#include "core/ltask.h"

#include "core/lmem.h"

/* this is the only reason C11 support is needed, i cba to write windows/linux specific stuff to get
   the current time in ms also side note: microsoft? more like micropenis */
long laikaT_getTime()
{
    struct timespec ts;
    timespec_get(&ts, TIME_UTC);
    return ts.tv_sec * 1000 +
           ts.tv_nsec / 1000000; /* convert time (seconds & nanoseconds) to milliseconds */
}

void laikaT_initTaskService(struct sLaika_taskService *service)
{
    service->headTask = NULL;
}

void laikaT_cleanTaskService(struct sLaika_taskService *service)
{
    struct sLaika_task *curr = service->headTask, *last;

    /* walk though tasks, freeing all */
    while (curr != NULL) {
        last = curr;
        curr = curr->next;
        laikaM_free(last);
    }
}

void scheduleTask(struct sLaika_taskService *service, struct sLaika_task *task)
{
    struct sLaika_task *curr = service->headTask, *last = NULL;

    task->scheduled = laikaT_getTime() + task->delta;

    /* search list for task for which we're scheduled before */
    while (curr != NULL && curr->scheduled < task->scheduled) {
        last = curr;
        curr = curr->next;
    }

    /* if we stopped at the first head item, set it */
    if (curr == service->headTask) {
        task->next = service->headTask;
        service->headTask = task;
    } else {
        /* add to list */
        task->next = curr;
        if (last)
            last->next = task;
    }
}

void unscheduleTask(struct sLaika_taskService *service, struct sLaika_task *task)
{
    struct sLaika_task *curr = service->headTask, *last = NULL;

    if (task == service->headTask) { /* if task is root, set root to next */
        service->headTask = task->next;
    } else {
        /* find in list */
        while (curr != task) {
            last = curr;
            curr = curr->next;
        }

        /* unlink */
        last->next = task->next;
        task->next = NULL;
    }
}

struct sLaika_task *laikaT_newTask(struct sLaika_taskService *service, int delta,
                                   taskCallback callback, void *uData)
{
    struct sLaika_task *task = laikaM_malloc(sizeof(struct sLaika_task));

    task->callback = callback;
    task->uData = uData;
    task->delta = delta;
    task->next = NULL;

    scheduleTask(service, task);
    return task;
}

void laikaT_delTask(struct sLaika_taskService *service, struct sLaika_task *task)
{
    unscheduleTask(service, task);
    laikaM_free(task);
}

void laikaT_pollTasks(struct sLaika_taskService *service)
{
    struct sLaika_task *last, *curr = service->headTask;
    clock_t currTick = laikaT_getTime();

    /* run each task, list is already sorted from closest scheduled task to furthest */
    while (curr != NULL &&
           curr->scheduled <= currTick) { /* if scheduled time is greater than currTime, all events
                                             that follow are also not scheduled yet */
        /* walk to next task */
        last = curr;
        curr = curr->next;

        /* reset task timer */
        unscheduleTask(service, last);
        scheduleTask(service, last);

        /* dispatch task callback */
        last->callback(service, last, currTick, last->uData);
    }
}

/* will return the delta time in ms till the next event. -1 for no tasks scheduled */
int laikaT_timeTillTask(struct sLaika_taskService *service)
{
    if (service->headTask) {
        int pause = service->headTask->scheduled - laikaT_getTime();
        return (pause > 0) ? pause : 0;
    } else
        return -1; /* no tasks scheduled */
}