ci(pr): implement release pr detection

Ref: #65
Signed-off-by: Philip Gerke <me@philipgerke.com>

Author: pgerke

.github/actions/detect-version-change/action.yml

@@ -0,0 +1,41 @@
+name: "Detect commitizen version change"
+description: "Checks if the 'version' key in .cz.json has changed compared to the previous commit."
+outputs:
+  version_changed:
+    description: "Boolean indicating if the version has changed"
+    value: ${{ steps.check.outputs.version_changed }}
+runs:
+  using: "composite"
+  steps:
+    - name: Checkout previous commit
+      uses: actions/checkout@v4
+      with:
+        fetch-depth: 2
+
+    - name: Extract version from previous commit
+      id: old_version
+      shell: bash
+      run: |
+        OLD_VERSION=$(git show HEAD^:package.json | jq -r '.version // "not_found"')
+        echo "OLD_VERSION=$OLD_VERSION" >> $GITHUB_ENV
+        echo "Previous version: $OLD_VERSION"
+
+    - name: Extract version from current commit
+      id: new_version
+      shell: bash
+      run: |
+        NEW_VERSION=$(jq -r '.version // "not_found"' package.json)
+        echo "NEW_VERSION=$NEW_VERSION" >> $GITHUB_ENV
+        echo "Current version: $NEW_VERSION"
+
+    - name: Compare versions
+      id: check
+      shell: bash
+      run: |
+        if [ "$OLD_VERSION" != "$NEW_VERSION" ]; then
+          echo "Version changed from $OLD_VERSION to $NEW_VERSION"
+          echo "version_changed=true" >> $GITHUB_OUTPUT
+        else
+          echo "No version change detected"
+          echo "version_changed=false" >> $GITHUB_OUTPUT
+        fi

.github/actions/get-version-and-changelog/action.yml

@@ -0,0 +1,35 @@
+name: "Get Version and Changelog"
+description: "Get the new version and changelog entry from commitizen"
+outputs:
+  version:
+    description: "The new version"
+    value: ${{ steps.version.outputs.version }}
+  changelog:
+    description: "The changelog entry for the new version"
+    value: ${{ steps.changelog.outputs.changelog }}
+runs:
+  using: "composite"
+  steps:
+    - name: Checkout code
+      uses: actions/checkout@v4
+      with:
+        fetch-depth: 0
+        fetch-tags: true
+    - name: Install Commitizen
+      shell: bash
+      run: pip install commitizen
+    - name: Get new version
+      shell: bash
+      id: version
+      run: |
+        cz version -p
+        echo "version=$(cz version -p)" >> $GITHUB_OUTPUT
+    - name: Extract Changelog Entry
+      shell: bash
+      id: changelog
+      run: |
+        {
+          echo "changelog<<EOF"
+          cz ch ${{ steps.version.outputs.version }} --dry-run
+          echo "EOF"
+        } >> "$GITHUB_OUTPUT"

.github/workflows/pr_release_check.yml

@@ -0,0 +1,56 @@
+name: PR Release Check
+
+on:
+  pull_request:
+    types: [opened, synchronize]
+
+jobs:
+  check_release_trigger:
+    name: Check if PR will trigger a Release
+    runs-on: ubuntu-latest
+    outputs:
+      version_changed: ${{ steps.detect_version_change.outputs.version_changed }}
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+      - name: Detect version change
+        id: detect_version_change
+        uses: ./.github/actions/detect-version-change
+
+  update_pr_comment:
+    name: Update PR Comment
+    runs-on: ubuntu-latest
+    needs: check_release_trigger
+    if: ${{ needs.check_release_trigger.outputs.version_changed }} == "true"
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+      - name: Add "release" label
+        uses: actions-ecosystem/action-add-labels@v1
+        with:
+          labels: release
+      - name: Get new version and changelog
+        id: extract_version
+        uses: ./.github/actions/get-version-and-changelog
+      - name: Find Comment
+        uses: peter-evans/find-comment@v3
+        id: fc
+        with:
+          issue-number: ${{ github.event.pull_request.number }}
+          comment-author: "github-actions[bot]"
+          body-includes: ✅ **This PR will trigger a new release upon merge!** 🚀
+      - name: Comment on PR if release will be triggered
+        uses: peter-evans/create-or-update-comment@v4
+        with:
+          comment-id: ${{ steps.fc.outputs.comment-id }}
+          issue-number: ${{ github.event.pull_request.number }}
+          body: |
+            ✅ **This PR will trigger a new release upon merge!** 🚀
+
+            ## 📢 Planned version: v${{ steps.extract_version.outputs.version }}
+
+            🔍 **Changelog for the new version:**
+            ```markdown
+            ${{ steps.extract_version.outputs.changelog }}
+            ```
+          edit-mode: replace