#include <sys/wait.h>
#include <sys/time.h>
#include <unistd.h>
#include <signal.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#include "as5.h"

#define NUM_READERS 4
#define NUM_WRITERS 3

void randStartProcs(SysSemaphores *pStart)
{
	int started[NUM_READERS+NUM_WRITERS];
	int count = 0;
	int index;

	srand((unsigned)time(NULL));

	for (int i = 0; i < NUM_READERS+NUM_WRITERS; ++i)
		started[i] = 0;

	while (count < NUM_READERS+NUM_WRITERS)
	{
		index = rand() % (NUM_READERS+NUM_WRITERS);
		if (!started[index])
		{
			count++;
			pStart->Signal(index);
			started[index] = 1;
			milliSleep(5);
		}
	}
}

void orderedStartProcs(SysSemaphores *pStart)
{
	//Order: W,R,R,R,W,R,W
	pStart->Signal(6);
	milliSleep(5);
	pStart->Signal(0);
	milliSleep(5);
	pStart->Signal(1);
	milliSleep(5);
	pStart->Signal(2);
	milliSleep(5);
	pStart->Signal(5);
	milliSleep(5);
	pStart->Signal(3);
	milliSleep(5);
	pStart->Signal(4);
}

int StartProcs(SysSemaphores *pStart, int argc, char **argv)
{
	int rand = 0;

	for (int i = 1; i < argc; ++i)
		if (strcmp(argv[i], "-r"))
		{
			printf("Usage:\r\n\t%s [-r]\r\n\t\t-r\tRandomly start readers/writers\r\n\t\t\tOtherwise, ordered starting: W,R,R,R,W,R,W\r\n\r\n", argv[0]);
			return -1;
		}
		else rand = 1;

	if (rand)
		randStartProcs(pStart);
	else orderedStartProcs(pStart);

	return 0;
}

struct timeval startTime;

int main(int argc, char **argv)
{
	int Pid;
	int Status;
	void *ShmPtr;
	SysSemaphores sems(3, 0666 | IPC_CREAT);
	SysSemaphores startProc(NUM_READERS+NUM_WRITERS, 0666 | IPC_CREAT);
	SysSharedMem shm(SHM_SIZE, 0666 | IPC_CREAT);

	ERROR("SetVal", sems.SetVal(SEM_QUEUE, 1));
	ERROR("SetVal", sems.SetVal(SEM_MUTEX, 1));
	ERROR("SetVal", sems.SetVal(SEM_WRITE, 1));

	for (int i = 0; i < NUM_READERS+NUM_WRITERS; ++i)
		ERROR("SetVal", startProc.SetVal(i, 0));

	gettimeofday(&startTime, NULL);


	for (int i = 1; i <= NUM_READERS; ++i)	//make some readers
	{
		Pid=fork();

		if (Pid==0) // child
		{
			//attach shared memory to process
			ShmPtr = shm.Attach(SHM_R);

			startProc.Wait(i-1);
			ReaderFunction(&sems, (char*)ShmPtr);

			shm.Detach(ShmPtr);
			exit(0);
		}
	}

	for (int i = 1; i <= NUM_WRITERS; ++i) // make some writers
	{
		Pid=fork();

		if (Pid==0) // child
		{
			//attach shared memory to process
			ShmPtr = shm.Attach(SHM_W);

			startProc.Wait(i+NUM_READERS-1);
			WriterFunction(&sems, (char*)ShmPtr);

			shm.Detach(ShmPtr);
			exit(0);
		}
	}

	if (StartProcs(&startProc, argc, argv) == -1)
	{
		killpg(0, SIGKILL);
	}

	//Wait for children to finish
	for (int i = 0; i < NUM_READERS+NUM_WRITERS; ++i)
		wait(&Status);


	return 0;
}


void milliSleep(int millisecs)
{
	usleep(millisecs*1000);
}

long getTime()
{
	struct timeval tv;

	gettimeofday(&tv, NULL);

	return (tv.tv_sec - startTime.tv_sec) * 1000000 + (tv.tv_usec - startTime.tv_usec);
}