/**
 * @license
 * Copyright Google Inc. 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
 */


// tslint:disable:no-console
module.exports = (gulp) => () => {
  try {
    const validateCommitMessage = require('../validate-commit-message');
    const shelljs = require('shelljs');

    shelljs.set('-e');  // Break on error.

    let baseBranch = 'master';
    const currentVersion = require('semver').parse(require('../../package.json').version);
    const baseHead =
        shelljs
            .exec(`git ls-remote --heads origin ${currentVersion.major}.${currentVersion.minor}.*`)
            .trim()
            .split('\n')
            .pop();
    if (baseHead) {
      const match = /refs\/heads\/(.+)/.exec(baseHead);
      baseBranch = match && match[1] || baseBranch;
    }

    // We need to fetch origin explicitly because it might be stale.
    // I couldn't find a reliable way to do this without fetch.
    const result = shelljs.exec(
        `git fetch origin ${baseBranch} && git log --reverse --format=%s HEAD ^origin/${baseBranch}`);

    if (result.code) {
      throw new Error(`Failed to fetch commits: ${result.stderr}`);
    }

    const commitsByLine = result.trim().split(/\n/).filter(line => line != '');

    console.log(`Examining ${commitsByLine.length} commits between HEAD and ${baseBranch}`);

    if (commitsByLine.length == 0) {
      console.log(`There are zero new commits between this HEAD and ${baseBranch}`);
    }

    const someCommitsInvalid = !commitsByLine.every(validateCommitMessage);

    if (someCommitsInvalid) {
      throw new Error(
          'Please fix the failing commit messages before continuing...\n' +
          'Commit message guidelines: https://github.com/angular/angular/blob/master/CONTRIBUTING.md#-commit-message-guidelines');
    }
  } catch (err) {
    console.error(err);
    process.exit(1);
  }
};