/* *************************************************************************
 * Program ID : TelnetClient_I2CSlave.pde
 * Created by CH, Chen (2011.9.11/Taiwan)
 * Two roles of this device:
 * 1. I2C Slave: Receive request from Master device(NXT or another Arduino)
 * 2. Telent client: According to the request from the I2C master, 
 *    build command string and then transfer to telnet server for executing. 
 * ************************************************************************* */
#include <SPI.h>
#include <Ethernet.h>
#include <Wire.h>

// I2C Slave address
#define THIS_DEVICE             0x31
// I2C Register layout
#define THIS_DEVICE_INFO        0x00
#define TELNET_DISPLAY_RGB      0x41
#define TELNET_DISPLAY_TEXT     0x42
#define TELNET_DISPLAY_INTEGER  0x43
#define TELNET_GET_TEMPERATURE  0x44
#define TELNET_READ_TEMPERATURE 0x45

#define MAX_DATA_LENGTH         8

char receiveBuf[MAX_DATA_LENGTH+1];
byte requestRegister, requestCommand;
boolean isDisplayRGB=false, isDisplayText=false, isDisplayInteger=false;

uint8_t deviceInfo[9] = "TELNET-S";

// Ethernet shield 
byte mac[]     = {0x90, 0xA2, 0xDA, 0x00, 0x52, 0xE0};
byte ip[]      = {192, 168, 11, 112};
byte server[]  = {192, 168, 11, 110};
Client client(server, 23);

// Telenet formatting data code
const char COMMAND_LEADING_CODE    = '@';
const char COMMAND_DISPLAY_RGB     = 'L';
const char COMMAND_DISPLAY_TEXT    = 'T';
const char COMMAND_DISPLAY_INTEGER = 'N';
const char COMMAND_ENDING_CODE     = '%';

void setup() {
  Serial.begin(9600);
  
  Ethernet.begin(mac, ip);
  delay(1000);
  
  Wire.begin(THIS_DEVICE);
  Wire.onReceive(receiveEvent);    
  Wire.onRequest(requestEvent);   
}

void loop()
{
  if (isDisplayRGB)               requestDisplayRGB(receiveBuf);
  else if (isDisplayText)         requestDisplayText(receiveBuf);
       else if (isDisplayInteger) requestDisplayInteger(atoi(receiveBuf));
}

// I2C - onReceive() Handler
void receiveEvent(int howMany)
{  
  int byteCnt = 0;  
  requestRegister = Wire.receive();
  int nbytesReady = Wire.available();
  switch (requestRegister) {
    case TELNET_DISPLAY_RGB:
         isDisplayRGB     = true;
         isDisplayText    = false;
         isDisplayInteger = false;
         for (byteCnt=0; byteCnt<min(nbytesReady, MAX_DATA_LENGTH); byteCnt++)
             receiveBuf[byteCnt] = (char)Wire.receive();
         receiveBuf[byteCnt] = 0;
         break;
    case TELNET_DISPLAY_TEXT:
         isDisplayRGB     = false;
         isDisplayText    = true;
         isDisplayInteger = false;
         for (byteCnt=0; byteCnt<min(nbytesReady, MAX_DATA_LENGTH); byteCnt++)
             receiveBuf[byteCnt] = (char)Wire.receive();
         receiveBuf[byteCnt] = 0;
         break;
    case TELNET_DISPLAY_INTEGER:
         isDisplayRGB     = false;
         isDisplayText    = false;
         isDisplayInteger = true;
         for (byteCnt=0; byteCnt<min(nbytesReady, MAX_DATA_LENGTH); byteCnt++)
             receiveBuf[byteCnt] = (char)Wire.receive();
         receiveBuf[byteCnt] = 0;
         break;
  }
}

// I2C - onRequest() Handler
void requestEvent()
{
 if (requestRegister == THIS_DEVICE_INFO) {
    Wire.send(deviceInfo, 8);
   }
}

// Ethernet shield - Connect to telnet server 
void connectToServer() 
{
  client.flush();
  client.stop();
  delay(1);
  Serial.println("Connecting..");
  if (client.connect()) Serial.println("Connected");
}

// Send RGB LED display request to telnet server
void requestDisplayRGB(char displayRGB[]) 
{
  if (!client.connected()) connectToServer();
  
  client.write(COMMAND_LEADING_CODE);
  client.write(COMMAND_DISPLAY_RGB);
  for (int xcnt=0; xcnt<strlen(displayRGB); xcnt++)
      client.write(displayRGB[xcnt]);
  client.write(COMMAND_ENDING_CODE);
  delay(1);
}

// Send text string disply on 4Digits-7Seg LED request to telnet server
void requestDisplayText(char displayText[]) 
{
  if (!client.connected()) connectToServer();
  
  client.write(COMMAND_LEADING_CODE);
  client.write(COMMAND_DISPLAY_TEXT);
  for (int xcnt=0; xcnt<strlen(displayText); xcnt++)
      client.write(displayText[xcnt]);
  client.write(COMMAND_ENDING_CODE);
  delay(1);
}

// Send integer value disply on 4Dig-7Seg LED request to telnet server
// Integer value must between 9999 - -999(for 4-digits display)
void requestDisplayInteger(int displayInteger) 
{
  char strInteger[5];  
  itoa(displayInteger, strInteger, 10);  
  if (!client.connected())  connectToServer();
  
  client.write(COMMAND_LEADING_CODE);
  client.write(COMMAND_DISPLAY_TEXT);
  for (int xcnt=0; xcnt<strlen(strInteger); xcnt++)
      client.write(strInteger[xcnt]);
  client.write(COMMAND_ENDING_CODE);
  delay(1);
}