# 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.

# A template for an action that builds a Go binary. Users should instead use the
# go_binary or go_test rules.
#
# Every go_build target with any go_dependencies declared has a new GOPATH
# constructed. The scopes contained within go_dependencies define symlinks that
# will be added to the GOPATH.
#
# Example:
# go_build("mypackage") {
#   gopackage = "fuchsia.googlesource.com/mypackage"
#   go_dependencies = [
#     {
#       package = "fuchsia.googlesource.com/mypackage"
#     },
#     {
#       source = "//third_party/golang/crypto"
#       package = "golang.org/x/crypto"
#     }
#   ]
# }
#
# The above go_dependencies declaration is most typical, it creates a GOPATH
# entry for "fuchsia.googlesource.com/mypackage" that points to the directory
# containing the caller BUILD.gn. If source is ever omitted, it is assumed to be
# the directory of the containing action.
#
# At miniumum there should be a go_dependencies declaration for the package to
# be built.

import("//build/toolchain/clang_toolchain.gni")

template("go_build") {
  assert(defined(invoker.gopackage),
         "gopackage must be defined for $target_name")

  action(target_name) {
    forward_variables_from(invoker, [ "deps" ])

    output_name = target_name
    if (defined(invoker.output_name)) {
      output_name = invoker.output_name
    }

    use_strip = is_fuchsia

    output_path = "${root_out_dir}/${output_name}"
    outputs = [
      output_path,
    ]

    if (use_strip) {
      unstripped_output_path = "${root_out_dir}/exe.unstripped/${output_name}"
      outputs += [ unstripped_output_path ]
    }

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

    go_dependencies = []
    if (defined(invoker.go_dependencies)) {
      # builds on this code path can be concurrent
      go_dependencies = invoker.go_dependencies
    } else {
      # only run one gobuild.py in parallel
      pool = "//build/go:go_pool"
    }

    args = [
      "--fuchsia-root",
      rebase_path("//."),
      "--root-out-dir",
      rebase_path(root_out_dir, root_build_dir),
      "--zircon-sysroot",
      rebase_path(zircon_sysroot),
      "--depfile",
      rebase_path(depfile),
      "--current-cpu",
      current_cpu,
      "--current-os",
      current_os,
      "--go-tool",
      rebase_path("//buildtools/go"),
      "--binname",
      output_name,
      "--toolchain-prefix",
      rebase_path(clang_prefix, "", root_build_dir),
    ]

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

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

    foreach(dep, go_dependencies) {
      if (!defined(dep.source)) {
        dep.source = "."
      }
      source = dep.source
      args += [
        "--go-dependency",
        dep.package + "=" + rebase_path(source),
      ]
    }

    args += [ invoker.gopackage ]

    if (!defined(deps)) {
      deps = []
    }

    deps += [ "//third_party/go:go_runtime" ]
  }
}