# Copyright 2020 The Pigweed Authors
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may not
# use this file except in compliance with the License. You may obtain a copy of
# the License at
#
#     https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations under
# the License.

import("//build_overrides/pigweed.gni")

import("$dir_pw_build/error.gni")
import("$dir_pw_build/input_group.gni")
import("$dir_pw_build/python_action.gni")
import("$dir_pw_build/target_types.gni")
import("$dir_pw_third_party/nanopb/nanopb.gni")

# Variables forwarded from the public pw_proto_library template to the final
# pw_source_set.
_forwarded_vars = [
  "testonly",
  "visibility",
]

# Internal template that invokes protoc with a pw_python_action. This should not
# be used outside of this file; use pw_proto_library instead.
#
# This creates the internal GN target $target_name.$language._gen that compiles
# proto files with protoc.
template("_pw_invoke_protoc") {
  _output = rebase_path(get_target_outputs(":${invoker.base_target}._metadata"))

  pw_python_action("$target_name._gen") {
    forward_variables_from(invoker, [ "metadata" ])
    script =
        "$dir_pw_protobuf_compiler/py/pw_protobuf_compiler/generate_protos.py"

    deps = [
             ":${invoker.base_target}._metadata",
             ":${invoker.base_target}._inputs",
           ] + invoker.deps

    args = [
             "--language",
             invoker.language,
             "--module-path",
             rebase_path("."),
             "--include-file",
             _output[0],
             "--out-dir",
             rebase_path(invoker.gen_dir),
           ] + rebase_path(invoker.sources)

    inputs = invoker.sources

    if (defined(invoker.plugin)) {
      inputs += [ invoker.plugin ]
      args += [ "--plugin-path=" + rebase_path(invoker.plugin) ]
    }

    if (defined(invoker.include_paths)) {
      args += [
        "--include-paths",
        string_join(";", rebase_path(invoker.include_paths)),
      ]
    }

    outputs = []
    foreach(extension, invoker.output_extensions) {
      foreach(proto,
              rebase_path(invoker.sources, get_path_info(".", "abspath"))) {
        _output = string_replace(proto, ".proto", extension)
        outputs += [ "${invoker.gen_dir}/$_output" ]
      }
    }

    if (outputs == []) {
      stamp = true
    }

    visibility = [ ":*" ]
  }
}

# Generates pw_protobuf C++ code for proto files, creating a source_set of the
# generated files. This is internal and should not be used outside of this file.
# Use pw_proto_library instead.
template("_pw_pwpb_proto_library") {
  _pw_invoke_protoc(target_name) {
    forward_variables_from(invoker, "*", _forwarded_vars)
    language = "pwpb"
    plugin = "$dir_pw_protobuf/py/pw_protobuf/plugin.py"
    deps += [ "$dir_pw_protobuf/py" ]
    output_extensions = [ ".pwpb.h" ]
  }

  # Create a library with the generated source files.
  pw_source_set(target_name) {
    forward_variables_from(invoker, _forwarded_vars)
    public_configs = [ ":${invoker.base_target}._include_path" ]
    deps = [ ":$target_name._gen" ]
    public_deps = [ dir_pw_protobuf ] + invoker.deps
    sources = get_target_outputs(":$target_name._gen")
    public = filter_include(sources, [ "*.pwpb.h" ])
  }
}

# Generates nanopb RPC code for proto files, creating a source_set of the
# generated files. This is internal and should not be used outside of this file.
# Use pw_proto_library instead.
template("_pw_nanopb_rpc_proto_library") {
  # Create a target which runs protoc configured with the nanopb_rpc plugin to
  # generate the C++ proto RPC headers.
  _pw_invoke_protoc(target_name) {
    forward_variables_from(invoker, "*", _forwarded_vars)
    language = "nanopb_rpc"
    plugin = "$dir_pw_rpc/py/pw_rpc/plugin_nanopb.py"
    deps += [ "$dir_pw_rpc/py" ]
    include_paths = [ "$dir_pw_third_party_nanopb/generator/proto" ]
    output_extensions = [ ".rpc.pb.h" ]
  }

