/*
  ESP8266 Pingcheck Wifi Module
  Pings three IP Addresses. If one of them responses, the light is on.
  2016 www.frag-duino.de
*/
 
#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ESP8266WebServer.h>
#include <EEPROM.h>
extern "C" {
#include "user_interface.h"
#include "ping.h"
}
 
ESP8266WebServer server(80);
 
/*
 * To set the new Wifi, enter credentials in the two variables and set RESET_EEPROM to true.
 * During the next start it will save it into the EEPROM.
 * Then set RESET_EEPROM to false and flash it again.
 * When wifi changes, remember to first change the name over the webinterface.
*/
 
#define RESET_EEPROM false
#define WIFI_SSID "Freifunk"
#define WIFI_PASSWORD ""
 
// Settings
const int PING_INTERVAL = 5000;
const int PIN_LED = 2;
const int count_hosts = 3;
int connection_try = 15;
char host1[15];
char host2[15];
char host3[15];
boolean host_is_online[] = {false, false, false};
 
// EEPROM Addresses
const int ADDRESS_IP1 = 0;
const int ADDRESS_IP2 = 15;
const int ADDRESS_IP3 = 30;
const int ADDRESS_INIT = 105; // - 99
const int ADDRESS_PASSWORD = 45; // - 75
const int ADDRESS_SSID = 75; // - 105
const int EEPROM_SIZE = 106;
 
// Variables
IPAddress network_ip;
char network_ssid[30];
char network_password[30];
struct ping_option pingopt;
unsigned long last_ping = 0;
unsigned long last_seen_online = 0;
unsigned long currentMillis = 0;
int currentHost = 0;
int state_LED = LOW;
boolean got_new_hosts;
boolean save_wifi;
 
// Save the current config
void writeIPtoEEPROM() {
  for (int i = 0; i < 15; i++) {
    EEPROM.write(ADDRESS_IP1 + i, host1[i]);
    EEPROM.write(ADDRESS_IP2 + i, host2[i]);
    EEPROM.write(ADDRESS_IP3 + i, host3[i]);
  }
  EEPROM.commit();
}
 
void writeSSIDtoEEPROM(String new_ssid) {
  for (int i = 0; i < 30; i++) {
    if (i < new_ssid.length())
      EEPROM.write(ADDRESS_SSID + i, new_ssid[i]);
    else
      EEPROM.write(ADDRESS_SSID + i, '\0');
  }
  EEPROM.commit();
}
 
void writePASSWORDtoEEPROM(String new_password) {
  for (int i = 0; i < 30; i++) {
    if (i < new_password.length())
      EEPROM.write(ADDRESS_PASSWORD + i, new_password[i]);
    else
      EEPROM.write(ADDRESS_PASSWORD + i, '\0');
  }
  EEPROM.commit();
}
 
// Reply is called, when response arrives
static void callback_reply (void* arg, void *pdata) {
  struct ping_resp *pingresp = (struct ping_resp *)pdata;
  if (pingresp->resp_time > 0) {
    Serial.println(" Response");
    last_seen_online = currentMillis;
    host_is_online[currentHost] = true;
  }
  else {
    Serial.println(" Timeout");
    host_is_online[currentHost] = false;
  }
}
 
// Sends an echo request to an IP-Address
void ping(uint32 ip)
{
  pingopt.ip = ip;
  pingopt.count = 1;
  pingopt.coarse_time = 200;
  pingopt.recv_function = &callback_reply;
  // pingopt.sent_function = NULL;
  ping_start(&pingopt);
}
 
 
boolean checkIPsyntax(String ip) {
  // Only 0-9 and dots
  for (int i = 0; i <= 33; i++)
    if (ip.indexOf(i) != -1)
      return false;
  if (ip.indexOf(0x2F) != -1)
    return false;
  for (int i = 0x3A; i <= 0x7F; i++)
    if (ip.indexOf(i) != -1)
      return false;
 
  // Count the amount of dots
  int dots = 0;
  for (int i = 0; i < ip.length(); i++)
    if (ip[i] == '.')
      dots++;
  if (dots != 3)
    return false;
 
  // Check the range of the oktets
  int dot_1 = ip.indexOf('.');
  int dot_2 = ip.indexOf('.', dot_1 + 1);
  int dot_3 = ip.indexOf('.', dot_2 + 1);
  int oktet_1 = ip.substring(0, dot_1).toInt();
  int oktet_2 = ip.substring(dot_1 + 1, dot_2).toInt();
  int oktet_3 = ip.substring(dot_2 + 1, dot_3).toInt();
  int oktet_4 = ip.substring(dot_3 + 1).toInt();
  if (oktet_1 >=  0 && oktet_1 <= 255 &&
      oktet_2 >= 0 && oktet_2 <= 255 &&
      oktet_3 >= 0 && oktet_3 <= 255 &&
      oktet_4 >= 0 && oktet_4 <= 255 )
    return true;
  else
    return false;
}
 
