//
// Copyright (c) 2013-2024 The SRS Authors
//
// SPDX-License-Identifier: MIT
//

#ifndef SRS_PROTOCOL_STREAM_HPP
#define SRS_PROTOCOL_STREAM_HPP

#include <srs_core.hpp>

#include <srs_protocol_io.hpp>
#include <srs_core_performance.hpp>
#include <srs_kernel_stream.hpp>

#ifdef SRS_PERF_MERGED_READ
/**
 * to improve read performance, merge some packets then read,
 * when it on and read small bytes, we sleep to wait more data.,
 * that is, we merge some data to read together.
 * @see https://github.com/ossrs/srs/issues/241
 */
class IMergeReadHandler
{
public:
    IMergeReadHandler();
    virtual ~IMergeReadHandler();
public:
    /**
     * when read from channel, notice the merge handler to sleep for
     * some small bytes.
     * @remark, it only for server-side, client srs-librtmp just ignore.
     */
    virtual void on_read(ssize_t nread) = 0;
};
#endif

/**
 * the buffer provices bytes cache for protocol. generally,
 * protocol recv data from socket, put into buffer, decode to RTMP message.
 * Usage:
 *       ISrsReader* r = ......;
 *       SrsFastStream* fb = ......;
 *       fb->grow(r, 1024);
 *       char* header = fb->read_slice(100);
 *       char* payload = fb->read_payload(924);
 */
// TODO: FIXME: add utest for it.
class SrsFastStream
{
private:
#ifdef SRS_PERF_MERGED_READ
    // the merged handler
    bool merged_read;
    IMergeReadHandler* _handler;
#endif
    // the user-space buffer to fill by reader,
    // which use fast index and reset when chunk body read ok.
    // ptr to the current read position.
    char* p;
    // ptr to the content end.
    char* end;
    // ptr to the buffer.
    //      buffer <= p <= end <= buffer+nb_buffer
    char* buffer;
    // the size of buffer.
    int nb_buffer;
public:
    // If buffer is 0, use default size.
    SrsFastStream(int size=0);
    virtual ~SrsFastStream();
public:
    /**
     * get the size of current bytes in buffer.
     */
    virtual int size();
    /**
     * get the current bytes in buffer.
     * @remark user should use read_slice() if possible,
     *       the bytes() is used to test bytes, for example, to detect the bytes schema.
     */
    virtual char* bytes();
    /**
     * create buffer with specifeid size.
     * @param buffer the size of buffer. ignore when smaller than SRS_MAX_SOCKET_BUFFER.
     * @remark when MR(SRS_PERF_MERGED_READ) disabled, always set to 8K.
     * @remark when buffer changed, the previous ptr maybe invalid.
     * @see https://github.com/ossrs/srs/issues/241
     */
    virtual void set_buffer(int buffer_size);
public:
    /**
     * read 1byte from buffer, move to next bytes.
     * @remark assert buffer already grow(1).
     */
    virtual char read_1byte();
    /**
     * read a slice in size bytes, move to next bytes.
     * user can use this char* ptr directly, and should never free it.
     * @remark user can use the returned ptr util grow(size),
     *       for the ptr returned maybe invalid after grow(x).
     */
    virtual char* read_slice(int size);
    /**
     * skip some bytes in buffer.
     * @param size the bytes to skip. positive to next; negative to previous.
     * @remark assert buffer already grow(size).
     * @remark always use read_slice to consume bytes, which will reset for EOF.
     *       while skip never consume bytes.
     */
    virtual void skip(int size);
public:
    /**
     * grow buffer to atleast required size, loop to read from skt to fill.
     * @param reader, read more bytes from reader to fill the buffer to required size.
     * @param required_size, loop to fill to ensure buffer size to required.
     * @return an int error code, error if required_size negative.
     * @remark, we actually maybe read more than required_size, maybe 4k for example.
     */
    virtual srs_error_t grow(ISrsReader* reader, int required_size);
public:
#ifdef SRS_PERF_MERGED_READ
    /**
     * to improve read performance, merge some packets then read,
     * when it on and read small bytes, we sleep to wait more data.,
     * that is, we merge some data to read together.
     * @param v true to ename merged read.
     * @param handler the handler when merge read is enabled.
     * @see https://github.com/ossrs/srs/issues/241
     * @remark the merged read is optional, ignore if not specifies.
     */
    virtual void set_merge_read(bool v, IMergeReadHandler* handler);
#endif
};

#endif