  # Create a library with the generated source files.
  pw_source_set(target_name) {
    forward_variables_from(invoker, _forwarded_vars)
    public_configs = [ ":${invoker.base_target}._include_path" ]
    deps = [ ":$target_name._gen" ]
    public_deps = [
                    ":${invoker.base_target}.nanopb",
                    "$dir_pw_rpc:server",
                    "$dir_pw_rpc/nanopb:method_union",
                    "$dir_pw_third_party/nanopb",
                  ] + invoker.deps
    public = get_target_outputs(":$target_name._gen")
  }
}

# Generates nanopb code for proto files, creating a source_set of the generated
# files. This is internal and should not be used outside of this file. Use
# pw_proto_library instead.
template("_pw_nanopb_proto_library") {
  # Create a target which runs protoc configured with the nanopb plugin to
  # generate the C proto sources.
  _pw_invoke_protoc(target_name) {
    forward_variables_from(invoker, "*", _forwarded_vars)
    language = "nanopb"
    plugin = "$dir_pw_third_party_nanopb/generator/protoc-gen-nanopb"
    include_paths = [ "$dir_pw_third_party_nanopb/generator/proto" ]
    output_extensions = [
      ".pb.h",
      ".pb.c",
    ]
  }

  # Create a library with the generated source files.
  pw_source_set(target_name) {
    forward_variables_from(invoker, _forwarded_vars)
    public_configs = [ ":${invoker.base_target}._include_path" ]
    deps = [ ":$target_name._gen" ]
    public_deps = [ "$dir_pw_third_party/nanopb" ] + invoker.deps
    sources = get_target_outputs(":$target_name._gen")
    public = filter_include(sources, [ "*.pb.h" ])
  }
}

# Generates raw RPC code for proto files, creating a source_set of the generated
# files. This is internal and should not be used outside of this file. Use
# pw_proto_library instead.
template("_pw_raw_rpc_proto_library") {
  # Create a target which runs protoc configured with the nanopb_rpc plugin to
  # generate the C++ proto RPC headers.
  _pw_invoke_protoc(target_name) {
    forward_variables_from(invoker, "*", _forwarded_vars)
    language = "raw_rpc"
    plugin = "$dir_pw_rpc/py/pw_rpc/plugin_raw.py"
    deps += [ "$dir_pw_rpc/py" ]
    output_extensions = [ ".raw_rpc.pb.h" ]
  }

  # Create a library with the generated source files.
  pw_source_set(target_name) {
    forward_variables_from(invoker, _forwarded_vars)
    public_configs = [ ":${invoker.base_target}._include_path" ]
    deps = [ ":$target_name._gen" ]
    public_deps = [
                    "$dir_pw_rpc:server",
                    "$dir_pw_rpc/raw:method_union",
                  ] + invoker.deps
    public = get_target_outputs(":$target_name._gen")
  }
}

# Generates Go code for proto files, listing the proto output directory in the
# metadata variable GOPATH. Internal use only.
template("_pw_go_proto_library") {
  _proto_gopath = "$root_gen_dir/go"

  _pw_invoke_protoc(target_name) {
    forward_variables_from(invoker, "*")
    language = "go"
    metadata = {
      gopath = [ "GOPATH+=" + rebase_path(_proto_gopath) ]
      external_deps = [
        "github.com/golang/protobuf/proto",
        "google.golang.org/grpc",
      ]
    }
    output_extensions = []  # Don't enumerate the generated .go files.
    gen_dir = "$_proto_gopath/src"
  }

  group(target_name) {
    deps = [ ":$target_name._gen" ]
  }
}

# Generates protobuf code from .proto definitions for various languages.
# For each supported generator, creates a sub-target named:
#
#   <target_name>.<generator>
#
# Args:
#  sources: List of input .proto files.
#  deps: List of other pw_proto_library dependencies.
#  inputs: Other files on which the protos depend (e.g. nanopb .options files).
#
template("pw_proto_library") {
  assert(defined(invoker.sources) && invoker.sources != [],
         "pw_proto_library requires .proto source files")

