name: build

on:
  push:
    branches: [main]
    tags: ['v*']
  pull_request:
    branches: [main]
  workflow_dispatch:

permissions:
  contents: write   # the release job attaches assets

env:
  ZLIB_VERSION: "1.3.1"

jobs:
  # ── Linux: x86_64 (native), x86/i686 (multilib), ARM64 & ARM32 (cross) ──────
  # zlib is built from source per target (static, PIC) so the artefacts are
  # self-contained and we avoid the multiarch apt dance. SDR++ core symbols are
  # resolved at load time (ELF --unresolved-symbols), so no SDR++ build is
  # needed — only its headers (fetched by scripts/fetch-sdrpp.sh).
  linux:
    runs-on: ubuntu-24.04
    strategy:
      fail-fast: false
      matrix:
        include:
          - target: linux-x86_64
            apt: ""
            toolchain: ""
            cflags: ""
          - target: linux-x86
            apt: "gcc-multilib g++-multilib"
            toolchain: ""
            cflags: "-m32"
          - target: linux-aarch64
            apt: "gcc-aarch64-linux-gnu g++-aarch64-linux-gnu"
            toolchain: "cmake/toolchains/linux-aarch64.cmake"
            # SDR++ headers pull in <fftw3.h>/<volk/*.h>; these are header-only
            # for us (never linked), so let the cross compiler find the amd64
            # copies at lowest priority without touching its own libc headers.
            cflags: "-idirafter /usr/include"
          - target: linux-armhf
            apt: "gcc-arm-linux-gnueabihf g++-arm-linux-gnueabihf"
            toolchain: "cmake/toolchains/linux-armhf.cmake"
            cflags: "-idirafter /usr/include"
    steps:
      - uses: actions/checkout@v4

      - name: Install build tools
        run: |
          sudo apt-get update
          # libfftw3-dev / libvolk-dev / libglfw3-dev / libzstd-dev supply the
          # (arch-independent) headers that SDR++ core headers include; we never
          # link them — sdrpp_core resolves at load time.
          sudo apt-get install -y --no-install-recommends \
            build-essential cmake ninja-build git curl ca-certificates \
            libfftw3-dev libvolk-dev libglfw3-dev libzstd-dev ${{ matrix.apt }}

      - name: Fetch SDR++ source (headers only)
        run: bash scripts/fetch-sdrpp.sh

      - name: Build zlib (static, PIC) for the target
        run: |
          set -eux
          curl -fsSL "https://github.com/madler/zlib/releases/download/v${ZLIB_VERSION}/zlib-${ZLIB_VERSION}.tar.gz" -o zlib.tar.gz
          tar xf zlib.tar.gz
          ZARGS=(-G Ninja -DCMAKE_BUILD_TYPE=Release
                 -DCMAKE_POSITION_INDEPENDENT_CODE=ON
                 -DCMAKE_INSTALL_PREFIX="$PWD/zinstall")
          if [ -n "${{ matrix.toolchain }}" ]; then
            ZARGS+=(-DCMAKE_TOOLCHAIN_FILE="$PWD/${{ matrix.toolchain }}")
          fi
          if [ -n "${{ matrix.cflags }}" ]; then
            ZARGS+=(-DCMAKE_C_FLAGS="${{ matrix.cflags }}")
          fi
          cmake -S "zlib-${ZLIB_VERSION}" -B zbuild "${ZARGS[@]}"
          cmake --build zbuild --target install

      - name: Configure
        run: |
          set -eux
          ARGS=(-G Ninja -DCMAKE_BUILD_TYPE=Release
                -DZLIB_LIBRARY="$PWD/zinstall/lib/libz.a"
                -DZLIB_INCLUDE_DIR="$PWD/zinstall/include")
          if [ -n "${{ matrix.toolchain }}" ]; then
            ARGS+=(-DCMAKE_TOOLCHAIN_FILE="$PWD/${{ matrix.toolchain }}")
          fi
          if [ -n "${{ matrix.cflags }}" ]; then
            ARGS+=(-DCMAKE_C_FLAGS="${{ matrix.cflags }}" -DCMAKE_CXX_FLAGS="${{ matrix.cflags }}")
          fi
          cmake -B build -S . "${ARGS[@]}"

      - name: Build
        run: cmake --build build -j

      - name: Collect artefact
        run: |
          set -eux
          mkdir -p dist
          cp build/j_alert_decoder.so "dist/j_alert_decoder-${{ matrix.target }}.so"
          file "dist/j_alert_decoder-${{ matrix.target }}.so"

      - uses: actions/upload-artifact@v4
        with:
          name: ${{ matrix.target }}
          path: dist/j_alert_decoder-${{ matrix.target }}.so
          if-no-files-found: error

  # ── Publish a GitHub Release with all binaries when a v* tag is pushed ──────
  release:
    needs: linux
    if: startsWith(github.ref, 'refs/tags/v')
    runs-on: ubuntu-24.04
    steps:
      - uses: actions/download-artifact@v4
        with:
          path: artifacts

      - name: List artefacts
        run: find artifacts -type f -name '*.so' -print

      - name: Publish release
        uses: softprops/action-gh-release@v2
        with:
          files: artifacts/**/*.so
          generate_release_notes: true
          fail_on_unmatched_files: true