name: 'Verify compiler version meets the project minimum'
description: 'Compares the installed compiler against the version in linux-build-deps/minimum-${compiler}-version.txt and reports whether we need to install a newer version and whether that version is available in the distro repos.'
inputs:
  compiler:
    description: 'gcc or clang'
    required: true
  packageManager:
    description: 'apt, dnf, pacman, or zypper'
    required: true
outputs:
  needs_install:
    description: 'true if default version is below the minimum'
    value: ${{ steps.check.outputs.needs_install }}
  available_in_distro:
    description: 'true if compiler-${min} can be installed from the distro repos'
    value: ${{ steps.check.outputs.available_in_distro }}
  cc:
    description: 'resolved C compiler binary name to use downstream'
    value: ${{ steps.check.outputs.cc }}
  cxx:
    description: 'resolved C++ compiler binary name to use downstream'
    value: ${{ steps.check.outputs.cxx }}
  version:
    description: 'the minimum version read from linux-build-deps/minimum-${compiler}-version.txt'
    value: ${{ steps.check.outputs.version }}
runs:
  using: composite
  steps:
    - id: check
      shell: bash
      run: |
        get_min()           { cat "linux-build-deps/minimum-$1-version.txt"; }
        get_default_major() { "$1" --version 2>/dev/null | head -1 | grep -oE '[0-9]+' | head -1; }
        cxx_for()           { case "$1" in gcc) echo g++ ;; clang) echo clang++ ;; esac; }

        probe_distro() {
          local compiler="$1" min="$2" package_manager="$3"
          case "$package_manager" in
            apt)    apt-cache show "${compiler}-${min}" >/dev/null 2>&1 ;;
            dnf)    return 1 ;;  # Fedora ships a single gcc/clang version, no -N packages
            pacman) return 1 ;;  # Arch ships a single gcc/clang version, no -N packages
            zypper) zypper -n se -x "${compiler}${min}" 2>/dev/null | grep -q "${compiler}${min}" ;;
            *)      return 1 ;;
          esac
        }

        compiler='${{ inputs.compiler }}'
        package_manager='${{ inputs.packageManager }}'
        min=$(get_min "$compiler")
        default_major=$(get_default_major "$compiler")
        cc_base="$compiler"
        cxx_base=$(cxx_for "$compiler")

        if [ -n "$default_major" ] && [ "$default_major" -ge "$min" ]; then
          needs_install=false
          cc="$cc_base"; cxx="$cxx_base"
          available_in_distro=true
        else
          needs_install=true
          cc="$cc_base-$min"; cxx="$cxx_base-$min"
          probe_distro "$cc_base" "$min" "$package_manager" && available_in_distro=true || available_in_distro=false
        fi

        echo "compiler=$compiler  min=$min  default_major=${default_major:-NONE}"
        echo "needs_install=$needs_install  available_in_distro=$available_in_distro  cc=$cc  cxx=$cxx"
        {
          echo "needs_install=$needs_install"
          echo "available_in_distro=$available_in_distro"
          echo "cc=$cc"
          echo "cxx=$cxx"
          echo "version=$min"
        } >> "$GITHUB_OUTPUT"