//read out 5 slider values and store them on the SD card
//read out the data from SD card as int or string
//this might be useful if you want to save data before arduino is shut down
//and reload data at new start up


#include <SD.h>
#include <SPI.h>

#define chipSelect 10
#define saveButton 2 //yellow
#define loadButton 3 //green
#define deleteButton 4 //blue
#define printVariablesButton 5 //gray
#define MAX_MESSAGE_LENGTH 12
#define NUMBER_OF_PARAMETERS 5
#define slider1 A0 //green
#define slider2 A1 //braun
#define slider3 A2 //orange
#define slider4 A3 //purple
#define slider5 A4 //white

int parameter[NUMBER_OF_PARAMETERS];

void initializeSDcard(){ //function for initializion of the SD card
  Serial.print("Initializing SD card...");
  if (!SD.begin(chipSelect)) {
    Serial.println("Card failed, or not present");
    return;
  }
  Serial.println("card initialized.");
}

void setup(){
  pinMode(saveButton, INPUT_PULLUP); //set pins to input and add software pullup
  pinMode(loadButton, INPUT_PULLUP);
  pinMode(deleteButton, INPUT_PULLUP);
  pinMode(printVariablesButton, INPUT_PULLUP);
  Serial.begin(9600);
  while (!Serial) {delay(10);}// wait for serial port to connect.
  initializeSDcard(); //initialze the SD card
}

void saveDataToSD(int parameter_pos, int value){ //function to save data to sd 
  deleteDataFromSD(); //before save new data to sd card delete old file
  String dataString = "";
  parameter[parameter_pos]=value;
  for(int i = 0; i<NUMBER_OF_PARAMETERS; i++){
    dataString = String(parameter[i]);
    File dataFile = SD.open("datalog.txt", FILE_WRITE); // open the file named datalog.txt on the sd card
    if (dataFile) { // if the file is available, write the contents of datastring to it
      dataFile.println(dataString);
      dataFile.close();
      Serial.println("data saved!");
    }else { // if the file isn't open, pop up an error:
      Serial.println("error opening datalog.txt");
    } 
  }  
}

void loadDataFromSD(){ //function to read out sd card as string and print
  Serial.println("load data");
    File dataFile = SD.open("datalog.txt"); //open up datalog2.txt and then print all of its contents  
    if(dataFile) {
      Serial.println("datalog:");
      while (dataFile.available()) {
        Serial.write(dataFile.read());
      }
      dataFile.close(); // close the file:
    }else{
      Serial.println("error opening datalog.txt"); // if the file didn't open, print an error:
    }
}

void deleteDataFromSD(){ //function to delete the file datalog.txt
  SD.remove("datalog.txt"); 
  Serial.println("data deleted");
}

int readoutSDAsInt(int i){ //function to readout sd card and return data at line i as int 
  int parameter_pos = 0;
  File dataFile = SD.open("datalog.txt");
  if(dataFile){
    while (dataFile.available()){
      static char message[MAX_MESSAGE_LENGTH];//create a place to hold the incoming message
      static unsigned int message_pos = 0;
      char inByte = dataFile.read();//read the next available byte in the serial receive buffer
      if(inByte != '\n' && (message_pos < MAX_MESSAGE_LENGTH - 1)){//check not terminating character
        message[message_pos] = inByte;//add the incoming byte to our message
        message_pos++;
      }else{
        message[message_pos] = '\0';//add nul charakter to string
        parameter[parameter_pos] = atoi(message);
        message_pos = 0;//reset for the next message
        parameter_pos++;
      }
    }
      dataFile.close();
    }else{
      Serial.println("error opening datalog.txt"); // if the file didn't open, print an error:
    }
  return parameter[i];
}

void loop(){
  delay(100);
  if(digitalRead(saveButton) == LOW) { //if the save button is low, read out all sliders and save to sd card
    saveDataToSD(0,analogRead(slider1));
    saveDataToSD(1,analogRead(slider2));
    saveDataToSD(2,analogRead(slider3));
    saveDataToSD(3,analogRead(slider4));
    saveDataToSD(4,analogRead(slider5));
    Serial.println("saved all sliders");
    
  }
  if(digitalRead(loadButton) == LOW) {loadDataFromSD();}
  if(digitalRead(deleteButton)==LOW) {deleteDataFromSD();}
  if(digitalRead(printVariablesButton)==LOW){
    Serial.println("Readout >parameters[]<:");
    for(int i = 0; i<NUMBER_OF_PARAMETERS; i++){
      Serial.print("Slider ");
      Serial.print(i+1);
      Serial.print(": ");
      Serial.println(readoutSDAsInt(i));
    }
  }

}