# Copyright 2017 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/allowlist_v2.gni")
import("//build/cml/cml.gni")
import("//build/cmx/cmx.gni")
import("//build/images/args.gni")
import("//build/images/manifest.gni")
import("//build/testing/test_spec.gni")
import("//src/sys/pkg/bin/pm/pm.gni")

# Generate a list of package metadata exported from all packages in the
# transitive closure of declared dependencies, with an implied barrier at each
# package (dependency chains cease processing at package targets).
#
# 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:
#
#       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_index_entries
#         The metafar index entries are aggregated in image builds to produce
#         manifests of packages to publish to a repository.
#
#       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
#         [list of labels] This is passed to walk_keys and can be used as a barrier to
#         control dependency propgatation below a package target.
#
#   data_deps (optional)
#   deps (optional)
#   metadata (optional)
#   output_conversion (optional)
#   outputs (optional)
#   public_deps (optional)
#   rebase (optional)
#   testonly (optional)
#   visibility (optional)
#     Same as for any GN `generated_file()` target.
template("package_metadata_list") {
  generated_file(target_name) {
    forward_variables_from(invoker,
                           [
                             "data_deps",
                             "data_keys",
                             "deps",
                             "metadata",
                             "output_conversion",
                             "outputs",
                             "public_deps",
                             "rebase",
                             "testonly",
                             "visibility",
                           ])

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

    walk_keys = [ "package_barrier" ]
  }
}

# Generate a list of fuchsia-pkg URLs for component from all packages in the
# transitive closure of declared dependencies, with an implied barrier at each
# package (dependency chains cease processing at package targets).
#
# Parameters
#
#   data_deps (optional)
#   deps (optional)
#   outputs (optional)
#   public_deps (optional)
#   testonly (optional)
#   visibility (optional)
#     Same as for any GN `generated_file()` target.
template("component_index_metadata_list") {
  generated_file(target_name) {
    forward_variables_from(invoker,
                           [
                             "data_deps",
                             "deps",
                             "outputs",
                             "public_deps",
                             "testonly",
                             "visibility",
                           ])

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

    data_keys = [ "component_index" ]
    walk_keys = [ "component_index_barrier" ]
  }
}

