name: Fuzzing

# spell-checker:ignore (people) taiki-e
# spell-checker:ignore (misc) fuzzer uufuzz

env:
  CARGO_INCREMENTAL: "0"

on:
  push:
    branches: [ main, master ]
  pull_request:
    branches: [ main, master ]

permissions:
  contents: read # to fetch code (actions/checkout)

# End the current execution if there is a new changeset in the PR.
concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: ${{ github.ref != 'refs/heads/main' }}

jobs:
  uufuzz-examples:
    name: Build and test uufuzz examples
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v4
      with:
        persist-credentials: false
    - name: Install Rust
      uses: dtolnay/rust-toolchain@stable
    - name: Build uufuzz library
      run: |
        cd fuzz/uufuzz
        cargo build --release
    - name: Run uufuzz tests
      run: |
        cd fuzz/uufuzz
        cargo test --lib
    - name: Build and run uufuzz examples
      run: |
        cd fuzz/uufuzz
        echo "Building all examples..."
        cargo build --examples --release

        # Run all examples except integration_testing (which has FD issues in CI)
        for example in examples/*.rs; do
          example_name=$(basename "$example" .rs)
          if [ "$example_name" != "integration_testing" ]; then
            cargo run --example "$example_name" --release
          fi
        done

  fuzz-build:
    name: Build the fuzzers
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v4
      with:
        persist-credentials: false
    - name: Install Rust
      uses: dtolnay/rust-toolchain@stable
    - name: Install `cargo-fuzz`
      uses: taiki-e/install-action@v2
      with:
        tool: cargo-fuzz
    - name: Emulate a nightly toolchain
      run: |
        echo "RUSTC_BOOTSTRAP=1" >> "${GITHUB_ENV}"
    - name: Run `cargo-fuzz build`
      # Force the correct target
      # https://github.com/rust-fuzz/cargo-fuzz/issues/398
      run: cargo fuzz build --target $(rustc --print host-tuple)

  fuzz-run:
    needs: fuzz-build
    name: Fuzz
    runs-on: ubuntu-latest
    timeout-minutes: 5
    env:
      RUN_FOR: 60
    strategy:
      fail-fast: false
      matrix:
        test-target:
          # fuzz_grep is a differential fuzzer against GNU grep; it currently
          # surfaces compatibility differences, so it is not expected to pass yet.
          - { name: fuzz_grep, should_pass: false }

    steps:
    - uses: actions/checkout@v4
      with:
        persist-credentials: false
    - name: Install Rust
      uses: dtolnay/rust-toolchain@stable
    - name: Install `cargo-fuzz`
      uses: taiki-e/install-action@v2
      with:
        tool: cargo-fuzz
    - name: Emulate a nightly toolchain
      run: |
        echo "RUSTC_BOOTSTRAP=1" >> "${GITHUB_ENV}"
    - name: Run ${{ matrix.test-target.name }} for ${{ env.RUN_FOR }} seconds
      id: run_fuzzer
      shell: bash
      continue-on-error: ${{ !matrix.test-target.should_pass }}
      run: |
        mkdir -p fuzz/stats
        STATS_FILE="fuzz/stats/${{ matrix.test-target.name }}.txt"
        # Force the correct target
        # https://github.com/rust-fuzz/cargo-fuzz/issues/398
        cargo fuzz run --target $(rustc --print host-tuple) ${{ matrix.test-target.name }} -- -max_total_time=${{ env.RUN_FOR }} -timeout=${{ env.RUN_FOR }} -detect_leaks=0 -print_final_stats=1 2>&1 | tee "$STATS_FILE"

        # Save should_pass value for later inspection
        echo "${{ matrix.test-target.should_pass }}" > "fuzz/stats/${{ matrix.test-target.name }}.should_pass"

        # Print stats to job output for immediate visibility
        echo "----------------------------------------"
        echo "FUZZING STATISTICS FOR ${{ matrix.test-target.name }}"
        echo "----------------------------------------"
        echo "Runs:           $(grep -q "stat::number_of_executed_units" "$STATS_FILE" && grep "stat::number_of_executed_units" "$STATS_FILE" | awk '{print $2}' || echo "unknown")"
        echo "Execution Rate: $(grep -q "stat::average_exec_per_sec" "$STATS_FILE" && grep "stat::average_exec_per_sec" "$STATS_FILE" | awk '{print $2}' || echo "unknown") execs/sec"
        echo "New Units:      $(grep -q "stat::new_units_added" "$STATS_FILE" && grep "stat::new_units_added" "$STATS_FILE" | awk '{print $2}' || echo "unknown")"
        echo "Expected:       ${{ matrix.test-target.should_pass }}"
        if grep -q "SUMMARY: " "$STATS_FILE"; then
          echo "Status:         $(grep "SUMMARY: " "$STATS_FILE" | head -1)"
        else
          echo "Status:         Completed"
        fi
        echo "----------------------------------------"

        # Add summary to GitHub step summary
        echo "### Fuzzing Results for ${{ matrix.test-target.name }}" >> "$GITHUB_STEP_SUMMARY"
        echo "" >> "$GITHUB_STEP_SUMMARY"
        echo "| Metric | Value |" >> "$GITHUB_STEP_SUMMARY"
        echo "|--------|-------|" >> "$GITHUB_STEP_SUMMARY"
        if grep -q "stat::number_of_executed_units" "$STATS_FILE"; then
          echo "| Runs | $(grep "stat::number_of_executed_units" "$STATS_FILE" | awk '{print $2}') |" >> "$GITHUB_STEP_SUMMARY"
        fi
        if grep -q "stat::average_exec_per_sec" "$STATS_FILE"; then
          echo "| Execution Rate | $(grep "stat::average_exec_per_sec" "$STATS_FILE" | awk '{print $2}') execs/sec |" >> "$GITHUB_STEP_SUMMARY"
        fi
        if grep -q "stat::new_units_added" "$STATS_FILE"; then
          echo "| New Units | $(grep "stat::new_units_added" "$STATS_FILE" | awk '{print $2}') |" >> "$GITHUB_STEP_SUMMARY"
        fi
        echo "| Should pass | ${{ matrix.test-target.should_pass }} |" >> "$GITHUB_STEP_SUMMARY"
        if grep -q "SUMMARY: " "$STATS_FILE"; then
          echo "| Status | $(grep "SUMMARY: " "$STATS_FILE" | head -1) |" >> "$GITHUB_STEP_SUMMARY"
        else
          echo "| Status | Completed |" >> "$GITHUB_STEP_SUMMARY"
        fi
        echo "" >> "$GITHUB_STEP_SUMMARY"
    - name: Upload Stats
      if: always()
      uses: actions/upload-artifact@v4
      with:
        name: fuzz-stats-${{ matrix.test-target.name }}
        path: |
          fuzz/stats/${{ matrix.test-target.name }}.txt
          fuzz/stats/${{ matrix.test-target.name }}.should_pass
        retention-days: 5