#!/usr/bin/env python
# Copyright 2023 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""Code generator for proto descriptors used for on-device model execution.

This script generates a C++ source file containing the proto descriptors.

To check the type annotations in this file, install mypy then:

autoninja -C $OUT_DIR protoc
$OUT_DIR/protoc -I=../../../third_party/protobuf/src \
    --pyi_out=. \
    ../../../third_party/protobuf/src/google/protobuf/descriptor.proto
mypy gen_on_device_proto_descriptors.py
"""
from __future__ import annotations

from collections.abc import Callable, Iterator
import dataclasses
import functools
from io import StringIO
import optparse
import os
import collections
import re
import sys
from typing import IO

_HERE_PATH = os.path.dirname(__file__)
_SRC_PATH = os.path.normpath(os.path.join(_HERE_PATH, '..', '..', '..'))
sys.path.insert(0, os.path.join(_SRC_PATH, 'third_party', 'protobuf',
                                'python'))

from google.protobuf import descriptor_pb2


# Enum types to be supported by PARSER_KIND_FIELDWISE. Supporting all possible
# enum types used in response fields by default adds 21k of binary size, in
# large part from the string-encoded enums themselves. The allowlist avoids
# those costs except for types where they are known to be used.
PARSER_KIND_FIELDWISE_ENUM_ALLOWLIST = set((
    'ExampleForTestingResponse.ExampleInsideMessageEnum',
    'ExampleForTestingOutsideMessageEnum',
))


def IsEnumTypeNameSupported(type_name: str) -> bool:
    return (type_name.replace('optimization_guide.proto.', '')
            in PARSER_KIND_FIELDWISE_ENUM_ALLOWLIST)


def EnsureEnumAllowlistIsValid(descriptors: DescriptorDb):
    try:
        for enum_name in PARSER_KIND_FIELDWISE_ENUM_ALLOWLIST:
            descriptors.GetEnumDescriptors(
                ['.optimization_guide.proto.' + enum_name])
    except KeyError:
        raise RuntimeError(
            f'enum type {enum_name} was not found among the known enums'
        ) from None


class Error(Exception):
    pass


class Type:
    """Aliases for FieldDescriptorProto::Type(s)."""
    DOUBLE = 1
    FLOAT = 2
    INT64 = 3
    UINT64 = 4
    INT32 = 5
    FIXED64 = 6
    FIXED32 = 7
    BOOL = 8
    STRING = 9
    GROUP = 10
    MESSAGE = 11
    BYTES = 12
    UINT32 = 13
    ENUM = 14
    SFIXED32 = 15
    SFIXED64 = 16
    SINT32 = 17
    SINT64 = 18


@dataclasses.dataclass(frozen=True)
class BaseValueType:
    cpptype: str
    getIfFn: str


class VType:
    """Base::Value types."""
    DOUBLE = BaseValueType("std::optional<double>", "Double")
    BOOL = BaseValueType("std::optional<bool>", "Bool")
    INT = BaseValueType("std::optional<int>", "Int")
    STRING = BaseValueType("std::string*", "String")
    BLOB = BaseValueType("BlobStorage*", "Blob")
    DICT = BaseValueType("Dict*", "Dict")
    LIST = BaseValueType("List*", "List")


BASE_VALUE_TYPES = {
    Type.DOUBLE: VType.DOUBLE,
    Type.FLOAT: VType.DOUBLE,
    Type.INT64: VType.INT,
    Type.UINT64: VType.INT,
    Type.INT32: VType.INT,
    Type.FIXED64: VType.INT,
    Type.FIXED32: VType.INT,
    Type.BOOL: VType.BOOL,
    Type.STRING: VType.STRING,
    Type.GROUP: VType.STRING,  # Not handled
    Type.MESSAGE: VType.DICT,  # Not handled
    Type.BYTES: VType.STRING,  # Not handled
    Type.UINT32: VType.INT,
    Type.ENUM: VType.INT,  # Not handled
    Type.SFIXED32: VType.INT,
    Type.SFIXED64: VType.INT,
    Type.SINT32: VType.INT,
    Type.SINT64: VType.INT,
}


@dataclasses.dataclass(frozen=True)
class Message:
    desc: descriptor_pb2.DescriptorProto
    package: str
    parent_names: tuple[str, ...] = ()

    @functools.cached_property
    def type_name(self) -> str:
        """Returns the value returned for MessageLite::GetTypeName()."""
        return '.'.join((self.package, *self.parent_names, self.desc.name))

