/*
This program is distributed under the terms of the 'MIT license'. The text
of this licence follows...

Copyright (c) 2006 J.D.Medhurst (a.k.a. Tixy)

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

/**
@file

@brief Implementation of Y-Modem transmit protocol.
*/

#include "../common/common.h"
#include "ymodem_tx.h"


#include <string.h> // for memcpy and memset


/**
Minimum time in milli-seconds to wait for response from receiver.
*/
const unsigned SendTimeout = 11*1000;


/**
Process response from receiver.

@param c	Value received from InChar.

@return One if received an ACKnowledge,
		zero if received a Negative AcKnowledge,
		or a negative error value.
*/
int YModemTx::ProcessResponse(int c)
	{
	if(c<0)
		return c;
	if(c==CAN)
		{
		if(CancelCount++)
			return ErrorTranferTerminatedByReceiver;
		return 0;
		}
	CancelCount = 0;
	if(c==ACK)
		return 1;
	return 0;
	}


/**
Begin the Y-Modem transfer.

@param timeout	Time in milliseconds to wait receiver to become ready.

@return Zero if transfer initialisation was successful, or an error code on failure.
*/
int YModemTx::SendInitialise(unsigned timeout)
	{
	if(timeout<SendTimeout)
		timeout = SendTimeout;

	while(InChar(0)>=0) // flush input buffers
		{}

	CancelCount = 0;

	int c;
	for(;;)
		{
		const unsigned timeoutStep = 10;
		c = InChar(timeoutStep);
		if(c=='G')
			{
			SendCRC = true;
			WaitForBlockACK = false;
			break;
			}
		else if(c=='C')
			{
			SendCRC = true;
			WaitForBlockACK = true;
			break;
			}
		else if(c==NAK)
			{
			SendCRC = false;
			WaitForBlockACK = true;
			break;
			}
		if(c<0 && c!=ErrorTimeout)
			return c;
		if(timeout<timeoutStep)
			return ErrorTimeout;
		timeout -= timeoutStep;
		}

	ModeChar = c;
	return 0;
	}


/**
Send a single block of data.
A zero sized block terminates the transfer.

@param data		The data to transfer.
@param size		Size of data.

@return The number of transfered, or an error code on failure.
		The number of bytes may be less than \a size.

@pre SendInitialise() must have been successful.
*/
int YModemTx::SendBlock(const uint8_t* data, size_t size)
	{
	uint8_t block[1+2+1024+2];	// buffer to hold data in the block
	int retryCount = 10;		// number of attempts to send the block
	bool waitForBlockACK = WaitForBlockACK;

change_mode:

	size_t blockSize = (Use1KBlocks && size>=1024) ? 1024 : 128;
	size_t dataSize = size<blockSize ? size : blockSize;	// size of data to send in block

	if(!dataSize)
		{
		// all bytes sent, so end transfer by sending a single EOT...
		block[0] = EOT;
		blockSize = 1;
		waitForBlockACK = true;
		}
	else
		{
		// make block header...
		block[0] = blockSize==1024 ? STX : SOH;
		block[1] = BlockNumber&0xffu;
		block[2] = (~BlockNumber)&0xffu;

		// copy data for block (padding with EOF)...
		memcpy(block+3,data,dataSize);
		memset(block+3+dataSize,26,blockSize-dataSize);

		// append checksum/crc...
		if(SendCRC)
			{
			uint16_t crc = CRC16(block+3,blockSize);
			blockSize += 3;
			block[blockSize++] = (uint8_t)(crc>>8);
			block[blockSize++] = (uint8_t)crc;
			}
		else
			{
			uint8_t sum = Checksum(block+3,blockSize);
			blockSize += 3;
			block[blockSize++] = sum;
			}
		}

do_retry:
	// count attenpts...
	if(!retryCount--)
		return ErrorBlockRetriesExceded;

	uint8_t* out = block;
	size_t outSize = blockSize;
	for(;;)
		{
		// send some data...
		int result = Port.Out(out,outSize,1000);
		if(result<0)
			return result; // return error
		if(result==0)
			return ErrorTimeout;

		// adjust for data remaining...
		out += result;
		outSize -= result;

		// end if done...
		if(!outSize)
			break;