 
void handleRoot() {
  Serial.print(currentMillis);
  Serial.print(": HTTP-Request with ");
  got_new_hosts = false;
  save_wifi = false;
  String temp_ssid;
  String temp_password;
 
  if (server.args() > 0) {
    Serial.print(server.args());
    Serial.print(" args: ");
    for (int a = 0; a < server.args(); a++) {
      Serial.print("[");
      Serial.print(server.argName(a));
      Serial.print("=");
      Serial.print(server.arg(a));
      Serial.print("]");
 
      if (server.arg(a) == "Restart")  // Restart ESP8266
        system_restart();
      else if (server.arg(a) == "Save-Wifi") {
        Serial.println("OK, Save-Wifi");
        save_wifi = true;
      } else if (server.argName(a) == "ssid") {
        for (int i = 0; i < 30; i++) {
          if (i < server.arg(a).length())
            network_ssid[i] = server.arg(a)[i];
          else
            network_ssid[i] = '\0';
        }
      } else if (server.argName(a) == "password") {
        for (int i = 0; i < 30; i++) {
          if (i < server.arg(a).length())
            network_password[i] = server.arg(a)[i];
          else
            network_password[i] = '\0';
        }
      } else if (server.argName(a) == "ip1" && checkIPsyntax(server.arg(a))) {
        memset(host1, 0, sizeof(host1));
        for (int i = 0; i < server.arg(a).length(); i++)
          host1[i] = server.arg(a)[i];
        got_new_hosts = true;
        Serial.print(" OK1 ");
      } else if (server.argName(a) == "ip2" && checkIPsyntax(server.arg(a))) {
        memset(host2, 0, sizeof(host2));
        for (int i = 0; i < server.arg(a).length(); i++)
          host2[i] = server.arg(a)[i];
        got_new_hosts = true;
        Serial.print(" OK2 ");
      } else if (server.argName(a) == "ip3" && checkIPsyntax(server.arg(a))) {
        memset(host3, 0, sizeof(host3));
        for (int i = 0; i < server.arg(a).length(); i++)
          host3[i] = server.arg(a)[i];
        got_new_hosts = true;
        Serial.print(" OK3 ");
      } else
        Serial.print(" NACK; ");
    }
  } else Serial.print("no args");
  Serial.println(".");
 
  // Save it
  if (got_new_hosts)
    writeIPtoEEPROM();
 
  if (save_wifi) {
    writeSSIDtoEEPROM(network_ssid);
    if (temp_password != "notchanged")
      writePASSWORDtoEEPROM(network_password);
  }
 
  // Print the HTML-Page
  String result = "<html><head><title>PingCheck</title></head>\r\n<body>\r\n";
  result += "PingCheck 2.0 (2015 Marcel Imig <a href=\"http://www.frag-duino.de\">www.frag-duino.de</a>)<br><br>\r\n\r\n";
  result += "<fieldset name=\"wifistatus\"><legend>Wifi status</legend><form action=\"\" method=\"post\">";
 
  result += "<table>\r\n";
 
  result += "<tr><td><b>Network SSID:</b></td>\r\n";
  result += "<td><input type=\"text\" name=\"ssid\" value=\"";
  result += network_ssid;
  result += "\" maxlength=\"30\"></td>\r\n</tr>\r\n";
  result += "<tr><td><b>Network Password:</b></td>\r\n";
  result += "<td><input type=\"password\" name=\"password\" value=\"notchanged\" maxlength=\"30\"></td>\r\n</tr>\r\n";
  result += "</td>\r\n</tr>\r\n</table>\r\n";
 
  result += "<input type=\"Submit\" name=\"send\" value=\"Save-Wifi\" >\r\n";
  result += "<input type=\"Submit\" name=\"send\" value=\"Restart\" ></form></fieldset>\r\n\r\n<br>\r\n<br>\r\n";
 
  result += "<fieldset name=\"hosts\"><legend>Hosts</legend>\r\n<b>Monitoring IPs:</b><br><br>\r\n\r\n";
  result += "<form action=\"\" method=\"post\">";
  result += "IP1: <input type=\"text\" name=\"ip1\" value=\"";
  result += host1;
  result += "\" ";
  if (host_is_online[0])
    result += "style=\"background-color:green\"";
  else
    result += "style=\"background-color:red\"";
  result += " maxlength=\"15\"><br>\r\n";
 
  result += "IP2: <input type=\"text\" name=\"ip2\" value=\"";
  result += host2;
  result += "\" ";
  if (host_is_online[1])
    result += "style=\"background-color:green\"";
  else
    result += "style=\"background-color:red\"";
  result += " maxlength=\"15\"><br>\r\n";
 
