/**
 * @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 {promises as fs} from 'fs';
import * as Ora from 'ora';
import {join} from 'path';
import * as semver from 'semver';

import {debug, error, green, info, promptConfirm, red, warn, yellow} from '../../utils/console';
import {getListCommitsInBranchUrl, getRepositoryGitUrl} from '../../utils/git/github-urls';
import {GitClient} from '../../utils/git/index';
import {BuiltPackage, ReleaseConfig} from '../config';
import {ActiveReleaseTrains} from '../versioning/active-release-trains';
import {runNpmPublish} from '../versioning/npm-publish';

import {FatalReleaseActionError, UserAbortedReleaseActionError} from './actions-error';
import {getCommitMessageForRelease, getReleaseNoteCherryPickCommitMessage} from './commit-message';
import {changelogPath, packageJsonPath, waitForPullRequestInterval} from './constants';
import {invokeReleaseBuildCommand, invokeYarnInstallCommand} from './external-commands';
import {findOwnedForksOfRepoQuery} from './graphql-queries';
import {getPullRequestState} from './pull-request-state';
import {getDefaultExtractReleaseNotesPattern, getLocalChangelogFilePath} from './release-notes';

/** Interface describing a Github repository. */
export interface GithubRepo {
  owner: string;
  name: string;
}

/** Interface describing a Github pull request. */
export interface PullRequest {
  /** Unique id for the pull request (i.e. the PR number). */
  id: number;
  /** URL that resolves to the pull request in Github. */
  url: string;
  /** Fork containing the head branch of this pull request. */
  fork: GithubRepo;
  /** Branch name in the fork that defines this pull request. */
  forkBranch: string;
}

/** Constructor type for a instantiating a release action */
export interface ReleaseActionConstructor<T extends ReleaseAction = ReleaseAction> {
  /** Whether the release action is currently active. */
  isActive(active: ActiveReleaseTrains): Promise<boolean>;
  /** Constructs a release action. */
  new(...args: [ActiveReleaseTrains, GitClient, ReleaseConfig, string]): T;
}

/**
 * Abstract base class for a release action. A release action is selectable by the caretaker
 * if active, and can perform changes for releasing, such as staging a release, bumping the
 * version, cherry-picking the changelog, branching off from master. etc.
 */
export abstract class ReleaseAction {
  /** Whether the release action is currently active. */
  static isActive(_trains: ActiveReleaseTrains): Promise<boolean> {
    throw Error('Not implemented.');
  }

  /** Gets the description for a release action. */
  abstract getDescription(): Promise<string>;
  /**
   * Performs the given release action.
   * @throws {UserAbortedReleaseActionError} When the user manually aborted the action.
   * @throws {FatalReleaseActionError} When the action has been aborted due to a fatal error.
   */
  abstract perform(): Promise<void>;

  /** Cached found fork of the configured project. */
  private _cachedForkRepo: GithubRepo|null = null;

  constructor(
      protected active: ActiveReleaseTrains, protected git: GitClient,
      protected config: ReleaseConfig, protected projectDir: string) {}

  /** Updates the version in the project top-level `package.json` file. */
  protected async updateProjectVersion(newVersion: semver.SemVer) {
    const pkgJsonPath = join(this.projectDir, packageJsonPath);
    const pkgJson = JSON.parse(await fs.readFile(pkgJsonPath, 'utf8'));
    pkgJson.version = newVersion.format();
    // Write the `package.json` file. Note that we add a trailing new line
    // to avoid unnecessary diff. IDEs usually add a trailing new line.
    await fs.writeFile(pkgJsonPath, `${JSON.stringify(pkgJson, null, 2)}\n`);
    info(green(`  ✓   Updated project version to ${pkgJson.version}`));
  }

  /** Gets the most recent commit of a specified branch. */
  private async _getCommitOfBranch(branchName: string): Promise<string> {
    const {data: {commit}} =
        await this.git.github.repos.getBranch({...this.git.remoteParams, branch: branchName});
    return commit.sha;
  }

