#include <stdlib.h>
#include "scheduler.h"

struct Process* rr(struct Process* head, struct Process* current)
{
    if (current && current->next != head)
        return current->next;
    if (head->next != head)
        return head->next;
    return NULL;
}

struct Process* fcfs(struct Process* head, struct Process* current)
{
    if(current && current->cycles_todo)
        return current;
    if(current && current->next != head)
        return current->next;
    if(head->next != head)
        return head->next;
    return NULL;
}

struct Process* spn(struct Process* head, struct Process* current)
{
    if(current && current->cycles_todo)
		return current;
    if(head->next != head)
    {
        struct Process* result = head->next;
        struct Process* tmp = head->next->next;
        while(tmp != head)
        {
            if(tmp->cycles_todo < result->cycles_todo)
                result = tmp;
            tmp = tmp->next;
        }
        return result;
    }
	return NULL;
}

struct Process* srt(struct Process* head, struct Process* unused)
{
    (void)unused;           // second param not used so declared void
    if(head->next != head)
    {
        struct Process* result = head->next;
        struct Process* tmp = head->next->next;
        while(tmp != head)
        {
            if(tmp->cycles_todo < result->cycles_todo)
                result = tmp;
            tmp = tmp->next;
        }
        return result;
    }
    return NULL;
}

struct Process* hrrnNonPreemptive(struct Process* head, struct Process* current)
{
    if(current && current->cycles_todo)
        return current;
    if(head->next != head)
    {
        struct Process* result = head->next;
        uint64_t result_rr = (result->cycles_done) ? ((result->cycles_waited/result->cycles_done)+1) : (result->cycles_waited+1);
        struct Process* tmp = head->next->next;
        while(tmp != head)
        {
            uint64_t tmp_rr =  (tmp->cycles_done) ? ((tmp->cycles_waited/tmp->cycles_done)+1) : (tmp->cycles_waited+1);
            if(tmp_rr > result_rr)
            {
                result = tmp;
                result_rr = tmp_rr;
            }
            tmp = tmp->next;
        }
        return result;
    }
    return NULL;
}

struct Process* hrrnPreemptive(struct Process* head, struct Process* current) {
	return NULL;
}