/*
   Master script combine functions
   -> Rotation measurement
   -> Time reading from RTC
*/
//library includes
#include <RTClib.h>
#include <ArduinoJson.h>
#include <SPI.h>
#include <SD.h>

//library inits
RTC_DS3231 rtc;
File myFile;

//test options
#define SET_RTC_DATE true   //set this to true to initialize the RTC clock with the time of the code upload

//settings that need to be adjusted
#define RADIUS 10           // definiert den Rotorradius in cm

//static settings
#define BAUD 9600
#define REEDPIN 2           //io pin for reed contact (with exterenal 10k pullup resistor to vcc)
#define DEBOUNCETIME 200    //debouncing interval
#define INTERVAL 1000       //calculation interval in which the values get sent to serial


//constant numbers
#define PI 3.1415926535897932384626433832795    // definiere PI

//mapping arrays
char daysOfTheWeek[7][12] = {
  "Sunday",
  "Monday",
  "Tuesday",
  "Wednesday",
  "Thursday",
  "Friday",
  "Saturday"
};

//variables
volatile unsigned int contacts;
volatile unsigned long time_inbetween_interrupts;     // Periodendauer in ms
unsigned long lastmillis;
unsigned int lastcontacts;

// create a StaticJsonDocument for the json data
StaticJsonDocument<200> doc;

void setup() {
  attachInterrupt(digitalPinToInterrupt(REEDPIN), count, FALLING);     // setzt ISR fürs hochzählen
  Serial.begin(BAUD);

  // set up rtc module
  if (! rtc.begin()) {
    Serial.println("Couldn't find RTC");
    Serial.println("halting program, reset to retry");
    Serial.flush();
    while (1);
  }

  //if this is the first time you use the RTC module you can set the time of the module with this function,
  //disable afterwards in the #define of SET_RTC_DATE
  if (SET_RTC_DATE) {
    // get the compile time
    DateTime compileTime = DateTime(F(__DATE__), F(__TIME__));

    // define your time offset (for example, Berlin is UTC+2 or UTC+1 depending on daylight saving)
    int offsetHours = 2; // change this to your offset

    // adjust the compile time to UTC
    DateTime UTCTime = compileTime.unixtime() - offsetHours * 3600;

    // set the RTC time
    rtc.adjust(UTCTime);
  }

  // set up sd card
  Serial.print("Initializing SD card...");
  if (!SD.begin(4)) {
    Serial.println("initialization failed!");
    Serial.println("halting program, reset to retry");
    while (1);
  }
  Serial.println("initialization done.");

  // open the file. note that only one file can be open at a time,
  // so you have to close this one before opening another.
  myFile = SD.open("test.txt", FILE_WRITE);

  // if the file opened okay, write to it:
  if (myFile) {
    Serial.print("Writing to test.txt...");
    myFile.println("testing 1, 2, 3.");
    // close the file:
    myFile.close();
    Serial.println("done.");
  } else {
    // if the file didn't open, print an error:
    Serial.println("error opening test.txt");
  }

  // re-open the file for reading:
  myFile = SD.open("test.txt");
  if (myFile) {
    Serial.println("test.txt:");

    // read from the file until there's nothing else in it:
    while (myFile.available()) {
      Serial.write(myFile.read());
    }
    // close the file:
    myFile.close();
  } else {
    // if the file didn't open, print an error:
    Serial.println("error opening test.txt");
  }
}

void loop() {
  //function runs if the time since the last run is greater than the configured interval
  if (lastmillis + INTERVAL <= millis()) {
    //store time of running the function
    lastmillis = millis();
    DateTime now = rtc.now();

    //date calculations
    uint32_t timestamp = now.unixtime();

    //calculations
    float rpm = 1000.0 / time_inbetween_interrupts;
    float rs = (2 * PI * RADIUS) / time_inbetween_interrupts * 10;   // Bahngeschwindigkeitsformel (https://www.leifiphysik.de/mechanik/kreisbewegung/grundwissen/bahngeschwindigkeit-und-winkelgeschwindigkeit)
    float ws = 0.5921 * rpm + 2.3654;     // Windgeschwindigkeit wird berechnet

    //serial outputs
    Serial.print("timestamp:");   Serial.print(String(timestamp));                  Serial.print(",");
    Serial.print("rpm:");         Serial.print(String(rpm));                        Serial.print(",");
    Serial.print("rs:");          Serial.print(String(rs));                         Serial.print(",");
    Serial.print("ws:");          Serial.print(String(ws));                         Serial.print(",");
    Serial.print("contacts:");    Serial.print(String(contacts));                   Serial.print(",");
    Serial.print("delay:");       Serial.print(String(time_inbetween_interrupts));  Serial.println();

    //json output
    doc["timestamp"] = timestamp;
    doc["rpm"] = rpm;
    doc["rs"] = rs;
    doc["ws"] = ws;
    doc["contacts"] = contacts;
    doc["delay"] = time_inbetween_interrupts;

    // serialize json and send it via the Serial interface
    serializeJson(doc, Serial);
    Serial.println();

    //reset contact counter to 0
    contacts = 0;
  }
}

//interrupt routine defined in setup
void count() {
  static unsigned long last_interrupt_time = 0;
  unsigned long interrupt_time = millis();
  //skipping impulses if they happen to fast (debouncing)
  if (interrupt_time - last_interrupt_time > DEBOUNCETIME) {
    contacts++;     // erhöht die gezählten Kontakte
    time_inbetween_interrupts = interrupt_time - last_interrupt_time;
  }

  last_interrupt_time = interrupt_time;
}



/* graveyard
    int year = now.year();
    int month = now.month();
    int day = now.month();
    int hour = now.month();
    int minute = now.month();
    int second = now.month()

    Serial.print("year:");  Serial.print(String(year));  Serial.print(",");
    Serial.print("month:"); Serial.print(String(month));  Serial.print(",");
    Serial.print("day:");   Serial.print(String(day));  Serial.print(",");
    Serial.print("hour:");  Serial.print(String(hour));  Serial.print(",");
    Serial.print("minute:");Serial.print(String(minute));  Serial.print(",");
    Serial.print("second:");Serial.print(String(second));  Serial.println();
*/