are
    if (
      typeof requirements != 'object' ||
      Array.isArray(requirements) ||
      Object.keys(requirements).some((name) => typeof requirements[name] != 'string')
    ) {
      logger.warn(`requirements metadata of package ${packageJson.name} is malformed. Ignoring.`);
    } else {
      result.requirements = requirements;
    }
  }

  if (metadata['migrations']) {
    const migrations = metadata['migrations'];
    if (typeof migrations != 'string') {
      logger.warn(`migrations metadata of package ${packageJson.name} is malformed. Ignoring.`);
    } else {
      result.migrations = migrations;
    }
  }

  return result;
}

function _usageMessage(
  options: UpdateSchema,
  infoMap: Map<string, PackageInfo>,
  logger: logging.LoggerApi,
) {
  const packageGroups = new Map<string, string>();
  const packagesToUpdate = [...infoMap.entries()]
    .map(([name, info]) => {
      let tag = options.next
        ? info.npmPackageJson['dist-tags']['next']
          ? 'next'
          : 'latest'
        : 'latest';
      let version = info.npmPackageJson['dist-tags'][tag];
      let target = info.npmPackageJson.versions[version];

      const versionDiff = semver.diff(info.installed.version, version);
      if (
        versionDiff !== 'patch' &&
        versionDiff !== 'minor' &&
        /^@(?:angular|nguniversal)\//.test(name)
      ) {
        const installedMajorVersion = semver.parse(info.installed.version)?.major;
        const toInstallMajorVersion = semver.parse(version)?.major;
        if (
          installedMajorVersion !== undefined &&
          toInstallMajorVersion !== undefined &&
          installedMajorVersion < toInstallMajorVersion - 1
        ) {
          const nextMajorVersion = `${installedMajorVersion + 1}.`;
          const nextMajorVersions = Object.keys(info.npmPackageJson.versions)
            .filter((v) => v.startsWith(nextMajorVersion))
            .sort((a, b) => (a > b ? -1 : 1));

          if (nextMajorVersions.length) {
            version = nextMajorVersions[0];
            target = info.npmPackageJson.versions[version];
            tag = '';
          }
        }
      }

      return {
        name,
        info,
        version,
        tag,
        target,
      };
    })
    .filter(
      ({ info, version, target }) =>
        target?.['ng-update'] && semver.compare(info.installed.version, version) < 0,
    )
    .map(({ name, info, version, tag, target }) => {
      // Look for packageGroup.
      const packageGroup = target['ng-update']['packageGroup'];
      if (packageGroup) {
        const packageGroupName = target['ng-update']['packageGroupName'] || packageGroup[0];
        if (packageGroupName) {
          if (packageGroups.has(name)) {
            return null;
          }

          packageGroup.forEach((x: string) => packageGroups.set(x, packageGroupName));
          packageGroups.set(packageGroupName, packageGroupName);
          name = packageGroupName;
        }
      }

      let command = `ng update ${name}`;
      if (!tag) {
        command += `@${semver.parse(version)?.major || version}`;
      } else if (tag == 'next') {
        command += ' --next';
      }

      return [name, `${info.installed.version} -> ${version} `, command];
    })
    .filter((x) => x !== null)
    .sort((a, b) => (a && b ? a[0].localeCompare(b[0]) : 0));

  if (packagesToUpdate.length == 0) {
    logger.info('We analyzed your package.json and everything seems to be in order. Good work!');

    return;
  }

  logger.info('We analyzed your package.json, there are some packages to update:\n');

  // Find the largest name to know the padding needed.
  let namePad = Math.max(...[...infoMap.keys()].map((x) => x.length)) + 2;
  if (!Number.isFinite(namePad)) {
    namePad = 30;
  }
  const pads = [namePad, 25, 0];

  logger.info(
    '  ' + ['Name', 'Version', 'Command to update'].map((x, i) => x.padEnd(pads[i])).join(''),
  );
  logger.info(' ' + '-'.repeat(pads.reduce((s, x) => (s += x), 0) + 20));

  packagesToUpdate.forEach((fields) => {
    if (!fields) {
      return;
    }

    logger.info('  ' + fields.map((x, i) => x.padEnd(pads[i])).join(''));
  });

  logger.info(
    `\nThere might be additional packages which don't provide 'ng update' capabilities that are outdated.\n` +
      `You can update the additional packages by running the update command of your package manager.`,
  );

  return;
}

function _buildPackageInfo(
  tree: Tree,
  packages: Map<string, VersionRange>,
  allDependencies: ReadonlyMap<string, VersionRange>,
  npmPackageJson: NpmRepositoryPackageJson,
  logger: logging.LoggerApi,
): PackageInfo {
  const name = npmPackageJson.name;
  const packageJsonRange = allDependencies.get(name);
  if (!packageJsonRange) {
    throw new SchematicsException(`Package ${JSON.stringify(name)} was not found in package.json.`);
  }

