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// cs/net/rpc/rpc.hh
#ifndef CS_NET_RPC_RPC_HH
#define CS_NET_RPC_RPC_HH
#include <iomanip>
#include <iostream>
#include <map>
#include <sstream>
#include <string>
#include <type_traits>
#include "cs/log.hh"
#include "cs/net/http/request.hh"
#include "cs/net/http/response.hh"
#include "cs/net/json/object.hh"
#include "cs/result.hh"
#include "cs/util/di/context.gpt.hh"
// Requires four arguments. Use ::cs::util::di::Context<>
// (or CTX()) as ctx_ when the RPC does not use context.
#define DECLARE_RPC(rpc_, req_, res_, ctx_) \
class rpc_ : public ::cs::net::rpc::RPCBaseSelector< \
rpc_, req_, res_, ctx_>::type { \
public: \
using Base = \
::cs::net::rpc::RPCBaseSelector<rpc_, req_, res_, \
ctx_>::type; \
using Base::Base; \
cs::ResultOr<res_> Process( \
const req_& request) override; \
};
#define IMPLEMENT_RPC(rpc_, req_, res_) \
::cs::ResultOr<res_> rpc_::Process(const req_& request)
namespace cs::net::rpc {
std::string QueryParamsToJson(
std::map<std::string, std::string> map);
// Helper to match Content-Type against a base media type,
// ignoring parameters like charset.
inline bool MatchesContentType(
const std::string& content_type,
const std::string& expected) {
std::string base = content_type;
size_t semi = content_type.find(';');
if (semi != std::string::npos) {
base = content_type.substr(0, semi);
}
while (!base.empty() &&
static_cast<unsigned char>(base.back()) <= ' ') {
base.pop_back();
}
return base == expected;
}
template <typename T>
ResultOr<T> ExtractProtoFromRequest(
cs::net::http::Request request) {
std::string json_body = "{}";
if (request.method() == "GET") {
json_body = QueryParamsToJson(request._query_params);
} else if (request.method() == "POST" ||
request.method() == "PUT" ||
request.method() == "PATCH" ||
request.method() == "DELETE") {
// Determine content type, default to the HTML form.
std::string content_type;
if (request.headers().count("Content-Type") > 0) {
content_type = request.headers()["Content-Type"];
} else {
LOG(WARNING)
<< "No Content-Type header found, "
<< "defaulting to "
<< cs::net::http::kContentTypeXWwwFormUrlEncoded
<< ENDL;
content_type =
cs::net::http::kContentTypeXWwwFormUrlEncoded;
}
// Use content type to parse user's input data.
if (MatchesContentType(
content_type,
cs::net::http::
kContentTypeXWwwFormUrlEncoded)) {
std::map<std::string, std::string> form_data =
request.ParseFormUrlEncoded(request.body());
json_body = QueryParamsToJson(form_data);
} else if (MatchesContentType(
content_type,
cs::net::http::
kContentTypeApplicationJson)) {
json_body = request.body();
}
} else {
return cs::InvalidArgument("Unknown HTTP method '" +
request.method() + "'");
}
return T().Parse(json_body);
};
// Consolidated RPC: 4 template params, use
// ::cs::util::di::Context<> when no context.
// HttpHandler(Request, AppCtx&) receives context
// as second parameter.
template <typename Implementation, typename RequestProto,
typename ResponseProto, typename ContextType>
class RPC {
public:
using RequestType = RequestProto;
using ResponseType = ResponseProto;
template <typename AppCtx = ContextType>
static cs::net::http::Response HttpHandler(
cs::net::http::Request request, AppCtx& ctx) {
RequestProto request_proto;
SET_OR_RET(
request_proto,
ExtractProtoFromRequest<RequestProto>(request));
Implementation implementation(ctx);
SET_OR_RET(ResponseProto response,
implementation.Process(request_proto));
return cs::net::http::Response(
cs::net::http::HTTP_200_OK,
cs::net::http::kContentTypeApplicationJson,
response.Serialize());
}
RPC() : ctx_(nullptr) {}
template <typename Ctx>
explicit RPC(Ctx& ctx) : ctx_(InitContext(ctx)) {
if constexpr (!std::is_same_v<
ContextType,
::cs::util::di::Context<>>) {
static_assert(
cs::util::di::SubsetOf<ContextType, Ctx>::value,
"Context must provide all types required by this "
"RPC");
}
}
template <typename Ctx>
static ContextType* InitContext(Ctx& ctx) {
if constexpr (std::is_same_v<
ContextType,
::cs::util::di::Context<>>) {
(void)ctx;
static ::cs::util::di::Context<> default_ctx;
return &default_ctx;
} else {
return &ctx;
}
}
virtual ~RPC() = default;
virtual ResultOr<ResponseProto> Process(
const RequestProto& request) = 0;
protected:
ResultOr<ContextType*> GetContext() const {
if (ctx_ == nullptr) {
return cs::InvalidArgument("Context not set");
}
return ctx_;
}
private:
ContextType* ctx_;
};
template <typename Rpc, typename Req, typename Res,
typename Ctx>
struct RPCBaseSelector {
using type = RPC<Rpc, Req, Res, Ctx>;
};
} // namespace cs::net::rpc
#endif // CS_NET_RPC_RPC_HH