/*
 * BufferCore.cpp
 *
 *  Created on: 18 May 2016
 *      Author: wentzelc
 */

// redA Libraries
#include "BufferCore.h"

// Standard C/C++ Libraries
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

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

/***** Rolling Buffer *****/

CRollingBuffer::CRollingBuffer( int BufferSize ) : BufSize( BufferSize )
{
    // Create Buffer
    if (BufSize)
    {
        // Create Buffer
        Buffer = (char *)malloc( BufSize+1 );
        memset( Buffer, 0, BufSize+1 );

        // Create temp output buffer big enough to handle all data
        OutBuffer = (char *)malloc( BufSize+1 );
    }
    else {
        // No buffers created
        Buffer = NULL;
        OutBuffer = NULL;
    }

    // Set pointers
    BufStart    = 0;
    BufEnd      = 0;
    BufLen      = 0;
}
//---------------------------------------------------------------------------

CRollingBuffer::~CRollingBuffer()
{
    // Destroy Buffer
    if (Buffer) {
        free( Buffer );
    }
    if (OutBuffer) {
        free( OutBuffer );
    }
}
//---------------------------------------------------------------------------

// Clear all data from buffer
int CRollingBuffer::Reset()
{
    int BytesCleared    = 0;

    // Clear buffer
    BytesCleared = BufLen;

    // Reset pointers
    BufStart    = 0;
    BufEnd      = 0;
    BufLen      = 0;

    return BytesCleared;
}
//---------------------------------------------------------------------------

// Return specific character for current rolling data
char CRollingBuffer::PeekChar( int Pos )
{
    char    CharValue   = 0;

    // Validate buffer and Pos
    if (!BufSize || (Pos < 0) || (Pos > BufLen)) {
        return 0;
    }

    // Get char
    if (BufStart + Pos < BufSize) {
        CharValue = Buffer[ BufStart+Pos ];
    }
    else {
        CharValue = Buffer[ BufStart+Pos-BufSize ];
    }

    // Return char
    return CharValue;
}
//---------------------------------------------------------------------------

// Return pointer direct to buffer
// Data is not removed from buffer
// Return number of contiguous chars (cannot rollover)
int CRollingBuffer::PeekDirect( char ** Data, int PeekPos )
{
    int     BytesReturned   = 0;
    int     StartPos        = 0;

    // Validate
    if (!BufSize || !Data || (PeekPos > BufLen)) {
        *Data = NULL;
        return 0;
    }

    // Get reference
    if (BufStart + StartPos < BufSize) {
        StartPos = BufStart + PeekPos;
        BytesReturned = (StartPos + BufLen > BufSize)? BufSize - StartPos : BufLen;
    }
    else {
        StartPos = BufStart + PeekPos - BufSize;
        BytesReturned = (StartPos + BufLen > BufEnd) ? BufEnd - StartPos : BufLen;
    }

    // Return buffer pointer
    *Data = &Buffer[StartPos];
    return BytesReturned;
}
//---------------------------------------------------------------------------

// Return "stitched" buffer data copied to pointer
// Pointer is created if NULL passed
// Data is not removed from buffer
int CRollingBuffer::Peek( char ** Data, int PeekPos, int MaxLen )
{
    int     BytesReturned   = 0;
    int     StartPos        = 0;

    // Validate
    if (!BufSize || !Data || !MaxLen || (PeekPos < 0) || (PeekPos > BufLen)) {
        *Data = NULL;
        return 0;
    }

    // Get buffer start position
    if (BufStart + StartPos < BufSize) {
        StartPos = BufStart + PeekPos;
    }
    else {
        StartPos = BufStart + PeekPos - BufSize;
    }

    // Validate MaxLen
    if ((MaxLen == -1) || (MaxLen > BufSize)) {
        MaxLen = BufSize;
    }
    BytesReturned = (MaxLen > BufLen - PeekPos)? (BufLen - PeekPos) : MaxLen;

