backstage

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#!/usr/bin/env node
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/*
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 * Copyright 2022 The Backstage Authors
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 *
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 * Licensed under the Apache License, Version 2.0 (the "License");
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 * you may not use this file except in compliance with the License.
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 * You may obtain a copy of the License at
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 *
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 *     http://www.apache.org/licenses/LICENSE-2.0
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 *
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 * Unless required by applicable law or agreed to in writing, software
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 * distributed under the License is distributed on an "AS IS" BASIS,
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 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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 * See the License for the specific language governing permissions and
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 * limitations under the License.
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 */
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const { execFile: execFileCb } = require('child_process');
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const { promisify } = require('util');
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const { resolve: resolvePath } = require('path');
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const execFile = promisify(execFileCb);
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async function hasNewChangesets(baseRef, headRef) {
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  if (!baseRef) {
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    throw new Error('baseRef is required');
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  }
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  if (!headRef) {
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    throw new Error('headRef is required');
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  }
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  const { stdout } = await execFile('git', [
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    'diff',
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    '--compact-summary',
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    baseRef,
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    headRef,
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    '--',
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    '.changeset/*.md',
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    ':(exclude).changeset/create-app-*.md',
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  ]);
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  return stdout.includes('(new)');
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}
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function getReleaseOfMonth(year, month) {
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  const base = new Date(Date.UTC(year, month));
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  const wednesdayOffset =
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    base.getUTCDay() > 3 ? 10 - base.getUTCDay() : 3 - base.getUTCDay();
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  const thirdWednesdayOffset = wednesdayOffset + 7 * 2;
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  const releaseOffset = thirdWednesdayOffset - 1;
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  const releaseDay = new Date(
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    Date.UTC(base.getUTCFullYear(), base.getUTCMonth(), releaseOffset + 1),
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  );
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  return releaseDay;
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}
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function getReleaseSchedule() {
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  const firstReleaseYear = 2022;
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  const firstReleaseMonth = 2;
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  return Array(100)
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    .fill(0)
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    .map((_, i) => {
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      const date = getReleaseOfMonth(firstReleaseYear, firstReleaseMonth + i);
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      return { version: `1.${i}.0`, date };
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    });
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}
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function getCurrentRelease() {
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  const { version: releaseVersion } = require(resolvePath('package.json'));
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  const match = releaseVersion.match(/^(\d+\.\d+\.\d+)/);
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  if (!match) {
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    throw new Error(`Failed to parse release version, '${releaseVersion}'`);
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  }
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  const [versionStr] = match;
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  if (versionStr === releaseVersion) {
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    return releaseVersion;
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  }
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  const [major, minor] = versionStr.split('.').map(Number);
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  return `${major}.${minor - 1}.0`;
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}
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function findNextRelease(currentRelease, releaseSchedule) {
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  const currentIndex = releaseSchedule.findIndex(
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    r => r.version === currentRelease,
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  );
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  if (currentIndex === -1) {
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    throw new Error(
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      `Failed to find current release '${currentRelease}' in release schedule`,
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    );
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  }
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  return releaseSchedule[currentIndex + 1];
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}
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async function main() {
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  const [diffBaseRefRef = 'origin/master', diffHeadRef = 'HEAD'] =
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    process.argv.slice(2);
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  const needsMessage = await hasNewChangesets(diffBaseRefRef, diffHeadRef);
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  if (!needsMessage) {
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    return;
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  }
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  const currentRelease = getCurrentRelease();
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  const releaseSchedule = getReleaseSchedule();
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  const nextRelease = findNextRelease(currentRelease, releaseSchedule);
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  const scheduledDate = nextRelease.date
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    .toUTCString()
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    .replace(/\s*\d+:\d+:\d+.*/, '');
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  process.stdout.write(
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    [
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      'Thank you for contributing to Backstage! The changes in this pull request will be part',
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      `of the \`${nextRelease.version}\` release, scheduled for ${scheduledDate}.`,
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    ].join(' '),
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  );
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}
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main().catch(error => {
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  console.error(error.stack);
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  process.exit(1);
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});
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