build/bazel/export_fuchsia_package_to_bazel.gni

# Copyright 2022 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/bazel/bazel_inputs.gni")
import("//build/components/fuchsia_package_archive.gni")
import("//build/packages/prebuilt_package.gni")

# Exports a fuchsia package built via GN to be used within
# the Bazel build graph as bazel_input_resource with a .far resource.
#
# Usage:
#
# 1. Wrap an existing GN fuchsia_package rule with:
# ```
# fuchsia_package("foo") {
#   ...
# }
#
# export_fuchsia_package_to_bazel("foo_for_bazel") {
#   package = ":foo"
# }
# ```
# 2. On the Bazel side, the .far file should be loaded using:
#    ```
#    fuchsia_prebuilt_package(
#      name = "foo",
#      archive = "@gn_targets//{gn_dir}:foo.archive"
#    )
#    ```
#    Where {gn_dir} matches the target's definition's directory.
#
# Parameters
#
#   package (required)
#     A 'fuchsia_package' target label.
#
#   package_name (optional)
#     The name to overwrite the underlying fuchsia_package target name.
#     Default is the name of the 'package' label.
#
#   gn_targets_name (optional)
#      Which target name to use in the @gn_targets repository for
#      this package. Default is package_name.
#
#   deps (optional)
#   testonly (optional)
#   visibility (optional)
#     Usual GN meanings.
#
template("export_fuchsia_package_to_bazel") {
  assert(defined(invoker.package), "Must specify package.")

  targets = {
    package_name = get_label_info(invoker.package, "name")
    if (defined(invoker.package_name)) {
      package_name = invoker.package_name
    }
    archive_label = "${target_name}.archive"
  }

  files = {
    bazel_output = "${targets.package_name}.far"
  }

  fuchsia_package_archive(targets.archive_label) {
    forward_variables_from(invoker,
                           [
                             "deps",
                             "testonly",
                             "visibility",
                             "applicable_licenses",
                           ])
    package = invoker.package
  }

  bazel_input_resource(target_name) {
    forward_variables_from(invoker,
                           [
                             "gn_target_names",
                             "deps",
                             "testonly",
                             "visibility",
                             "applicable_licenses",
                           ])
    deps = [ ":${targets.archive_label}" ]
    sources = get_target_outputs(":${targets.archive_label}")
    outputs = [ files.bazel_output ]

    if (!defined(gn_targets_name)) {
      gn_targets_name = targets.package_name
    }
  }
}