# Defines a package
#
# The package template is used to define a unit of related code and data.
# A package always has a name (defaulting to the target name) and lists of
# scopes describing the components of the package.
#
# Parameters
#
#   meta (optional)
#     [list of scopes] Defines the metadata entries in the package. A metadata
#     entry is typically a source file and is placed in the `meta/` directory of
#     the assembled package.
#
#     Entries in a scope in the meta list:
#
#       path (required)
#         [path] Location of entry in source or build directory. If the
#         resource is checked in, this will typically be specified as a
#         path relative to the BUILD.gn file containing the `package()`
#         target. If the resource is generated, this will typically be
#         specified relative to `$target_gen_dir`.
#
#       dest (required)
#         [path] Location the resource will be placed within `meta/`.
#
#   binary (optional, *DEPRECATED*)
#     [string] The path to the primary binary for the package, relative to
#     `$root_out_dir`. The binary will be placed in the assembled package at
#     `bin/app` and will be executed by default when running the package.
#
#   binaries (optional)
#     [list of scopes] Defines the binaries in the package. A binary is
#     typically produced by the build system and is placed in the `bin/`
#     directory of the assembled package.
#
#     Entries in a scope in the binaries list:
#
#       name (required)
#         [string] Name of the binary.
#
#       source (optional)
#         [path] Location of the binary in the build directory if it is not
#         at `$root_out_dir/$name`.
#
#       dest (optional)
#         [path] Location the binary will be placed within `bin/`.
#
#       shell (optional)
#         [boolean] (default: false) When true, the binary is runnable from the shell.
#         Shell binaries are run in the shell namespace and are not run as components.
#
#   tests (optional)
#     [list of scopes] Defines the test binaries in the package. A test is
#     typically produced by the build system and is placed in the `test/`
#     directory of the assembled package.
#
#     Entries in a scope in the tests list:
#
#       name (required)
#         [string] Name of the test.
#
#       dest (optional, default: name)
#         [path] Location the binary will be placed within `test/`.
#
#       disabled (optional)
#         [bool] Whether to disable the test on continuous integration
#         jobs. This can be used when a test is temporarily broken, or if
#         it is too flaky or slow for CI. The test will also be skipped by
#         the `runtests` command.
#
#       environments (optional, default: [ { dimensions = { device_type = "QEMU" } } ])
#         [list of scopes] Device environments in which the test should run.
#
#         Each scope in $environments contains:
#
#           dimensions (required)
#             [scope] Dimensions of bots to target. Valid dimensions are
#             element-wise subsets of the test platform entries defined in
#             //build/testing/platforms.gni.
#
#           tags (optional)
#             [list of strings] Keys on which tests may be grouped. Tests with
#             given keys will be run (1) together, and (2) only with support
#             from the Infrastructure team. Labels are used as an escape hatch
#             from the default testing pipeline for special tests or environments.
#
#   drivers (optional)
#     [list of scopes] Defines the drivers in the package. A driver is
#     typically produced by the build system and is placed in the `driver/`
#     directory of the assembled package.
#
#     Entries in a scope in the drivers list:
#
#       name (required)
#         [string] Name of the driver.
#
#   loadable_modules (optional)
#     [list of scopes] Defines the loadable modules in the package.  These
#     are produced by `loadable_module()` GN targets, and are typically
#     placed in the `lib/` directory of the assembled packaged.
#
#     Entries in a scope in the loadable_modules list:
#
#       name (required)
#         [string] Name of the loadable_module.
#
#       dest (optional, default: "lib")
#         [string] Location the binary will be placed in the package.
#
#   libraries (optional, *DEPRECATED*)
#     [list of scopes] Defines the (shared) libraries in the package. A library
#     is placed in the `lib/` directory of the assembled package.
#
#     This is deprecated but is necessary in some `system_image` packages
#     that install libraries used by things that don't properly isolate
#     their dependencies.  Do not use it unless you are sure you have to.
#
#     Entries in a scope in the libraries list:
#
#       name (required)
#         [string] Name of the library
#
#       source (optional)
#         [path] Location of the binary in the build directory if it is not at
#         `$root_out_dir/$name`
#
#       dest (optional)
#         [path] Location the binary will be placed within `lib/`
#
#   resources (optional)
#     [list of scopes] Defines the resources in the package. A resource is a
#     data file that may be produced by the build system, checked in to a
#     source repository, or produced by another system that runs before the
#     build. Resources are placed in the `data/` directory of the assembled
#     package.
#
#     Entries in a scope in the resources list:
#
#       path (required)
#         [path] Location of resource in source or build directory. If the
#         resource is checked in, this will typically be specified as a
#         path relative to the BUILD.gn file containing the `package()`
#         target. If the resource is generated, this will typically be
#         specified relative to `$target_gen_dir`.
#
#       dest (required)
#         [path] Location the resource will be placed within `data/`.
#
#   extra (optional)
#     [list of paths] Manifest files containing extra entries, which
#     might be generated by the build.
#
#   deps (optional)
#   public_deps (optional)
#   data_deps (optional)
#   testonly (optional)
#     Usual GN meanings.
#
template("package") {
  if (current_toolchain == target_toolchain) {
    forward_variables_from(invoker, [ "testonly" ])
    pkg_target_name = target_name
    pkg = {
      package_version = "0"  # placeholder
      forward_variables_from(
          invoker,
          [
            "binaries",
            "binary",
            "data_deps",
            "deprecated_misc_storage",
            "deprecated_shell",
            "deprecated_system_image",  # TODO(bwb) remove after soft-transition
            "__deprecated_system_image",
            "deps",
            "global_data",
            "public_deps",
            "drivers",
            "extra",
            "libraries",
            "loadable_modules",
            "meta",
            "package_name",
            "resources",
            "rootjob_svc",
            "rootresource_svc",
            "visibility",
            "tests",
          ])
      if (!defined(binaries)) {
        binaries = []
      }
      if (!defined(__deprecated_system_image) &&
          !defined(deprecated_system_image)) {
        __deprecated_system_image = false
      }
      if (defined(deprecated_system_image)) {
        __deprecated_system_image = deprecated_system_image
      }
      if (!defined(deps)) {
        deps = []
      }
      if (!defined(data_deps)) {
        data_deps = []
      }
      if (!defined(public_deps)) {
        public_deps = []
      }
      if (!defined(extra)) {
        extra = []
      }
      if (!defined(drivers)) {
        drivers = []
      }
      if (!defined(loadable_modules)) {
        loadable_modules = []
      }
      if (!defined(libraries)) {
        libraries = []
      }
      if (!defined(meta)) {
        meta = []
      }
      if (!defined(package_name)) {
        package_name = pkg_target_name
      }
      if (!defined(resources)) {
        resources = []
      }
      if (!defined(tests)) {
        tests = []
      }
    }

