#include <Ethernet.h>
#include "MD5.h"

EthernetServer server(80);

void setup(void) {
  pinMode(4, OUTPUT);
  digitalWrite(4, HIGH);
  Ethernet.init(10);

  byte mac[] = { 0xA8, 0x61, 0x0A, 0xAE, 0x6F, 0x4A };
  while (Ethernet.begin(mac) == 0) {
    delay(1000);
  }

  server.begin();
}


void loop() {
  EthernetClient client = server.accept();

  if (client) {
    byte cmd = client.read();
    switch (cmd) {
      case 1:
        {
          sendSMS(client);
          break;
        }
    }
    client.stop();
  }
  delay(15);
}

char* readWithSize(EthernetClient client, byte size) {
  while (client.available() == 0) {
    delay(250);
  }

  char* result = (char*) malloc(sizeof(char) * size+1);
  for (int i = 0; i < size; i++) {
    result[i] = client.read();
  }
  result[size] = '\0';
  return result;
}

char* readStringUntil(EthernetClient client, char c) {
  while (client.available() == 0) {
    delay(250);
  }

  char last = '\0';
  const byte size = 140;
  char* result = (char*) malloc(sizeof(char) * size);
  for (byte i = 0; i < size; i++) {
    result[i] = ' ';
  }
  result[size] = '\0';
  byte i = 0;
  while (last != c && i < size) {
    last = client.read();
    if (last != c) {
      result[i] = last;
      i++;
    }
  }
  result[i] = '\0';
  return result;
}

void sendSMS(EthernetClient client) {
  // get all from client
  char* phone = readWithSize(client, 10);
  char* hash = readWithSize(client, 32);
  char* msg = readStringUntil(client, 1);

  // Check hash
  unsigned char* h = MD5::make_hash(msg);
  char* md5str = MD5::make_digest(h, 16);

  if (strcmp(md5str, hash) != 0) {
    // do something
    write(client, "error: corrupted message: hash not matching");
    free(md5str);
    free(h);
    free(msg);
    free(hash);
    free(phone);
    return;
  }
  free(md5str);
  free(h);
  free(hash);

  // do the sms thing

  // Clean all
  free(msg);
  free(phone);
  write(client, "done");
}

void write(EthernetClient client, char* payload) {
  while (!client.availableForWrite()) {
    delay(250);
  }

  client.print(payload);
  client.flush();
}