    @functools.cached_property
    def cpp_name(self) -> str:
        """Returns the fully qualified c++ type name."""
        namespace = self.package.replace('.', '::')
        classname = '_'.join((*self.parent_names, self.desc.name))
        return f'{namespace}::{classname}'

    @functools.cached_property
    def iname(self) -> str:
        """Returns the identifier piece for generated function names."""
        return '_' + self.type_name.replace('.', '_')

    @functools.cached_property
    def fields(self) -> tuple[Field, ...]:
        return tuple(Field(fdesc) for fdesc in self.desc.field)


@dataclasses.dataclass(frozen=True)
class Field:
    desc: descriptor_pb2.FieldDescriptorProto

    @property
    def tag_number(self):
        return self.desc.number

    @property
    def name(self):
        return self.desc.name

    @property
    def type(self) -> int:
        return self.desc.type

    @property
    def is_repeated(self):
        return self.desc.label == 3

    @property
    def typename(self):
        return self.desc.type_name.replace('.', '_')


@dataclasses.dataclass(frozen=True)
class EnumType:
    desc: descriptor_pb2.EnumDescriptorProto
    package: str
    parent_names: tuple[str, ...] = ()

    @property
    def name(self):
        return self.desc.name

    @functools.cached_property
    def type_name(self) -> str:
        """Returns the value returned for MessageLite::GetTypeName()."""
        return '.'.join((self.package, *self.parent_names, self.desc.name))

    @functools.cached_property
    def cpp_name(self) -> str:
        """Returns the fully qualified c++ type name."""
        namespace = self.package.replace('.', '::')
        typename = '_'.join((*self.parent_names, self.desc.name))
        return f'{namespace}::{typename}'

    @functools.cached_property
    def enclosing_cpp_type(self) -> str:
        """Returns the fully qualified C++ type name enclosing the enum values.

        For enums defined in messages this is the message type rather than the
        enum type. e.g. for ExampleInsideMessageEnum defined within
        optimization_guide::proto::ExampleForTestingResponse this will be
        optimization_guide::proto::ExampleForTestingResponse.

        Using the enclosing type is required because, for enums defined in
        messages, the enum values are only aliased to their expected names
        within the message class. In the enum itself they have names like
        ExampleForTestingResponse_ExampleInsideMessageEnum_VALUE0.
        """
        if not self.parent_names: return self.cpp_name

        namespace = self.package.replace('.', '::')
        classname = '_'.join(self.parent_names)
        return f'{namespace}::{classname}'

    @functools.cached_property
    def values(self):
        return tuple(EnumValue(desc) for desc in self.desc.value)


@dataclasses.dataclass(frozen=True)
class EnumValue:
    desc: descriptor_pb2.EnumValueDescriptorProto

    @property
    def name(self):
        return self.desc.name

    @property
    def number(self):
        return self.desc.number


@dataclasses.dataclass()
class DescriptorDb:
    _file_names: set[str] = dataclasses.field(default_factory=set)
    _known_messages: dict[str,
                          Message] = dataclasses.field(default_factory=dict)
    _known_enums: dict[str, Enum] = dataclasses.field(default_factory=dict)

    def _AddEnumType(self, enum_type: EnumType):
        self._known_enums['.' + enum_type.type_name] = enum_type

    def _AddMessage(self, msg: Message) -> None:
        self._known_messages['.' + msg.type_name] = msg
        for nested_type in msg.desc.nested_type:
            self._AddMessage(
                Message(desc=nested_type,
                        package=msg.package,
                        parent_names=(*msg.parent_names, msg.desc.name)))
        for nested_enum in msg.desc.enum_type:
            self._AddEnumType(
                EnumType(desc=nested_enum,
                         package=msg.package,
                         parent_names=(*msg.parent_names, msg.desc.name)))

    def AddFileDescriptorSet(self,
                             fds: descriptor_pb2.FileDescriptorSet) -> None:
        for f in fds.file:
            if f.package != 'optimization_guide.proto.registry':
                self._file_names.add(f.name)
            for m in f.message_type:
                self._AddMessage(Message(desc=m, package=f.package))
            for e in f.enum_type:
                self._AddEnumType(EnumType(desc=e, package=f.package))

    def GetMessageForField(self, field: Field) -> Message:
        return self._known_messages[field.desc.type_name]

    def GetMessages(self, message_types: set[str]) -> list[Message]:
        return [self._known_messages[t] for t in sorted(message_types)]

