update-changelog.yml

name: "Update Changelog"

on:
  release:
    types:
      - published

permissions:
  id-token: write
  contents: write
  pull-requests: write

jobs:
  update-changelog:
    runs-on: ["ubuntu-latest"]
    steps:
      - name: Current Release
        id: current-release
        uses: actions/github-script@v6
        with:
          script: |
            const event = ${{ toJSON(github.event) }};

            const tag = event.release.tag_name;
            const body = event.release.body;

            console.log(`Current release tag: ${tag}`);
            console.log(`Current release body: ${body}`);

            core.setOutput('tag', tag);
            core.setOutput('body', Buffer.from(body).toString('base64'));

      - name: Previous Release
        id: previous-release
        uses: actions/github-script@v6
        with:
          script: |
            const releases = await github.rest.repos.listReleases({
                ...context.repo
            });

            const currentReleaseIndex = releases.data.findIndex(release => "${{ steps.current-release.outputs.tag }}" === context.payload.release.tag_name);

            const previousRelease = releases.data[currentReleaseIndex + 1];
            const tag = previousRelease.tag_name;

            console.log(`Previous release tag: ${tag}`);

            core.setOutput('tag', tag);

      - name: Checkout Current Release
        uses: actions/checkout@v3
        with:
          ref: "${{ steps.current-release.outputs.tag }}"
          path: current

      - name: Checkout Previous Release
        uses: actions/checkout@v3
        with:
          ref: "${{ steps.previous-release.outputs.tag }}"
          path: previous

      - name: Find Updated CHANGELOG.md files
        id: updated
        uses: actions/github-script@v6
        with:
          script: |
            const path = require('path');
            const fs = require('fs');
            const crypto = require('crypto');

            function findChangelogs(dir, fileList = []) {
              const files = fs.readdirSync(dir);

              files.forEach(file => {
                if (fs.statSync(path.join(dir, file)).isDirectory()) {
                  fileList = findChangelogs(path.join(dir, file), fileList);
                } else if (file === 'CHANGELOG.md') {
                  fileList.push(path.join(dir, file));
                }
              });

              return fileList;
            }

            function calculateHash(file) {
              const hash = crypto.createHash('md5');
              const fileContent = fs.readFileSync(file);

              hash.update(fileContent);

              return hash.digest('hex');
            }

            function trimPath(relativePath) {
              return relativePath
                .replace('modules/', '')
                .replace('/CHANGELOG.md', '');
            }

            const currentChangeLogFiles = findChangelogs('./current/modules');
            const components = [];

            for (let i = 0; i < currentChangeLogFiles.length; i++) {
              const currentReleaseFile = currentChangeLogFiles[i];
              const relativePath = currentReleaseFile.replace(/^current\//, '');
              const previousReleaseFile = `previous/${relativePath}`

              if (!fs.existsSync(previousReleaseFile)) {
                console.log(`New CHANGELOG.md found: ${relativePath}`);
                components.push(trimPath(relativePath));
                continue;
              }

              if (calculateHash(currentReleaseFile) !== calculateHash(previousReleaseFile)) {
                console.log(`CHANGELOG.md changed: ${relativePath}`);
                components.push(trimPath(relativePath));
              } else {
                console.log(`${relativePath} didn't change. Skipping ...`);
              }
            }

            core.setOutput('components', JSON.stringify(components));

      - name: Checkout
        uses: actions/checkout@v3

      - name: Generate Changelog
        uses: actions/github-script@v6
        with:
          script: |
            const fs = require('fs');

            const tag = "${{ steps.current-release.outputs.tag }}";
            let body = Buffer.from("${{ steps.current-release.outputs.body }}", 'base64').toString('utf-8');
            const updatedComponents = JSON.parse(`${{ steps.updated.outputs.components }}`);

            let affectedComponents = "";
            if (updatedComponents.length > 0) {
              affectedComponents += "\n\n";
              affectedComponents += "## Affected Components\n";

              for (let i = 0; i < updatedComponents.length; i++) {
                const relativePath = updatedComponents[i];
                affectedComponents += `- [${relativePath}](https://docs.cloudposse.com/components/library/aws/${relativePath}#changelog)\n`
              }

              affectedComponents += "\n\n";
            }

            const content = `\n## ${tag}\n\n${affectedComponents}\n\n${body}\n`

            console.log(content);

            const filePath = 'CHANGELOG.md'
            const fileContent = fs.readFileSync(filePath, 'utf-8');
            const lines = fileContent.split('\n');

            lines.splice(1, 0, content);

            const updatedContent = lines.join('\n');
            fs.writeFileSync(filePath, updatedContent, 'utf-8');

      - name: Create Pull Request
        uses: peter-evans/create-pull-request@v6
        with:
          title: 'Update Changelog for `${{ steps.current-release.outputs.tag }}`'
          body: 'Update Changelog for [`${{ steps.current-release.outputs.tag }}`](${{ github.event.release.html_url }})'
          base: main
          branch: "changelog/${{ steps.current-release.outputs.tag }}"
          delete-branch: "true"
          commit-message: "Update Changelog for ${{ steps.current-release.outputs.tag }}"
          labels: |
            no-release