# 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.

# Generates a manifest containing the list of distributable objects in the given
# dependency tree.
#
# Distributable objects are binaries and data files eligible for inclusion in a
# build product destined to be used at runtime. Objects within the dependency
# tree defined by the `deps` and `data_deps` parameters of dependents end up
# included in the resulting manifest file.
#
# This template produces a file using the JSON format listing all distributable
# objects, with entries that look like:
# ```
# [
#   {
#     "destination": "bin/foobar",
#     "source": "obj/path/to/foobar"
#     "label": "//path/to/foobar"
#   }
# ]
# ```
#
# See //docs/concepts/build_system/internals/distribution_manifest.md for
# more details.
#
# Parameters
#
#   deps (optional)
#     [list of labels] The targets to generate a manifest for.
#     See `gn help` for more details.
#
#   data_deps, testonly, visibility, metadata (optional)
#     See `gn help`.
#
#   outputs (optional)
#     Singleton list containing the path to the manifest file.
#     Defaults to `[ "$target_gen_dir/$target_name.dist" ]`.
template("distribution_manifest") {
  main_target = target_name
  generate_target = "${target_name}_generate"

  # Build the name of the output file.
  if (defined(invoker.outputs)) {
    _outputs = invoker.outputs
    assert(_outputs != [] && _outputs == [ _outputs[0] ],
           "Outputs list must have exactly one element.")
    manifest_file = _outputs[0]
  } else {
    manifest_file = "$target_gen_dir/$target_name.dist"
  }
  intermediate_file = "$manifest_file.partial"

  # Gather metadata about runtime objects.
  generated_file(generate_target) {
    forward_variables_from(invoker,
                           [
                             "deps",
                             "testonly",
                           ])

    visibility = [
      ":$main_target",
      ":${main_target}__hermetic_inputs",
    ]

    # See //docs/concepts/build_system/internals/distribution_manifest.md
    # for the schema of `distribution_entries` and `distribution_entries_files`,
    # which correspond to "regular" and "file" entries, respectively.
    data_keys = [
      # A list of scopes describing files that may be added to runtime.
      "distribution_entries",

      # A list of scopes representing data files listing distributable objects.
      "distribution_entries_files",
    ]
    walk_keys = [ "distribution_entries_barrier" ]

    outputs = [ intermediate_file ]

    output_conversion = "json"
  }

  # Detect collisions in metadata entries.
  action(main_target) {
    forward_variables_from(invoker,
                           [
                             "data_deps",
                             "deps",
                             "testonly",
                             "visibility",
                           ])

    script = "//build/dist/expand_and_find_conflicting_dist_entries.py"

    sources = [ intermediate_file ]
    outputs = [ manifest_file ]
    inputs = [ "//build/dist/distribution_manifest.py" ]

    args = [
      "--input",
      rebase_path(intermediate_file, root_build_dir),
      "--output",
      rebase_path(manifest_file, root_build_dir),
    ]

    if (!defined(deps)) {
      deps = []
    }
    deps += [ ":$generate_target" ]

    # This flag will make the build system call script with
    # an extra --hermetic-inputs-file=PATH argument to generate
    # a depfile, which is needed for list input files referenced
    # by distribution_entries_files metadata values.
    hermetic_inputs_file = "$target_gen_dir/${main_target}.hermetic_inputs"

    metadata = {
      # Add a barrier here to avoid double of inclusion of elements listed in
      # the generated manifest.
      distribution_entries_barrier = []

      if (defined(invoker.metadata)) {
        forward_variables_from(invoker.metadata, "*")
      }
    }
  }
}

# Adds distribution entries from a given distribution manifest file.
#
# Use this template to ensure that all entries from a given input
# distribution manifest file are collected through distribution_manifest() or
# fini_manifest() when this target is part of their dependency tree.
#
# See documentation for distribution_manifest() for the file format.
#
# Parameters
#
#   file (required)
#     Path to a distribution manifest file.
#
#   deps
#   testonly
#   visibility
template("distribution_entries_file") {
  assert(defined(invoker.file), "Must specify file")
  group(target_name) {
    forward_variables_from(invoker,
                           [
                             "deps",
                             "testonly",
                             "visibility",
                           ])
    metadata = {
      distribution_entries_files = [
        {
          file = rebase_path(invoker.file, root_build_dir)
          label = get_label_info(":$target_name", "label_with_toolchain")
        },
      ]
    }
  }
}

# Creates distribution entries from a given FINI manifest file.
#
# Parameters
#
#   file (required)
#     Path to a FINI file.
#
#   deps
#   testonly
#   visibility
template("distribution_entries_from_fini") {
  assert(defined(invoker.file), "Must specify file")
  _output = "$target_out_dir/${target_name}_distribution_manifest"
  _label = get_label_info(":$target_name", "label_with_toolchain")

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

    script = "//build/dist/convert_fini_to_manifest.py"

    inputs = [ invoker.file ]
    outputs = [ _output ]

    args = [
      "--input",
      rebase_path(invoker.file, root_build_dir),
      "--output",
      rebase_path(_output, root_build_dir),
      "--label",
      rebase_path(_label, root_build_dir),
    ]

    metadata = {
      distribution_entries_files = [
        {
          file = rebase_path(_output, root_build_dir)
          label = _label
        },
      ]
    }
  }
}