    def GetEnumDescriptors(self,
                           enum_types: Iterable[str]) -> Iterable[EnumType]:
        return [self._known_enums[t] for t in sorted(enum_types)]

    def GetAllTransitiveDeps(self, message_types: set[str]) -> list[Message]:
        seen = message_types
        stack = list(message_types)
        while stack:
            msg = self._known_messages[stack.pop()]
            field_types = {
                field.desc.type_name
                for field in msg.fields if field.type == Type.MESSAGE
            }
            stack.extend(field_types - seen)
            seen.update(field_types)
        return self.GetMessages(seen)

    def _GetRegistryMsg(self) -> Message:
        return self._known_messages[
            '.optimization_guide.proto.registry.OnDeviceFeatureProtoRegistry']

    def YieldMessagesWithRole(self, role: str):
        for entry_field in self._GetRegistryMsg().fields:
            logging_data_msg = self._known_messages[entry_field.desc.type_name]
            for field in logging_data_msg.fields:
                if field.name == role:
                    yield field.desc.type_name

    def GetIncludes(self) -> Iterator[str]:
        """Returns the set of includes that cover all known messages types."""
        pattern = re.compile(
            r'.*(components/optimization_guide/proto/.*)\.proto')
        for name in self._file_names:
            if m := pattern.match(name):
                yield m.group(1) + '.pb.h'


def GetReferencedEnumTypeNames(
        writable_messages: Iterable[Message]) -> Iterable[str]:
    for message in writable_messages:
        for field in message.fields:
            if field.type == Type.ENUM:
                yield field.desc.type_name


def GenerateEnumDescriptors(out: IO[str],
                            fds: descriptor_pb2.FileDescriptorSet,
                            descriptors: DescriptorDb):
    responses = set(descriptors.YieldMessagesWithRole('response'))
    writable_messages = descriptors.GetAllTransitiveDeps(responses)

    enum_type_names = GetReferencedEnumTypeNames(writable_messages)
    enum_types = descriptors.GetEnumDescriptors(enum_type_names)

    out.write(
        '// DO NOT MODIFY. GENERATED BY gen_on_device_proto_descriptors.py\n')
    out.write('\n')

    out.write(f'#include <string_view>\n')
    out.write('\n')

    for include in sorted(descriptors.GetIncludes()):
        out.write(f'#include "{include}"\n')
    out.write('\n')

    out.write('namespace optimization_guide {\n')
    out.write('\n')

    out.write('template <typename T>\n')
    out.write('struct EnumTraits {\n')
    out.write('  static_assert(false, "EnumTraits not defined for type T");\n')
    out.write('};\n')
    out.write('\n')

    out.write('template <typename T>\n')
    out.write('struct EnumNameAndValue {\n')
    out.write('  std::string_view name;\n')
    out.write('  T value;\n')
    out.write('};\n')
    out.write('\n')

    for enum_type in enum_types:
        if not IsEnumTypeNameSupported(enum_type.type_name):
            continue

        out.write('template <>\n')
        out.write(f'struct EnumTraits<{enum_type.cpp_name}> {{\n')
        out.write(f'  using Type = {enum_type.cpp_name};\n')
        if enum_type.enclosing_cpp_type == enum_type.cpp_name:
            enclosing_type = 'Type'
        else:
            enclosing_type = enum_type.enclosing_cpp_type
        out.write(f'  using EnclosingType = {enclosing_type};\n')
        out.write('  static constexpr std::array<EnumNameAndValue<Type>, '
                  f'{len(enum_type.values)}> values = {{\n')
        for value in enum_type.values:
            out.write(f'    EnumNameAndValue<Type>{{"{value.name}", '
                      f'EnclosingType::{value.name}}},\n')
        out.write('  };\n')
        out.write('};\n')
        out.write('\n')

    out.write('}  // namespace optimization_guide\n')
    out.write('\n')


def GenerateProtoDescriptors(out: IO[str], descriptors: DescriptorDb):
    """Generate the on_device_model_execution_proto_descriptors.cc content."""