  _common = {
    base_target = target_name
    gen_dir = "$target_gen_dir/protos"
    sources = invoker.sources
  }

  if (defined(invoker.deps)) {
    _deps = invoker.deps
  } else {
    _deps = []
  }

  # For each proto target, create a file which collects the base directories of
  # all of its dependencies to list as include paths to protoc.
  generated_file("$target_name._metadata") {
    # Collect metadata from the include path files of each dependency.
    deps = process_file_template(_deps, "{{source}}._metadata")

    data_keys = [ "protoc_includes" ]
    outputs = [ "$target_gen_dir/${target_name}_includes.txt" ]

    # Indicate this library's base directory for its dependents.
    metadata = {
      protoc_includes = [ rebase_path(".") ]
    }
  }

  # Toss any additional inputs into an input group dependency.
  if (defined(invoker.inputs)) {
    pw_input_group("$target_name._inputs") {
      inputs = invoker.inputs
      visibility = [ ":*" ]
    }
  } else {
    group("$target_name._inputs") {
      visibility = [ ":*" ]
    }
  }

  # Create a config with the generated proto directory, which is used for C++.
  config("$target_name._include_path") {
    include_dirs = [ _common.gen_dir ]
    visibility = [ ":*" ]
  }

  # Enumerate all of the protobuf generator targets.

  _pw_pwpb_proto_library("$target_name.pwpb") {
    forward_variables_from(invoker, _forwarded_vars)
    forward_variables_from(_common, "*")
    deps = process_file_template(_deps, "{{source}}.pwpb")
  }

  if (dir_pw_third_party_nanopb != "") {
    _pw_nanopb_rpc_proto_library("$target_name.nanopb_rpc") {
      forward_variables_from(invoker, _forwarded_vars)
      forward_variables_from(_common, "*")
      deps = process_file_template(_deps, "{{source}}.nanopb_rpc")
    }

    _pw_nanopb_proto_library("$target_name.nanopb") {
      forward_variables_from(invoker, _forwarded_vars)
      forward_variables_from(_common, "*")
      deps = process_file_template(_deps, "{{source}}.nanopb")
    }
  } else {
    pw_error("$target_name.nanopb_rpc") {
      message =
          "\$dir_pw_third_party_nanopb must be set to generate nanopb RPC code."
    }

    pw_error("$target_name.nanopb") {
      message =
          "\$dir_pw_third_party_nanopb must be set to compile nanopb protobufs."
    }
  }

  _pw_raw_rpc_proto_library("$target_name.raw_rpc") {
    forward_variables_from(invoker, _forwarded_vars)
    forward_variables_from(_common, "*", [ "deps" ])
    deps = process_file_template(_deps, "{{source}}.raw_rpc")
  }

  _pw_go_proto_library("$target_name.go") {
    sources = invoker.sources
    deps = process_file_template(_deps, "{{source}}.go")
    base_target = _common.base_target
  }

  # All supported pw_protobuf generators.
  _protobuf_generators = [
    "pwpb",
    "nanopb",
    "nanopb_rpc",
    "raw_rpc",
    "go",
  ]

  # If the user attempts to use the target directly instead of one of the
  # generator targets, run a script which prints a nice error message.
  pw_python_action(target_name) {
    script = string_join("/",
                         [
                           dir_pw_protobuf_compiler,
                           "py",
                           "pw_protobuf_compiler",
                           "proto_target_invalid.py",
                         ])
    args = [
             "--target",
             target_name,
             "--dir",
             get_path_info(".", "abspath"),
             "--root",
             "//",
           ] + _protobuf_generators
    stamp = true
  }
}