name: CI

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

env:
  CARGO_TERM_COLOR: always
  RUSTFLAGS: "-D warnings"

jobs:
  check:
    name: Check
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: dtolnay/rust-toolchain@stable
      - uses: Swatinem/rust-cache@v2
      - run: cargo check --all-targets

  fmt:
    name: Format
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: dtolnay/rust-toolchain@stable
        with:
          components: rustfmt
      - run: cargo fmt --all -- --check

  clippy:
    name: Clippy
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: dtolnay/rust-toolchain@stable
        with:
          components: clippy
      - uses: Swatinem/rust-cache@v2
      - run: cargo clippy --all-targets -- -D warnings

  test:
    name: Test
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: dtolnay/rust-toolchain@stable
      - uses: Swatinem/rust-cache@v2
      - run: cargo test --all-targets

  examples:
    name: Build Examples
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: dtolnay/rust-toolchain@stable
      - uses: Swatinem/rust-cache@v2
      - run: cargo build --release
      - name: Verify committed ROMs match their .ne sources
        # Every example has a committed .nes file under examples/. The
        # compiler is deterministic (verified: same input → byte-identical
        # output), so rebuilding each example into a tmp directory and
        # diffing against the committed ROM catches "someone edited a .ne
        # file but forgot to regenerate the ROM" at PR time.
        run: |
          mkdir -p /tmp/reprotest
          fail=0
          for f in examples/*.ne; do
            name=$(basename "$f" .ne)
            ./target/release/nescript build "$f" --output "/tmp/reprotest/$name.nes"
            if ! cmp -s "examples/$name.nes" "/tmp/reprotest/$name.nes"; then
              echo "::error file=examples/$name.ne::committed examples/$name.nes is stale; rerun \`cargo run --release -- build examples/$name.ne\` and commit the new ROM"
              fail=1
            fi
          done
          if [ $fail -ne 0 ]; then
            exit 1
          fi
      - name: Verify ROMs are valid iNES
        run: |
          for f in examples/*.nes; do
            echo "==> Checking $f"
            # iNES magic: first 4 bytes must be "NES\x1a"
            header=$(od -A n -t x1 -N 4 "$f" | tr -d ' ')
            if [ "$header" != "4e45531a" ]; then
              echo "FAIL: $f is not a valid iNES ROM (header: $header)"
              exit 1
            fi
            size=$(stat -c%s "$f")
            echo "    OK: $size bytes"
          done

  emulator:
    name: Emulator Smoke Test
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: dtolnay/rust-toolchain@stable
      - uses: Swatinem/rust-cache@v2
      - uses: actions/setup-node@v4
        with:
          node-version: '22'
      - name: Install Chrome runtime deps for puppeteer
        # puppeteer ships its own Chrome for Testing binary via the
        # package's postinstall hook, but the runner image is missing
        # a handful of shared libs that Chrome needs to launch.
        run: |
          sudo apt-get update
          sudo apt-get install -y --no-install-recommends \
            libnss3 \
            libatk-bridge2.0-0 \
            libatk1.0-0 \
            libatspi2.0-0 \
            libcups2t64 \
            libdbus-1-3 \
            libdrm2 \
            libgbm1 \
            libpango-1.0-0 \
            libxcomposite1 \
            libxdamage1 \
            libxfixes3 \
            libxkbcommon0 \
            libxrandr2 \
            libasound2t64
      - name: Build compiler
        run: cargo build --release
      - name: Compile all .ne examples
        # Overwrites the committed examples/*.nes in the CI workspace
        # (the workspace is ephemeral; the committed ROMs aren't
        # touched). This is load-bearing: the goldens must be diffed
        # against what *this* compiler produces, not against the ROMs
        # an earlier commit happened to ship, otherwise a broken
        # compiler change can still pass the emulator job as long as
        # the contributor forgot to rebuild the ROMs. The `examples`
        # job catches that second case via its reproducibility diff.
        run: |
          for f in examples/*.ne; do
            echo "==> Compiling $f"
            ./target/release/nescript build "$f"
          done
      - name: Install emulator harness dependencies
        working-directory: tests/emulator
        run: npm ci
      - name: Diff each ROM's framebuffer against its golden
        working-directory: tests/emulator
        run: node run_examples.mjs
      - name: Verify docs/platformer.gif is up to date
        # The README embeds docs/platformer.gif as the project demo.
        # gifenc + jsnes are deterministic, so rebuilding the gif from
        # the current compiler should byte-match the committed copy.
        # If it doesn't, the contributor changed the compiler / source
        # / harness in a way that affects the observable gameplay of
        # platformer.ne but forgot to regenerate the gif — the fix is
        # the exact command printed in the error.
        working-directory: tests/emulator
        run: |
          node record_gif.mjs platformer 360 2 /tmp/platformer.gif
          if ! cmp -s ../../docs/platformer.gif /tmp/platformer.gif; then
            echo "::error file=docs/platformer.gif::committed docs/platformer.gif is stale; rerun \`node tests/emulator/record_gif.mjs platformer 360 2 docs/platformer.gif\` and commit the new gif"
            exit 1
          fi
      - name: Upload actual + diff PNGs on failure
        if: failure()
        uses: actions/upload-artifact@v4
        with:
          name: emulator-diff
          # `actual/` holds the run's output and red-highlighted diff
          # PNGs for any ROM that didn't match its golden. `report.json`
          # has the per-example pass/fail/diff counts. `goldens/` is
          # included too so reviewers can compare the three side by side
          # without cloning the repo.
          path: |
            tests/emulator/actual/
            tests/emulator/goldens/
            tests/emulator/report.json