    assert(pkg.package_name != "tests" && pkg.package_name != "app" &&
               pkg.package_name != "bin" && pkg.package_name != "pkg" &&
               pkg.package_name != "lib" && pkg.package_name != "package" &&
               pkg.package_name != "binary" && pkg.package_name != "service" &&
               pkg.package_name != "svc" && pkg.package_name != "component",
           "${pkg.package_name} is too generic a name for a package")

    pkg_label = get_label_info(":$pkg_target_name", "label_no_toolchain")
    pkg_desc = "Package ${pkg_label} (${pkg.package_name}):"
    if (pkg.__deprecated_system_image) {
      assert(
          pkg.meta == [],
          "$pkg_desc __deprecated_system_image (likely from driver_package) incompatible with meta")
      assert(
          !defined(pkg.binary),
          "$pkg_desc __deprecated_system_image (likely from driver_package) incompatible with binary")

      # Only appmgr can contribute binaries to /system/bin.
      assert(pkg.binaries == [] || pkg.package_name == "appmgr",
             "no new packages are allowed to add binaries to /system/bin")

      assert(pkg.tests == [], "tests are not allowed in /system")
    } else {
      assert(pkg.drivers == [],
             "$pkg_desc drivers requires __deprecated_system_image")
      assert(pkg.libraries == [],
             "$pkg_desc libraries requires __deprecated_system_image")
      if (defined(pkg.binary)) {
        pkg.binaries += [
          {
            name = "app"
            source = pkg.binary
          },
        ]
      }
    }

    # Validate .cmx files
    foreach(meta, pkg.meta) {
      if (get_path_info(meta.dest, "extension") == "cmx") {
        validate = "validate_" + pkg_target_name + "_" +
                   get_path_info(meta.dest, "file")
        cmx_validate(validate) {
          data = meta.path

          # the cmx file may be generated by one of this package's dependencies,
          # but we don't know which one, so depend on all package deps here.
          deps = pkg.deps
          public_deps = pkg.public_deps
          extra_schemas = []

          # Remove this validation when the "deprecated-misc-storage" feature is removed.
          if (!defined(pkg.deprecated_misc_storage)) {
            extra_schemas += [
              {
                schema = "//build/cmx/block_deprecated_misc_storage.json"
                error_msg = "The 'deprecated-misc-storage' feature is deprecated and guarded by an allowlist."
              },
            ]
          }

