name: Fuzz

on:
  push:
    branches: [main]
  schedule:
    - cron: '0 3 * * *'
  workflow_dispatch:
    inputs:
      duration:
        description: 'Seconds per fuzz target'
        required: false
        default: '300'

concurrency:
  group: fuzz-${{ github.ref }}
  cancel-in-progress: true

jobs:
  fuzz:
    name: Fuzz (${{ matrix.target }})
    runs-on: ubuntu-latest
    strategy:
      fail-fast: false
      matrix:
        target:
          - decode_comprehensive
          - decode_image
    steps:
      - uses: actions/checkout@v6
      - uses: dtolnay/rust-toolchain@nightly
      - uses: Swatinem/rust-cache@v2
        with:
          key: fuzz-${{ matrix.target }}
          cache-directories: fuzz/target

      - name: Install cargo-fuzz
        run: cargo install cargo-fuzz --locked

      - name: Determine duration
        id: duration
        run: |
          if [ "${{ github.event_name }}" = "schedule" ]; then
            echo "seconds=300" >> "$GITHUB_OUTPUT"
          elif [ "${{ github.event_name }}" = "workflow_dispatch" ]; then
            echo "seconds=${{ github.event.inputs.duration || '300' }}" >> "$GITHUB_OUTPUT"
          else
            echo "seconds=60" >> "$GITHUB_OUTPUT"
          fi

      - name: Seed corpus
        run: |
          mkdir -p fuzz/corpus/${{ matrix.target }}
          cp fuzz/regression/* fuzz/corpus/${{ matrix.target }}/ 2>/dev/null || true
          cp fuzz/seed_corpus/${{ matrix.target }}/* fuzz/corpus/${{ matrix.target }}/ 2>/dev/null || true

      - name: Fuzz ${{ matrix.target }}
        run: |
          cargo +nightly fuzz run ${{ matrix.target }} \
            -- -max_total_time=${{ steps.duration.outputs.seconds }} \
               -dict=fuzz/tiff.dict \
               -rss_limit_mb=2048

      - name: Upload crashes
        if: failure()
        uses: actions/upload-artifact@v4
        with:
          name: fuzz-crashes-${{ matrix.target }}
          path: fuzz/artifacts/
          retention-days: 30

  regression:
    name: Fuzz regression
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v6
      - uses: dtolnay/rust-toolchain@stable
      - uses: Swatinem/rust-cache@v2
      - name: Build
        run: cargo build
      - name: Regression seeds
        run: |
          if [ -d fuzz/regression ] && [ "$(ls fuzz/regression/ 2>/dev/null | wc -l)" -gt 0 ]; then
            cargo test --test fuzz_regression 2>/dev/null || echo "No regression test found — seeds exist but no test harness"
          fi