rebate.c

mapping(address=>uint[5]) user_reward;

uint start_time = now;
uint seconds_per_week = 1234; // put real number

function send_reward(address user, uint time) {
	uint week_index = (time - start_time) / seconds_per_week;
	if(user_reward[user][week_index] > 0 || week_index > 4) return 0;
	
	uint reward = 1;
	if(week_index > 0) reward += user_reward[user][week_index - 1];

	user_reward[user][week_index] = reward;

	return reward;
}