build/python/fidl_python.gni

# Copyright 2025 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/toolchain.gni")
import("//build/python/python_library.gni")

# Generates Python bindings for a FIDL library.
#
# Parameters
#
#  * library_name
#    - Required: The name of the FIDL library.
#    - Type: string
#
#  * fidl_gen_dir
#    - Required: The directory under which bindings should be generated.
#    - Type: path
#
#  * fidl_ir_json
#    - Required: The path to the associated FIDL IR JSON file.
#    - Type: path
#
#  * fidl_ir_target
#    - Required: The label of the target that generates the FIDL IR JSON file.
#    - Type: label
#  * deps
#    - Optional: Dependencies added unaltered to the deps for this library.
#         Used only to set non-fidl python bindings. The use of public_deps is
#         instead of deps is strongly advised.
#
#  * testonly, visibility, public_deps
#    - Optional: Usual GN meanings.
#
template("fidl_python") {
  assert(defined(invoker.library_name),
         "fidl_python(\"$target_name\") must define `library_name`")
  assert(defined(invoker.fidl_gen_dir),
         "fidl_python(\"$target_name\") must define `fidl_gen_dir`")
  assert(defined(invoker.fidl_ir_json),
         "fidl_python(\"$target_name\") must define `fidl_ir_json`")
  assert(defined(invoker.fidl_ir_target),
         "fidl_python(\"$target_name\") must define `fidl_ir_target`")

  generation_target = "${target_name}_generate"

  forward_variables_from(invoker, [ "fidl_gen_dir" ])

  python_library_name = "fidl_" + string_replace(invoker.library_name, ".", "_")

  if (is_fidl_toolchain) {
    not_needed(invoker,
               [
                 "deps",
                 "visibility",
                 "fidl_target",
               ])
    compiled_action(generation_target) {
      forward_variables_from(invoker,
                             [
                               "applicable_licenses",
                               "testonly",
                               "fidl_ir_json",
                               "fidl_ir_target",
                               "public_deps",
                             ])
      visibility = [
        ":*",
        "//tools/fidl/fidlgen_python:*",
      ]

      tool = "//tools/fidl/fidlgen_python"
      mnemonic = "FIDLGEN"

      inputs = [
        fidl_ir_json,
        "//prebuilt/third_party/black/linux-x64/black",
        "//.gitignore",
        "//pyproject.toml",
      ]

      output = "$fidl_gen_dir/$python_library_name/__init__.py"
      outputs = [ output ]

      args = [
        "--fidl-ir-json",
        rebase_path(fidl_ir_json, root_build_dir),
        "--output",
        rebase_path(output, root_build_dir),
        "--black",
        rebase_path("//prebuilt/third_party/black/linux-x64/black",
                    root_build_dir),
        "--pyproject-toml",
        rebase_path("//pyproject.toml", root_build_dir),
      ]

      deps = [ fidl_ir_target ]

      metadata = {
        generated_sources = rebase_path(outputs, root_build_dir)
        fidl_python_output = [ rebase_path(fidl_gen_dir, root_build_dir) ]
      }
    }
  } else {
    not_needed(invoker,
               [
                 "fidl_ir_json",
                 "fidl_ir_target",
               ])

    python_library(target_name) {
      forward_variables_from(invoker,
                             [
                               "applicable_licenses",
                               "testonly",
                               "visibility",
                               "deps",
                               "library_name",
                               "fidl_target",
                             ])

      library_name = python_library_name
      source_root = "$fidl_gen_dir/$python_library_name"

      # TODO(https://fxbug.dev/394425397): These dependencies should be lifted into proper
      # locations adjacent or within fidlgen_python. Ideally, this can be done when the dependency
      # on dynamic Python bindings is removed. Otherwise, the dynamic Python bindings would have to
      # point to the new location, causing similar dissonance.
      library_deps = [
        "//src/developer/ffx/lib/fuchsia-controller:fidl_bindings",
        "//src/developer/ffx/lib/fuchsia-controller:fuchsia_controller_py",
        "//src/developer/ffx/lib/fuchsia-controller/cpp:fidl_codec",
      ]
      data_deps = [
        ":${fidl_target}_host_test_data",
        "//src/developer/ffx/lib/fuchsia-controller/tests:fuchsia_controller_test_data",
      ]
      if (defined(invoker.public_deps)) {
        foreach(dep, invoker.public_deps) {
          label = get_label_info(dep, "label_no_toolchain")
          library_deps += [ "${label}_python" ]
        }
      }
      sources = [ "__init__.py" ]
      if (!defined(deps)) {
        deps = []
      }
      deps += [ ":$generation_target($fidl_toolchain)" ]
    }
  }
}