    requests = set(descriptors.YieldMessagesWithRole('request'))
    responses = set(descriptors.YieldMessagesWithRole('response'))
    readable_messages = descriptors.GetAllTransitiveDeps(requests | responses)
    writable_messages = descriptors.GetAllTransitiveDeps(responses)

    out.write(
        '// DO NOT MODIFY. GENERATED BY gen_on_device_proto_descriptors.py\n')
    out.write('\n')

    out.write(
        '#include "components/optimization_guide/core/model_execution/on_device_model_execution_proto_descriptors.h"\n'  # pylint: disable=line-too-long
    )
    out.write('\n')

    includes = set(descriptors.GetIncludes()).union({
        'base/values.h',
        'components/optimization_guide/core/optimization_guide_util.h',
        'components/optimization_guide/core/model_execution/value_converter.h',
    })
    for include in sorted(includes):
        out.write(f'#include "{include}"\n')
    out.write('\n')

    out.write('namespace optimization_guide {\n')
    out.write('\n')
    out.write('namespace {\n')
    _GetProtoValue.GenPrivate(out, readable_messages)
    _SetProtoValueFromString.GenPrivate(out, writable_messages)
    _ConvertValue.GenPrivate(out, writable_messages)
    out.write('}  // namespace\n\n')
    _GetProtoValue.GenPublic(out)
    _GetProtoFromAny.GenPublic(out, readable_messages)
    _BuildMessage.GenPublic(out, writable_messages)
    _SetProtoValueFromString.GenPublic(out)
    _SetProtoFieldString(readable_messages).GenPublic(out)
    _GetProtoMessage(readable_messages).GenPublic(out)
    _GetProtoMutableMessage(readable_messages).GenPublic(out)
    _GetProtoRepeatedSize(readable_messages).GenPublic(out)
    _AddProtoMessage(readable_messages).GenPublic(out)
    _GetProtoMutableRepeatedMessage(readable_messages).GenPublic(out)
    _ConvertValue.GenPublic(out, writable_messages)
    out.write('}  // namespace optimization_guide\n')
    out.write('\n')


class _GetProtoValue:
    """Namespace class for GetProtoValue method builders."""

    @classmethod
    def GenPublic(cls, out: IO[str]):
        out.write("""
          std::optional<proto::Value> GetProtoValue(
              const google::protobuf::MessageLite& msg,
              const proto::ProtoField& proto_field) {
            return GetProtoValue(msg, proto_field, /*index=*/0);
          }
        """)

    @classmethod
    def GenPrivate(cls, out: IO[str], messages: list[Message]):
        out.write("""
          std::optional<proto::Value> GetProtoValue(
              const google::protobuf::MessageLite& msg,
              const proto::ProtoField& proto_field, int32_t index) {
            if (index >= proto_field.proto_descriptors_size()) {
              return std::nullopt;
            }
            int32_t tag_number =
                proto_field.proto_descriptors(index).tag_number();
        """)

        for msg in messages:
            cls._IfMsg(out, msg)
        out.write('return std::nullopt;\n')
        out.write('}\n\n')  # End function

    @classmethod
    def _IfMsg(cls, out: IO[str], msg: Message):
        if msg.type_name == "optimization_guide.proto.Media":
            return
        if all(field.is_repeated for field in msg.fields):
            # Omit the empty case to avoid unused variable warnings.
            return
        out.write(f'if (msg.GetTypeName() == "{msg.type_name}") {{\n')
        out.write(f'const {msg.cpp_name}& casted_msg = ')
        out.write(f'  static_cast<const {msg.cpp_name}&>(msg);\n')
        out.write('switch (tag_number) {\n')
        for field in msg.fields:
            if field.is_repeated:
                continue
            cls._FieldCase(out, field)
        out.write('}\n')  # End switch
        out.write('}\n\n')  # End if statement

    @classmethod
    def _FieldCase(cls, out: IO[str], field: Field):
        out.write(f'case {field.tag_number}: {{\n')
        name = f'casted_msg.{field.name}()'
        if field.type == Type.MESSAGE:
            out.write(f'return GetProtoValue({name}, proto_field, index+1);\n')
        else:
            out.write('proto::Value value;\n')
            if field.type in {Type.DOUBLE, Type.FLOAT}:
                out.write(
                    f'value.set_float_value(static_cast<double>({name}));\n')
            elif field.type in {Type.INT64, Type.UINT64}:
                out.write(
                    f'value.set_int64_value(static_cast<int64_t>({name}));\n')
            elif field.type in {Type.INT32, Type.UINT32, Type.ENUM}:
                out.write(
                    f'value.set_int32_value(static_cast<int32_t>({name}));\n')
            elif field.type in {Type.BOOL}:
                out.write(f'value.set_boolean_value({name});\n')
            elif field.type in {Type.STRING}:
                out.write(f'value.set_string_value({name});\n')
            else:
                raise Error()
            out.write('return value;\n')
        out.write('}\n')  # End case


class _GetProtoFromAny:
    """Namespace class for GetProtoFromAny method builders."""