  result += "IP3: <input type=\"text\" name=\"ip3\" value=\"";
  result += host3;
  result += "\" ";
  if (host_is_online[2])
    result += "style=\"background-color:green\"";
  else
    result += "style=\"background-color:red\"";
  result += " maxlength=\"15\"><br>\r\n";
  result += "<input type=\"Submit\" name=\"send\" value=\"Save\"> \r\n";
  result += "<input type=\"Submit\" name=\"send\" value=\"Refresh\">\r\n\r\n</form>\r\n";
  result += "</body>\r\n</html>";
  server.send(200, "text / html", result);
}
 
void handleDump() {
  Serial.println("EEPROM:");
  for (int i = 0; i < EEPROM_SIZE; i++) {
    Serial.print(i);
    Serial.print(": ");
    Serial.println((char) EEPROM.read(i));
  }
  Serial.println("END");
  server.send(200, "text / html", "DUMPED ON SERIAL OUTPUT");
}
 
 
void setup() {
  // Initialize Serial and LEDs
  Serial.begin(115200);
  delay(20);
  Serial.println("\r\n Ready ");
  pinMode(PIN_LED, OUTPUT);
  digitalWrite(PIN_LED, HIGH);
 
  // Read IPs and Wifi-credentials from EEPROM
  EEPROM.begin(EEPROM_SIZE);
 
  if (RESET_EEPROM) { // First start, initialize EEPROM
    strncpy(host1, "192.168.123.1", 13);
    strncpy(host2, "8.8.8.8", 7);
    strncpy(host3, "8.8.4.4", 7);
 
    writeSSIDtoEEPROM(WIFI_SSID);
    writePASSWORDtoEEPROM(WIFI_PASSWORD);
    writeIPtoEEPROM();
 
    Serial.println("EEPROM initialized");
    while (true)
    {
      digitalWrite(PIN_LED, HIGH);
      delay(100);
      digitalWrite(PIN_LED, LOW);
      delay(100);
    }
  } else {
    // Read from EEPROM
    for (int i = 0; i < 15; i++) {
      host1[i] = EEPROM.read(ADDRESS_IP1 + i);
      host2[i] = EEPROM.read(ADDRESS_IP2 + i);
      host3[i] = EEPROM.read(ADDRESS_IP3 + i);
    }
    for (int i = 0; i < 30; i++) // SSID
      network_ssid[i] = EEPROM.read(ADDRESS_SSID + i);
    for (int i = 0; i < 30; i++) // Password
      network_password[i] = EEPROM.read(ADDRESS_PASSWORD + i);
  }
 
  // Print hosts
  Serial.println("Hosts from EEPROM:");
  Serial.print("[1]: ");
  Serial.println(host1);
  Serial.print("[2]: ");
  Serial.println(host2);
  Serial.print("[3]: ");
  Serial.println(host3);
  Serial.print("Wifi from EEPROM: \"");
  Serial.print(network_ssid);
  Serial.print("\" \"");
  Serial.print(network_password);
  Serial.println("\"\r\n");
 
  // Connect to AP
  WiFi.mode(WIFI_STA); // Set to client
  WiFi.begin(network_ssid, network_password);
 
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.println(".");
    if (state_LED == HIGH)
      state_LED = LOW;
    else
      state_LED = HIGH;
    digitalWrite(PIN_LED, state_LED);
  }
 
  Serial.print("Connected to ");
  Serial.println(network_ssid);
  Serial.print("IP address: ");
  network_ip = WiFi.localIP();
  Serial.println(network_ip);
 
  // Start the server
  server.on("/", handleRoot);
  server.on("/dump/", handleDump);
  server.begin();
 
  digitalWrite(PIN_LED, HIGH);
  delay(250);
  digitalWrite(PIN_LED, LOW);
}
 
void loop() {
  server.handleClient();
  currentMillis = millis(); // Read current runtime
 
  if (WiFi.status() != WL_CONNECTED) {
    Serial.println("Not connected anymore, restarting");
    system_restart();
  }
 
  if (last_ping + PING_INTERVAL < currentMillis) {
    Serial.print(currentMillis);
    const char* host;
 
    currentHost = (currentHost + 1) % count_hosts;
    if (currentHost == 0)
      host = host1;
    else if (currentHost == 1)
      host = host2;
    else
      host = host3;
 
    uint32 address = ipaddr_addr(host);
    if (host[0] == '0' && host[2] == '0' && host[4] == '0' && host[6] == '0')
      Serial.println(": Skipping");
    else {
      Serial.print(": Pinging \"");
      Serial.print(host);
      Serial.print("\" - ");
      ping(address);
      last_ping = currentMillis;
    }
  }
 
  if (last_seen_online + (count_hosts * PING_INTERVAL) > currentMillis)
    state_LED = HIGH;
  else
    state_LED = LOW;
 
  digitalWrite(PIN_LED, state_LED);
}