class R < Formula
  desc "Software environment for statistical computing"
  homepage "https://www.r-project.org/"
  url "https://cran.r-project.org/src/base/R-4/R-4.1.0.tar.gz"
  sha256 "e8e68959d7282ca147360fc9644ada9bd161bab781bab14d33b8999a95182781"
  license "GPL-2.0-or-later"

  livecheck do
    url "https://cran.rstudio.com/banner.shtml"
    regex(%r{href=(?:["']?|.*?/)R[._-]v?(\d+(?:\.\d+)+)\.t}i)
  end

  bottle do
    sha256 arm64_big_sur: "bb731e6ec573c08d37da048a4a69411177b58f9d7ad4f340728fcef2e4c3c06e"
    sha256 big_sur:       "4803c5d4e8888494d62c078b658174a23815efbef798c307f565431fe52eed12"
    sha256 catalina:      "452a71839e33b5f1868845f54953ddcecfaca5c1cb61e58290130d9b3d9abda1"
    sha256 mojave:        "cf4d202d1bfd57554ab37830308517045f7841d7061957cf7555600b57917928"
  end

  depends_on "pkg-config" => :build
  depends_on "gcc" # for gfortran
  depends_on "gettext"
  depends_on "jpeg"
  depends_on "libpng"
  depends_on "openblas"
  depends_on "pcre2"
  depends_on "readline"
  depends_on "tcl-tk"
  depends_on "xz"

  # needed to preserve executable permissions on files without shebangs
  skip_clean "lib/R/bin", "lib/R/doc"

  def install
    # BLAS detection fails with Xcode 12 due to missing prototype
    # https://bugs.r-project.org/bugzilla/show_bug.cgi?id=18024
    ENV.append "CFLAGS", "-Wno-implicit-function-declaration"

    args = [
      "--prefix=#{prefix}",
      "--enable-memory-profiling",
      "--without-cairo",
      "--without-x",
      "--with-tcl-config=#{Formula["tcl-tk"].opt_lib}/tclConfig.sh",
      "--with-tk-config=#{Formula["tcl-tk"].opt_lib}/tkConfig.sh",
      "--with-aqua",
      "--with-blas=-L#{Formula["openblas"].opt_lib} -lopenblas",
      "--enable-R-shlib",
      "--disable-java",
    ]

    # Help CRAN packages find gettext and readline
    ["gettext", "readline", "xz"].each do |f|
      ENV.append "CPPFLAGS", "-I#{Formula[f].opt_include}"
      ENV.append "LDFLAGS", "-L#{Formula[f].opt_lib}"
    end

    system "./configure", *args
    system "make"
    ENV.deparallelize do
      system "make", "install"
    end

    cd "src/nmath/standalone" do
      system "make"
      ENV.deparallelize do
        system "make", "install"
      end
    end

    r_home = lib/"R"

    # make Homebrew packages discoverable for R CMD INSTALL
    inreplace r_home/"etc/Makeconf" do |s|
      s.gsub!(/^CPPFLAGS =.*/, "\\0 -I#{HOMEBREW_PREFIX}/include")
      s.gsub!(/^LDFLAGS =.*/, "\\0 -L#{HOMEBREW_PREFIX}/lib")
      s.gsub!(/.LDFLAGS =.*/, "\\0 $(LDFLAGS)")
    end

    include.install_symlink Dir[r_home/"include/*"]
    lib.install_symlink Dir[r_home/"lib/*"]

    # avoid triggering mandatory rebuilds of r when gcc is upgraded
    inreplace lib/"R/etc/Makeconf", Formula["gcc"].prefix.realpath,
                                    Formula["gcc"].opt_prefix
  end

  def post_install
    short_version =
      `#{bin}/Rscript -e 'cat(as.character(getRversion()[1,1:2]))'`.strip
    site_library = HOMEBREW_PREFIX/"lib/R/#{short_version}/site-library"
    site_library.mkpath
    ln_s site_library, lib/"R/site-library"
  end

  test do
    assert_equal "[1] 2", shell_output("#{bin}/Rscript -e 'print(1+1)'").chomp
    assert_equal ".dylib", shell_output("#{bin}/R CMD config DYLIB_EXT").chomp
    assert_equal "[1] \"aqua\"",
                 shell_output("#{bin}/Rscript -e 'library(tcltk)' -e 'tclvalue(.Tcl(\"tk windowingsystem\"))'").chomp

    system bin/"Rscript", "-e", "install.packages('gss', '.', 'https://cloud.r-project.org')"
    assert_predicate testpath/"gss/libs/gss.so", :exist?,
                     "Failed to install gss package"
  end
end