    // Copy Data from Buffer
    if (StartPos + BytesReturned <= BufSize) {
        memcpy( OutBuffer, &Buffer[StartPos], BytesReturned );
    }
    else {
        memcpy( OutBuffer, &Buffer[StartPos], BufSize-StartPos );                           // Copy from end of buffer
        memcpy( &OutBuffer[BufSize-StartPos], Buffer, (BytesReturned-(BufSize-StartPos)) ); // Copy rollover from start of buffer
    }

    // Zero terminate
    OutBuffer[BytesReturned] = 0;

    // Return Temp buffer
    *Data = OutBuffer;
    return BytesReturned;
}
//---------------------------------------------------------------------------

// Return "stitched" buffer data in temporary buffer
// Data is not removed from buffer
int CRollingBuffer::PeekCopy( char ** Data, int PeekPos, int MaxLen )
{
    int     BytesReturned   = 0;
    int     StartPos        = 0;

    // Check if any data
    if (!BufSize || !Data || !MaxLen || (PeekPos < 0) || (PeekPos > BufLen)) {
        if (*Data) (*Data)[0] = 0;
        return 0;
    }

    // Get start position
    if (BufStart + StartPos < BufSize) {
        StartPos = BufStart + PeekPos;
    }
    else {
        StartPos = BufStart + PeekPos - BufSize;
    }

    // Validate MaxLen
    if ((MaxLen == -1) || (MaxLen > BufSize)) {
        MaxLen = BufSize;
    }
    BytesReturned = (MaxLen > BufLen - PeekPos)? (BufLen - PeekPos) : MaxLen;

    // Allocate memory
    if (!*Data)
        *Data = (char*)malloc( BytesReturned + 1 );

    // Copy Data from Buffer
    if (StartPos + BytesReturned <= BufSize) {
        memcpy( *Data, &Buffer[StartPos], BytesReturned );
    }
    else {
        memcpy( *Data, &Buffer[StartPos], BufSize-StartPos );                             // Copy from end of buffer
        memcpy( &(*Data)[BufSize-StartPos], Buffer, (BytesReturned-(BufSize-StartPos)) ); // Copy rollover from start of buffer
    }
    (*Data)[BytesReturned] = 0;

    return BytesReturned;
}
//---------------------------------------------------------------------------

// Look for first occurrence of character in buffer
bool CRollingBuffer::FindStr( const char * SearchStr, int SearchLen, int &FoundPos, int StartPos )
{
    char *  CheckPos    = NULL;
    char *  CheckLimit  = NULL;
    char *  MatchPos    = NULL;
    char *  MatchLimit  = NULL;

    // Check if buffer exists
    if (!BufSize || !SearchStr || !SearchLen) {
        FoundPos = -1;
        return false;
    }

    // Validate start Pos
    if (StartPos >= BufLen) {
        FoundPos = -1;
        return false;
    }

    // Get Search start point and limit
    CheckPos = (BufStart + StartPos < BufSize)? &Buffer[ BufStart+StartPos ] : &Buffer[ (BufStart+StartPos)-BufSize ];
    CheckLimit = &Buffer[BufSize-1];

    // Set Match start point and limit
    MatchPos   = (char*)SearchStr;
    MatchLimit = (char*)&SearchStr[SearchLen-1];

    // Search for char
    FoundPos = StartPos;
    while (FoundPos < BufLen)
    {
        // Check if char match
        if (*CheckPos == *MatchPos) {
            if (MatchPos == MatchLimit) {
                // Full match found
                FoundPos -= SearchLen-1;
                return true;
            }
            else {
                // Next char to match
                MatchPos++;
            }
        }
        else {
            // Reset match point
            MatchPos = (char*)SearchStr;
        }

        // Next char
        FoundPos++;
        if (CheckPos == CheckLimit) {
            CheckPos = Buffer;   // Roll-over, Start at beginning of buffer
        } else {
            CheckPos++;
        }
    }

    // Not Found
    FoundPos = -1;
    return false;
}
//---------------------------------------------------------------------------

// Remove data from start of buffer
int CRollingBuffer::Clear( int ClearLen )
{
    int BytesCleared;