          # TODO(jseibert): Remove this validation when the "deprecated-shell" feature is removed.
          if (!defined(pkg.deprecated_shell)) {
            extra_schemas += [
              {
                schema = "//build/cmx/block_deprecated_shell.json"
                error_msg = "The 'deprecated-shell' feature is deprecated and guarded by an allowlist."
              },
            ]
          }

          if (!defined(pkg.rootjob_svc)) {
            extra_schemas += [
              {
                schema = "//build/cmx/block_rootjob_svc.json"
                error_msg = "The 'fuchsia.boot.RootJob' service is guarded by an allowlist."
              },
            ]
          }
          if (!defined(pkg.rootresource_svc)) {
            extra_schemas += [
              {
                schema = "//build/cmx/block_rootresource_svc.json"
                error_msg = "The 'fuchsia.boot.RootResource' service is guarded by an allowlist."
              },
            ]
          }
        }

        pkg.deps += [ ":$validate" ]
      }
    }

    # Tag v2 components, so that later we can assert they are not in cache + universe.
    # TODO(46491) remove allowlist and cfv2 tag once CFv2 uses pkg-resolver to launch components.
    foreach(meta, pkg.meta) {
      if (get_path_info(meta.dest, "extension") == "cm") {
        # Only add v2 tag if meta.dest is NOT in the allowlist.
        if (v2_components_allowed_in_cache + [ meta.dest ] - [ meta.dest ] ==
            v2_components_allowed_in_cache) {
          pkg.deps += [ "//build/validate:cfv2_tag" ]
        }
      }
    }

    # Some kinds of tests need to inject things into their test package
    # manifests. For example, Rust tests all need access to the process
    # launcher when rust_panic=abort. We collect this information as metadata.
    if (pkg.tests != []) {
      metadata_manifest_patches =
          "$target_out_dir/pkg_meta/$target_name.test_metadata"
      metadata_manifest_target_name = "${target_name}_test_metadata"
      generated_file(metadata_manifest_target_name) {
        outputs = [ metadata_manifest_patches ]
        output_conversion = "json"
        data_keys = [ "test_metadata_manifest_patches" ]
        walk_keys = [ "test_barrier" ]
        forward_variables_from(pkg,
                               [
                                 "deps",
                                 "public_deps",
                                 "data_deps",
                               ])
      }
      pkg.deps += [ ":$metadata_manifest_target_name" ]
    }

    # TODO: this doesn't handle the case where the profile variant is enabled only for
    # a single target rather than the entire build.
    needs_debugdata =
        select_variant + [ "profile" ] - [ "profile" ] != select_variant
    not_needed([ "needs_debugdata" ])

    # cmx_format will minify cmx files in non-debug builds, and pretty-print cmx
    # files in debug builds
    formatted_manifest = []
    component_indices = []
    foreach(meta, pkg.meta) {
      if (get_path_info(meta.dest, "extension") == "cmx") {
        manifest_deps = []
        manifest_deps = pkg.deps
        manifest_path = meta.path

        if (needs_debugdata) {
          merge_target = "debugdata_" + pkg_target_name + "_" +
                         get_path_info(meta.dest, "file")
          cmx_merge(merge_target) {
            sources = [
              rebase_path(meta.path),
              rebase_path("//build/config/sanitizers/debugdata.cmx"),
            ]
            deps = pkg.deps
          }
          manifest_deps += [ ":${merge_target}" ]
          merged_outputs = []
          merged_outputs = get_target_outputs(":${merge_target}")
          manifest_path = merged_outputs[0]
        }

        # This is where we add sys.process.Launcher to test packages which
        # need it (see above).
        if (pkg.tests != []) {
          merge_target = "process_launcher_" + pkg_target_name + "_" +
                         get_path_info(meta.dest, "file")
          cmx_merge(merge_target) {
            #conditional_file = metadata_manifest_patches
            sources = [
              manifest_path,
              metadata_manifest_patches,
            ]
            deps = manifest_deps + [ ":$metadata_manifest_target_name" ]
          }
          manifest_deps += [ ":${merge_target}" ]
          merged_outputs = []
          merged_outputs = get_target_outputs(":${merge_target}")
          manifest_path = merged_outputs[0]
        }

