pipeline.yml

name: CI/CD Pipeline

# Workflow triggers
on:
  push:
    branches: [ "main" ]
  pull_request: 
    branches: [ "main" ]
  # Schedule pipeline to run monday midnight after sunday ends
  schedule:
    - cron: 0 0 * * MON
  # Enable manual runs of workflow
  workflow_dispatch:

# Workflow stages
jobs:      
  # Perform Lint Checks
  lint:
    name: Style and Lint Checks
    runs-on: ubuntu-latest
    defaults:
      run:
        working-directory: ./
    steps:
    - uses: actions/checkout@v4
    - name: Use Node.js 20.x
      uses: actions/setup-node@v4
      with:
        node-version: '20.x'
    - name: Install pnpm
      run: npm install -g pnpm
    - name: Install Dependencies
      run: pnpm install
    - name: Run lint script
      run: pnpm run lint

  # Run Unit Tests
  test:
    name: Unit Tests
    needs: lint
    runs-on: ubuntu-latest
    defaults:
      run:
        working-directory: ./
    steps:
    - uses: actions/checkout@v4
    - name: Use Node.js 20.x
      uses: actions/setup-node@v4
      with:
        node-version: 20.x
    - name: Install pnpm
      run: npm install -g pnpm
    - name: Install dependencies
      run: pnpm install
    - name: Run unit tests with jest
      run: pnpm run test

  # Build Application
  build:
    name: Build Application
    needs: test
    runs-on: ubuntu-latest
    defaults:
      run:
        working-directory: ./
    steps:
    - uses: actions/checkout@v4
    - name: Use Node.js 20.x
      uses: actions/setup-node@v4
      with:
        node-version: '20.x'
    - name: Install pnpm
      run: npm install -g pnpm
    - name: Install Dependencies
      run: pnpm install
    - name: Compile TypeScript into JavaScript
      run: pnpm run build

  # Detect if there were code changes on PR and push and save the result to:
  #   - File artifact
  #   - Environment variable (only available within the scope of this job, thus need artifact to pass to other jobs)
  detect-code-changes:
    name: Detect Code Changes
    if: github.event_name == 'push' || github.event_name == 'pull_request' 
    runs-on: ubuntu-latest
    needs: build
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0
      - name: Get changed files
        id: changed-files
        uses: tj-actions/changed-files@v41.1.1
      - name: Set CHANGED_FILES as environment variable
        env: 
          CHANGED_FILES: ${{ steps.changed-files.outputs.all_changed_files }}
        run: echo "CHANGED_FILES=${{ steps.changed-files.outputs.all_changed_files }}" >> $GITHUB_ENV
      - name: Check for non-Markdown and non-pipeline changes
        run: |
          NON_MD_PIPELINE_CHANGES=$(echo "$CHANGED_FILES" | grep -vE '(\.md$|\.github/workflows/)' || echo '')
          if [ -n "$NON_MD_PIPELINE_CHANGES" ]; then
            echo "true" > code_changes.txt
          else
            echo "false" > code_changes.txt
          fi
      - name: Upload code_changes.txt as an artifact
        uses: actions/upload-artifact@v4
        with:
          name: code-changes-artifact
          path: code_changes.txt

  # Verify new NPM version is updated during push and PR. 
  # Skips version number check step if there were code changes
  verify-npm-version:
    name: Verify Updated NPM version (if code changed)
    if: github.event_name == 'push' || github.event_name == 'pull_request'
    needs: detect-code-changes
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0 # Fetches all history for all branches and tags
      - name: Use Node.js
        uses: actions/setup-node@v4
        with:
          node-version: '20.x'
          registry-url: 'https://registry.npmjs.org/'
      - uses: actions/download-artifact@v4
        with:
          name: code-changes-artifact # get artifact containing whether there were code changes
      - name: Read Code Changes Flag From Artifact
        run: |
          echo "CODE_CHANGES=$(cat code_changes.txt)" >> $GITHUB_ENV
      - name: Install dependencies
        run: npm install
      - name: Check if version number is updated
        if: env.CODE_CHANGES == 'true' # only run verification if there were code changes
        id: check_version
        run: |
          LATEST_TAG=$(git describe --tags --abbrev=0)
          PACKAGE_VERSION=$(node -p "require('./package.json').version")
          if [ "$LATEST_TAG" = "v$PACKAGE_VERSION" ]; then
            echo "Version in package.json is already published. Exiting..."
            exit 1
          fi
          
  # Publish to NPM if the event was 'push'.
  # Runs the publish to NPM step only if there were code changes
  publish-npm:
    name: Publish to NPM (if code changed)
    if: github.event_name == 'push'
    needs: verify-npm-version
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0 # Fetches all history for all branches and tags
      - name: Use Node.js
        uses: actions/setup-node@v4
        with:
          node-version: '20.x'
          registry-url: 'https://registry.npmjs.org/'
      - uses: actions/download-artifact@v4
        with:
          name: code-changes-artifact # get artifact containing whether there were code changes
      - name: Read Code Changes Flag From Artifact
        run: |
          echo "CODE_CHANGES=$(cat code_changes.txt)" >> $GITHUB_ENV
      - name: Install dependencies
        run: npm install
      - name: Get package version number
        run: echo "PACKAGE_VERSION=$(node -p "require('./package.json').version")" >> $GITHUB_ENV
      - name: Publish to NPM
        if: env.CODE_CHANGES == 'true' && env.PACKAGE_VERSION
        run: npm publish
        env:
          NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}

  # Create Release on GitHub if the event was 'push'.
  # Runs the release step only if there were code changes
  release:
    name: Create Release (if code changed)
    if: github.event_name == 'push'
    needs: verify-npm-version
    runs-on: ubuntu-latest
    steps:
      - name: Checkout code
        uses: actions/checkout@v4
      - uses: actions/download-artifact@v4
        with:
          name: code-changes-artifact # get artifact containing whether there were code changes
      - name: Read Code Changes Flag From Artifact
        run: |
          echo "CODE_CHANGES=$(cat code_changes.txt)" >> $GITHUB_ENV
      - name: Extract version number
        run: echo "RELEASE_VERSION=$(jq -r .version package.json)" >> $GITHUB_ENV
      - name: Create Release
        if: env.CODE_CHANGES == 'true'
        uses: actions/create-release@v1
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        with:
          tag_name: ${{ env.RELEASE_VERSION }}
          release_name: Release ${{ env.RELEASE_VERSION }}
          draft: false
          prerelease: false