step_agent.h

void step_agent(CCpr *env, int i) {

  int action = env->actions[i];

  int dr = 0;
  int dc = 0;

  switch (action) {
  case 0:
    dr = -1;
    break; // UP
  case 1:
    dr = 1;
    break; // DOWN
  case 2:
    dc = -1;
    break; // LEFT
  case 3:
    dc = 1;
    break; // RIGHT
  }

  if (action != 4)
    env->logs[i].moves += 1;

  // Get next row and column
  Agent *agent = &env->agents[i];

  int next_r = agent->r + dr;
  int next_c = agent->c + dc;

  int prev_grid_idx = grid_index(env, agent->r, agent->c);
  int next_grid_idx = env->width * next_r + next_c;
  int tile = env->grid[next_grid_idx];

  // Anything above should be obstacle
  if (tile >= INTERACTIVE_FOOD) {
    env->logs[i].score += env->reward_move;
    env->rewards[i] += env->reward_move;
    next_r = agent->r;
    next_c = agent->c;
    next_grid_idx = env->width * next_r + next_c;
    tile = env->grid[next_grid_idx];
  }

  // Interactive food logic
  int neighboors[4] = {
      grid_index(env, next_r - 1, next_c), // Up
      grid_index(env, next_r + 1, next_c), // Down
      grid_index(env, next_r, next_c + 1), // Right
      grid_index(env, next_r, next_c - 1)  // Left
  };

  for (int j = 0; j < 4; j++) {
    int grid_idx = neighboors[j];
    // If neighbooring grid tile is interactive food
    if (env->grid[grid_idx] == INTERACTIVE_FOOD) {
      // If was already marked as "ready to collect"
      if (CHECK_BIT(env->interactive_food_agent_count, grid_idx)) {
        reward_agents_near(env, grid_idx);
      } else {
        // First agent detected
        SET_BIT(env->interactive_food_agent_count, grid_idx);
      }
    }
  }

  switch (tile) {
  case NORMAL_FOOD:
    env->logs[i].score += env->reward_food;
    env->rewards[i] = env->reward_food;
    // spawn_food(env);
    remove_food(env, next_grid_idx);
    add_log(env->log_buffer, &env->logs[i]);
    env->logs[i] = (Log){0};
    break;
  case EMPTY:
    env->logs[i].score += env->reward_move;
    env->rewards[i] = env->reward_move;
    break;
  }

  int agent_tile = get_agent_tile_from_id(agent->id);

  env->grid[prev_grid_idx] = EMPTY;
  env->grid[next_grid_idx] = agent_tile;
  agent->r = next_r;
  agent->c = next_c;
}