# 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.

# Generate a list of package metadata exported from all packages in the
# transitive closure of declared dependencies.
#
# Parameters
#
#   data_keys (required)
#     [list of strings] A list of package target metadata keys to collect into a
#     list. See gn help for data_keys for more information.
#
#     Well known package metadata:
#
#       package_names
#
#       snapshot_entries
#         The snapshot entries are consumed for the production of the snapshots
#         that feed into `fx delta` for version to version OTA size computations.
#
#       blob_manifests
#         The blob manifests are aggregated by the image build process to produce
#         manifests to publish to repositories and to produce manifests to write
#         into blobfs images.
#
#       meta_far_merkle_index_entries
#         The metafar merkle index entries are aggregated in image builds to
#         produce package server indices for base serving.
#
#       package_output_manifests
#         The path of each output manifest for each package.
#
#       package_barrier
#         Metadata barrier.
#
#   data_deps (optional)
#   data_keys (optional)
#   deps (optional)
#   output_conversion (optional)
#   outputs (optional)
#   public_deps (optional)
#   rebase (optional)
#   testonly (optional)
#   visibility (optional)
#     Same as for any GN `generated_file()` target.
template("generate_package_metadata") {
  generated_file(target_name) {
    forward_variables_from(invoker,
                           [
                             "data_deps",
                             "data_keys",
                             "deps",
                             "output_conversion",
                             "outputs",
                             "public_deps",
                             "rebase",
                             "testonly",
                             "visibility",
                           ])

    if (!defined(outputs)) {
      outputs = [ target_gen_dir + "/" + target_name ]
    }

    walk_keys = [ "package_barrier" ]
  }
}

# Defines package metadata.
#
# This metadata is collected by `generate_package_metadata`.
# The caller should add a dep on the given target name for the metadata to take effect.
#
# Parameters (see `generate_package_metadata` for full definitions)
#
#   package_name (required)
#   snapshot_entry (required)
#   blob_manifest (required)
#   meta_far_merkle_index_entry (required)
#   package_output_manifest (required)
#   testonly (optional)
#   visibility (optional)
template("define_package_metadata") {
  assert(defined(invoker.package_name), "Missing package_name")
  assert(defined(invoker.snapshot_entry), "Missing snapshot_entry")
  assert(defined(invoker.blob_manifest), "Missing blob_manifest")
  assert(defined(invoker.meta_far_merkle_index_entry),
         "Missing meta_far_merkle_index_entry")
  assert(defined(invoker.package_output_manifest),
         "Missing package_output_manifest")

  group(target_name) {
    forward_variables_from(invoker,
                           [
                             "testonly",
                             "visibility",
                           ])
    metadata = {
      package_names = [ invoker.package_name ]
      snapshot_entries = [ invoker.snapshot_entry ]
      blob_manifests = [ rebase_path(invoker.blob_manifest, root_build_dir) ]
      meta_far_merkle_index_entries = [ invoker.meta_far_merkle_index_entry ]
      package_output_manifests = [ invoker.package_output_manifest ]
    }
  }
}