#pragma once

#include "message_structs.h"
#include "schema_generated.h"
#include <flatbuffers/flatbuffers.h>
#include <algorithm>

using FBB = flatbuffers::FlatBufferBuilder;
using MetadataOffset = flatbuffers::Offset<fb::MsgMetadata>;

/**
 * @brief Encode a message of type T into a flatbuffer object, placing it
 * into the flatbuffer builder fbb and returning its offset within the builder.
 *
 * This function should be specialized to support encoding various message
 * types T.
 *
 * @tparam T the type to encode
 * @param fbb a Flatbuffer builder to store the encoded message in
 * @param msg the message object to encode
 * @param metadata an optional metadata object, created with encode_metadata().
 * Pass 0 to let the metadata field be null.
 * @return flatbuffers::uoffset_t the offset of the encoded message within the
 * Flatbuffer being built in fbb.
 */
template <typename T>
static flatbuffers::uoffset_t encode(
    FBB& fbb, const T& msg, const MetadataOffset& metadata);

// *** utility functions ***
static flatbuffers::Offset<fb::MsgMetadata> encode_metadata(
    FBB& fbb, const std::string& msg_type, const std::string& topic) {
  return fb::CreateMsgMetadataDirect(fbb, msg_type.c_str(), topic.c_str());
}

/**
 * @brief Create a flatbuffer vector from a vector of items by calling
 * encode<T>() on each item.
 *
 * @tparam TEncoded the target flatbuffers type to encode to
 * @tparam T the source message type to encode from
 * @param fbb the flatbuffer builder in which to create the vector
 * @param metadata an optional metadata item to pass to encode() (pass 0 for
 * null)
 * @param src the vector of messages to encode
 * @return flatbuffers::uoffset_t the offset of the vector within fbb
 */
template <typename TEncoded, typename T>
static flatbuffers::uoffset_t encode_vector(
    FBB& fbb, const MetadataOffset& metadata, std::vector<T> src) {
  std::vector<flatbuffers::Offset<TEncoded>> dst(src.size());
  std::transform(
      src.begin(), src.end(), dst.begin(), [&fbb, &metadata](const T& item) {
        return encode<T>(fbb, item, metadata);
      });
  return fbb.CreateVector(dst).o;
}

// *** specializations below ***

// amrl_msgs/RobofleetSubscription
template <>
flatbuffers::uoffset_t encode(
    FBB& fbb, const RobofleetSubscription& msg, const MetadataOffset& metadata) {
  return fb::amrl_msgs::CreateRobofleetSubscriptionDirect(
             fbb, metadata, msg.topic_regex.c_str(), msg.action)
      .o;
}