#include <Arduino.h>
#include <Wire.h>
#include <U8g2lib.h>

// OLED
U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(
  U8G2_R0,
  U8X8_PIN_NONE
);

// Boss size
#define BOSS_W 22
#define BOSS_H 19

// Boss pixel art
const char bossMonster[BOSS_H][BOSS_W + 1] = {
  "........#####..###....",
  ".......##.##.######...",
  "###...#####..#####....",
  "##############.##.....",
  "##.##############.....",
  ".#..###.#.#..#####....",
  ".#####..####..####..##",
  "..##...######....#####",
  ".##...###.###.##.#####",
  ".#....###.###..#######",
  ".#....######....#####.",
  ".#.#.........##.####..",
  ".#######......#####...",
  ".##.#.#.#...##.##....",
  ".##.####..##.####.....",
  ".#.#.#.....####.##....",
  ".#.......######.##....",
  "..##########.######...",
  ".....###.##...#####..."
};

// Boss data
struct Boss {
  int x;
  int y;
  int verticalDirection;
  bool charging;
  bool returning;
  unsigned long lastCharge;
};

Boss boss;

// Start boss
void startBoss() {
  boss.x = 128;
  boss.y = 25;

  boss.verticalDirection = 1;

  boss.charging = false;
  boss.returning = false;

  boss.lastCharge = millis();
}

// Update boss
void updateBoss() {

  // Enter from right
  if (
    boss.x > 100 &&
    !boss.charging &&
    !boss.returning
  ) {
    boss.x -= 1;
    return;
  }

  // Charge every 5 seconds
  if (
    !boss.charging &&
    !boss.returning &&
    millis() - boss.lastCharge > 5000
  ) {
    boss.charging = true;
    boss.lastCharge = millis();
  }

  // Move quickly to the left
  if (boss.charging) {
    boss.x -= 3;

    if (boss.x <= 55) {
      boss.x = 55;

      boss.charging = false;
      boss.returning = true;
    }

    return;
  }

  // Return to the right
  if (boss.returning) {
    boss.x += 3;

    if (boss.x >= 100) {
      boss.x = 100;

      boss.returning = false;
      boss.lastCharge = millis();
    }

    return;
  }

  // Move up and down
  boss.y += boss.verticalDirection;

  if (boss.y <= 12) {
    boss.y = 12;
    boss.verticalDirection = 1;
  }

  if (boss.y >= 44) {
    boss.y = 44;
    boss.verticalDirection = -1;
  }
}

// Draw boss
void drawBoss() {
  for (int y = 0; y < BOSS_H; y++) {
    for (int x = 0; x < BOSS_W; x++) {
      if (bossMonster[y][x] == '#') {
        u8g2.drawPixel(
          boss.x + x,
          boss.y + y
        );
      }
    }
  }
}

// Setup
void setup() {
  Wire.begin();

  u8g2.begin();

  startBoss();
}

// Loop
void loop() {
  updateBoss();

  u8g2.clearBuffer();

  drawBoss();

  u8g2.sendBuffer();

  delay(30);
}