class GoAT18 < Formula
  desc "Go programming environment (1.8)"
  homepage "https://golang.org"
  url "https://dl.google.com/go/go1.8.7.src.tar.gz"
  sha256 "5911e751807eebbc1980dad4305ef5492b96d6cd720bf93cbcefa86e1c195f9e"

  bottle do
    sha256 "966cd8372e51eac622c71c1c6dac4efc3b6525f7b6d175f8fb7f5e176a20f18d" => :mojave
    sha256 "733f30d527cce89faaddbc72687189dcc802d5c2a5bc31c4f2a43f00e0b61a61" => :high_sierra
    sha256 "692609a4bb340c24339ccab7d582be096324540fde4782e40340bd2965b71fbb" => :sierra
    sha256 "1537db5b5475f963a0818228ee8730c5dc80f360d54b598d242a6f974fc1ff5b" => :el_capitan
  end

  keg_only :versioned_formula

  depends_on :macos => :mountain_lion

  resource "gotools" do
    url "https://go.googlesource.com/tools.git",
        :branch => "release-branch.go1.8"
  end

  # Don't update this unless this version cannot bootstrap the new version.
  resource "gobootstrap" do
    url "https://storage.googleapis.com/golang/go1.7.darwin-amd64.tar.gz"
    version "1.7"
    sha256 "51d905e0b43b3d0ed41aaf23e19001ab4bc3f96c3ca134b48f7892485fc52961"
  end

  # Backports the following commit from 1.10/1.11:
  # https://github.com/golang/go/commit/1a92cdbfc10e0c66f2e015264a39159c055a5c15
  patch do
    url "https://github.com/Homebrew/formula-patches/raw/e089e057dbb8aff7d0dc36a6c1933c29dca9c77e/go%401.9/go_19_load_commands.patch"
    sha256 "771b67df44e3d5d5d7c01ea4a0d1693032bc880ea4f16cf82c1bacb42bfd9b10"
  end

  def install
    (buildpath/"gobootstrap").install resource("gobootstrap")
    ENV["GOROOT_BOOTSTRAP"] = buildpath/"gobootstrap"

    cd "src" do
      ENV["GOROOT_FINAL"] = libexec
      ENV["GOOS"]         = "darwin"
      system "./make.bash", "--no-clean"
    end

    (buildpath/"pkg/obj").rmtree
    rm_rf "gobootstrap" # Bootstrap not required beyond compile.
    libexec.install Dir["*"]
    bin.install_symlink Dir[libexec/"bin/go*"]

    system bin/"go", "install", "-race", "std"

    # Build and install godoc
    ENV.prepend_path "PATH", bin
    ENV["GOPATH"] = buildpath
    (buildpath/"src/golang.org/x/tools").install resource("gotools")
    cd "src/golang.org/x/tools/cmd/godoc/" do
      system "go", "build"
      (libexec/"bin").install "godoc"
    end
    bin.install_symlink libexec/"bin/godoc"
  end

  def caveats; <<~EOS
    A valid GOPATH is required to use the `go get` command.
    If $GOPATH is not specified, $HOME/go will be used by default:
      https://golang.org/doc/code.html#GOPATH

    You may wish to add the GOROOT-based install location to your PATH:
      export PATH=$PATH:#{opt_libexec}/bin
  EOS
  end

  test do
    (testpath/"hello.go").write <<~EOS
      package main

      import "fmt"

      func main() {
          fmt.Println("Hello World")
      }
    EOS
    # Run go fmt check for no errors then run the program.
    # This is a a bare minimum of go working as it uses fmt, build, and run.
    system bin/"go", "fmt", "hello.go"
    assert_equal "Hello World\n", shell_output("#{bin}/go run hello.go")

    # godoc was installed
    assert_predicate libexec/"bin/godoc", :exist?
    assert_predicate libexec/"bin/godoc", :executable?

    ENV["GOOS"] = "freebsd"
    system bin/"go", "build", "hello.go"
  end
end