        component_indices += [ "fuchsia-pkg://fuchsia.com/" + pkg.package_name +
                               "#meta/" + meta.dest ]
        format =
            "format_" + pkg_target_name + "_" + get_path_info(meta.dest, "file")
        cmx_format(format) {
          data = rebase_path(manifest_path)
          deps = manifest_deps
        }
        formatted_outputs = []
        formatted_outputs = get_target_outputs(":$format")
        meta.path = formatted_outputs[0]
        pkg.deps += [ ":$format" ]
      } else if (get_path_info(meta.path, "extension") == "cml") {
        component_indices += [ "fuchsia-pkg://fuchsia.com/" + pkg.package_name +
                               "#meta/" + meta.dest ]
        compiled = "compiled_" + pkg_target_name + "_" +
                   get_path_info(meta.dest, "file")

        cm(compiled) {
          data = rebase_path(meta.path)
          deps = pkg.deps
          public_deps = pkg.public_deps
        }
        pkg.deps += [ ":$compiled" ]
        compiled_outputs = []
        compiled_outputs = get_target_outputs(":$compiled")
        meta.path = compiled_outputs[0]
      }
      formatted_manifest += [ meta ]
    }

    # Collect the package's primary manifest.  For a system_image package,
    # this is its contributions to the /system manifest.  For an isolated
    # package, this is the manifest for the package's `pkg/` filesystem.
    pkg_manifest = []
    foreach(meta, formatted_manifest) {
      pkg_manifest += [
        {
          dest = "meta/${meta.dest}"
          source = rebase_path(meta.path)
        },
      ]
    }
    shell_binaries = []
    foreach(binary, pkg.binaries) {
      if (defined(binary.dest)) {
        dest = binary.dest
      } else {
        dest = binary.name
      }
      dest = "bin/${dest}"

      if (defined(binary.shell) && binary.shell) {
        shellfile = target_gen_dir + "/" + dest + ".shell"
        write_file(
            shellfile,
            [ "#!resolve fuchsia-pkg://fuchsia.com/${pkg.package_name}#${dest}" ])
        shell_binaries +=
            [ "${dest}=" + rebase_path(shellfile, root_build_dir) ]

        # The shell environment is not intended for production use.
        pkg.deps += [ "//build/validate:non_production_tag" ]
      }

      pkg_manifest += [
        {
          dest = dest

          if (defined(binary.source)) {
            source = binary.source
          } else {
            source = binary.name
          }
          source = rebase_path(source, "", root_out_dir)
        },
      ]
    }

    foreach(test, pkg.tests) {
      assert(!defined(test.tags),
             "tags are only valid within an environment scope")

      # It's a common mistake to specify "tags" in the scope of the test
      # instead of in an environment scope.
      is_disabled = defined(test.disabled) && test.disabled

      if (defined(test.dest)) {
        dest = test.dest
      } else {
        dest = test.name
      }
      if (is_disabled) {
        dest = "disabled/${dest}"
      }

      if (bootfs_only) {
        url_scheme_and_host = "fuchsia-boot://"
        url_pkg_name = ""
        dest = "test/sys/$dest"
        path = "/boot/$dest"
      } else {
        url_scheme_and_host = "fuchsia-pkg://fuchsia.com"
        dest = "test/$dest"
        if (pkg.__deprecated_system_image) {
          url_pkg_name = "system"
          path = "/system/$dest"
        } else {
          url_pkg_name = pkg.package_name
          path = ""
        }
      }

      url_resource_path = dest
      dest_name = get_path_info(dest, "name")
      not_needed([ "dest_name" ])

      # Check that all tests are components with cmx/cm files at the expected path.
      if (!pkg.__deprecated_system_image && !bootfs_only && !is_disabled &&
          (!defined(require_bare_tests_allowlist) ||
           !require_bare_tests_allowlist)) {
        require_bare_tests_allowlist = true
        foreach(meta, pkg.meta) {
          extension = get_path_info(meta.dest, "extension")
          if (extension == "cmx" || extension == "cm") {
            meta_name = get_path_info(meta.dest, "name")
            if (dest_name == meta_name) {
              require_bare_tests_allowlist = false
              url_resource_path = "meta/${meta.dest}"
            }
          }
        }
      }

      url = "${url_scheme_and_host}/${url_pkg_name}#${url_resource_path}"

