#include "clock.h"


/*
TODO: Add functions to set the system time and date.
*/


// ------ UPTIME AND DATETIME --------------------------------------------------

// Uptime is the number of 1/256th second ticks elapsed since the emulator began.
static u32 uptime;

// Increment the local uptime value.
void uptime_handler(void) { uptime++; }

// Configure timer 0 to increment the local uptime value every tick.
void init_nds_clock(void) {
    // Start a 256Hz timer to increment the uptime value.
    timerStart(0, ClockDivider_1024, TIMER_FREQ_1024(256), uptime_handler);
}

// Return the current time and date.
struct tm* get_datetime(void) {
    time_t timestamp = time(NULL);
    struct tm* datetime = localtime(&timestamp);
    return datetime;
}


// ------ TIMERS ---------------------------------------------------------------

// Reset a clock timer.
void timer_reset(ClockTimer *timer) {
    timer->end = 0;
    timer->read = 0;
    timer->write = 0;
}

// Update the cached read value of a timer.
void timer_read(ClockTimer *timer) {
    if (timer->end > uptime) {
        timer->read = timer->end - uptime;
    } else {
        timer->read = 0;
        timer->end = 0;
    }
}

// Update the value of a timer using the cached write value.
void timer_write(ClockTimer *timer) {
    if (timer->write) {
        timer->end = uptime + timer->write;
    } else {
        timer->end = 0;
    }
}


// ------ CLOCK ----------------------------------------------------------------

// Reset the clock device.
void clock_reset(ClockDevice *clock) {
    clock->start = uptime;
    timer_reset(&clock->t1);
    timer_reset(&clock->t2);
    timer_reset(&clock->t3);
    timer_reset(&clock->t4);
}

// Update the cached uptime value.
void clock_uptime_read(ClockDevice *clock) {
    clock->uptime = uptime - clock->start;
}

// Return true if any timer has expired.
bool clock_check_timers(ClockDevice *clock) {
    bool output = false;
    if (clock->t1.end && clock->t1.end <= uptime) { clock->t1.end = 0; output = true; }
    if (clock->t2.end && clock->t2.end <= uptime) { clock->t2.end = 0; output = true; }
    if (clock->t3.end && clock->t3.end <= uptime) { clock->t3.end = 0; output = true; }
    if (clock->t4.end && clock->t4.end <= uptime) { clock->t4.end = 0; output = true; }
    return output;
}