#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <Wire.h>
#include <map>
#include <utility>

#define WIDTH 128 // OLED display width, in pixels
#define HEIGHT 64 // OLED display height, in pixels
#define WHITE SSD1306_WHITE


// Reset pin not used with the XIAO RP2040, set to -1
Adafruit_SSD1306 display(WIDTH, HEIGHT, &Wire, -1, 1700000UL, 1700000UL);

constexpr int CELL_SIZE = 2;
constexpr int GRID_W = WIDTH/CELL_SIZE;
constexpr int GRID_H = HEIGHT/CELL_SIZE;

uint8_t grid[GRID_W * GRID_H];

// index helper function
inline int idx(int x, int y) {return y*GRID_W + x; }

// set/get helpers
inline void setCell(int x, int y, uint8_t alive) {
  if ((unsigned)x < (unsigned)GRID_W && (unsigned)y < (unsigned)GRID_H)
    grid[idx(x, y)] = alive ? 1 : 0;
}

inline uint8_t getCell(int x, int y) {
  if ((unsigned)x < (unsigned)GRID_W && (unsigned)y < (unsigned)GRID_H)
    return grid[idx(x, y)];
}

// draw a cell

inline void drawCellBlock(int cx, int cy, uint8_t alive) {
  int px = cx*CELL_SIZE;
  int py = cy*CELL_SIZE;
  if (alive) {
    for (int dy = 0; dy < CELL_SIZE; ++dy) 
      for (int dx = 0; dx < CELL_SIZE; ++dx)
        display.drawPixel(px + dx, py+dy, WHITE);
  } 
}

void drawGrid() {
  display.clearDisplay();

  for (int y = 0; y < GRID_H; ++y) {
    for (int x = 0; x < GRID_W; ++x) {
      if (grid[idx(x, y)]) drawCellBlock(x, y, 1);
    }
  }
  display.display();
}
void seedTest() {
  for (int y = 0; y < GRID_H; ++y) {
    for (int x = 0; x < GRID_W; ++x) {
      setCell(x, y, ((x^y)&1));
    }
  }

  for (int y = 2; y < 6; ++y)
    for (int x = 2; x < 6; ++x)
      setCell(x, y, 1);
}

void setup() {
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    for(;;);
  }
  seedTest();
  drawGrid();
}

void loop() {
  // nothing yet — next step we'll animate
}