    @classmethod
    def GenPublic(cls, out: IO[str], messages: list[Message]):
        out.write("""
          std::unique_ptr<google::protobuf::MessageLite> GetProtoFromAny(
              const proto::Any& msg) {
        """)

        for msg in messages:
            cls._IfMsg(out, msg)
        out.write('return nullptr;\n')
        out.write('}\n\n')  # End function

    @classmethod
    def _IfMsg(cls, out: IO[str], msg: Message):
        out.write(f"""if (msg.type_url() ==
                    "type.googleapis.com/{msg.type_name}") {{
            """)
        out.write(
            f'auto casted_msg = ParsedAnyMetadata<{msg.cpp_name}>(msg);\n')
        out.write("""
            std::unique_ptr<google::protobuf::MessageLite> copy(
                casted_msg->New());\n
        """)
        out.write('copy->CheckTypeAndMergeFrom(*casted_msg);\n')
        out.write('return copy;\n')
        out.write('}\n\n')  # End if statement


class _GetProtoMessage:
    """Code generator for _GetProtoMessage."""

    def __init__(self, supported_messages: list[Message]):
        self._supported_messages = supported_messages

    def GenPublic(self, out: IO[str]):
        out.write("""
          const google::protobuf::MessageLite* GetProtoMessage(
              const google::protobuf::MessageLite* msg,
              int32_t tag_number) {
          """)
        for msg in self._supported_messages:
            self._IfMsg(out, msg)
        out.write('return nullptr;\n')
        out.write('}\n\n')  # End function

    def IsSupported(self, field: Field) -> bool:
        return field.type == Type.MESSAGE and not field.is_repeated

    def _IfMsg(self, out: IO[str], msg: Message):
        if not any(self.IsSupported(field) for field in msg.fields):
            return
        out.write(f'if (msg->GetTypeName() == "{msg.type_name}") {{\n')
        out.write(
            f'auto* typed_msg = static_cast<const {msg.cpp_name}*>(msg);\n')
        out.write('switch (tag_number) {\n')
        for field in msg.fields:
            if self.IsSupported(field):
                self.FieldCase(out, msg, field)
        out.write('}\n')  # End switch
        out.write('}\n\n')  # End if statement

    def FieldCase(self, out: IO[str], msg: Message, field: Field):
        out.write(f'case {field.tag_number}: {{\n')
        out.write(f'return &typed_msg->{field.name}();\n')
        out.write('}\n')  # End case


class _GetProtoMutableMessage:
    """Code generator for _GetProtoMutableMessage."""

    def __init__(self, supported_messages: list[Message]):
        self._supported_messages = supported_messages

    def GenPublic(self, out: IO[str]):
        out.write("""
          google::protobuf::MessageLite* GetProtoMutableMessage(
              google::protobuf::MessageLite* msg,
              int32_t tag_number) {
          """)
        for msg in self._supported_messages:
            self._IfMsg(out, msg)
        out.write('return nullptr;\n')
        out.write('}\n\n')  # End function

    def IsSupported(self, field: Field) -> bool:
        return field.type == Type.MESSAGE and not field.is_repeated

    def _IfMsg(self, out: IO[str], msg: Message):
        if not any(self.IsSupported(field) for field in msg.fields):
            return
        out.write(f'if (msg->GetTypeName() == "{msg.type_name}") {{\n')
        out.write(f'auto* typed_msg = static_cast<{msg.cpp_name}*>(msg);\n')
        out.write('switch (tag_number) {\n')
        for field in msg.fields:
            if self.IsSupported(field):
                self.FieldCase(out, msg, field)
        out.write('}\n')  # End switch
        out.write('}\n\n')  # End if statement

    def FieldCase(self, out: IO[str], msg: Message, field: Field):
        out.write(f'case {field.tag_number}: {{\n')
        out.write(f'return typed_msg->mutable_{field.name}();\n')
        out.write('}\n')  # End case


class _AddProtoMessage:
    """Code generator for _AddProtoMessage."""