  /** Verifies that the latest commit for the given branch is passing all statuses. */
  protected async verifyPassingGithubStatus(branchName: string) {
    const commitSha = await this._getCommitOfBranch(branchName);
    const {data: {state}} = await this.git.github.repos.getCombinedStatusForRef(
        {...this.git.remoteParams, ref: commitSha});
    const branchCommitsUrl = getListCommitsInBranchUrl(this.git, branchName);

    if (state === 'failure') {
      error(
          red(`  ✘   Cannot stage release. Commit "${commitSha}" does not pass all github ` +
              `status checks. Please make sure this commit passes all checks before re-running.`));
      error(`      Please have a look at: ${branchCommitsUrl}`);

      if (await promptConfirm('Do you want to ignore the Github status and proceed?')) {
        info(yellow(
            `  ⚠   Upstream commit is failing CI checks, but status has been ` +
            `forcibly ignored.`));
        return;
      }
      throw new UserAbortedReleaseActionError();
    } else if (state === 'pending') {
      error(
          red(`  ✘   Commit "${commitSha}" still has pending github statuses that ` +
              `need to succeed before staging a release.`));
      error(red(`      Please have a look at: ${branchCommitsUrl}`));
      if (await promptConfirm('Do you want to ignore the Github status and proceed?')) {
        info(yellow(
            `  ⚠   Upstream commit is pending CI, but status has been ` +
            `forcibly ignored.`));
        return;
      }
      throw new UserAbortedReleaseActionError();
    }

    info(green('  ✓   Upstream commit is passing all github status checks.'));
  }

  /** Generates the changelog for the specified for the current `HEAD`. */
  private async _generateReleaseNotesForHead(version: semver.SemVer) {
    const changelogPath = getLocalChangelogFilePath(this.projectDir);
    await this.config.generateReleaseNotesForHead(changelogPath);
    info(green(`  ✓   Updated the changelog to capture changes for "${version}".`));
  }

  /** Extract the release notes for the given version from the changelog file. */
  private _extractReleaseNotesForVersion(changelogContent: string, version: semver.SemVer): string
      |null {
    const pattern = this.config.extractReleaseNotesPattern !== undefined ?
        this.config.extractReleaseNotesPattern(version) :
        getDefaultExtractReleaseNotesPattern(version);
    const matchedNotes = pattern.exec(changelogContent);
    return matchedNotes === null ? null : matchedNotes[1];
  }

  /**
   * Prompts the user for potential release notes edits that need to be made. Once
   * confirmed, a new commit for the release point is created.
   */
  protected async waitForEditsAndCreateReleaseCommit(newVersion: semver.SemVer) {
    info(yellow(
        `  ⚠   Please review the changelog and ensure that the log contains only changes ` +
        `that apply to the public API surface. Manual changes can be made. When done, please ` +
        `proceed with the prompt below.`));

    if (!await promptConfirm('Do you want to proceed and commit the changes?')) {
      throw new UserAbortedReleaseActionError();
    }

    // Commit message for the release point.
    const commitMessage = getCommitMessageForRelease(newVersion);
    // Create a release staging commit including changelog and version bump.
    await this.createCommit(commitMessage, [packageJsonPath, changelogPath]);

    info(green(`  ✓   Created release commit for: "${newVersion}".`));
  }

  /**
   * Gets an owned fork for the configured project of the authenticated user. Aborts the
   * process with an error if no fork could be found. Also caches the determined fork
   * repository as the authenticated user cannot change during action execution.
   */
  private async _getForkOfAuthenticatedUser(): Promise<GithubRepo> {
    if (this._cachedForkRepo !== null) {
      return this._cachedForkRepo;
    }

    const {owner, name} = this.git.remoteConfig;
    const result = await this.git.github.graphql.query(findOwnedForksOfRepoQuery, {owner, name});
    const forks = result.repository.forks.nodes;

    if (forks.length === 0) {
      error(red(`  ✘   Unable to find fork for currently authenticated user.`));
      error(red(`      Please ensure you created a fork of: ${owner}/${name}.`));
      throw new FatalReleaseActionError();
    }

    const fork = forks[0];
    return this._cachedForkRepo = {owner: fork.owner.login, name: fork.name};
  }

  /** Checks whether a given branch name is reserved in the specified repository. */
  private async _isBranchNameReservedInRepo(repo: GithubRepo, name: string): Promise<boolean> {
    try {
      await this.git.github.repos.getBranch({owner: repo.owner, repo: repo.name, branch: name});
      return true;
    } catch (e) {
      // If the error has a `status` property set to `404`, then we know that the branch
      // does not exist. Otherwise, it might be an API error that we want to report/re-throw.
      if (e.status === 404) {
        return false;
      }
      throw e;
    }
  }

  /** Finds a non-reserved branch name in the repository with respect to a base name. */
  private async _findAvailableBranchName(repo: GithubRepo, baseName: string): Promise<string> {
    let currentName = baseName;
    let suffixNum = 0;
    while (await this._isBranchNameReservedInRepo(repo, currentName)) {
      suffixNum++;
      currentName = `${baseName}_${suffixNum}`;
    }
    return currentName;
  }