    // Validate ClearLen
    if (ClearLen == -1) {
        BytesCleared = BufLen;
    }
    else {
        BytesCleared = (ClearLen > BufLen)? BufLen : ClearLen;
    }

    // Update Buffer pointers
    if (BufStart + BytesCleared < BufSize) {
        BufStart += BytesCleared;
    } else {
        BufStart = (BytesCleared-(BufSize-BufStart));    // Copy roll-over from start of buffer
    }
    BufLen -= BytesCleared;

    return BytesCleared;
}
//---------------------------------------------------------------------------

// Add bytes to end of buffer
// Perform roll over if requied
// Option to overwrite existing data if longer than buffer length
int CRollingBuffer::Push( bool Overwrite, const char * Data, int Len )
{
    int     BytesPushed     = 0;
    int     TotalPushed     = 0;
    int     BufRemain       = 0;
    int     DataRemain;

    // Validate Buffer and Len
    if (!BufSize || !Data || !Len) {
        return 0;
    }
    else if (Len == -1) {
        Len = strlen( Data );
    }

    // Prevent overwrite
    DataRemain = (!Overwrite && (Len > BufSize-BufLen))? BufSize-BufLen : Len;

    // Read Data into buffer
    while (DataRemain)
    {
        // Read from file descriptor
        BufRemain = BufSize - BufEnd;
        BytesPushed = ((BufRemain > DataRemain)? DataRemain : BufRemain);
        memcpy( &Buffer[BufEnd], &Data[TotalPushed], BytesPushed );

        // Update Data Pointers
        TotalPushed += BytesPushed;
        DataRemain -= BytesPushed;

        // Update Buffer Pointers
        BufLen += BytesPushed;
        BufEnd += BytesPushed;
        if (BufEnd >= BufSize) {
            // Rolling over end of buffer, start at beginning
            BufEnd = 0;
        }
        if (BufLen > BufSize) {
            // Head has caught up with tail, move tail up
            BufLen = BufSize;
            BufStart = BufEnd;
        }
    }

    return TotalPushed;
}
//---------------------------------------------------------------------------

// Read first-in bytes from buffer
// Return "stitched" buffer data in temporary buffer
int CRollingBuffer::Pop( char ** Data, int MaxLen )
{
    int     BytesWritten    = 0;

    // Read & clear data
    BytesWritten = Peek( Data, 0, MaxLen );
    Clear( BytesWritten );

    // Return temp buffer
    return BytesWritten;
}
//---------------------------------------------------------------------------

// Read first-in bytes from buffer
// Return "stitched" buffer data copied to pointer which if created if NULL
int CRollingBuffer::PopCopy( char ** Data, int MaxLen )
{
    int     BytesWritten    = 0;

    // Copy & clear data
    BytesWritten = PeekCopy( Data, 0, MaxLen );
    Clear( BytesWritten );

    // Return temp buffer
    return BytesWritten;
}
//---------------------------------------------------------------------------

// Read File descriptor directly into rolling buffer
int CRollingBuffer::ReadFromFD( int Handle, int MaxRead, bool Overwrite )
{
    int     BytesRead       = 0;
    int     TotalRead       = 0;
    int     BufRemain       = 0;
    int     DataRemain      = 0;

    // Check if buffer created
    if (!BufSize) {
        return 0;
    }

    // Read file descriptor into buffer
    if (Overwrite && (MaxRead > BufLen)) {
        DataRemain = MaxRead;
    }
    else {
        DataRemain = BufLen;
    }
    while (DataRemain)
    {
        // Read from file descriptor
        BufRemain = BufSize - BufEnd;
        BytesRead = read( Handle, &Buffer[BufEnd], ((BufRemain > DataRemain)? DataRemain : BufRemain) );
        if (BytesRead <= 0) {
            break;
        }