    def __init__(self, supported_messages: list[Message]):
        self._supported_messages = supported_messages

    def GenPublic(self, out: IO[str]):
        out.write("""
          int AddProtoMessage(
              google::protobuf::MessageLite* msg,
              int32_t tag_number) {
          """)
        for msg in self._supported_messages:
            self._IfMsg(out, msg)
        out.write('return 0;\n')
        out.write('}\n\n')  # End function

    def IsSupported(self, field: Field) -> bool:
        return field.type == Type.MESSAGE and field.is_repeated

    def _IfMsg(self, out: IO[str], msg: Message):
        if not any(self.IsSupported(field) for field in msg.fields):
            return
        out.write(f'if (msg->GetTypeName() == "{msg.type_name}") {{\n')
        out.write(f'auto* typed_msg = static_cast<{msg.cpp_name}*>(msg);\n')
        out.write('switch (tag_number) {\n')
        for field in msg.fields:
            if self.IsSupported(field):
                self.FieldCase(out, msg, field)
        out.write('}\n')  # End switch
        out.write('}\n\n')  # End if statement

    def FieldCase(self, out, msg: Message, field: Field):
        out.write(f'case {field.tag_number}: {{\n')
        out.write(f'typed_msg->add_{field.name}();\n')
        out.write(f'return typed_msg->{field.name}_size();\n')
        out.write('}\n')  # End case


class _GetProtoRepeatedSize:
    """Code generator for _AddProtoMessage."""

    def __init__(self, supported_messages: list[Message]):
        self._supported_messages = supported_messages

    def GenPublic(self, out: IO[str]):
        out.write("""
          int GetProtoRepeatedSize(
              const google::protobuf::MessageLite* msg,
              int32_t tag_number) {
          """)
        for msg in self._supported_messages:
            self._IfMsg(out, msg)
        out.write('return 0;\n')
        out.write('}\n\n')  # End function

    def IsSupported(self, field: Field) -> bool:
        return field.type == Type.MESSAGE and field.is_repeated

    def _IfMsg(self, out: IO[str], msg: Message):
        if not any(self.IsSupported(field) for field in msg.fields):
            return
        out.write(f'if (msg->GetTypeName() == "{msg.type_name}") {{\n')
        out.write(
            f'auto* typed_msg = static_cast<const {msg.cpp_name}*>(msg);\n')
        out.write('switch (tag_number) {\n')
        for field in msg.fields:
            if self.IsSupported(field):
                self.FieldCase(out, msg, field)
        out.write('}\n')  # End switch
        out.write('}\n\n')  # End if statement

    def FieldCase(self, out: IO[str], msg: Message, field: Field):
        out.write(f'case {field.tag_number}: {{\n')
        out.write(f'return typed_msg->{field.name}_size();\n')
        out.write('}\n')  # End case


class _GetProtoMutableRepeatedMessage:
    """Namespace class for GetProtoMutableRepeatedMessage method builder."""

    def __init__(self, supported_messages: list[Message]):
        self._supported_messages = supported_messages

    def GenPublic(self, out: IO[str]):
        out.write("""
          google::protobuf::MessageLite* GetProtoMutableRepeatedMessage(
              google::protobuf::MessageLite* parent,
              int32_t tag_number,
              int offset) {\n
        """)
        for msg in self._supported_messages:
            self._IfMsg(out, msg)
        out.write('return nullptr;\n')
        out.write('}\n\n')  # End function

    def IsSupported(self, field: Field) -> bool:
        return field.type == Type.MESSAGE and field.is_repeated

    def _IfMsg(self, out: IO[str], msg: Message):
        if not any(self.IsSupported(field) for field in msg.fields):
            return
        out.write(f'if (parent->GetTypeName() == "{msg.type_name}") {{\n')
        out.write(f'auto* typed_msg = static_cast<{msg.cpp_name}*>(parent);\n')
        out.write('switch (tag_number) {\n')
        for field in msg.fields:
            if self.IsSupported(field):
                self.FieldCase(out, msg, field)
        out.write('}\n')  # End switch
        out.write('}\n\n')  # End if statement

    def FieldCase(self, out: IO[str], msg: Message, field: Field):
        out.write(f'case {field.tag_number}: {{\n')
        out.write(f'if (offset >= typed_msg->{field.name}_size()) {{'
                  f'return nullptr; }};\n')
        out.write(f'return typed_msg->mutable_{field.name}(offset);\n')
        out.write('}\n')  # End case


class _SetProtoFieldString:
    """Code generator for SetProtoField with a string argument."""

