#include <SPI.h>
#include <Ethernet.h>
#include <string.h>

// Enter a MAC address and IP address for your controller below.
// The IP address will be dependent on your local network.
// gateway and subnet are optional:
byte mac[] = { 0x90, 0xA2, 0xDA, 0x00, 0x33, 0x75 };
byte ip[] = { 192, 168, 1, 10 };
byte gateway[] = { 192,168,1,1 };
byte subnet[] = { 255, 255, 255, 0 };
Server server(10050);                       // Zabbix agent listening port

// Set vars
String header= "ZBXD\1";                    //Zabbix Header
String input;                               //Define input
String output;                              //Define output string
String cmdout;                              //Command output string (for tests)
long int datalen = 0;                      //Lenth of data output field

//boolean gotAMessage = false; // whether or not you got a message from the client yet

void setup() {
  // open the serial port
  Serial.begin(9600);
  Serial.println( "Arduino is starting up" );
  delay(3000);
  // initialize the ethernet device
  Serial.println( "Setting up the network");
  Ethernet.begin(mac, ip, gateway, subnet);
  // Start server
  Serial.println( "Starting listener");
  server.begin();
  // We're done
  Serial.println( "Startup is complete, listening for incoming requests");
}

long long endian_swap(unsigned int x) {
   x = (x>>24) |
   ((x<<8) & 0x00FF0000) |
   ((x>>8) & 0x0000FF00) |
   (x<<24);
}

void loop() {
  // listen for incoming clients
  Client client = server.available();
  if (client) {
    //boolean currentLineIsBlank = true;
    while (client.connected()) {
      if (client.available()) {
        char c = client.read();

        // Read input until newline
        if (c != '\n') {
          input += c;
        }

        //When newline reached, interpret the command
        if (c == '\n') {
          Serial.println(input);
          if ( input.indexOf("agent.ping") != -1) {
           cmdout = "1";
          }
          else {
            cmdout = "ZBX_NOTSUPPORTED";
          }

          datalen = cmdout.length();
          datalen = endian_swap(datalen);

          output += header;
          output.concat(datalen);
          output += cmdout;
          client.print(output);
          Serial.println(output);
          break;
        }
      }
    }
    // give the Zabbix Server time to receive the data
    delay(10);
    // close the connection:
    client.flush();
    client.stop();
    // Empty the strings for the next connection
    input = "";
    output = "";
   }
}