#include <Adafruit_ILI9341.h>

#define CS   10
#define DC   9
#define RST  8
#define MOSI 11
#define MISO 12
#define CLK  13

Adafruit_ILI9341 display = Adafruit_ILI9341(CS, DC, MOSI, CLK, RST, MISO);

#define TFT_WIDTH display.width() // 320
#define TFT_HEIGHT display.height() // 240

#define PADDING 5

#define GRID_START_X 5
#define GRID_START_Y 20
#define GRID_WIDTH TFT_WIDTH - 2*PADDING // 310
#define GRID_HEIGHT TFT_HEIGHT - PADDING - GRID_START_Y // 215

typedef struct {
  float x_min, x_max, x_step;
  float y_min, y_max, y_step;
  String x_label, y_label;
  uint16_t grid_color;
} Graph;

#define BACK_CLR ILI9341_BLACK
#define GRID_CLR ILI9341_RED

void render(Graph* g) {
  display.fillScreen(BACK_CLR);

  display.drawRect(GRID_START_X, GRID_START_Y, GRID_WIDTH, GRID_HEIGHT, GRID_CLR);
  display.drawRect(GRID_START_X+1, GRID_START_Y+1, GRID_WIDTH-2, GRID_HEIGHT-2, GRID_CLR);
  display.setCursor(GRID_START_X, 1);

  display.setTextSize(2);
  display.print("y = 2x + 1");

  
}

void setup() {
  display.begin();
  display.setRotation(1);
  display.fillScreen(BACK_CLR);

  Graph graph = {-2, 2, 1, -2, 2, 1, "x", "y", GRID_CLR};

  render(&graph);
}

void loop() {
  // put your main code here, to run repeatedly:

}