      if (!is_disabled) {
        test_spec_name = "${pkg.package_name}_${dest}_test_spec"
        main_target_name = target_name
        pkg.deps += [ ":$test_spec_name" ]

        test_spec(test_spec_name) {
          name = test.name
          target = main_target_name
          path = path
          package_url = url
          forward_variables_from(test, [ "environments" ])
        }
      } else {
        not_needed([
                     "path",
                     "url",
                   ])
      }

      pkg_manifest += [
        {
          dest = dest
          source = rebase_path(test.name, "", root_out_dir)
        },
      ]
    }

    foreach(module, pkg.loadable_modules) {
      pkg_manifest += [
        {
          if (defined(module.dest)) {
            dest = module.dest
          } else {
            dest = "lib"
          }
          dest += "/${module.name}"
          source = rebase_path(module.name, "", root_out_dir)
        },
      ]
    }
    foreach(driver, pkg.drivers) {
      pkg_manifest += [
        {
          dest = "driver/${driver.name}"
          source = rebase_path(driver.name, "", root_out_dir)
        },
      ]
    }
    foreach(resource, pkg.resources) {
      pkg_manifest += [
        {
          dest = "data/${resource.dest}"
          source = rebase_path(resource.path)
        },
      ]
    }

    # TODO(mcgrathr): Remove this when we can!  Packages installing
    # libraries in the system image is all kinds of wrong.
    foreach(library, pkg.libraries) {
      pkg_manifest += [
        {
          if (defined(library.dest)) {
            dest = library.dest
          } else {
            dest = library.name
          }
          dest = "lib/${dest}"
          if (defined(library.source)) {
            source = library.source
          } else {
            # TODO(mcgrathr): This breaks when everything is a variant so
            # that only this here is using the non-variant shlib build.
            source = get_label_info(shlib_toolchain, "name")
            source += "/${library.name}"
          }
          source = rebase_path(source, "", root_out_dir)
        },
      ]
    }

    # Collect all the arguments describing input manifest files
    # and all the entries we've just synthesized in `pkg_manifest`.
    manifest_sources = pkg.extra
    manifest_args = []
    foreach(manifest_file, pkg.extra) {
      manifest_file = rebase_path(manifest_file, root_build_dir)
      manifest_args += [ "--manifest=${manifest_file}" ]
    }
    manifest_args += [ "--entry-manifest=${pkg_label}" ]
    foreach(entry, pkg_manifest) {
      manifest_sources += [ entry.source ]
      manifest_args += [ "--entry=${entry.dest}=${entry.source}" ]
    }

    pkg.metadata = {
      if (defined(invoker.metadata)) {
        forward_variables_from(invoker.metadata, "*")
      }
      shell_binary_entries = shell_binaries

      # Subtle: we only want dependency on the package target to consume
      # package metadata propagation for the package we're building, never
      # for transitive package dependencies of this package. In the fuchsia
      # package case, we want to therefore only include our local package
      # build target. For the system image package case, we don't want to
      # include anything.
      package_barrier = []
    }

    if (defined(pkg.visibility)) {
      pkg.visibility += [
        ":$target_name",

        # TODO(raggi): tighten build/images visibility once we've
        # finished doing large scale cleanups.
        "//build/images:*",
        "//build/packages/*",
        "//bundles/*",
        "//garnet/packages/*",
        "//src/modular/bundles/*",
        "//topaz/packages/*",
        "//vendor/*",
      ]
    }

    # An empty package() target doesn't actually generate a package at all.
    # Conveniently, an empty system_image package has exactly that effect.
    if (manifest_sources == []) {
      pkg.__deprecated_system_image = true
    }

    if (pkg.__deprecated_system_image || bootfs_only) {
      system_rsp_label = pkg_target_name + ".system.rsp"

