From 05df0a37b18228109cfa592b4fa2d78331383e6e Mon Sep 17 00:00:00 2001
From: David Given <dg@cowlark.com>
Date: Fri, 14 May 2021 23:29:16 +0200
Subject: [PATCH] Add (pretty basic) config dumping and documentation help.

---
 lib/flags.cc          | 40 ++++++++++++++++++++++++++++++++++++++++
 lib/proto.cc          | 21 +++++++++++++++++++++
 lib/proto.h           |  3 +++
 src/fe-read.cc        |  5 -----
 tests/proto.cc        | 19 +++++++++++++++++++
 tests/testproto.proto |  4 +++-
 6 files changed, 86 insertions(+), 6 deletions(-)

diff --git a/lib/flags.cc b/lib/flags.cc
index 1e5bae3d..0831e1e1 100644
--- a/lib/flags.cc
+++ b/lib/flags.cc
@@ -3,6 +3,7 @@
 #include "proto.h"
 #include "utils.h"
 #include "fmt/format.h"
+#include <google/protobuf/text_format.h>
 #include <regex>
 
 static FlagGroup* currentFlagGroup;
@@ -10,6 +11,8 @@ static std::vector<Flag*> all_flags;
 static std::map<const std::string, Flag*> flags_by_name;
 
 static void doHelp();
+static void doShowConfig();
+static void doDoc();
 
 static FlagGroup helpGroup;
 static ActionFlag helpFlag = ActionFlag(
@@ -17,6 +20,16 @@ static ActionFlag helpFlag = ActionFlag(
     "Shows the help.",
     doHelp);
 
+static ActionFlag showConfigFlag = ActionFlag(
+    { "--show-config", "-c" },
+    "Shows the currently set configuration and halts.",
+    doShowConfig);
+
+static ActionFlag docFlag = ActionFlag(
+    { "--doc" },
+    "Shows the available configuration options.",
+    doDoc);
+
 FlagGroup::FlagGroup(const std::initializer_list<FlagGroup*> groups):
     _groups(groups.begin(), groups.end())
 {
@@ -239,3 +252,30 @@ static void doHelp()
     }
     exit(0);
 }
+
+static void doShowConfig()
+{
+	std::string s;
+	google::protobuf::TextFormat::PrintToString(config, &s);
+	std::cout << s << '\n';
+
+	exit(0);
+}
+
+static void doDoc()
+{
+	const auto fields = findAllProtoFields(&config);
+	for (const auto field : fields)
+	{
+		const std::string& path = field.first;
+		const google::protobuf::FieldDescriptor* f = field.second;
+
+		if (f->type() == google::protobuf::FieldDescriptor::TYPE_MESSAGE)
+			continue;
+
+		std::string helpText = f->options().GetExtension(help);
+		std::cout << fmt::format("{}: {}\n", path, helpText);
+	}
+
+	exit(0);
+}
diff --git a/lib/proto.cc b/lib/proto.cc
index 6004e8e0..4f1c227b 100644
--- a/lib/proto.cc
+++ b/lib/proto.cc
@@ -132,3 +132,24 @@ std::set<unsigned> iterate(const RangeProto& range)
 	return set;
 }
 
+std::map<std::string, const google::protobuf::FieldDescriptor*> findAllProtoFields(google::protobuf::Message* message)
+{
+	std::map<std::string, const google::protobuf::FieldDescriptor*> fields;
+	const auto* descriptor = message->GetDescriptor();
+
+	std::function<void(const google::protobuf::Descriptor*, const std::string&)> recurse =
+		[&](auto* d, const auto& s) {
+			for (int i=0; i<d->field_count(); i++)
+			{
+				const google::protobuf::FieldDescriptor* f = d->field(i);
+				std::string n = s + f->name();
+				if (f->type() == google::protobuf::FieldDescriptor::TYPE_MESSAGE)
+					recurse(f->message_type(), n + ".");
+				fields[n] = f;
+			}
+		};
+
+	recurse(descriptor, "");
+	return fields;
+}
+
diff --git a/lib/proto.h b/lib/proto.h
index dde58cc2..77f91de9 100644
--- a/lib/proto.h
+++ b/lib/proto.h
@@ -12,6 +12,9 @@ extern void setProtoByString(google::protobuf::Message* message, const std::stri
 
 extern std::set<unsigned> iterate(const RangeProto& range);
 
+extern std::map<std::string, const google::protobuf::FieldDescriptor*>
+		findAllProtoFields(google::protobuf::Message* message);
+
 extern ConfigProto config;
 
 #endif
diff --git a/src/fe-read.cc b/src/fe-read.cc
index 457ecf33..8bf304c5 100644
--- a/src/fe-read.cc
+++ b/src/fe-read.cc
@@ -28,11 +28,6 @@ int mainRead(int argc, const char* argv[])
 	if (!config.has_input() || !config.has_output())
 		Error() << "incomplete config (did you remember to specify the format?)";
 
-	std::string s;
-	google::protobuf::TextFormat::PrintToString(config, &s);
-	std::cout << s << '\n';
-	exit(0);
-
 	std::unique_ptr<FluxSource> fluxSource(FluxSource::create(config.input().disk()));
 	std::unique_ptr<AbstractDecoder> decoder(AbstractDecoder::create(config.decoder()));
 	std::unique_ptr<ImageWriter> writer(ImageWriter::create(config.output().file()));
diff --git a/tests/proto.cc b/tests/proto.cc
index 2fc204cb..12184b57 100644
--- a/tests/proto.cc
+++ b/tests/proto.cc
@@ -98,12 +98,31 @@ static void test_range(void)
 	}
 }
 
+static void test_fields(void)
+{
+	TestProto proto;
+	auto fields = findAllProtoFields(&proto);
+	AssertThat(fields, HasLength(13));
+}
+
+static void test_options(void)
+{
+	TestProto proto;
+	const auto* descriptor = proto.descriptor();
+	const auto* field = descriptor->FindFieldByName("i64");
+	const auto& options = field->options();
+	const std::string s = options.GetExtension(help);
+	AssertThat(s, Equals("i64"));
+}
+
 int main(int argc, const char* argv[])
 {
 	test_setting();
 	test_config();
 	test_load();
 	test_range();
+	test_fields();
+	test_options();
     return 0;
 }
 
diff --git a/tests/testproto.proto b/tests/testproto.proto
index aef9ec46..5ce39e83 100644
--- a/tests/testproto.proto
+++ b/tests/testproto.proto
@@ -1,11 +1,13 @@
 syntax = "proto2";
 
+import "lib/common.proto";
+
 message TestProto {
 	message SubMessageProto {
 		optional string s = 1;
 	}
 
-	optional int64 i64 = 1;
+	optional int64 i64 = 1 [(help)="i64"];
 	optional int32 i32 = 2;
 	optional uint64 u64 = 3;
 	optional uint32 u32 = 4;