  /**
   * Creates a local branch from the current Git `HEAD`. Will override
   * existing branches in case of a collision.
   */
  protected async createLocalBranchFromHead(branchName: string) {
    this.git.run(['checkout', '-B', branchName]);
  }

  /** Pushes the current Git `HEAD` to the given remote branch in the configured project. */
  protected async pushHeadToRemoteBranch(branchName: string) {
    // Push the local `HEAD` to the remote branch in the configured project.
    this.git.run(['push', this.git.repoGitUrl, `HEAD:refs/heads/${branchName}`]);
  }

  /**
   * Pushes the current Git `HEAD` to a fork for the configured project that is owned by
   * the authenticated user. If the specified branch name exists in the fork already, a
   * unique one will be generated based on the proposed name to avoid collisions.
   * @param proposedBranchName Proposed branch name for the fork.
   * @param trackLocalBranch Whether the fork branch should be tracked locally. i.e. whether
   *   a local branch with remote tracking should be set up.
   * @returns The fork and branch name containing the pushed changes.
   */
  private async _pushHeadToFork(proposedBranchName: string, trackLocalBranch: boolean):
      Promise<{fork: GithubRepo, branchName: string}> {
    const fork = await this._getForkOfAuthenticatedUser();
    // Compute a repository URL for pushing to the fork. Note that we want to respect
    // the SSH option from the dev-infra github configuration.
    const repoGitUrl =
        getRepositoryGitUrl({...fork, useSsh: this.git.remoteConfig.useSsh}, this.git.githubToken);
    const branchName = await this._findAvailableBranchName(fork, proposedBranchName);
    const pushArgs: string[] = [];
    // If a local branch should track the remote fork branch, create a branch matching
    // the remote branch. Later with the `git push`, the remote is set for the branch.
    if (trackLocalBranch) {
      await this.createLocalBranchFromHead(branchName);
      pushArgs.push('--set-upstream');
    }
    // Push the local `HEAD` to the remote branch in the fork.
    this.git.run(['push', repoGitUrl, `HEAD:refs/heads/${branchName}`, ...pushArgs]);
    return {fork, branchName};
  }

  /**
   * Pushes changes to a fork for the configured project that is owned by the currently
   * authenticated user. A pull request is then created for the pushed changes on the
   * configured project that targets the specified target branch.
   * @returns An object describing the created pull request.
   */
  protected async pushChangesToForkAndCreatePullRequest(
      targetBranch: string, proposedForkBranchName: string, title: string,
      body?: string): Promise<PullRequest> {
    const repoSlug = `${this.git.remoteParams.owner}/${this.git.remoteParams.repo}`;
    const {fork, branchName} = await this._pushHeadToFork(proposedForkBranchName, true);
    const {data} = await this.git.github.pulls.create({
      ...this.git.remoteParams,
      head: `${fork.owner}:${branchName}`,
      base: targetBranch,
      body,
      title,
    });

    info(green(`  ✓   Created pull request #${data.number} in ${repoSlug}.`));
    return {
      id: data.number,
      url: data.html_url,
      fork,
      forkBranch: branchName,
    };
  }

  /**
   * Waits for the given pull request to be merged. Default interval for checking the Github
   * API is 10 seconds (to not exceed any rate limits). If the pull request is closed without
   * merge, the script will abort gracefully (considering a manual user abort).
   */
  protected async waitForPullRequestToBeMerged(id: number, interval = waitForPullRequestInterval):
      Promise<void> {
    return new Promise((resolve, reject) => {
      debug(`Waiting for pull request #${id} to be merged.`);

      const spinner = Ora().start(`Waiting for pull request #${id} to be merged.`);
      const intervalId = setInterval(async () => {
        const prState = await getPullRequestState(this.git, id);
        if (prState === 'merged') {
          spinner.stop();
          info(green(`  ✓   Pull request #${id} has been merged.`));
          clearInterval(intervalId);
          resolve();
        } else if (prState === 'closed') {
          spinner.stop();
          warn(yellow(`  ✘   Pull request #${id} has been closed.`));
          clearInterval(intervalId);
          reject(new UserAbortedReleaseActionError());
        }
      }, interval);
    });
  }