    def __init__(self, supported_messages: list[Message]):
        self._supported_messages = supported_messages

    def GenPublic(self, out: IO[str]):
        out.write("""
          ProtoStatus SetProtoField(
              google::protobuf::MessageLite* msg,
              int32_t tag_number,
              const std::string& value) {
          """)
        for msg in self._supported_messages:
            self._IfMsg(out, msg)
        out.write('return ProtoStatus::kError;\n')
        out.write('}\n\n')  # End function

    def IsSupported(self, field: Field) -> bool:
        return field.type == Type.STRING and not field.is_repeated

    def _IfMsg(self, out, msg: Message):
        if not any(self.IsSupported(field) for field in msg.fields):
            return
        out.write(f'if (msg->GetTypeName() == "{msg.type_name}") {{\n')
        out.write(f'auto* typed_msg = static_cast<{msg.cpp_name}*>(msg);\n')
        out.write('switch (tag_number) {\n')
        for field in msg.fields:
            if self.IsSupported(field):
                self.FieldCase(out, msg, field)
        out.write('}\n')  # End switch
        out.write('}\n\n')  # End if statement

    def FieldCase(self, out, msg: Message, field: Field):
        out.write(f'case {field.tag_number}: {{\n')
        out.write(f'typed_msg->set_{field.name}(value);\n')
        out.write(f'return ProtoStatus::kOk;\n')
        out.write('}\n')  # End case


class _BuildMessage:
    """Namespace class for BuildMessage method builders."""

    @classmethod
    def GenPublic(cls, out: IO[str], messages: list[Message]):
        out.write('std::unique_ptr<google::protobuf::MessageLite> ')
        out.write('BuildMessage(\n')
        out.write('    const std::string& proto_name) {\n')
        for msg in messages:
            cls._IfMsg(out, msg)
        out.write('  return nullptr;\n')
        out.write('}\n')

    @classmethod
    def _IfMsg(cls, out: IO[str], msg: Message):
        out.write(f'if (proto_name == "{msg.type_name}") {{\n')
        out.write(f'  return std::make_unique<{msg.cpp_name}>();\n')
        out.write('}\n')


class _SetProtoValueFromString:
    """Namespace class for SetProtoValueFromString method builders."""

    @classmethod
    def GenPublic(cls, out: IO[str]):
        out.write("""
      ProtoStatus SetProtoValueFromString(
          google::protobuf::MessageLite* msg,
          const proto::ProtoField& proto_field,
          const std::string& value) {
        return SetProtoValueFromString(msg, proto_field, value, /*index=*/0);
      }
    """)

    @classmethod
    def GenPrivate(cls, out: IO[str], messages: list[Message]):
        out.write("""
      ProtoStatus SetProtoValueFromString(
          google::protobuf::MessageLite* msg,
          const proto::ProtoField& proto_field,
          const std::string& value,
          int32_t index) {
        if (index >= proto_field.proto_descriptors_size()) {
          return ProtoStatus::kError;
        }
    """)
        for msg in messages:
            cls._IfMsg(out, msg)
        out.write("""
        return ProtoStatus::kError;
      }
    """)

    @classmethod
    def _IsSupported(cls, field: Field):
        if field.is_repeated or field.type == Type.MESSAGE:
            return False

        if field.type == Type.ENUM:
            if not IsEnumTypeNameSupported(field.typename):
                return False

        return True

    @classmethod
    def _IfMsg(cls, out: IO[str], msg: Message):
        if not any(cls._IsSupported(field) for field in msg.fields):
            return

        out.write(f'if (msg->GetTypeName() == "{msg.type_name}") {{\n')
        out.write(f'  auto* typed_msg = static_cast<{msg.cpp_name}*>(msg);\n')
        out.write(
            '  switch (proto_field.proto_descriptors(index).tag_number()) {\n')
        for field in msg.fields:
            if cls._IsSupported(field):
                cls._FieldCase(out, msg, field)
        out.write('    default:\n')
        out.write('      return ProtoStatus::kError;\n')
        out.write('  }\n')
        out.write('  return ProtoStatus::kOk;\n')
        out.write('}\n')  # End if statement

    @classmethod
    def _FieldCase(cls, out: IO[str], msg: Message, field: Field):
        out.write(f'    case {field.tag_number}: {{\n')
        if field.type == Type.STRING:
            out.write(f'      typed_msg->set_{field.name}(value);\n')
        else:
            out.write('      using FieldType = '
                      f'decltype(typed_msg->{field.name}());\n')
            out.write(
                '      base::expected<FieldType, ProtoStatus> result =\n'
                '          ValueConverter<FieldType>::TryConvertFromString('
                'value);\n')
            out.write('      if (!result.has_value()) {\n')

            out.write('        return ProtoStatus::kError;\n')
            out.write('      }\n')
            out.write(f'      typed_msg->set_{field.name}(result.value());\n')
        out.write('      break;\n')
        out.write('    }\n')


class _ConvertValue:
    """Namespace class for base::Value->Message method builders."""

