detect if php installatin is required or not

Author: matthewbaggett

action.yml

@@ -25,7 +25,7 @@ runs:
     - uses: actions/checkout@v4
 
     - id: read-php-version
-      name: "Read PHP Version"
+      name: "Read PHP Version in Composer"
       shell: bash
       working-directory: ${{ inputs.working_directory }}
       run: |
@@ -48,7 +48,29 @@ runs:
         echo "No PHP version detected"
         exit 0;
 
+    - id: read-system-php-version
+      name: "Read System PHP Version"
+      shell: bash
+      if: ${{ steps.read-php-version.outputs.php_version == '' }}
+      run: |
+          php_version=$(php -v | head -n 1 | cut -d ' ' -f 2 | cut -d '.' -f 1,2)
+          echo "No composer.json detected, falling back to system PHP version $php_version"
+          echo "php_version=$php_version" >> $GITHUB_OUTPUT
+
+    - id: decide-php-version
+      name: "Decide PHP Version"
+      shell: bash
+      run: |
+        echo "Requested PHP Version: ${{ steps.read-php-version.outputs.php_version }}"
+        echo "System PHP Version: ${{ steps.read-system-php-version.outputs.php_version }}"
+        if [ "${{ steps.read-php-version.outputs.php_version }}" != "" ] && [ "${{ steps.read-php-version.outputs.php_version }}" != "${{ steps.read-system-php-version.outputs.php_version }}" ]; then
+          echo "Switching PHP version to ${{ steps.read-php-version.outputs.php_version }}"
+        else
+          echo "Keeping system PHP version ${{ steps.read-system-php-version.outputs.php_version }}"
+        fi
+
     - uses: shivammathur/setup-php@v2
+      if: ${{ steps.read-system-php-version.outputs.php_version != '' || steps.read-php-version.outputs.php_version != steps.read-system-php-version.outputs.php_version }}
       with:
         php-version: ${{ steps.read-php-version.outputs.php_version }}
         tools: ${{ inputs.php_tools }}