# Copyright 2017 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import("//build/config/clang/clang.gni")
import("//build/config/sysroot.gni")
import("//build/host.gni")

declare_args() {
  #   gocache_dir
  #     Directory GOCACHE environment variable will be set to. This directory
  #     will have build and test results cached, and is safe to be written to
  #     concurrently. If overridden, this directory must be a full path.
  gocache_dir = rebase_path("$root_out_dir/.gocache")

  #   go_vet_enabled
  #     [bool] if false, go vet invocations are disabled for all builds.
  go_vet_enabled = false
}

# A template for an action that builds a Go binary. Users should instead use the
# go_binary or go_test rules.
#
# Parameters
#
#   gopackages (optional)
#     List of packages to build. Exactly one of gopackages or library must be
#     set.
#
#   library (optional)
#     Alternative to gopackages, a library GN label corresponding to the
#     package to build.
#
#   deps (optional)
#     List of labels representing go_library targets this target depends on.
#
#   non_go_deps (optional)
#     List of labels this target depends on that are not Go libraries.
#
#   skip_vet (optional)
#     Whether to skip running go vet for this target. This flag should _only_
#     be used for packages in the Go source tree itself that otherwise match
#     whitelist entries in go vet all. Go vet is only run if go_vet_enabled is
#     true.
#
#   test (optional, default: false)
#     Whether this target defines a test.
#
template("go_build") {
  forward_variables_from(invoker, [ "visibility" ])

  main_target_name = target_name

  output_name = target_name
  if (defined(invoker.output_name)) {
    output_name = invoker.output_name
  }
  output_path = "${root_out_dir}/${output_name}"

  use_strip = is_fuchsia
  if (use_strip) {
    unstripped_output_path = "${root_out_dir}/exe.unstripped/${output_name}"
  }

  action(main_target_name) {
    deps = []
    if (defined(invoker.non_go_deps)) {
      deps += invoker.non_go_deps
    }

    go_deps = []
    if (defined(invoker.deps)) {
      go_deps += invoker.deps
    }
    if (defined(invoker.library)) {
      # It's redundant to include the `library` label in `deps` because we'll add
      # it implicitly.
      assert(go_deps + [ invoker.library ] - [ invoker.library ] == go_deps,
             "library should not be listed in deps")

      go_deps += [ invoker.library ]
    }
    args = []

    # TODO(fxbug.dev/42136747): Delete `gopackages` in favor of `library`.
    if (defined(invoker.gopackages) == defined(invoker.library)) {
      assert(false, "Exactly one of gopackages or library must be set")
    } else if (defined(invoker.gopackages)) {
      gopackages = invoker.gopackages

      # Multi-package support was never implemented and is no longer planned as
      # `gopackages` is slated for deletion as part of https://fxbug.dev/42136747.
      assert(gopackages == [ gopackages[0] ],
             "gopackages only supports one package")
      foreach(gopackage, gopackages) {
        args += [
          "--package",
          gopackage,
        ]
      }
    } else if (defined(invoker.library)) {
      _gen_dir = get_label_info(invoker.library, "target_gen_dir")
      _name = get_label_info(invoker.library, "name")
      args += [
        "--library-metadata",
        rebase_path("${_gen_dir}/${_name}.go_deps", root_build_dir),
      ]
    }

    pool = "//build/go:pool($default_toolchain)"

    outputs = [ output_path ]

    if (use_strip) {
      outputs += [ unstripped_output_path ]
    }

    script = "//build/go/build.py"
    depfile = "${output_path}.d"

    sources = [ "//build/go/gen_library_metadata.py" ]

    godepfile = "//sysroot/golang/bin/godepfile"
    inputs = [ godepfile ]

    args += [
      "--godepfile",
      rebase_path(godepfile, "", root_build_dir),
      "--root-out-dir",
      rebase_path(root_out_dir, root_build_dir),
      "--depfile",
      rebase_path(depfile),
      "--current-cpu",
      current_cpu,
      "--current-os",
      current_os,
      "--binname",
      output_name,
      "--go-cache",
      gocache_dir,
      "--cc",
      rebase_path("$clang_prefix/clang", "", root_build_dir),
      "--cxx",
      rebase_path("$clang_prefix/clang++", "", root_build_dir),
      "--objcopy",
      rebase_path("$clang_prefix/llvm-objcopy", "", root_build_dir),
      "--sysroot",
      sysroot,
      "--target",
      clang_target,
    ]

    if (defined(invoker.skip_vet) && !invoker.skip_vet && go_vet_enabled) {
      args += [ "--vet" ]
    }

    if (is_fuchsia) {
      deps += [
        "//sdk/lib/fdio",
        "//third_party/go:go_runtime",
      ]

      args += [
        # GN provides no way to propagate include paths like this, so, this
        # is brittle.
        "--include-dir",
        rebase_path("//sdk/lib/fdio/include"),
        "--include-dir",
        rebase_path("//zircon/third_party/ulib/musl/include"),
        "--include-dir",
        rebase_path("//zircon/system/public"),
        "--include-dir",
        rebase_path("//zircon/system/ulib/zircon/include"),
        "--go-root",
        rebase_path("$host_tools_dir/goroot"),
      ]

      foreach(target, zircon_legacy_targets) {
        if (target.target_name == "zircon") {
          _libs = target.libs
          lib = _libs[0]
          assert(_libs == [ lib ])
          _libs = []
          args += [
            "--lib-dir",
            rebase_path(get_path_info("$zircon_root_build_dir/$lib", "dir")),
          ]
        }
      }

      # See //build/config/fuchsia:fdio_config.
      args += [
        "--lib-dir",
        rebase_path(get_label_info("//build/config/fuchsia:fdio_config",
                                   "target_gen_dir")),
      ]
    } else {
      args += [
        "--go-root",
        rebase_path("//sysroot/golang/"),
      ]
    }

    if (use_strip) {
      args += [
        "--unstripped-binname",
        rebase_path("${root_out_dir}/exe.unstripped/${output_name}",
                    root_build_dir),
      ]
    }

    # Add needed arguments for the buildidtool. We should add the stamp file
    # output by buildidtool to the list of outputs for this action but because
    # Ninja (and by consequence GN) limits us to one depfile where that depfile
    # has only one output and we need the depfile for other things we don't
    # list it as an output.
    args += [
      "--buildidtool",
      rebase_path("//sysroot/bin/buildidtool", root_build_dir),
      "--build-id-dir",
      ".build-id",
    ]

    if (defined(invoker.test) && invoker.test) {
      testonly = true
      args += [ "--is-test=true" ]
    }

    if (go_deps != []) {
      deps += go_deps
      args += [ "--go-dep-files" ]
      foreach(dep, go_deps) {
        gen_dir = get_label_info(dep, "target_gen_dir")
        name = get_label_info(dep, "name")
        args += [ rebase_path("$gen_dir/$name.go_deps") ]
      }
    }
  }
}