  /**
   * Prepend releases notes for a version published in a given branch to the changelog in
   * the current Git `HEAD`. This is useful for cherry-picking the changelog.
   * @returns A boolean indicating whether the release notes have been prepended.
   */
  protected async prependReleaseNotesFromVersionBranch(
      version: semver.SemVer, containingBranch: string): Promise<boolean> {
    const {data} = await this.git.github.repos.getContents(
        {...this.git.remoteParams, path: '/' + changelogPath, ref: containingBranch});
    const branchChangelog = Buffer.from(data.content, 'base64').toString();
    let releaseNotes = this._extractReleaseNotesForVersion(branchChangelog, version);
    // If no release notes could be extracted, return "false" so that the caller
    // can tell that changelog prepending failed.
    if (releaseNotes === null) {
      return false;
    }
    const localChangelogPath = getLocalChangelogFilePath(this.projectDir);
    const localChangelog = await fs.readFile(localChangelogPath, 'utf8');
    // If the extracted release notes do not have any new lines at the end and the
    // local changelog is not empty, we add lines manually so that there is space
    // between the previous and cherry-picked release notes.
    if (!/[\r\n]+$/.test(releaseNotes) && localChangelog !== '') {
      releaseNotes = `${releaseNotes}\n\n`;
    }
    // Prepend the extracted release notes to the local changelog and write it back.
    await fs.writeFile(localChangelogPath, releaseNotes + localChangelog);
    return true;
  }

  /** Checks out an upstream branch with a detached head. */
  protected async checkoutUpstreamBranch(branchName: string) {
    this.git.run(['fetch', this.git.repoGitUrl, branchName]);
    this.git.run(['checkout', 'FETCH_HEAD', '--detach']);
  }

  /**
   * Creates a commit for the specified files with the given message.
   * @param message Message for the created commit
   * @param files List of project-relative file paths to be commited.
   */
  protected async createCommit(message: string, files: string[]) {
    this.git.run(['commit', '--no-verify', '-m', message, ...files]);
  }

  /**
   * Creates a cherry-pick commit for the release notes of the specified version that
   * has been pushed to the given branch.
   * @returns a boolean indicating whether the commit has been created successfully.
   */
  protected async createCherryPickReleaseNotesCommitFrom(
      version: semver.SemVer, branchName: string): Promise<boolean> {
    const commitMessage = getReleaseNoteCherryPickCommitMessage(version);

    // Fetch, extract and prepend the release notes to the local changelog. If that is not
    // possible, abort so that we can ask the user to manually cherry-pick the changelog.
    if (!await this.prependReleaseNotesFromVersionBranch(version, branchName)) {
      return false;
    }

    // Create a changelog cherry-pick commit.
    await this.createCommit(commitMessage, [changelogPath]);

    info(green(`  ✓   Created changelog cherry-pick commit for: "${version}".`));
    return true;
  }

  /**
   * Stages the specified new version for the current branch and creates a
   * pull request that targets the given base branch.
   * @returns an object describing the created pull request.
   */
  protected async stageVersionForBranchAndCreatePullRequest(
      newVersion: semver.SemVer, pullRequestBaseBranch: string): Promise<PullRequest> {
    await this.updateProjectVersion(newVersion);
    await this._generateReleaseNotesForHead(newVersion);
    await this.waitForEditsAndCreateReleaseCommit(newVersion);

    const pullRequest = await this.pushChangesToForkAndCreatePullRequest(
        pullRequestBaseBranch, `release-stage-${newVersion}`,
        `Bump version to "v${newVersion}" with changelog.`);

    info(green('  ✓   Release staging pull request has been created.'));
    info(yellow(`      Please ask team members to review: ${pullRequest.url}.`));

    return pullRequest;
  }

  /**
   * Checks out the specified target branch, verifies its CI status and stages
   * the specified new version in order to create a pull request.
   * @returns an object describing the created pull request.
   */
  protected async checkoutBranchAndStageVersion(newVersion: semver.SemVer, stagingBranch: string):
      Promise<PullRequest> {
    await this.verifyPassingGithubStatus(stagingBranch);
    await this.checkoutUpstreamBranch(stagingBranch);
    return await this.stageVersionForBranchAndCreatePullRequest(newVersion, stagingBranch);
  }

  /**
   * Cherry-picks the release notes of a version that have been pushed to a given branch
   * into the `next` primary development branch. A pull request is created for this.
   * @returns a boolean indicating successful creation of the cherry-pick pull request.
   */
  protected async cherryPickChangelogIntoNextBranch(
      newVersion: semver.SemVer, stagingBranch: string): Promise<boolean> {
    const nextBranch = this.active.next.branchName;
    const commitMessage = getReleaseNoteCherryPickCommitMessage(newVersion);

