action.yml

name: Universal package
description: Create universal Homebrew package which contains x86_64 and arm64

# Instead of using the default binary installed by Homebrew, we need to build our own because third-party libraries are
# statically linked in MacVim, and need to be built against MACOSX_DEPLOYMENT_TARGET to ensure the built binary will
# work on supported macOS versions. Another reason for building our own custom package is to build a unviersal binary
# that has both x86_64 and arm64 arch, as Homebrew's distributed bottles are thin binaries with only one arch.
#
# We still use Homebrew to manage the library because their formulas are up to date and have correct build instructions
# that will work. This way we don't have to manually configure, build, and update the package info.

inputs:
  formula:
    description: Formula name
    required: true
  contents:
    description: Path for contents in package's keg
    required: true
  gnuiconv:
    description: Use the Homebrew GNU libiconv instead of system one
    type: boolean
    required: false
runs:
  using: 'composite'
  steps:
    - name: Set up formula
      id: setup-formula
      shell: bash
      run: |
        echo '::group::Set up formula'
        set -o pipefail
        formula=${{ inputs.formula }}

        # Need to make sure we get the latest before patching. Otherwise Homebrew may later try to get the latest
        # version and stomp what we have here.
        brew update

        brew cat ${formula} >${formula}.rb

        if [[ "${{ inputs.gnuiconv }}" == "true" ]]; then
          # Modify formula to build using Homebrew libiconv. Usually just adding "depends_on" is enough, but since we
          # override "CC" to use vanilla system clang, we need to manually inject the compilation/link flags to specify
          # the locations.
          sed -i.bak '/^[[:blank:]]*def install$/i\'$'\n  depends_on "libiconv"\n' ${formula}.rb
          sed -i.bak '/^[[:blank:]]*def install$/a\'$'\n    ENV["CFLAGS"] += " -I'$(brew --prefix)$'/opt/libiconv/include"\n' ${formula}.rb
          sed -i.bak '/^[[:blank:]]*def install$/a\'$'\n    ENV["LDFLAGS"] += " -L'$(brew --prefix)$'/opt/libiconv/lib"\n' ${formula}.rb
        fi

        # Patch the official Homebrew formula to explicitly build for min deployment target and a universal binary. We
        # also need to explicitly use system Clang because Homebrew's bundled clang script tries to inject -march
        # compiler flags that will cause universal builds to fail as Clang does not like that.
        sed -i.bak '/^[[:blank:]]*def install$/a\'$'\n    ENV["MACOSX_DEPLOYMENT_TARGET"] = "'${MACOSX_DEPLOYMENT_TARGET}$'"\n' ${formula}.rb
        sed -i.bak '/^[[:blank:]]*def install$/a\'$'\n    ENV["CC"] = "/usr/bin/clang"\n' ${formula}.rb
        sed -i.bak '/^[[:blank:]]*def install$/a\'$'\n    ENV["CFLAGS"] = "-arch x86_64 -arch arm64"\n' ${formula}.rb
        sed -i.bak '/^[[:blank:]]*def install$/a\'$'\n    ENV["LDFLAGS"] = "-arch x86_64 -arch arm64"\n' ${formula}.rb

        # Homebrew requires formula files to be placed in taps and disallows
        # installing from raw paths, so we manually create a taps folder for a
        # 'macvim-dev/deps' tap.
        FORMULA_DIR="$(brew --repository)/Library/Taps/macvim-dev/homebrew-deps/Formula/"
        mkdir -p "$FORMULA_DIR"
        cp ${formula}.rb "$FORMULA_DIR"

        # Uninstall the already installed formula because we want to build our own
        brew uninstall --ignore-dependencies ${formula} || true

        # Extract Xcode version to serve as part of the key for caching
        xcode_version=$(xcodebuild -version | tail -1 | sed -E 's/Build version (.*)/\1/')
        echo "xcode_version=$xcode_version" >> $GITHUB_OUTPUT

        # Find Homebrew's install location which could be /usr/local or /opt/homebrew
        brew_prefix=$(brew --prefix)
        echo "brew_prefix=$brew_prefix" >> $GITHUB_OUTPUT

        echo '::endgroup::'

    - name: Restore keg cache
      id: cache-keg-restore
      uses: actions/cache/restore@v5
      with:
        path: ${{ steps.setup-formula.outputs.brew_prefix }}/Cellar/${{ inputs.formula }}
        key: ${{ inputs.formula }}-homebrew-cache-custom-unified-prefix${{ steps.setup-formula.outputs.brew_prefix }}-xcode${{ steps.setup-formula.outputs.xcode_version }}-${{ hashFiles(format('{0}.rb', inputs.formula)) }}

    - name: Install formula
      id: install-formula
      shell: bash
      run: |
        echo '::group::Install formula'
        formula=${{ inputs.formula }}

        # We don't want brew to go upgrade all our dependents for now. They are
        # time consuming and sometimes cause problems with the CI environment
        # where they fail to link in random binaries (e.g. Python's 2to3),
        # which cause brew install to return non-zero and fail the build.
        export HOMEBREW_NO_INSTALLED_DEPENDENTS_CHECK=1

        # This will be a no-op if formula was cached. We check if the package
        # exists first just to avoid an "already installed" warning.
        brew list ${formula} &>/dev/null || brew install --quiet --formula -s macvim-dev/deps/${formula}

        # If formula was cached, this step is necessary to relink it to brew prefix (e.g. /usr/local)
        # The "-f" is there to force link keg-only formulas. Homebrew doesn't provide a command to just link in the
        # optional /opt/homebrew/opt/... folders, so we have to resort to doing this.
        brew unlink ${formula} && brew link -f ${formula}
        echo '::endgroup::'

        echo '::group::Verify built version'
        contents=($(IFS=,; for x in ${{ inputs.contents }}; do echo ${x}; done))

        for content in "${contents[@]}"; do
          # Print out the archs and verify they are universal fat binary.
          lipo -info $(brew --prefix)/${content} | grep 'x86_64 arm64'

          # Make sure deployment target is correct. Later macOS versions have a different binary format (just search for
          # "minos") but for 10.13 we need to look for LC_VERSION_MIN_MACOSX.
          otool -l $(brew --prefix)/${content} | grep -A 2 LC_VERSION_MIN_MACOSX | tail -1 | grep "${MACOSX_DEPLOYMENT_TARGET}"
        done

        echo '::endgroup::'

    - name: Save keg cache
      id: cache-keg-save
      uses: actions/cache/save@v5
      # We always save the generated artifact even if the whole run
      # fails due to other issues. This helps debugging build
      # failure issues faster if the cache doesn't already exist as
      # we want subsequent runs to not have to re-generate this
      # artifact again.
      if: always() && steps.cache-keg-restore.outputs.cache-hit != 'true' && steps.install-formula.conclusion == 'success'
      with:
        path: ${{ steps.setup-formula.outputs.brew_prefix }}/Cellar/${{ inputs.formula }}
        key: ${{ steps.cache-keg-restore.outputs.cache-primary-key }}