name: Merge-Checker

on:
  pull_request:
    branches: ["**"]
    paths-ignore:
        - 'unit-tests/timing-results/**'

jobs:
  build_and_test:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout source code
        uses: actions/checkout@v3
        with:
          persist-credentials: true
          fetch-depth: 0

      - name: Install dependencies (CMake + Ninja + build tools)
        run: |
          sudo apt-get update
          sudo apt-get install -y cmake ninja-build build-essential time git

      - name: Configure project with CMake
        run: cmake -G Ninja -S . -B build/

      - name: Build with Ninja
        run: ninja -C build/

      - name: Run matrix-timing-tests with per-test timing output and save results
        run: |
          mkdir -p unit-tests/timing-results
          if [ -x build/unit-tests/matrix-timing-tests ]; then
            echo "Running matrix-timing-tests with timing"
            /usr/bin/time -v build/unit-tests/matrix-timing-tests -d yes &> unit-tests/timing-results/matrix-timing-tests.txt
            cat unit-tests/timing-results/matrix-timing-tests.txt
          else
            echo "matrix-timing-tests executable not found or not executable"
            exit 1
          fi
      - name: Compare timing results
        id: check_diff
        run: |
          # Ensure the previous version exists (from git)
          git show origin/${{ github.event.pull_request.head.ref }}:unit-tests/timing-results/matrix-timing-tests.txt > old.txt || echo "" > old.txt
          cp unit-tests/timing-results/matrix-timing-tests.txt new.txt

          echo "Comparing timing results..."

          CHANGED=0
          awk '
            BEGIN { change_threshold=0.1 }
            /^[0-9]+\.[0-9]+ s: / {
              new_time = $1
              label = substr($0, index($0, ":") + 2)
              if (label_times[label]) {
                old_time = label_times[label]
                delta = new_time - old_time
                if (delta < 0) delta = -delta
                if (delta >= change_threshold) {
                  changed = 1
                }
              } else {
                changed = 1
              }
            }
            FILENAME=="old.txt" && /^[0-9]+\.[0-9]+ s: / {
              label = substr($0, index($0, ":") + 2)
              label_times[label] = $1
            }
            END {
              exit changed == 1 ? 0 : 1
            }
          ' old.txt new.txt

      - name: Commit and push timing results
        if: steps.check_diff.outcome == 'success' && github.event.pull_request.head.repo.full_name == github.repository
        run: |
          git config --global user.name "ci-bot"
          git config --global user.email "ci-bot@local"

          BRANCH_NAME="${{ github.event.pull_request.head.ref }}"
          git stash
          echo "Checking out source branch $BRANCH_NAME"
          git fetch origin "$BRANCH_NAME"
          git checkout "$BRANCH_NAME"
          git pull

          echo "Checking if last commit was a timing update"
          LAST_COMMIT_MSG=$(git log -1 --pretty=%B)

          if echo "$LAST_COMMIT_MSG" | grep -q "Update matrix-timing-tests timings"; then
            echo "Last commit was a timing update, skipping commit."
            exit 0
          else
            echo "Last commit name was: $LAST_COMMIT_MSG"
            git stash pop
          fi

          git add unit-tests/timing-results/matrix-timing-tests.txt

          if git diff --quiet --cached; then
            echo "No changes to commit"
          else
            git commit -m "Update matrix-timing-tests timings [skip ci]"
            git push origin "$BRANCH_NAME"
          fi