  // Find out the currently installed version. Either from the package.json or the node_modules/
  // TODO: figure out a way to read package-lock.json and/or yarn.lock.
  let installedVersion: string | undefined | null;
  const packageContent = tree.read(`/node_modules/${name}/package.json`);
  if (packageContent) {
    const content = JSON.parse(packageContent.toString()) as JsonSchemaForNpmPackageJsonFiles;
    installedVersion = content.version;
  }
  if (!installedVersion) {
    // Find the version from NPM that fits the range to max.
    installedVersion = semver.maxSatisfying(Object.keys(npmPackageJson.versions), packageJsonRange);
  }

  if (!installedVersion) {
    throw new SchematicsException(
      `An unexpected error happened; could not determine version for package ${name}.`,
    );
  }

  const installedPackageJson = npmPackageJson.versions[installedVersion] || packageContent;
  if (!installedPackageJson) {
    throw new SchematicsException(
      `An unexpected error happened; package ${name} has no version ${installedVersion}.`,
    );
  }

  let targetVersion: VersionRange | undefined = packages.get(name);
  if (targetVersion) {
    if (npmPackageJson['dist-tags'][targetVersion]) {
      targetVersion = npmPackageJson['dist-tags'][targetVersion] as VersionRange;
    } else if (targetVersion == 'next') {
      targetVersion = npmPackageJson['dist-tags']['latest'] as VersionRange;
    } else {
      targetVersion = semver.maxSatisfying(
        Object.keys(npmPackageJson.versions),
        targetVersion,
      ) as VersionRange;
    }
  }

  if (targetVersion && semver.lte(targetVersion, installedVersion)) {
    logger.debug(`Package ${name} already satisfied by package.json (${packageJsonRange}).`);
    targetVersion = undefined;
  }

  const target: PackageVersionInfo | undefined = targetVersion
    ? {
        version: targetVersion,
        packageJson: npmPackageJson.versions[targetVersion],
        updateMetadata: _getUpdateMetadata(npmPackageJson.versions[targetVersion], logger),
      }
    : undefined;

  // Check if there's an installed version.
  return {
    name,
    npmPackageJson,
    installed: {
      version: installedVersion as VersionRange,
      packageJson: installedPackageJson,
      updateMetadata: _getUpdateMetadata(installedPackageJson, logger),
    },
    target,
    packageJsonRange,
  };
}

function _buildPackageList(
  options: UpdateSchema,
  projectDeps: Map<string, VersionRange>,
  logger: logging.LoggerApi,
): Map<string, VersionRange> {
  // Parse the packages options to set the targeted version.
  const packages = new Map<string, VersionRange>();
  const commandLinePackages =
    options.packages && options.packages.length > 0 ? options.packages : [];

  for (const pkg of commandLinePackages) {
    // Split the version asked on command line.
    const m = pkg.match(/^((?:@[^/]{1,100}\/)?[^@]{1,100})(?:@(.{1,100}))?$/);
    if (!m) {
      logger.warn(`Invalid package argument: ${JSON.stringify(pkg)}. Skipping.`);
      continue;
    }

    const [, npmName, maybeVersion] = m;

    const version = projectDeps.get(npmName);
    if (!version) {
      logger.warn(`Package not installed: ${JSON.stringify(npmName)}. Skipping.`);
      continue;
    }

    packages.set(npmName, (maybeVersion || (options.next ? 'next' : 'latest')) as VersionRange);
  }

  return packages;
}

function _addPackageGroup(
  tree: Tree,
  packages: Map<string, VersionRange>,
  allDependencies: ReadonlyMap<string, VersionRange>,
  npmPackageJson: NpmRepositoryPackageJson,
  logger: logging.LoggerApi,
): void {
  const maybePackage = packages.get(npmPackageJson.name);
  if (!maybePackage) {
    return;
  }

