diff-last-run.yml

name: Diff with last workflow run
on:
  workflow_call:
    inputs:
      CHECK_DIFF_LOCATIONS:
        type: string
        required: true
    outputs:
      CHANGES:
        description: "Whether the given directories have changed since the last successfull workflow run."
        value: ${{ jobs.diff.outputs.CHANGES }}

jobs:
  diff:
    runs-on: ubuntu-latest
    outputs:
      CHANGES: ${{ steps.git_changes.outputs.CHANGES }}
    steps:
      - name: Get last run commit SHA
        run: |
          LAST_RUN_SHA=$(curl --fail -s -S --request GET \
          --url https://api.github.com/repos/${{ github.repository }}/actions/runs?branch=${{ github.head_ref || github.ref_name }} \
          --header 'authorization: Bearer ${{ secrets.GITHUB_TOKEN }}' \
          | jq -r '.workflow_runs[] | select(.conclusion == "success") | .head_sha' | head -1)
          echo LAST_RUN_SHA=$LAST_RUN_SHA >> $GITHUB_ENV
        shell: bash

      - name: Checkout current version
        uses: actions/checkout@v4

      - name: Checkout last build
        uses: actions/checkout@v4
        with:
          ref: ${{ env.LAST_RUN_SHA }}

      - name: Check for changes
        id: git_changes
        run: |
          if git diff --exit-code ${{ env.LAST_RUN_SHA }} ${{ github.sha }} -- ${{ inputs.CHECK_DIFF_LOCATIONS }} .github/workflows/; then
            echo "CHANGES=false" >> $GITHUB_OUTPUT
          else
            echo "CHANGES=true" >> $GITHUB_OUTPUT
          fi
        shell: bash