    @classmethod
    def GenPublic(cls, out: IO[str], messages: list[Message]):
        out.write(f"""
          std::optional<proto::Any> ConvertToAnyWrappedProto(
              const base::Value& object, const std::string& type_name) {{
            proto::Any any;
            any.set_type_url("type.googleapis.com/" + type_name);
        """)
        for msg in messages:
            out.write(f"""
            if (type_name == "{msg.type_name}") {{
              {msg.cpp_name} msg;
              if (Convert{msg.iname}(object, msg)) {{
                msg.SerializeToString(any.mutable_value());
                return any;
              }}
            }}
          """)

        out.write(f"""
            return std::nullopt;
          }}
        """)

    @classmethod
    def GenPrivate(cls, out: IO[str], messages: list[Message]):
        for msg in messages:
            out.write(f"""
            bool Convert{msg.iname}(
                const base::Value& object, {msg.cpp_name}& proto);
          """)
        for msg in messages:
            cls._DefineConvert(out, msg)

    @classmethod
    def _DefineConvert(cls, out: IO[str], msg: Message):
        out.write(f"""
          bool Convert{msg.iname}(
              const base::Value& object, {msg.cpp_name}& proto) {{
            const base::Value::Dict* asdict = object.GetIfDict();
            if (!asdict) {{
              return false;
            }}
        """)
        for field in msg.fields:
            if field.type == Type.GROUP:
                continue
            if field.type == Type.ENUM:
                continue
            out.write('if (const base::Value* field_value =\n')
            out.write(f'     asdict->Find("{field.desc.json_name}")) {{')
            cls._FieldCase(out, msg, field)
            out.write(f'}}')
        out.write(f"""
            return true;
          }}
        """)

    @classmethod
    def _FieldCase(cls, out: IO[str], msg: Message, field: Field):
        if field.is_repeated:
            out.write(f"""
              const auto* lst = field_value->GetIfList();
              if (!lst) {{
                return false;
              }}
              for (const base::Value& entry_value : *lst) {{
            """)
            if field.type == Type.MESSAGE:
                out.write(f"""
                  if (!Convert{field.typename}(
                      entry_value, *proto.add_{field.name}())) {{
                    return false;
                  }}
                """)
            else:
                vtype = BASE_VALUE_TYPES[field.type]
                out.write(f"""
                  const {vtype.cpptype} v = entry_value.GetIf{vtype.getIfFn}();
                  if (!v) {{
                    return false;
                  }}
                  proto.add_{field.name}(*v);
                """)
            out.write("}")  # end for loop
        else:
            if field.type == Type.MESSAGE:
                out.write(f"""
                  if (!Convert{field.typename}(
                      *field_value, *proto.mutable_{field.name}())) {{
                    return false;
                  }}
                """)
                return
            else:
                vtype = BASE_VALUE_TYPES[field.type]
                out.write(f"""
                  const {vtype.cpptype} v = field_value->GetIf{vtype.getIfFn}();
                  if (!v) {{
                    return false;
                  }}
                  proto.set_{field.name}(*v);
                """)


def main(argv):
    parser = optparse.OptionParser()
    parser.add_option('--input_file', action='append', default=[])
    parser.add_option('--proto_descriptors_cc')
    parser.add_option('--enum_templates_h')
    options, _ = parser.parse_args(argv)

    input_files = list(options.input_file)

    # Write to standard output or file specified by --proto_descriptors_cc.
    out_cc = getattr(sys.stdout, 'buffer', sys.stdout)
    if options.proto_descriptors_cc:
        out_cc = open(options.proto_descriptors_cc, 'wb')

    descriptors = DescriptorDb()
    for input_file in input_files:
        fds = descriptor_pb2.FileDescriptorSet()
        with open(input_file, 'rb') as fp:
            fds.ParseFromString(fp.read())
            descriptors.AddFileDescriptorSet(fds)

    out_cc_str = StringIO()
    GenerateProtoDescriptors(out_cc_str, descriptors)
    out_cc.write(out_cc_str.getvalue().encode('utf-8'))

    if options.proto_descriptors_cc:
        out_cc.close()

    if options.enum_templates_h:
        EnsureEnumAllowlistIsValid(descriptors)
        with open(options.enum_templates_h, 'w') as out:
            GenerateEnumDescriptors(out, fds, descriptors)

    return 0


if __name__ == '__main__':
    sys.exit(main(sys.argv[1:]))