        // Update Buffer Pointers
        DataRemain -= BytesRead;
        TotalRead += BytesRead;
        BufLen += BytesRead;
        BufEnd += BytesRead;
        if (BufEnd >= BufSize) {
            // Rolling over end of buffer, start at beginning
            BufEnd = 0;
        }
        if (BufLen > BufSize) {
            // Head is caught up with tail, move tail up
            BufLen = BufSize;
            BufStart = BufEnd;
        }
    }
    return TotalRead;
}
//---------------------------------------------------------------------------

// Write given number of bytes directly from buffer to File descriptor
int CRollingBuffer::WriteToFD( int Handle, int MaxLen )
{
    int     BytesWritten    = 0;
    int     TotalWritten    = 0;
    int     BufRemain       = 0;
    int     DataRemain      = 0;
    int     ReadPos         = 0;

    // Check if buffer created
    if (!BufSize) {
        return 0;
    }

    // Read Data into buffer
    ReadPos = BufStart;
    DataRemain = (MaxLen == -1)? BufLen : MaxLen;
    while (DataRemain)
    {
        // Read from file descriptor
        BufRemain = BufSize - ReadPos;
        BytesWritten = write( Handle, &Buffer[ReadPos], ((BufRemain > DataRemain)? DataRemain : BufRemain) );
        if (BytesWritten <= 0) {
            break;
        }

        // Update Data Pointers
        TotalWritten += BytesWritten;
        DataRemain -= BytesWritten;

        // Update Buffer Pointers
        ReadPos += BytesWritten;
        if (ReadPos >= BufSize) {
            ReadPos = 0;   // Rolling over end of buffer, start at beginning
        }
    }

    return TotalWritten;
}
//---------------------------------------------------------------------------


/***** Shifting Buffer *****/

CShiftBuffer::CShiftBuffer( int BufferSize ) : BufSize( BufferSize )
{
    // Create Buffer
    if (BufSize)
    {
        // Create Buffer
        Buffer = (char *)malloc( BufSize+1 );
        Buffer[0] = 0;

        // Create temp output buffer big enough to handle all data
        OutBuffer = (char *)malloc( BufSize+1 );
    }
    else {
        // No buffers created
        Buffer = NULL;
        OutBuffer = NULL;
    }

    // Set vars
    BufLen      = 0;
}
//---------------------------------------------------------------------------

CShiftBuffer::~CShiftBuffer()
{
    // Destroy Buffer
    if (Buffer) {
        free( Buffer );
    }
    if (OutBuffer) {
        free( OutBuffer );
    }
}
//---------------------------------------------------------------------------

// Clear all data from buffer
int CShiftBuffer::Reset()
{
    int BytesCleared    = 0;

    // Reset buffer
    BytesCleared = BufLen;
    BufLen = 0;
    Buffer[0] = 0;

    return BytesCleared;
}
//---------------------------------------------------------------------------

// Return specific character for current rolling data
char CShiftBuffer::PeekChar( int Pos )
{
    // Validate buffer and Pos
    if (!BufSize || (Pos < 0) || (Pos > BufLen)) {
        return 0;
    }

    // Return char
    return Buffer[Pos];
}
//---------------------------------------------------------------------------

// Return pointer direct to buffer
// Return number of contiguous chars (cannot rollover)
int CShiftBuffer::PeekDirect( char ** Data, int PeekPos )
{
    // Validate
    if (!BufSize || !Data || (PeekPos > BufLen)) {
        *Data = NULL;
        return 0;
    }

    // Return buffer pointer
    *Data = &Buffer[PeekPos];
    return (BufLen - PeekPos);
}
//---------------------------------------------------------------------------

// Copy data into temporary buffer
int CShiftBuffer::Peek( char ** Data, int PeekPos, int MaxLen )
{
    int     BytesReturned   = 0;

    // Validate
    if (!BufSize || !Data || !MaxLen || (PeekPos < 0) || (PeekPos > BufLen)) {
        *Data = NULL;
        return 0;
    }

    // Calculate bytes to return
    if ((MaxLen == -1) || (MaxLen > BufSize)) {
        MaxLen = BufSize;
    }
    BytesReturned = (MaxLen > BufLen - PeekPos)? (BufLen - PeekPos) : MaxLen;

