build/intl/intl_strings.gni

# 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/fidl.gni")
import("//build/fidl/fidl_library.gni")

# Generates localized assets from source localized strings.
#
# Please see `//src/intl/example/BUILD.gn` for example use of the target.
#
# Example instantiation:
#
# ```
# import("//build/intl/strings.gni")
# intl_strings("foo") {
#   source = "strings.xml"
#   source_locale = "en"
#   output_locales = ["en", "fr", "es"]
#   library = "fuchsia.intl.l10n"
# }
# ```
#
# Inputs:
#
# - Needs an input XML file (by convention named `strings.xml`), in the Android
# strings resource format to represent the source externalized strings.
#
# - Needs, for each supported language `foo`, an input XML file (by convention
# named `strings_foo.xml`) which contains equivalent messages to those in
# `strings.xml`.  The source language is not special, so for example if your
# `strings.xml` contains English strings, you still need `strings_en.xml`.
#
# Outputs:
#
# - An includable source file (language-dependent!) with generated constants
# that refer to all messages in the `strings.xml` file.
#
# - A set of files named "$target_gen_dir/lang/foo.json" for every `lang`,
# which maps the string IDs to messages in the appropriate language.  See
# `//src/intl/example/BUILD.gn` for an example of how to bundle these files into
# a Fuchsia package.
#
# Parameters:
#
#   library: (required string), a dot-separated library name to be
#     used for the generated code.  For example, in C++, the generated constants
#     will be wrapped into a nested namespace `fuchsia::intl::l10n` in the
#     example above.
#
#   source: (required string), the source XML file containing
#     Android-compatible externalized strings.
#
#   source_locale: (optional string, default "en-US"), the source locale that
#     the file specified under `source` is written in.  This is used for
#     bookkeeping only, the source locale is otherwise not special in any way.
#
#   output_locales: (required list of strings), the list of locales for which
#     to generate the localized assets.  By convention, if the `source` is
#     `strings.xml`, then a localized asset for language `foo` needs a source
#     file named `strings_foo.xml`.
#
template("intl_strings") {
  # Best practices forward.
  forward_variables_from(invoker,
                         [
                           "testonly",
                           "visibility",
                           "library",
                           "source",
                           "output_locales",
                         ])

  assert(defined(library), "Parameter library=... is required")

  assert(defined(source), "Parameter source=... is required")

  source_locale = "en-US"
  if (defined(invoker.source_locale)) {
    source_locale = invoker.source_locale
  }

  assert(defined(output_locales), "Parameter output_locales=[...] is required")

  base_name = invoker.target_name
  target_name = invoker.target_name
  base_source = get_path_info(source, "name")

  # Every target we generate in this template needs to be added here, so it
  # could become a dependency of the final generated group target.
  group_deps = []

  # Generate a JSON file for each locale.  Collect all files into a group.
  manifest_resources = []
  locale_resources = []
  foreach(locale, output_locales) {
    target_strings_file = "${base_source}_${locale}.xml"
    output_file_name = "${target_gen_dir}/${locale}/${base_name}.json"
    locale_resources += [
      {
        foo = rebase_path(output_file_name, root_build_dir)
        dest = "assets/locales/${locale}/${base_name}.json"
        path = rebase_path(output_file_name)
      },
    ]

    # TODO(fmil): This is an experiment with manifest file.
    manifest_source_path = rebase_path(output_file_name, root_build_dir)
    manifest_target_path = "assets/locales/${locale}/${base_name}.json"
    manifest_resources += [ "${manifest_target_path}=${manifest_source_path}" ]

    compiled_action_name = "${base_name}_to_json_${locale}"
    group_deps += [ ":${compiled_action_name}" ]

    compiled_action(compiled_action_name) {
      tool = "//src/intl/strings_to_json:strings_to_json_bin"
      tool_output_name = "strings_to_json"

      sources = [ source ]

      outputs = [ output_file_name ]

      args = [
        "--source-locale",
        source_locale,
        "--source-strings-file",
        rebase_path(source, root_build_dir),
        "--target-locale",
        locale,
        "--target-strings-file",
        rebase_path(target_strings_file, root_build_dir),
        "--output",
        rebase_path(output_file_name, root_build_dir),
      ]
    }
  }  # for_each

  strings_to_fidl_name = "${target_name}_fidl"
  generated_fidl_file_name = "${target_gen_dir}/${base_source}.fidl"

  manifest_file = "${target_gen_dir}/${base_name}.manifest"
  write_file(manifest_file, manifest_resources)

  group("${base_name}_l10n_assets_group") {
    metadata = {
      resources = locale_resources
      manifest = manifest_resources
    }
  }

  group_deps += [ ":${base_name}_l10n_assets" ]
  generated_file("${base_name}_l10n_assets") {
    deps = [ ":${base_name}_l10n_assets_group" ]
    outputs = [ "${target_gen_dir}/${base_name}_l10n_assets.json" ]
    data_keys = [ "resources" ]
    output_conversion = "json"
  }

  if (current_toolchain == fidl_toolchain) {
    # Generates a FIDL file with all the strings constants defined.
    # It is only ran in the FIDL toolchain because we want to run this
    # conversion only once.
    compiled_action(strings_to_fidl_name) {
      tool = "//src/intl/strings_to_fidl:strings_to_fidl_bin"
      tool_output_name = "strings_to_fidl"

      sources = [ source ]

      outputs = [ generated_fidl_file_name ]

      args = [
        "--input",
        rebase_path(source, root_build_dir),
        "--output",
        rebase_path(generated_fidl_file_name, root_build_dir),
        "--library",
        library,
      ]
    }  # compiled_action

    # Generates the FIDL library based on the generated FIDL file from the
    # above target.  This invocation is special because it needs to depend
    # on a non-fidl library.  It must be a special invocation because all
    # FIDL invocations in different toolchain assume that the dependencies
    # have FIDL subtargets.
    fidl(library) {
      sources = [ generated_fidl_file_name ]
      non_fidl_deps = [ ":${strings_to_fidl_name}" ]

      # Since we use FIDL as intermediate representation and nobody will read
      # it, we don't need to lint.
      should_lint = false
    }
  } else {
    # The non-FIDL toolchain FIDL libraries are built normally; except based
    # off of the generated FIDL file.
    fidl(library) {
      sources = [ generated_fidl_file_name ]
    }
  }

  # This group target has the same name as the template invoker, and contains
  # all generated targets as its deps, so that all the deps are executed when
  # the template is expanded.
  group_deps += [
    ":${library}",
    ":${strings_to_fidl_name}($fidl_toolchain)",
  ]
  group(target_name) {
    public_deps = group_deps
  }
}