#ifndef DISPLAY_H
#define DISPLAY_H

#include "Color.h"
#include "Adafruit_NeoPixel.h"
#include "Vector.h"

#define SYMBOL_COUNT          15
#define DISPLAY_CHAR_WIDTH    3
#define DISPLAY_CHAR_HEIGHT   5

extern bool SYMBOLS[SYMBOL_COUNT][DISPLAY_CHAR_WIDTH * DISPLAY_CHAR_HEIGHT];

class Display {

public:

    const uint8_t width;

    const uint8_t height;

    const size_t pixelCount;

    const size_t pixelByteCount;

    bool fpsShow = false;

private:

    Adafruit_NeoPixel leds;

    unsigned long fpsLastMillis = 0;

    int fps = 0;

    Color *buffer = nullptr;

    uint8_t brightness = 10;

public:

    Display(uint8_t width, uint8_t height) :
        width(width), height(height),
        pixelCount(width * height),
        pixelByteCount(pixelCount * sizeof(Color)),
        leds(pixelCount, GPIO_NUM_13) {
      buffer = (Color *) malloc(pixelByteCount);
      if (buffer == nullptr) {
        Serial.print("+-----------------------------------------------+\n");
        Serial.print("| OUT OF MEMORY: Cannot allocate double-buffer! |\n");
        Serial.print("+-----------------------------------------------+\n");
      }
    }

    ~Display() {
      if (buffer == nullptr) {
        return;
      }
      free(buffer);
      buffer = nullptr;
    }

    void setup() {
      leds.begin();
      clear();
      flush();
    }

    void loop() {
      calculateFPS();
      drawFpsBorder();
      if (isDirty()) {
        flush();
      }
    }

    void setBrightness(uint8_t value) {
      brightness = value;
    }

    uint8_t getBrightness() const {
      return brightness;
    }

    void clear() {
      if (buffer == nullptr) {
        return;
      }
      memset(buffer, 0, pixelByteCount);
    }

    uint8_t print(uint8_t xPos, uint8_t yPos, uint8_t index, Color color) {
      if (index >= SYMBOL_COUNT) {
        Serial.printf("Cannot print symbol #%u.\n", index);
        index = SYMBOL_COUNT - 1;
      }
      bool *symbolBit = SYMBOLS[index];
      for (uint8_t y = 0; y < DISPLAY_CHAR_HEIGHT; ++y) {
        for (uint8_t x = 0; x < DISPLAY_CHAR_WIDTH; ++x) {
          if (*(symbolBit++)) {
            set(xPos + x, yPos + y, color);
          } else {
            set(xPos + x, yPos + y, BLACK);
          }
        }
      }
      return DISPLAY_CHAR_WIDTH;
    }

    void set(Vector *pos, Color color) {
      set((uint8_t) round(pos->x), (uint8_t) round(pos->y), color);
    }

    void set(uint8_t x, uint8_t y, Color color) {
      if (x >= width || y >= height) {
        return;
      }
      if ((y % 2) != 0) {
        x = width - x - 1;
      }
      set(y * width + x, color);
    }

    void set(uint16_t index, Color color) {
      if (buffer == nullptr) {
        return;
      }
      buffer[index] = {
          // yes, correct order is GRB !!!
          (uint8_t) (color.g * brightness >> 8),
          (uint8_t) (color.r * brightness >> 8),
          (uint8_t) (color.b * brightness >> 8)
      };
    }

private:

    void flush() {
      if (buffer == nullptr) {
        return;
      }
      memcpy(leds.getPixels(), buffer, pixelByteCount);
      leds.show();
    }

    bool isDirty() const {
      if (buffer == nullptr) {
        return false;
      }
      return memcmp(leds.getPixels(), buffer, pixelByteCount) != 0;
    }

    void calculateFPS() {
      fps = (int) round(1000.0 / (millis() - fpsLastMillis));
      fpsLastMillis = millis();
    }

    void drawFpsBorder() {
      if (!fpsShow) {
        return;
      }

      int frames = fps;

      Color color = RED;
      if (frames > 3 * 76) {
        frames -= 3 * 76;
        color = WHITE;
      } else if (frames > 2 * 76) {
        frames -= 2 * 76;
        color = BLUE;
      } else if (frames > 76) {
        frames -= 76;
        color = GREEN;
      }

      for (int x = 0; x <= width - 1 && frames-- > 0; x++) {
        set(x, 0, color);
      }
      for (int y = 0; y <= height - 1 && frames-- > 0; y++) {
        set(width - 1, y, color);
      }
      for (int x = width - 1; x >= 0 && frames-- > 0; x--) {
        set(x, height - 1, color);
      }
      for (int y = height - 1; y >= 0 && frames-- > 0; y--) {
        set(0, y, color);
      }
    }

};

#endif