name: Android

on: [push, pull_request]

jobs:
  build-android:
    name: NDK-${{matrix.abi}}-${{matrix.build_type}}-${{matrix.lib}}
    runs-on: ${{matrix.os}}
    defaults:
      run:
        shell: bash -e -o pipefail {0}
    env:
      CCACHE_DIR: ${{github.workspace}}/ccache
      CMAKE_GENERATOR: Ninja
      DEBIAN_FRONTEND: noninteractive
    strategy:
      fail-fast: true
      matrix:
        os:
          - ubuntu-20.04
        abi:
          - arm64-v8a
          - armeabi-v7a
          - x86
          - x86_64
        build_type:
          - Release
        lib:
          - shared
          - static
        android_api_level:
          - '28'

    steps:
      - name: Setup Dependencies
        run: |
          sudo apt-get update
          sudo apt-get install -y \
            ccache \
            git \
            ninja-build

      - uses: actions/checkout@v4
        with:
          submodules: recursive

      # Ensure the declared NDK version is always installed even if it's removed
      # from the virtual environment.
      - name: Setup NDK
        env:
          ANDROID_NDK_VERSION: 27.2.12479018
          ANDROID_SDK_ROOT: /usr/local/lib/android/sdk
        run: |
          echo 'y' | ${{env.ANDROID_SDK_ROOT}}/cmdline-tools/latest/bin/sdkmanager --install 'ndk;${{env.ANDROID_NDK_VERSION}}'
          echo "ANDROID_NDK_ROOT=${{env.ANDROID_SDK_ROOT}}/ndk/${{env.ANDROID_NDK_VERSION}}" >> $GITHUB_ENV

      - name: Cache Eigen
        id: cache-eigen
        uses: actions/cache@v4
        with:
          path: eigen/
          key: NDK-${{matrix.os}}-eigen-3.4.0-${{matrix.abi}}

      - name: Download Eigen
        if: steps.cache-eigen.outputs.cache-hit != 'true'
        run: |
          wget https://gitlab.com/libeigen/eigen/-/archive/3.4.0/eigen-3.4.0.zip
          unzip eigen-3.4.0.zip

      - name: Setup Eigen
        if: steps.cache-eigen.outputs.cache-hit != 'true'
        run: |
          cmake -S eigen-3.4.0 -B build-eigen \
                -DBUILD_TESTING=OFF \
                -DCMAKE_ANDROID_API=${{matrix.android_api_level}} \
                -DCMAKE_ANDROID_ARCH_ABI=${{matrix.abi}} \
                -DCMAKE_ANDROID_STL_TYPE=c++_shared \
                -DCMAKE_Fortran_COMPILER= \
                -DCMAKE_INSTALL_PREFIX=${{github.workspace}}/eigen \
                -DCMAKE_SYSTEM_NAME=Android \
                -DEIGEN_BUILD_DOC=OFF
          cmake --build build-eigen \
                --config ${{matrix.build_type}} \
                --target install

      - name: Cache Build
        id: cache-build
        uses: actions/cache@v4
        with:
          path: ${{env.CCACHE_DIR}}
          key: NDK-${{matrix.os}}-ccache-${{matrix.abi}}-${{matrix.build_type}}-${{matrix.lib}}-${{github.run_id}}
          restore-keys: NDK-${{matrix.os}}-ccache-${{matrix.abi}}-${{matrix.build_type}}-${{matrix.lib}}-

      - name: Setup Environment
        if: matrix.build_type == 'Release'
        run: |
          echo 'CXXFLAGS=-flto' >> $GITHUB_ENV

      - name: Configure
        run: |
          cmake -S . -B build_${{matrix.abi}} \
                -DBUILD_SHARED_LIBS=${{matrix.lib == 'shared'}} \
                -DCMAKE_ANDROID_API=${{matrix.android_api_level}} \
                -DCMAKE_ANDROID_ARCH_ABI=${{matrix.abi}} \
                -DCMAKE_ANDROID_STL_TYPE=c++_shared \
                -DCMAKE_BUILD_TYPE=${{matrix.build_type}} \
                -DCMAKE_C_COMPILER_LAUNCHER=$(which ccache) \
                -DCMAKE_CXX_COMPILER_LAUNCHER=$(which ccache) \
                -DCMAKE_FIND_ROOT_PATH="${{github.workspace}}/eigen" \
                -DCMAKE_SYSTEM_NAME=Android

      - name: Build
        run: |
          cmake --build build_${{matrix.abi}} \
                --config ${{matrix.build_type}}