# Copyright 2020 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/compiled_action.gni")
import("//build/fidl/toolchain.gni")

# Declares a Measure Tape.
#
# This target generates an HLCPP measuring tape for one or multiple target types.
#
# Parameters
#
#   fidls (required)
#     A list of GN depedencies. All those depedencies must be `fidl` targets.
#
#   target_type (required)
#     The fully qualified FIDL type for which to generate a measuring tape.
template("measure_tape") {
  assert(defined(invoker.fidls))
  assert(defined(invoker.target_type))

  # targets
  fidl_targets = invoker.fidls
  source_set_target_name = target_name
  config_target_name = "${target_name}_config"
  gen_target_name = "${target_name}_gen"

  out_cc = "${target_gen_dir}/measure_tape/hlcpp/${target_name}.cc"
  out_h = "${target_gen_dir}/measure_tape/hlcpp/${target_name}.h"

  # arguments for code generation tool
  gen_args = [
    "--target-type",
    invoker.target_type,
    "--out-cc",
    rebase_path(out_cc),
    "--out-h",
    rebase_path(out_h),
    "--h-include-path",
    "measure_tape/hlcpp/${target_name}.h",
  ]
  foreach(fidl, invoker.fidls) {
    fidl_target =
        get_label_info(fidl, "label_no_toolchain") + "($fidl_toolchain)"
    json_file = get_label_info(fidl_target, "target_gen_dir") + "/" +
                get_label_info(fidl_target, "name") + ".fidl.json"
    gen_args += [
      "--json",
      rebase_path(json_file, root_build_dir),
    ]
  }

  # source set configuration to support `#include <...>`
  config(config_target_name) {
    include_dirs = [ target_gen_dir ]
  }

  # source set consisting of the two generated files
  source_set(source_set_target_name) {
    forward_variables_from(invoker,
                           [
                             "defines",
                             "testonly",
                             "visibility",
                           ])
    sources = [
      out_cc,
      out_h,
    ]
    deps = [ ":$gen_target_name" ]
    public_deps = fidl_targets
    public_configs = [ ":$config_target_name" ]
  }

  # code generation
  compiled_action(gen_target_name) {
    tool = "//tools/fidl/measure-tape"

    args = gen_args
    outputs = [
      out_cc,
      out_h,
    ]
    deps = fidl_targets
    forward_variables_from(invoker, [ "testonly" ])
  }
}