// Oil Tank monitor with 7 hours between measurements

extern "C" {
#include "user_interface.h" // this is for the RTC memory read/write functions
}
uint32_t counter = 0;
uint32_t sleeps = 6;               // Number of sleeps between measurements, 6 is ok
#define SLEEP_TIME 4200000000ULL   // Sleep about 70 mins
//#define SLEEP_TIME 10000000ULL   // Sleep 10 secs for testing

#include <Wire.h>
#include <VL53L1X.h>
VL53L1X sensor;

#include <ESP8266WiFi.h>
#define WIFI_NAME "SSID"
#define PASSWORD "PASSWORD"   
#define TIMEOUT  5000                              // Timeout for server response.
#define THING_SPEAK_ADDRESS "api.thingspeak.com"
String writeAPIKey="API KEY";             // Change this to the write API key for your channel.
WiFiClient client;

void setup()
{ 
Serial.begin( 74880 );     // This speed displays bootup code
  
  system_rtc_mem_read(65, &counter, 4);  // read RTC memory

  Serial.println(counter);
  if (counter >= sleeps) counter=0;   // reset counter when reached maximum sleeps
  counter++;
  system_rtc_mem_write(65, &counter, 4);  // increment and save RTC memory
if (counter == (sleeps)) ESP.deepSleep(SLEEP_TIME); 
  if (counter != 1)   ESP.deepSleep(SLEEP_TIME, WAKE_RF_DISABLED); 

pinMode(15,OUTPUT);
digitalWrite(15,HIGH);   // Switch on sensor
  
  Wire.begin();
Wire.setClock(400000); // use 400 kHz I2C

  sensor.setTimeout(500);
if (!sensor.init())
  {
    Serial.println("Failed to detect and initialize sensor!");
    while (1);
  }
  
  sensor.setDistanceMode(VL53L1X::Long);
  sensor.setMeasurementTimingBudget(200000);     // Budget in us
  sensor.startContinuous(10000);                // Measurement rate ms

    connectWifi();
    
}
void loop() {      
          HTTPPost();    
    delay( 1000 );
    
    ESP.deepSleep(SLEEP_TIME, WAKE_RF_DISABLED);
delay(100);
}

int connectWifi()     // Connect to WiFi
{
  //  WiFi.mode(WIFI_STA);      
    
    while (WiFi.status() != WL_CONNECTED) {
        WiFi.begin( WIFI_NAME , PASSWORD );
        Serial.println( "Connecting to Wi-Fi" );
        delay( 5000 );
    }
    Serial.println( "Connected" );  // Inform the serial monitor.
}
   
int HTTPPost(){     // Measure and post data to ThingSpeak
  
    if (client.connect( THING_SPEAK_ADDRESS , 80 )){

       // Build the postData string.  

       int  tank = sensor.read();
    int strength = WiFi.RSSI();

    digitalWrite(15,LOW);    // Turn off VL53L1X
    
       String postData= "api_key=" + writeAPIKey ;

   postData += "&field1=";
    postData += String(tank);
    postData += "&field2=";
    postData += String(strength);

        // POST data via HTTP.
        Serial.println( "Connecting to ThingSpeak for update..." );
        Serial.println();
        
        client.println( "POST /update HTTP/1.1" );
        client.println( "Host: api.thingspeak.com" );
        client.println( "Connection: close" );
        client.println( "Content-Type: application/x-www-form-urlencoded" );
        client.println( "Content-Length: " + String( postData.length() ) );
        client.println();
        client.println( postData );
        
        Serial.println( postData );
        
        String answer=getResponse();
        Serial.println( answer );

         Serial.println(tank);
          Serial.println(strength);

//       Serial.println(WiFi.RSSI());
// Serial.println(tank);
         
    }
    else
    {
      Serial.println ( "Connection Failed" );
    }    
}
// Collect the response and build it into a string.
String getResponse(){
  String response;
  long startTime = millis();
  delay( 200 );
  while ( client.available() < 1 && (( millis() - startTime ) < TIMEOUT ) ){
        delay( 5 );
  }
  if( client.available() > 0 ){ // Get response from server.
     char charIn;
     do {
         charIn = client.read(); // Read a char from the buffer.
         response += charIn;     // Append the char to the string response.
        } while ( client.available() > 0 );
    }
  client.stop();
          return response;
}