    // Copy Data from Buffer
    memcpy( OutBuffer, &Buffer[PeekPos], BytesReturned );
    OutBuffer[BytesReturned] = 0;

    // Return Temp buffer
    *Data = OutBuffer;
    return BytesReturned;
}
//---------------------------------------------------------------------------

// Return "stitched" buffer data in temporary buffer
// Data is not removed from buffer
int CShiftBuffer::PeekCopy( char ** Data, int PeekPos, int MaxLen )
{
    int     BytesReturned   = 0;
    int     StartPos        = 0;

    // Check if any data
    if (!BufSize || !Data || !MaxLen || (PeekPos < 0) || (PeekPos > BufLen)) {
        if (*Data) (*Data)[0] = 0;
        return 0;
    }

    // Calculate bytes to return
    if ((MaxLen == -1) || (MaxLen > BufSize)) {
        MaxLen = BufSize;
    }
    BytesReturned = (MaxLen > BufLen - PeekPos)? (BufLen - PeekPos) : MaxLen;

    // Allocate memory
    if (!*Data)
        *Data = (char*)malloc( BytesReturned + 1 );

    // Copy Data from Buffer
    memcpy( *Data, &Buffer[StartPos], BytesReturned );
    (*Data)[BytesReturned] = 0;

    return BytesReturned;
}
//---------------------------------------------------------------------------

// Look for first occurrence of character in buffer
bool CShiftBuffer::FindStr( const char * SearchStr, int SearchLen, int &FoundPos, int StartPos )
{
    char *  CheckPos    = NULL;
    char *  CheckLimit  = NULL;
    char *  MatchPos    = NULL;
    char *  MatchLimit  = NULL;

    // Check if buffer exists
    if (!BufSize || !SearchStr || !SearchLen) {
        FoundPos = -1;
        return false;
    }

    // Validate start Pos
    if (StartPos >= BufLen) {
        FoundPos = -1;
        return false;
    }

    // Get Search start point and limit
    CheckPos = &Buffer[StartPos];
    CheckLimit = &Buffer[BufLen-1];

    // Set Match start point and limit
    MatchPos   = (char*)SearchStr;
    MatchLimit = (char*)&SearchStr[SearchLen-1];

    // Search for char
    FoundPos = StartPos;
    while (FoundPos < BufLen)
    {
        // Check if char match
        if (*CheckPos == *MatchPos) {
            if (MatchPos == MatchLimit) {
                // Full match found
                FoundPos -= SearchLen-1;
                return true;
            }
            else {
                // Next char to match
                MatchPos++;
            }
        }
        else {
            // Reset match point
            MatchPos = (char*)SearchStr;
        }

        // Next char
        FoundPos++;
        if (CheckPos == CheckLimit) {
            break;
        } else {
            CheckPos++;
        }
    }

    // Not Found
    FoundPos = -1;
    return false;
}
//---------------------------------------------------------------------------

// Remove data from start of buffer
int CShiftBuffer::Clear( int ClearLen )
{
    int BytesCleared;

    // Validate ClearLen
    if ((ClearLen == -1) || (ClearLen >= BufLen))
    {
        // Clear all data
        BytesCleared = BufLen;
        BufLen = 0;
        Buffer[0] = 0;
    }
    else {
        // Shift remaining data
        BytesCleared = ClearLen;
        memmove( Buffer, &Buffer[ClearLen], BufLen-ClearLen );   // Shift remaining old data left
        BufLen -= ClearLen;
        Buffer[BufLen] = 0;
    }

    return BytesCleared;
}
//---------------------------------------------------------------------------

// Add bytes to end of buffer
// Option to overwrite existing data if longer than buffer length
int CShiftBuffer::Push( bool Overwrite, const char * Data, int Len )
{
    int     BytesPushed     = 0;
    int     BufRemain       = 0;

    // Validate Buffer and Len
    if (!BufSize || !Data || !Len) {
        return 0;
    }
    else if (Len == -1) {
        Len = strlen( Data );
    }