    // Checkout the next branch.
    await this.checkoutUpstreamBranch(nextBranch);

    // Cherry-pick the release notes into the current branch. If it fails,
    // ask the user to manually copy the release notes into the next branch.
    if (!await this.createCherryPickReleaseNotesCommitFrom(newVersion, stagingBranch)) {
      error(yellow(`  ✘   Could not cherry-pick release notes for v${newVersion}.`));
      error(
          yellow(`      Please copy the release notes manually into the "${nextBranch}" branch.`));
      return false;
    }

    // Create a cherry-pick pull request that should be merged by the caretaker.
    const {url} = await this.pushChangesToForkAndCreatePullRequest(
        nextBranch, `changelog-cherry-pick-${newVersion}`, commitMessage,
        `Cherry-picks the changelog from the "${stagingBranch}" branch to the next ` +
            `branch (${nextBranch}).`);

    info(green(
        `  ✓   Pull request for cherry-picking the changelog into "${nextBranch}" ` +
        `has been created.`));
    info(yellow(`      Please ask team members to review: ${url}.`));
    return true;
  }

  /**
   * Creates a Github release for the specified version in the configured project.
   * The release is created by tagging the specified commit SHA.
   */
  private async _createGithubReleaseForVersion(
      newVersion: semver.SemVer, versionBumpCommitSha: string) {
    const tagName = newVersion.format();
    await this.git.github.git.createRef({
      ...this.git.remoteParams,
      ref: `refs/tags/${tagName}`,
      sha: versionBumpCommitSha,
    });
    info(green(`  ✓   Tagged v${newVersion} release upstream.`));

    await this.git.github.repos.createRelease({
      ...this.git.remoteParams,
      name: `v${newVersion}`,
      tag_name: tagName,
    });
    info(green(`  ✓   Created v${newVersion} release in Github.`));
  }

  /**
   * Builds and publishes the given version in the specified branch.
   * @param newVersion The new version to be published.
   * @param publishBranch Name of the branch that contains the new version.
   * @param npmDistTag NPM dist tag where the version should be published to.
   */
  protected async buildAndPublish(
      newVersion: semver.SemVer, publishBranch: string, npmDistTag: string) {
    const versionBumpCommitSha = await this._getCommitOfBranch(publishBranch);

    if (!await this._isCommitForVersionStaging(newVersion, versionBumpCommitSha)) {
      error(red(`  ✘   Latest commit in "${publishBranch}" branch is not a staging commit.`));
      error(red(`      Please make sure the staging pull request has been merged.`));
      throw new FatalReleaseActionError();
    }

    // Checkout the publish branch and build the release packages.
    await this.checkoutUpstreamBranch(publishBranch);

    // Install the project dependencies for the publish branch, and then build the release
    // packages. Note that we do not directly call the build packages function from the release
    // config. We only want to build and publish packages that have been configured in the given
    // publish branch. e.g. consider we publish patch version and a new package has been
    // created in the `next` branch. The new package would not be part of the patch branch,
    // so we cannot build and publish it.
    await invokeYarnInstallCommand(this.projectDir);
    const builtPackages = await invokeReleaseBuildCommand();

    // Create a Github release for the new version.
    await this._createGithubReleaseForVersion(newVersion, versionBumpCommitSha);

    // Walk through all built packages and publish them to NPM.
    for (const builtPackage of builtPackages) {
      await this._publishBuiltPackageToNpm(builtPackage, npmDistTag);
    }

    info(green(`  ✓   Published all packages successfully`));
  }

  /** Publishes the given built package to NPM with the specified NPM dist tag. */
  private async _publishBuiltPackageToNpm(pkg: BuiltPackage, npmDistTag: string) {
    debug(`Starting publish of "${pkg.name}".`);
    const spinner = Ora().start(`Publishing "${pkg.name}"`);

    try {
      await runNpmPublish(pkg.outputPath, npmDistTag, this.config.publishRegistry);
      spinner.stop();
      info(green(`  ✓   Successfully published "${pkg.name}.`));
    } catch (e) {
      spinner.stop();
      error(e);
      error(red(`  ✘   An error occurred while publishing "${pkg.name}".`));
      throw new FatalReleaseActionError();
    }
  }

  /** Checks whether the given commit represents a staging commit for the specified version. */
  private async _isCommitForVersionStaging(version: semver.SemVer, commitSha: string) {
    const {data} =
        await this.git.github.repos.getCommit({...this.git.remoteParams, ref: commitSha});
    return data.commit.message.startsWith(getCommitMessageForRelease(version));
  }
}