  const info = _buildPackageInfo(tree, packages, allDependencies, npmPackageJson, logger);

  const version =
    (info.target && info.target.version) ||
    npmPackageJson['dist-tags'][maybePackage] ||
    maybePackage;
  if (!npmPackageJson.versions[version]) {
    return;
  }
  const ngUpdateMetadata = npmPackageJson.versions[version]['ng-update'];
  if (!ngUpdateMetadata) {
    return;
  }

  let packageGroup = ngUpdateMetadata['packageGroup'];
  if (!packageGroup) {
    return;
  }
  if (Array.isArray(packageGroup) && !packageGroup.some((x) => typeof x != 'string')) {
    packageGroup = packageGroup.reduce((acc, curr) => {
      acc[curr] = maybePackage;

      return acc;
    }, {} as { [name: string]: string });
  }

  // Only need to check if it's an object because we set it right the time before.
  if (
    typeof packageGroup != 'object' ||
    packageGroup === null ||
    Object.values(packageGroup).some((v) => typeof v != 'string')
  ) {
    logger.warn(`packageGroup metadata of package ${npmPackageJson.name} is malformed.`);

    return;
  }

  Object.keys(packageGroup)
    .filter((name) => !packages.has(name)) // Don't override names from the command line.
    .filter((name) => allDependencies.has(name)) // Remove packages that aren't installed.
    .forEach((name) => {
      packages.set(name, packageGroup[name]);
    });
}

/**
 * Add peer dependencies of packages on the command line to the list of packages to update.
 * We don't do verification of the versions here as this will be done by a later step (and can
 * be ignored by the --force flag).
 * @private
 */
function _addPeerDependencies(
  tree: Tree,
  packages: Map<string, VersionRange>,
  allDependencies: ReadonlyMap<string, VersionRange>,
  npmPackageJson: NpmRepositoryPackageJson,
  npmPackageJsonMap: Map<string, NpmRepositoryPackageJson>,
  logger: logging.LoggerApi,
): void {
  const maybePackage = packages.get(npmPackageJson.name);
  if (!maybePackage) {
    return;
  }

  const info = _buildPackageInfo(tree, packages, allDependencies, npmPackageJson, logger);

  const version =
    (info.target && info.target.version) ||
    npmPackageJson['dist-tags'][maybePackage] ||
    maybePackage;
  if (!npmPackageJson.versions[version]) {
    return;
  }

  const packageJson = npmPackageJson.versions[version];
  const error = false;

  for (const [peer, range] of Object.entries(packageJson.peerDependencies || {})) {
    if (packages.has(peer)) {
      continue;
    }

    const peerPackageJson = npmPackageJsonMap.get(peer);
    if (peerPackageJson) {
      const peerInfo = _buildPackageInfo(tree, packages, allDependencies, peerPackageJson, logger);
      if (semver.satisfies(peerInfo.installed.version, range)) {
        continue;
      }
    }

    packages.set(peer, range as VersionRange);
  }

  if (error) {
    throw new SchematicsException('An error occured, see above.');
  }
}

function _getAllDependencies(tree: Tree): Array<readonly [string, VersionRange]> {
  const packageJsonContent = tree.read('/package.json');
  if (!packageJsonContent) {
    throw new SchematicsException('Could not find a package.json. Are you in a Node project?');
  }

  let packageJson: JsonSchemaForNpmPackageJsonFiles;
  try {
    packageJson = JSON.parse(packageJsonContent.toString()) as JsonSchemaForNpmPackageJsonFiles;
  } catch (e) {
    throw new SchematicsException('package.json could not be parsed: ' + e.message);
  }

  return [
    ...(Object.entries(packageJson.peerDependencies || {}) as Array<[string, VersionRange]>),
    ...(Object.entries(packageJson.devDependencies || {}) as Array<[string, VersionRange]>),
    ...(Object.entries(packageJson.dependencies || {}) as Array<[string, VersionRange]>),
  ];
}

function _formatVersion(version: string | undefined) {
  if (version === undefined) {
    return undefined;
  }

  if (!version.match(/^\d{1,30}\.\d{1,30}\.\d{1,30}/)) {
    version += '.0';
  }
  if (!version.match(/^\d{1,30}\.\d{1,30}\.\d{1,30}/)) {
    version += '.0';
  }
  if (!semver.valid(version)) {
    throw new SchematicsException(`Invalid migration version: ${JSON.stringify(version)}`);
  }

