Trigalarm/src/c/gentlewake.c

// lol the code in this file is mostly stolen from https://github.com/SeaPea/GentleWake

#include <pebble.h>

// A slightly more robust wakeup scheduler that retries on certain errors and
// can retry for a different wakeup time offset by retry_diff up to retry_max times
WakeupId wakeup_schedule_simple_robust(time_t wakeup_time, int8_t retry_diff, bool is_fallback) {
	WakeupId result = 0;
	uint8_t try_count = 0;

	result = wakeup_schedule(wakeup_time, is_fallback, true);

	if (result < 0) {
		// If result is negative, something went wrong, so make sure all wakeups for this app are cancelled and try again
		wakeup_cancel_all();

		result = wakeup_schedule(wakeup_time, is_fallback, true);

		if (result == E_RANGE) {
			// E_RANGE means some other app has the same wakeup time +/- 1 minute, so try to set
			// the wakeup for a time up to (retry_diff * 5) minutes before/after.
			while (result == E_RANGE && try_count++ < 5) {
				wakeup_time += retry_diff;
				result = wakeup_schedule(wakeup_time, is_fallback, true);
			}
		}
	}

	return result;
}