    // Copy Data to buffer
    BufRemain = BufSize - BufLen;
    if (Overwrite && (Len > BufRemain))
    {
        if (Len < BufSize) {
            memcpy( Buffer, &Buffer[Len-BufRemain], BufLen-(Len-BufRemain) );   // Shift remaining old data left
            memcpy( &Buffer[BufSize-Len], Data, Len );   // Copy new data
            BytesPushed = Len;
        }
        else {
            memcpy( Buffer, &Data[Len-BufSize], BufSize );   // Copy last portion of new data
            BytesPushed = Len;
        }

        // Update Pointers
        BufLen = BufSize;
        Buffer[BufLen] = 0;
    }
    else
    {
        // Copy first portion of new data to buffer
        BytesPushed = (Len > BufRemain)? BufRemain : Len;
        memcpy( &Buffer[BufLen], Data, BytesPushed );

        // Update Buffer Pointers
        BufLen += BytesPushed;
        Buffer[BufLen] = 0;
    }

    return BytesPushed;
}
//---------------------------------------------------------------------------

// Read first-in bytes from buffer
// Return "stitched" buffer data in temporary buffer
int CShiftBuffer::Pop( char ** Data, int MaxLen )
{
    int     BytesWritten    = 0;

    // Read and clear bytes
    BytesWritten = Peek( Data, 0, MaxLen );
    Clear( BytesWritten );

    return BytesWritten;
}
//---------------------------------------------------------------------------

// Read first-in bytes from buffer
// Return "stitched" buffer data copied to pointer which if created if NULL
int CShiftBuffer::PopCopy( char ** Data, int MaxLen )
{
    int     BytesWritten    = 0;

    // Copy and clear bytes
    BytesWritten = PeekCopy( Data, 0, MaxLen );
    Clear( BytesWritten );

    // Return temp buffer
    return BytesWritten;
}
//---------------------------------------------------------------------------

// Read File descriptor directly into buffer
int CShiftBuffer::ReadFromFD( int Handle, int MaxRead )
{
    int     BytesRead       = 0;
    int     TotalRead       = 0;
    int     DataRemain      = 0;

    // Check if buffer created
    if (!BufSize) {
        return 0;
    }

    // Read file descriptor into buffer
    DataRemain = ((MaxRead < 0) || (MaxRead > BufSize-BufLen))? BufSize-BufLen : MaxRead;
    while (DataRemain)
    {
        // Read from file descriptor
        BytesRead = read( Handle, &Buffer[BufLen], DataRemain );
        if (BytesRead <= 0) {
            break;
        }

        // Update Buffer Pointers
        DataRemain -= BytesRead;
        TotalRead += BytesRead;
        BufLen += BytesRead;
    }
    return TotalRead;
}
//---------------------------------------------------------------------------

// Write given number of bytes directly from buffer to File descriptor
int CShiftBuffer::WriteToFD( int Handle, int MaxLen )
{
    int     BytesWritten    = 0;
    int     TotalWritten    = 0;
    int     BufRemain       = 0;
    int     DataRemain      = 0;
    int     ReadPos         = 0;

    // Check if buffer created
    if (!BufSize) {
        return 0;
    }

    // Read Data into buffer
    ReadPos = 0;
    DataRemain = ((MaxLen == -1) || (MaxLen > BufLen))? BufLen : MaxLen;
    while (DataRemain)
    {
        // Read from file descriptor
        BufRemain = BufSize - ReadPos;
        BytesWritten = write( Handle, &Buffer[ReadPos], ((BufRemain > DataRemain)? DataRemain : BufRemain) );
        if (BytesWritten <= 0) {
            break;
        }

        // Update Data Pointers
        TotalWritten += BytesWritten;
        DataRemain -= BytesWritten;

        // Update Buffer Pointers
        ReadPos += BytesWritten;
        if (ReadPos >= BufSize) {
            ReadPos = 0;   // Rolling over end of buffer, start at beginning
        }
    }

    return TotalWritten;
}
//---------------------------------------------------------------------------