cast/streaming/sender_message.cc

// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "cast/streaming/sender_message.h"

#include <utility>
#include <variant>

#include "cast/streaming/message_fields.h"
#include "util/base64.h"
#include "util/enum_name_table.h"
#include "util/json/json_helpers.h"
#include "util/json/json_serialization.h"
#include "util/string_util.h"

namespace openscreen::cast {

namespace {

EnumNameTable<SenderMessage::Type, 4> kMessageTypeNames{
    {{kMessageTypeOffer, SenderMessage::Type::kOffer},
     {"GET_CAPABILITIES", SenderMessage::Type::kGetCapabilities},
     {"RPC", SenderMessage::Type::kRpc},
     {"INPUT", SenderMessage::Type::kInput}}};

SenderMessage::Type GetMessageType(const Json::Value& root) {
  std::string type;
  if (!json::TryParseString(root[kMessageType], &type)) {
    return SenderMessage::Type::kUnknown;
  }
  string_util::AsciiStrToUpper(type);
  ErrorOr<SenderMessage::Type> parsed = GetEnum(kMessageTypeNames, type);

  return parsed.value(SenderMessage::Type::kUnknown);
}

}  // namespace

// static
ErrorOr<SenderMessage> SenderMessage::Parse(const Json::Value& value) {
  if (!value) {
    return Error(Error::Code::kParameterInvalid, "Empty JSON");
  }

  SenderMessage message;
  if (!json::TryParseInt(value[kSequenceNumber], &(message.sequence_number))) {
    message.sequence_number = -1;
  }

  message.type = GetMessageType(value);
  switch (message.type) {
    case Type::kOffer: {
      Offer offer;
      if (Offer::TryParse(value[kOfferMessageBody], &offer).ok()) {
        message.body = std::move(offer);
        message.valid = true;
      }
    } break;

    case Type::kRpc: {
      std::string rpc_body;
      std::vector<uint8_t> rpc;
      if (json::TryParseString(value[kRpcMessageBody], &rpc_body) &&
          base64::Decode(rpc_body, &rpc)) {
        message.body = rpc;
        message.valid = true;
      }
    } break;

    case Type::kInput: {
      std::string input_body;
      std::vector<uint8_t> input;
      if (json::TryParseString(value[kInputMessageBody], &input_body) &&
          base64::Decode(input_body, &input)) {
        message.body = input;
        message.valid = true;
      }
    } break;

    case Type::kGetCapabilities:
      message.valid = true;
      break;

    default:
      break;
  }

  return message;
}

ErrorOr<Json::Value> SenderMessage::ToJson() const {
  OSP_CHECK(type != SenderMessage::Type::kUnknown)
      << "Trying to send an unknown message is a developer error";

  Json::Value root;
  ErrorOr<const char*> message_type = GetEnumName(kMessageTypeNames, type);
  root[kMessageType] = message_type.value();
  if (sequence_number >= 0) {
    root[kSequenceNumber] = sequence_number;
  }

  switch (type) {
    case SenderMessage::Type::kOffer:
      root[kOfferMessageBody] = std::get<Offer>(body).ToJson();
      break;

    case SenderMessage::Type::kRpc:
      root[kRpcMessageBody] =
          base64::Encode(std::get<std::vector<uint8_t>>(body));
      break;

    case SenderMessage::Type::kInput:
      root[kInputMessageBody] =
          base64::Encode(std::get<std::vector<uint8_t>>(body));
      break;

    case SenderMessage::Type::kGetCapabilities:
      break;

    default:
      OSP_NOTREACHED();
  }
  return root;
}

}  // namespace openscreen::cast