/**
 * @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 * as semver from 'semver';

import {semverInc} from '../../versioning/inc-semver';
import {computeNewPrereleaseVersionForNext} from '../../versioning/next-prerelease-version';
import {ReleaseTrain} from '../../versioning/release-trains';
import {ReleaseAction} from '../actions';

/**
 * Release action that cuts a prerelease for the next branch. A version in the next
 * branch can have an arbitrary amount of next pre-releases.
 */
export class CutNextPrereleaseAction extends ReleaseAction {
  /** Promise resolving with the new version if a NPM next pre-release is cut. */
  private _newVersion: Promise<semver.SemVer> = this._computeNewVersion();

  async getDescription() {
    const {branchName} = this._getActivePrereleaseTrain();
    const newVersion = await this._newVersion;
    return `Cut a new next pre-release for the "${branchName}" branch (v${newVersion}).`;
  }

  async perform() {
    const releaseTrain = this._getActivePrereleaseTrain();
    const {branchName} = releaseTrain;
    const newVersion = await this._newVersion;

    const {pullRequest: {id}, releaseNotes} =
        await this.checkoutBranchAndStageVersion(newVersion, branchName);

    await this.waitForPullRequestToBeMerged(id);
    await this.buildAndPublish(releaseNotes, branchName, 'next');

    // If the pre-release has been cut from a branch that is not corresponding
    // to the next release-train, cherry-pick the changelog into the primary
    // development branch. i.e. the `next` branch that is usually `master`.
    if (releaseTrain !== this.active.next) {
      await this.cherryPickChangelogIntoNextBranch(releaseNotes, branchName);
    }
  }

  /** Gets the release train for which NPM next pre-releases should be cut. */
  private _getActivePrereleaseTrain(): ReleaseTrain {
    return this.active.releaseCandidate ?? this.active.next;
  }

  /** Gets the new pre-release version for this release action. */
  private async _computeNewVersion(): Promise<semver.SemVer> {
    const releaseTrain = this._getActivePrereleaseTrain();
    // If a pre-release is cut for the next release-train, the new version is computed
    // with respect to special cases surfacing with FF/RC branches. Otherwise, the basic
    // pre-release increment of the version is used as new version.
    if (releaseTrain === this.active.next) {
      return await computeNewPrereleaseVersionForNext(this.active, this.config);
    } else {
      return semverInc(releaseTrain.version, 'prerelease');
    }
  }

  static async isActive() {
    // Pre-releases for the `next` NPM dist tag can always be cut. Depending on whether
    // there is a feature-freeze/release-candidate branch, the next pre-releases are either
    // cut from such a branch, or from the actual `next` release-train branch (i.e. master).
    return true;
  }
}