/*
 * Copyright (c) 2017-2019 Cisco and/or its affiliates.
 * Licensed 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.
 */

/**
 * Wrapper around event scheduler
 */

#ifndef streamBuffer_h
#define streamBuffer_h

#include <parc/algol/parc_EventQueue.h>
#include <stdbool.h>

void streamBuffer_Destroy(PARCEventQueue **bufferPtr);

/**
 * @function streamBuffer_SetWatermark
 * @abstract Sets the read and/or write watermarks
 * @discussion
 *   For a read watermark, when there is at least <code>low</code> bytes
 * available to read, the read callback will be fired.  If the bytes in the
 * buffer exceed <code>high</code>, the stream buffer will stop reading from the
 * network.
 *
 *   For a write watermark, when the bytes in the buffer fall below
 * <code>low</code>, the write callback is fired.   The <code>high</code>
 * watermark limits stream filters and shapers from exceeding that threashold on
 * what they write to the buffer.
 *
 */
void streamBuffer_SetWatermark(PARCEventQueue *buffer, bool setRead,
                               bool setWrite, size_t low, size_t high);

/**
 * @function streamBuffer_Flush
 * @abstract The buffer will read/write more data if available
 *
 * @return -1 error, 0 no more data, 1 more data
 */
int streamBuffer_Flush(PARCEventQueue *buffer, bool flushRead, bool flushWrite);

/**
 * @function streamBuffer_FlushCheckpoint
 * @abstract Flushes the stream, checkpointing all data in the buffer
 */
int streamBuffer_FlushCheckpoint(PARCEventQueue *buffer, bool flushRead,
                                 bool flushWrite);

/**
 * @function streamBuffer_FlushFinished
 * @abstract Flush the stream and indicate the end of new data
 */
int streamBuffer_FlushFinished(PARCEventQueue *buffer, bool flushRead,
                               bool flushWrite);

/**
 * @typedef StreamBufferReadWriteCallback
 * @abstract Callback when data is available or write space available
 * @constant user_data opaque data passed to
 * <code>StreamBuffer_SetCallbacks()</code>
 */
typedef void(StreamBufferReadWriteCallback)(PARCEventQueue *buffer,
                                            void *user_data);

/**
 * @typedef StreamBufferEventCallback
 * @abstract Callback on error or other event on the stream buffer
 * @constant what logical or of STREAM events.  STREAM_READING and
 * STREAM_WRITING indicate if the error was on the read or write direction.  The
 * conditions may be STREAM_ERROR, STREAM_EOF, STREAM_TIMEOUT, or
 * STREAM_CONNECTED.
 * @constant user_data opaque data passed to
 * <code>StreamBuffer_SetCallbacks()</code>
 */
typedef void(StreamBufferEventCallback)(PARCEventQueue *buffer, short what,
                                        void *user_data);

/**
 * Changes the callbacks for a buffer event.
 *
 * @param bufev the buffer event object for which to change callbacks
 * @param readcb callback to invoke when there is data to be read, or NULL if
 * no callback is desired
 * @param writecb callback to invoke when the file descriptor is ready for
 * writing, or NULL if no callback is desired
 * @param eventcb callback to invoke when there is an event on the file
 * descriptor
 * @param cbarg an argument that will be supplied to each of the callbacks
 * (readcb, writecb, and errorcb)
 * @see parcEventQueue_Create()
 */
void streamBuffer_SetCallbacks(PARCEventQueue *buffer,
                               PARCEventQueue_Callback *readCallback,
                               PARCEventQueue_Callback *writeCallback,
                               PARCEventQueue_EventCallback *eventCallback,
                               void *user_data);

/**
 * @function StreamBuffer_EnableCallbacks
 * @abstract Enables specified callbacks.  Does not affect others.
 * @discussion
 *   Enables disabled callbacks.  If a callback is already enabled, has no
 * effect. A "false" value does not disable it.
 */
void streamBuffer_EnableCallbacks(PARCEventQueue *buffer, bool enableRead,
                                  bool enableWrite);

/**
 * @function StreamBuffer_DisableCallbacks
 * @abstract Disables specified callbacks.  Does not affect others.
 * @discussion
 *   Disables enabled callbacks.  If a callback is already disabled, has no
 * effect. A "false" value does not enable it.
 */
void streamBuffer_DisableCallbacks(PARCEventQueue *buffer, bool disableRead,
                                   bool disableWrite);
#endif  // streamBuffer_h