#include <SPI.h>
#include <Button_SL.hpp>
#include <Streaming.h>
Print& cout {Serial};

// #define LEADING_ZEROS

//
// Global constants
//
namespace gc {
constexpr byte PinCS {10};         // SPI CS PIN
constexpr uint8_t PinBtn {4};      // Button Pin

constexpr uint8_t SegmentBits[10] = {
    // edDcgbfa    // D = decimal point
    0b11010111,   // 0
    0b00010100,   // 1
    0b11001101,   // 2
    0b01011101,   // 3
    0b00011110,   // 4
    0b01011011,   // 5
    0b11011011,   // 6
    0b00010101,   // 7
    0b11011111,   // 8
    0b01011111,   // 9
};
}   // namespace gc
//
// Global Variables/Objects
//
Btn::ButtonSL btn {gc::PinBtn};

//
// Send data to the shift register
//
void writeShiftRegister(uint16_t PinData) {
  digitalWrite(gc::PinCS, LOW);
  SPI.transfer(PinData >> 8);         // upper 8 Bits = digit selection
  SPI.transfer((PinData & 0x00FF));   // lower 8 Bits = segments of the digit
  digitalWrite(gc::PinCS, HIGH);
}

//
// Delete Digit on the display
//
void digitsOff() {
  writeShiftRegister(0x00);   // Clear Digits
}

//
// Show digit on the corresponding display position.
//
template <size_t N> void digitToDisplay(uint8_t (&Dgt)[N], uint8_t DotPos, uint8_t Idx) {
  uint16_t Mask = ~(1 << (Idx)) & 0x00FF;   // Set bit mask to display one of the four LED segments
  uint16_t Bits {Mask << 8};                // Highbyte (LED-Segment)
  Bits |= gc::SegmentBits[Dgt[Idx]];        // Lowbyte (Digit)
  // Test whether a dot must be displayed (DotPos > 0)
  if (DotPos > 0 && DotPos < N && Mask == (0x00FF - (1U << DotPos))) { Bits |= 0b00100000; }
  writeShiftRegister(Bits);
}

//
// Divide the Number into its decimal places
//
template <size_t N> uint8_t breakNumberDown(uint8_t (&Dgt)[N], uint16_t Nbr) {
  size_t Idx {0};
  do {
    Dgt[Idx] = Nbr % 10;
    Nbr /= 10;
  } while (Nbr && ++Idx < N);

  return Idx;
}

void sevenSegment(Btn::ButtonSL& b) {
  constexpr uint8_t MaxDigits {4};   // Max. displayable Digits
  static uint8_t Digits[MaxDigits];
  static uint16_t DotPos;
  static uint8_t ActiveDigit {0};
  static uint8_t NumDigits = 0;

  // Press the button to display a new number
  if (b.tick() == Btn::ButtonState::shortPressed) {
    uint16_t Number = random(1, 10000);
    cout << "\r\nNumber: " << _WIDTH(Number, 4) << "\r\n";
    DotPos = random(0, MaxDigits);
    NumDigits = breakNumberDown(Digits, Number);
    cout << "Dot Position: " << DotPos << "\r\nNr. of Digits: " << NumDigits + 1 << "\r\n";
  }
  digitToDisplay(Digits, DotPos, ActiveDigit);
#ifdef LEADING_ZEROS
  ActiveDigit = (ActiveDigit < MaxDigits - 1) ? ActiveDigit + 1 : 0;
#else
  // Decimal point position is greater than the number of Digits -> 0.X[XX]
  // If the position of the dot is greater than the number of decimal places of the random number,
  // a leading zero has to be displayed.
  NumDigits = (DotPos > NumDigits) ? DotPos : NumDigits;
  ActiveDigit = (ActiveDigit < NumDigits) ? ActiveDigit + 1 : 0;
#endif
}

//
// Main Program
//
void setup() {
  Serial.begin(115200);
  pinMode(gc::PinCS, OUTPUT);
  SPI.begin();
  btn.begin();
  randomSeed(analogRead(A0));
}

void loop() { sevenSegment(btn); }