      # System image packages just donate manifest arguments
      generate_response_file(system_rsp_label) {
        if (defined(pkg.visibility)) {
          visibility = pkg.visibility
        }
        deps = pkg.deps
        data_deps = pkg.data_deps
        public_deps = pkg.public_deps
        output_name = "${pkg_target_name}.system.rsp"
        response_file_contents = manifest_args
        metadata = {
          forward_variables_from(pkg.metadata, "*")

          system_image_rsps = [ "@" +
                                rebase_path(target_out_dir + "/" + output_name,
                                            root_build_dir) ]

          system_image_barrier = []
        }
      }
      not_needed([ "component_indices" ])
    }

    # Fuchsia package aggregates a manifest from it's arguments and builds a
    # metadata archive.

    manifest = "${pkg_target_name}.manifest"

    # Synthesize the meta/package file.
    pkg_meta_package = "${pkg_target_name}_meta_package.json"
    action(pkg_meta_package) {
      visibility = [ ":$manifest" ]
      script = "//build/gn/write_package_json.py"
      outputs = [ "$target_out_dir/$pkg_meta_package" ]
      args = [
        "--name",
        pkg.package_name,
        "--version",
        pkg.package_version,
        rebase_path(pkg_meta_package, root_build_dir, target_out_dir),
      ]
    }

    generate_manifest(manifest) {
      visibility = [ ":" + pkg_target_name ]
      sources = manifest_sources + get_target_outputs(":$pkg_meta_package")
      args =
          manifest_args + [ "--entry=meta/package=" +
                            rebase_path(pkg_meta_package, "", target_out_dir) ]
      deps = pkg.deps + [ ":$pkg_meta_package" ]
      public_deps = pkg.public_deps
    }

    # Next generate a sealed package file.
    pm_build(pkg_target_name) {
      if (defined(pkg.visibility)) {
        visibility = pkg.visibility
      }
      package_name = pkg.package_name
      manifest = ":$manifest"
      metadata = {
        forward_variables_from(pkg.metadata, "*")

        component_index = component_indices

        # We only ever want to collect the following component indices from
        # packages, not from dependencies of packages, so the barrier prevents
        # us from walking any further in the dependency chain. See `gn help
        # walk_keys` for more information on the mechanic.
        component_index_barrier = []
      }

      deps = pkg.deps
      data_deps = pkg.data_deps
      public_deps = pkg.public_deps

      if (pkg.__deprecated_system_image || bootfs_only) {
        public_deps += [ ":" + system_rsp_label ]
      }

      # Add the dep on the allowlist here rather than in pkg.deps earlier so that we can allow
      # specific targets by the package target's name using visibility.
      if (defined(pkg.deprecated_misc_storage)) {
        deps += [
          "${pkg.deprecated_misc_storage}:deprecated_misc_storage_allowlist",
        ]
      }
      if (defined(require_bare_tests_allowlist) &&
          require_bare_tests_allowlist) {
        deps += [ "//build:deprecated_bare_tests_allowlist" ]
      }
      if (defined(pkg.deprecated_shell)) {
        deps += [ "${pkg.deprecated_shell}:deprecated_shell_allowlist" ]
      }
      if (defined(pkg.global_data)) {
        deps += [ "${pkg.global_data}:global_data_allowlist" ]
      }
      if (defined(pkg.rootjob_svc)) {
        deps += [ "${pkg.rootjob_svc}:rootjob_svc_allowlist" ]
      }
      if (defined(pkg.rootresource_svc)) {
        deps += [ "${pkg.rootresource_svc}:rootresource_svc_allowlist" ]
      }
    }
  } else {
    # A reference from a different toolchain, e.g. a variant toolchain, is
    # just an indirect way to get the package into the system images.
    # Redirect it as data_deps on the $target_toolchain package.  This
    # really ought to be a pure redirect, i.e. public_deps.  But using
    # data_deps here avoids problems in case some dependency on a package()
    # target is not in data_deps as it (almost surely) should be.
    group(target_name) {
      forward_variables_from(invoker,
                             [
                               "visibility",
                               "testonly",
                             ])
      data_deps = [ ":$target_name($target_toolchain)" ]
    }

    # Suppress unused variable warnings.
    not_needed(invoker, "*")
  }
}