#!/usr/bin/env node
/* eslint-disable @backstage/no-undeclared-imports */
/*
 * Copyright 2020 The Backstage Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * This script creates a release on GitHub for the Backstage repository.
 * Given a git tag, it identifies the PR created by changesets which is responsible for creating
 * the git tag. It then uses the PR description consisting of changelogs for packages as the
 * release description.
 *
 * Example:
 *
 * Set GITHUB_TOKEN environment variable.
 *
 * (Dry Run mode, will create a DRAFT release, but will not publish it.)
 * (Draft releases are visible to maintainers and do not notify users.)
 * $ node scripts/get-release-description v0.4.1
 *
 * This will open the git tree at this tag https://github.com/backstage/backstage/tree/v0.4.1
 * It will identify https://github.com/backstage/backstage/pull/3668 as the responsible changeset PR.
 * And will use everything in the PR description under "Releases" section.
 *
 * (Production or GitHub Actions Mode)
 * $ node scripts/get-release-description v0.4.1 true
 *
 * This will do the same steps as above, and will publish the Release with the description.
 */

const { Octokit } = require('@octokit/rest');
const semver = require('semver');

// See Examples above to learn about these command line arguments.
const [TAG_NAME, BOOL_CREATE_RELEASE] = process.argv.slice(2);

if (!BOOL_CREATE_RELEASE) {
  console.log(
    '\nRunning script in Dry Run mode. It will output details, will create a draft release but will NOT publish it.',
  );
}

const GH_OWNER = 'backstage';
const GH_REPO = 'backstage';
const EXPECTED_COMMIT_MESSAGE = /^Merge pull request #(?<prNumber>[0-9]+) from/;
const CHANGESET_RELEASE_BRANCH = 'backstage/changeset-release/master';

// Initialize a GitHub client
const octokit = new Octokit({
  auth: process.env.GITHUB_TOKEN,
});

// Get the message of the commit responsible for a tag
async function getCommitUsingTagName(tagName) {
  // Get the tag SHA using the provided tag name
  const refData = await octokit.git.getRef({
    owner: GH_OWNER,
    repo: GH_REPO,
    ref: `tags/${tagName}`,
  });
  if (refData.status !== 200) {
    console.error('refData:');
    console.error(refData);
    throw new Error(
      'Something went wrong when getting the tag SHA using tag name',
    );
  }
  const tagSha = refData.data.object.sha;
  console.log(`SHA for the tag ${TAG_NAME} is ${tagSha}`);

  // Get the commit SHA using the tag SHA
  const tagData = await octokit.git.getTag({
    owner: GH_REPO,
    repo: GH_REPO,
    tag_sha: tagSha,
  });
  if (tagData.status !== 200) {
    console.error('tagData:');
    console.error(tagData);
    throw new Error(
      'Something went wrong when getting the commit SHA using tag SHA',
    );
  }
  const commitSha = tagData.data.object.sha;
  console.log(
    `The commit for the tag is https://github.com/backstage/backstage/commit/${commitSha}`,
  );

  // Get the commit message using the commit SHA
  const commitData = await octokit.git.getCommit({
    owner: GH_OWNER,
    repo: GH_REPO,
    commit_sha: commitSha,
  });
  if (commitData.status !== 200) {
    console.error('commitData:');
    console.error(commitData);
    throw new Error(
      'Something went wrong when getting the commit message using commit SHA',
    );
  }

  // Example Commit Message
  // Merge pull request #3555 from backstage/changeset-release/master Version Packages
  return { sha: commitSha, message: commitData.data.message };
}

// There is a PR number in our expected commit message. Get the description of that PR.
async function getReleaseDescriptionFromCommit(commit) {
  let pullRequestBody = undefined;

  const { data: pullRequests } =
    await octokit.repos.listPullRequestsAssociatedWithCommit({
      owner: GH_OWNER,
      repo: GH_REPO,
      commit_sha: commit.sha,
    });
  if (pullRequests.length === 1) {
    pullRequestBody = pullRequests[0].body;
  } else {
    console.warn(
      `Found ${pullRequests.length} pull requests for commit ${commit.sha}, falling back to parsing commit message`,
    );

    // It should exactly match the pattern of changeset commit message, or else will abort.
    const expectedMessage = RegExp(EXPECTED_COMMIT_MESSAGE);
    if (!expectedMessage.test(commit.message)) {
      throw new Error(
        `Expected regex did not match commit message: ${commit.message}`,
      );
    }

    // Get the PR description from the commit message
    const prNumber = commit.message.match(expectedMessage).groups.prNumber;
    console.log(
      `Identified the changeset Pull request - https://github.com/backstage/backstage/pull/${prNumber}`,
    );

    const { data } = await octokit.pulls.get({
      owner: GH_OWNER,
      repo: GH_REPO,
      pull_number: prNumber,
    });

    pullRequestBody = data.body;
  }

  // Use the PR description to prepare for the release description
  const isChangesetRelease = commit.message.includes(CHANGESET_RELEASE_BRANCH);
  if (isChangesetRelease) {
    const lines = pullRequestBody.split('\n');
    return lines.slice(lines.indexOf('# Releases') + 1).join('\n');
  }

  return pullRequestBody;
}

// Create Release on GitHub.
async function createRelease(releaseDescription) {
  // Create draft release if BOOL_CREATE_RELEASE is undefined
  // Publish release if BOOL_CREATE_RELEASE is not undefined
  const boolCreateDraft = !BOOL_CREATE_RELEASE;

  const releaseResponse = await octokit.repos.createRelease({
    owner: GH_REPO,
    repo: GH_REPO,
    tag_name: TAG_NAME,
    name: TAG_NAME,
    body: releaseDescription,
    draft: boolCreateDraft,
    prerelease: Boolean(semver.prerelease(TAG_NAME)),
  });

  if (releaseResponse.status === 201) {
    if (boolCreateDraft) {
      console.log('Created draft release! Click Publish to notify users.');
    } else {
      console.log('Published release!');
    }
    console.log(releaseResponse.data.html_url);
  } else {
    console.error(releaseResponse);
    throw new Error('Something went wrong when creating the release.');
  }
}

async function main() {
  const commit = await getCommitUsingTagName(TAG_NAME);
  const releaseDescription = await getReleaseDescriptionFromCommit(commit);
  await createRelease(releaseDescription);
}

main().catch(error => {
  console.error(error.stack);
  process.exit(1);
});