  return version;
}

/**
 * Returns whether or not the given package specifier (the value string in a
 * `package.json` dependency) is hosted in the NPM registry.
 * @throws When the specifier cannot be parsed.
 */
function isPkgFromRegistry(name: string, specifier: string): boolean {
  const result = npa.resolve(name, specifier);

  return !!result.registry;
}

export default function (options: UpdateSchema): Rule {
  if (!options.packages) {
    // We cannot just return this because we need to fetch the packages from NPM still for the
    // help/guide to show.
    options.packages = [];
  } else {
    // We split every packages by commas to allow people to pass in multiple and make it an array.
    options.packages = options.packages.reduce((acc, curr) => {
      return acc.concat(curr.split(','));
    }, [] as string[]);
  }

  if (options.migrateOnly && options.from) {
    if (options.packages.length !== 1) {
      throw new SchematicsException('--from requires that only a single package be passed.');
    }
  }

  options.from = _formatVersion(options.from);
  options.to = _formatVersion(options.to);
  const usingYarn = options.packageManager === 'yarn';

  return async (tree: Tree, context: SchematicContext) => {
    const logger = context.logger;
    const npmDeps = new Map(
      _getAllDependencies(tree).filter(([name, specifier]) => {
        try {
          return isPkgFromRegistry(name, specifier);
        } catch {
          logger.warn(`Package ${name} was not found on the registry. Skipping.`);

          return false;
        }
      }),
    );
    const packages = _buildPackageList(options, npmDeps, logger);

    // Grab all package.json from the npm repository. This requires a lot of HTTP calls so we
    // try to parallelize as many as possible.
    const allPackageMetadata = await Promise.all(
      Array.from(npmDeps.keys()).map((depName) =>
        getNpmPackageJson(depName, logger, {
          registry: options.registry,
          usingYarn,
          verbose: options.verbose,
        }),
      ),
    );

    // Build a map of all dependencies and their packageJson.
    const npmPackageJsonMap = allPackageMetadata.reduce((acc, npmPackageJson) => {
      // If the package was not found on the registry. It could be private, so we will just
      // ignore. If the package was part of the list, we will error out, but will simply ignore
      // if it's either not requested (so just part of package.json. silently).
      if (!npmPackageJson.name) {
        if (npmPackageJson.requestedName && packages.has(npmPackageJson.requestedName)) {
          throw new SchematicsException(
            `Package ${JSON.stringify(npmPackageJson.requestedName)} was not found on the ` +
              'registry. Cannot continue as this may be an error.',
          );
        }
      } else {
        // If a name is present, it is assumed to be fully populated
        acc.set(npmPackageJson.name, npmPackageJson as NpmRepositoryPackageJson);
      }

      return acc;
    }, new Map<string, NpmRepositoryPackageJson>());

    // Augment the command line package list with packageGroups and forward peer dependencies.
    // Each added package may uncover new package groups and peer dependencies, so we must
    // repeat this process until the package list stabilizes.
    let lastPackagesSize;
    do {
      lastPackagesSize = packages.size;
      npmPackageJsonMap.forEach((npmPackageJson) => {
        _addPackageGroup(tree, packages, npmDeps, npmPackageJson, logger);
        _addPeerDependencies(tree, packages, npmDeps, npmPackageJson, npmPackageJsonMap, logger);
      });
    } while (packages.size > lastPackagesSize);

    // Build the PackageInfo for each module.
    const packageInfoMap = new Map<string, PackageInfo>();
    npmPackageJsonMap.forEach((npmPackageJson) => {
      packageInfoMap.set(
        npmPackageJson.name,
        _buildPackageInfo(tree, packages, npmDeps, npmPackageJson, logger),
      );
    });

    // Now that we have all the information, check the flags.
    if (packages.size > 0) {
      if (options.migrateOnly && options.from && options.packages) {
        return;
      }

      const sublog = new logging.LevelCapLogger('validation', logger.createChild(''), 'warn');
      _validateUpdatePackages(packageInfoMap, !!options.force, !!options.next, sublog);

      _performUpdate(tree, context, packageInfoMap, logger, !!options.migrateOnly);
    } else {
      _usageMessage(options, packageInfoMap, logger);
    }
  };
}