		// poll for signal from receiver...
		result = ProcessResponse(InChar(10));
		if(result==ErrorTimeout)
			continue; // nothing received
		if(result<0)
			return result; // return error
		if(!result)
			goto retry; // negative acknowledge received
		}

	if(waitForBlockACK)
		{
		// wait for up to one second for block to be acknowledged...
		int c = InChar(1000);
		int result = ProcessResponse(c);
		if(result<0)
			return result; // return error
		if(!result)
			{
			// negagtive acknowledge received...
			if(c=='C' && !SendCRC)
				{
				// change to CRC mode if receiver sent 'C', and retry...
				SendCRC = true;
				goto change_mode;
				}
			goto retry;
			}
		}
	else
		{
		// check for receiver sending a cancel byte...
		int result = ProcessResponse(InChar(0));
		if(result<0)
			{
			if(result!=ErrorTimeout)
				return result; // return error if it's not a timeout
			}
		else
			{
			// ignore other responses
			}
		}

	// block transferred OK...
	++BlockNumber;
	return dataSize;

retry:
	while(InChar(500)>=0) // flush input buffers
		{}
	goto do_retry;
	}


/**
Send data.
A zero sized block terminates the transfer.

@param data		The data to transfer.
@param size		Size of data.

@return Zero if successful, or a negative error value if failed.

@pre SendInitialise() must have been successful.
*/
int YModemTx::SendData(const uint8_t* data, size_t size)
	{
	do
		{
		int result = SendBlock(data, size);
		if(result<0)
			return result;
		data += result;
		size -= result;
		}
	while(size);
	return 0;
	}


/**
Send an entire stread of data.

@param in	The stream of data to send.

@return Zero if successful, or a negative error value if failed.

@pre SendInitialise() must have been successful.
*/
int YModemTx::SendAll(InStream& in)
	{
	BlockNumber = 1; // first block to send is number one
	size_t size;
	do
		{
		// get data from input stream...
		uint8_t data[1024];
		int result = in.In(data,sizeof(data));
		if(result<0)
			return ErrorInputStreamError;

		// send data...
		size = result;
		result = SendData(data,size);
		if(result<0)
			return result;
		}
	while(size); // end when no more data left
	return 0;
	}


/**
Construct the data for the first block of a Y-Modem transfer.

@param[out] buffer		The buffer to store the constructed block. Size must be >=128 bytes.
@param fileName			The name of the file being transferred.
@param fileSize			The size of the file being transferred.

@return Zero if successful, or a negative error value if failed.
*/
int YModemTx::MakeBlock0(uint8_t* buffer, const char* fileName, size_t fileSize)
	{
	// setup buffer for block 0...
	uint8_t* out = buffer;
	uint8_t* outEnd = buffer+128-1;
	memset(buffer,0,128);

	// copy file name to block data...
	while(out<outEnd)
		{
		char c = *fileName++;
		if(c>='A' && c<='Z')
			c += 'a'-'A';	// convert name to lower-case
		else if(c=='\\')
			c = '/';		// convert back-slash to forward-slash
		*out++ = c;
		if(!c)
			break;			// end of name
		}

	// convert fileSize to a decimal number...
	char length[sizeof(size_t)*3+1]; // buffer big enough to hold length as decimal number
	char* lenEnd = length+sizeof(length);
	char* len = lenEnd;
	do
		{
		*--len = '0'+fileSize%10;	// prepend digit to buffer
		fileSize /= 10;
		}
	while(fileSize);				// end when all digits done

	// append file length to block data...
	while(out<outEnd && len<lenEnd)
		*out++ = *len++;

	// check that buffer was big enough...
	if(out>=outEnd)
		return ErrorFileNameTooLong;

	return 0; // OK
	}


YModemTx::YModemTx(SerialPort& port)
	: YModem(port)
	{
	}


int YModemTx::SendX(InStream& in, unsigned timeout, bool kMode)
	{
	Use1KBlocks = kMode;
	int result = SendInitialise(timeout);
	if(result<0)
		return result;
	return SendAll(in);
	}


int YModemTx::SendY(const char* fileName, size_t size, InStream& in, unsigned timeout)
	{
	Use1KBlocks = true;
	uint8_t buffer[128];
	int result = MakeBlock0(buffer,fileName,size);
	if(result<0)
		return result;

	result = SendInitialise(timeout);
	if(result<0 && result!=ErrorBlockRetriesExceded)
		return result;

	BlockNumber = 0;
	result = SendBlock(buffer,sizeof(buffer));
	if(result<0)
		return result;

	result = InChar(SendTimeout);
	if(result<0)
		return result;
	if(result!=ModeChar)
		return ErrorReceiverNotBehaving;

	result = SendAll(in);
	if(result<0)
		return result;

	result = InChar(SendTimeout);
	if(result<0)
		return result;
	if(result!=ModeChar)
		return ErrorReceiverNotBehaving;

	memset(buffer,0,sizeof(buffer));
	BlockNumber = 0;
	result = SendBlock(buffer,sizeof(buffer));
	if(result<0)
		return result;

	return 0;
	}