// Licensed to the Apache Software Foundation (ASF) under one

// or more contributor license agreements.  See the NOTICE file

// distributed with this work for additional information

// regarding copyright ownership.  The ASF licenses this file

// to you under the Apache License, Version 2.0 (the

// "License"); you may not use this file except in compliance

// with the License.  You may obtain a copy of the License at

//

//   http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing,

// software distributed under the License is distributed on an

// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

// KIND, either express or implied.  See the License for the

// specific language governing permissions and limitations

// under the License.

// mcpack2pb - Make protobuf be front-end of mcpack/compack

// Date: Mon Oct 19 17:17:36 CST 2015

#ifndef MCPACK2PB_MCPACK_MCPACK2PB_H

#define MCPACK2PB_MCPACK_MCPACK2PB_H

#include <google/protobuf/message.h>

#include <google/protobuf/io/zero_copy_stream_impl_lite.h>

#include "butil/containers/flat_map.h"

#include "butil/iobuf.h"

#include "mcpack2pb/parser.h"

#include "mcpack2pb/serializer.h"

namespace mcpack2pb {

typedef bool (*SetFieldFn)(::google::protobuf::Message* msg,

                           UnparsedValue& value);

// Mapping from filed name to its parsing&setting function.

typedef butil::FlatMap<butil::StringPiece, SetFieldFn> FieldMap;

enum SerializationFormat {

    FORMAT_COMPACK,

    FORMAT_MCPACK_V2

};

struct MessageHandler {

    // Parse `msg' from `input' as a mcpack_v2 or compack object.

    // Returns number of bytes consumed.

    size_t (*parse)(::google::protobuf::Message* msg,

                    ::google::protobuf::io::ZeroCopyInputStream* input);

    // Parse `msg' from `input' as a mcpack_v2 or compack object removed with header.

    // Returns true on success.

    bool (*parse_body)(::google::protobuf::Message* msg,

                       ::google::protobuf::io::ZeroCopyInputStream* input,

                       size_t size);

    // Serialize `msg' as a mcpack_v2 or compack object into `output'.

    // The serialization format is decided by `format'.

    // Returns true on success.

    bool (*serialize)(const ::google::protobuf::Message& msg,

                      ::google::protobuf::io::ZeroCopyOutputStream* output,

                      SerializationFormat format);

    // Serialize `msg' as a mcpack_v2 or compack object without header into

    // `serializer'. The serialization format is decided by `format'.

    // Returns true on success.

    void (*serialize_body)(const ::google::protobuf::Message& msg,

                           Serializer& serializer,

                           SerializationFormat format);

    // -------------------

    //  Helper functions

    // -------------------

    // Parse `msg' from IOBuf or array which may contain more data than just

    // the message.

    // Returns bytes parsed, 0 on error.

    size_t parse_from_iobuf_prefix(::google::protobuf::Message* msg,

                                   const ::butil::IOBuf& buf);

    size_t parse_from_array_prefix(::google::protobuf::Message* msg,

                                   const void* data, int size);

    // Parse `msg' from IOBuf or array which may just contain the message.

    // Returns true on success.

    bool parse_from_iobuf(::google::protobuf::Message* msg,

                          const ::butil::IOBuf& buf);

    bool parse_from_array(::google::protobuf::Message* msg,

                          const void* data, int size);

    // Serialize `msg' to IOBuf or string.

    // Returns true on success.

    bool serialize_to_iobuf(const ::google::protobuf::Message& msg,

                            ::butil::IOBuf* buf, SerializationFormat format);

    // TODO(gejun): serialize_to_string is not supported because OutputStream

    // requires the embedded zero-copy stream to return permanent memory blocks

    // to support reserve() however the string inside StringOutputStream may

    // be resized and invalidates previous returned memory blocks.

};

static const MessageHandler INVALID_MESSAGE_HANDLER = {NULL, NULL, NULL, NULL};

// if the *.pb.cc and *.pb.h was generated by mcpack2pb. This function will be

// called with the mcpack/compack parser and serializer BEFORE main().

void register_message_handler_or_die(const std::string& full_name,

                                     const MessageHandler& handler);

// Find the registered parser/serializer by `full_name'

// e.g. "example.SampleMessage".

// If the handler was not registered, function pointers inside are NULL.

MessageHandler find_message_handler(const std::string& full_name);

// inline impl.

inline size_t MessageHandler::parse_from_iobuf_prefix(

    ::google::protobuf::Message* msg, const ::butil::IOBuf& buf) {

    if (parse == NULL) {

        LOG(ERROR) << "`parse' is NULL";

        return 0;

    }

    ::butil::IOBufAsZeroCopyInputStream zc_stream(buf);

    return parse(msg, &zc_stream);

}

inline bool MessageHandler::parse_from_iobuf(

    ::google::protobuf::Message* msg, const ::butil::IOBuf& buf) {

    if (parse == NULL) {

        LOG(ERROR) << "`parse' is NULL";

        return 0;

    }

    ::butil::IOBufAsZeroCopyInputStream zc_stream(buf);

    return parse(msg, &zc_stream) == buf.size();

}

inline size_t MessageHandler::parse_from_array_prefix(

    ::google::protobuf::Message* msg, const void* data, int size) {

    if (parse == NULL) {

        LOG(ERROR) << "`parse' is NULL";

        return 0;

    }

    ::google::protobuf::io::ArrayInputStream zc_stream(data, size);

    return parse(msg, &zc_stream);

}

inline bool MessageHandler::parse_from_array(

    ::google::protobuf::Message* msg, const void* data, int size) {

    if (parse == NULL) {

        LOG(ERROR) << "`parse' is NULL";

        return 0;

    }

    ::google::protobuf::io::ArrayInputStream zc_stream(data, size);

    return (int)parse(msg, &zc_stream) == size;

}

inline bool MessageHandler::serialize_to_iobuf(

    const ::google::protobuf::Message& msg,

    ::butil::IOBuf* buf, SerializationFormat format) {

    if (serialize == NULL) {

        LOG(ERROR) << "`serialize' is NULL";

        return false;

    }

    ::butil::IOBufAsZeroCopyOutputStream zc_stream(buf);

    return serialize(msg, &zc_stream, format);

}

} // namespace mcpack2pb

#endif // MCPACK2PB_MCPACK_MCPACK2PB_H