Make plugin use betterproto generated classes internally

This means the betterproto plugin no longer needs to depend durectly on
protobuf.

This requires a small runtime hack to monkey patch some google types to
get around the fact that the compiler uses proto2, but betterproto
expects proto3.

Also:
- regenerate google.protobuf package
- fix a regex bug in the logic for determining whether to use a google
  wrapper type.
- fix a bug causing comments to get mixed up when multiple proto files
  generate code into a single python module

Author: nat-n

README.md

@@ -443,9 +443,9 @@ Assuming your `google.protobuf` source files (included with all releases of `pro
 
 ```sh
 protoc \
-    --plugin=protoc-gen-custom=betterproto/plugin.py \
+    --plugin=protoc-gen-custom=src/betterproto/plugin/main.py \
     --custom_opt=INCLUDE_GOOGLE \
-    --custom_out=betterproto/lib \
+    --custom_out=src/betterproto/lib \
     -I /usr/local/include/ \
     /usr/local/include/google/protobuf/*.proto
 ```

src/betterproto/__init__.py

@@ -1172,6 +1172,7 @@ def which_one_of(message: Message, group_name: str) -> Tuple[str, Optional[Any]]
     BytesValue,
     DoubleValue,
     Duration,
+    EnumValue,
     FloatValue,
     Int32Value,
     Int64Value,
@@ -1238,14 +1239,17 @@ def from_dict(self: T, value: Any) -> T:
 
 def _get_wrapper(proto_type: str) -> Type:
     """Get the wrapper message class for a wrapped type."""
+
+    # TODO: include ListValue and NullValue?
     return {
         TYPE_BOOL: BoolValue,
+        TYPE_BYTES: BytesValue,
+        TYPE_DOUBLE: DoubleValue,
+        TYPE_FLOAT: FloatValue,
+        TYPE_ENUM: EnumValue,
         TYPE_INT32: Int32Value,
-        TYPE_UINT32: UInt32Value,
         TYPE_INT64: Int64Value,
-        TYPE_UINT64: UInt64Value,
-        TYPE_FLOAT: FloatValue,
-        TYPE_DOUBLE: DoubleValue,
         TYPE_STRING: StringValue,
-        TYPE_BYTES: BytesValue,
+        TYPE_UINT32: UInt32Value,
+        TYPE_UINT64: UInt64Value,
     }[proto_type]

src/betterproto/lib/google/protobuf/__init__.py

@@ -3,26 +3,33 @@
 import os
 import sys
 
-from google.protobuf.compiler import plugin_pb2 as plugin
+from betterproto.lib.google.protobuf.compiler import (
+    CodeGeneratorRequest,
+    CodeGeneratorResponse,
+)
 
 from betterproto.plugin.parser import generate_code
+from betterproto.plugin.models import monkey_patch_oneof_index
 
 
 def main() -> None:
     """The plugin's main entry point."""
     # Read request message from stdin
     data = sys.stdin.buffer.read()
 
+    # Apply Work around for proto2/3 difference in protoc messages
+    monkey_patch_oneof_index()
+
     # Parse request
-    request = plugin.CodeGeneratorRequest()
-    request.ParseFromString(data)
+    request = CodeGeneratorRequest()
+    request.parse(data)
 
     dump_file = os.getenv("BETTERPROTO_DUMP")
     if dump_file:
         dump_request(dump_file, request)
 
     # Create response
-    response = plugin.CodeGeneratorResponse()
+    response = CodeGeneratorResponse()
 
     # Generate code
     generate_code(request, response)
@@ -34,7 +41,7 @@ def main() -> None:
     sys.stdout.buffer.write(output)
 
 
-def dump_request(dump_file: str, request: plugin.CodeGeneratorRequest) -> None:
+def dump_request(dump_file: str, request: CodeGeneratorRequest) -> None:
     """
     For developers: Supports running plugin.py standalone so its possible to debug it.
     Run protoc (or generate.py) with BETTERPROTO_DUMP="yourfile.bin" to write the request to a file.