#include <Wire.h>
#include <TEA5767.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);
#define ENC_CLK 32 //the following are the pins used for the KY-040 encoder
#define ENC_DT 33
#define ENC_SW 25

TEA5767 radio;
struct Station {
  float freq;
  const char *name;
};

Station presets[] = { //these are just the channels I selected, you can adjust them depending on your location
                      {88.1,  "Classical"},
                      {90.1,  "Christian Contemporary"},
                      {92.5,  "Big Country"},
                      {94.5,  "KGWD"},
                      {96.5,  "Life 96.5"},
                      {99.1,  "Kickin' Country"},
                      {102.3, "ESPN Sioux Falls"},
                      {107.5, "Faith Radio"}
};

const int NUM_PRESETS = sizeof(presets)/sizeof(presets[0]); //calculate total preset count
bool presetMode=false; //manual mode
int presetIndex=0; //track active preset station
float freq=96.5; //track frequency and start at 96.5

int lastCLK;
bool lastButton=HIGH;
unsigned long lastDebounce=0;

tea5767_info_t info;
void tune(float f){ //the range of frequencies is 87.5 -- 108.0
  if(f<87.5) f=87.5;
  if(f>108.0) f=108.0;
  freq=f; //update freq variable
  radio.setFrequency(freq); //command TEA5767
  delay(50);
  radio.getInfo(&info); //wait for a bit and update info
}

void drawUI(){
  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE); 

  display.setTextSize(2);
  display.setCursor(0,0);
  display.print(presetMode ? "PRESET ON" : "MANUAL ON"); // display what mode the user is on

  display.setTextSize(2);
  display.setCursor(0,24);
  display.print(freq,1);  //display the frequency
  display.print(" MHz");

  display.setTextSize(1);
  display.setCursor(0,54);

  if(presetMode)
    display.print(presets[presetIndex].name); // display what channel the user is on if they are using PRESET mode

  display.display();
}

void setup() {
  Serial.begin(115200);
  Wire.begin(21,22); // SDA and SCL pins
  pinMode(ENC_CLK,INPUT_PULLUP); //turn on the internal PULLUPS to avoid floating pins
  pinMode(ENC_DT,INPUT_PULLUP);
  pinMode(ENC_SW,INPUT_PULLUP);
  lastCLK=digitalRead(ENC_CLK);

  display.begin(SSD1306_SWITCHCAPVCC,0x3C); //turn on OLED
  display.clearDisplay();
  display.display();

  radio.awake(); // you have to turn off the STANDBY mode of the TEA5767
  delay(100);
  tune(freq);
  drawUI();
}

void loop() { //KY-040 logic
  int clk = digitalRead(ENC_CLK);
  if (clk != lastCLK && clk == LOW) {
    if (digitalRead(ENC_DT) != clk) {
      if (presetMode) {
        presetIndex = (presetIndex + 1) % NUM_PRESETS;
        tune(presets[presetIndex].freq);
      } else {
        tune(freq + 0.1); //if moving clockwise
      }
    } else {
      if (presetMode) {
        presetIndex--;
        if (presetIndex < 0) presetIndex = NUM_PRESETS - 1;
        tune(presets[presetIndex].freq);
      } else {
        tune(freq - 0.1); //if moving counterclockwise
      }
    }
    drawUI(); //refresh display
  }
  lastCLK = clk;
  bool reading = digitalRead(ENC_SW);

  if (reading != lastButton) {  // if the switch changed due to noise or pressing, reset timer
    lastDebounce = millis();
  }

  if ((millis() - lastDebounce) > 40) {  // Once state has been stable for > 40ms, process the state change
    static bool buttonState = HIGH;
    if (reading != buttonState) {
      buttonState = reading;
      if (buttonState == LOW) { // trigger when transition goes from HIGH to LOW (User pressed it)
        Serial.println("BUTTON PRESSED!");
        presetMode = !presetMode;
        Serial.print("Preset mode = ");
        Serial.println(presetMode ? "PRESET" : "MANUAL");

        if (presetMode) { // go to closest preset channel
          float best = 1000.0; 
          for (int i = 0; i < NUM_PRESETS; i++) {
            float d = fabs(freq - presets[i].freq);
            if (d < best) {
              best = d;
              presetIndex = i;
            }
          }
          tune(presets[presetIndex].freq);
        }
        drawUI();
      }
    }
  }
  lastButton = reading;
}