#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <time.h>
#define DEBUG 1
#define MAX_DATA 12

typedef struct subway{
	double nStartDistance[4];
	double nNowDistance[4];
	double nSpeed[4];
}subway_t;


pthread_mutex_t mutex=PTHREAD_MUTEX_INITIALIZER;

void Usage();
void PrintList(int CurrentSubway);

subway_t value;

char *pProgname;
char *pFilename;

void *GoSubwayGo(void *index)
{
	clock_t start, stop;
	double diff;
	int Subway;
	int Status;
	int GotThere = 1;
	    Status = pthread_mutex_lock(&mutex);
	Subway = atoi((char*) index);

	printf("Subway %d started\n", Subway+1);
   while (GotThere != 0)
   {
		printf("Subway: %d\n", Subway+1);
   	start = clock();
		diff = difftime(stop = clock(), start);

		if(value.nNowDistance[Subway] >= value.nSpeed[Subway])
		{
			value.nNowDistance[Subway] = value.nNowDistance[Subway] - value.nSpeed[Subway];
		}
		else value.nNowDistance[Subway] = 0;
		
		GotThere = value.nNowDistance[Subway];
		
	}
	      Status = pthread_mutex_unlock(&mutex);
	pthread_exit((void *) 0);
}

int main(int argc, char *argv[])
{
	FILE *file;
	char cBuffer[MAX_DATA];
	int nCount;
	pthread_t th[20];
  	
	pProgname = argv[0];
	
	if(argc != 2)
	{
		Usage();
 		return EXIT_FAILURE;
	}

	pFilename = argv[1];

	if((file = fopen(pFilename, "r")) == NULL)
	{
		fprintf(stderr, "%s: Can't open file %s\n", pProgname, pFilename);
		return EXIT_FAILURE;
	}

	for(nCount = 0; nCount < 4; nCount++)
	{
		if(fgets(cBuffer, MAX_DATA -1, file) == NULL)
		{
			fprintf(stderr, "%s: invalid file layout %s\n", pProgname, pFilename);
			return EXIT_FAILURE;
		}
		sscanf(cBuffer,"%lf %lf", &value.nStartDistance[nCount], &value.nSpeed[nCount]);
		value.nNowDistance[nCount] = value.nStartDistance[nCount] * 1000;
		value.nSpeed[nCount] = value.nSpeed[nCount] / 3.6;
	}
	
#if DEBUG
	for(nCount = 0; nCount < 4; nCount++) PrintList(nCount);	
#endif
	while((cBuffer[0] = getchar()) != 'S')
	{
		continue;
	}
	
	for(nCount = 0; nCount < 4; nCount++)
	{
		sprintf(cBuffer,"%d",nCount);
		if(pthread_create(&th[nCount], NULL, &GoSubwayGo, cBuffer) != 0)
		{
			fprintf(stderr, "%s: Error creating Thread\n", pProgname);
			return EXIT_FAILURE;	
		}
	}
									
	for(nCount = 0; nCount < 4; nCount++)
	{
		pthread_join(th[nCount], NULL);
	}
#if DEBUG
	for(nCount = 0; nCount < 4; nCount++) PrintList(nCount);
#endif
	return EXIT_SUCCESS;	
}	

void PrintList(int CurrentSubway)
{
	printf("%d: StartDistance: %.2lf km, NowDistance: %.2lf m, Speed: %.2lf m/s\n", 
			CurrentSubway, value.nStartDistance[CurrentSubway], value.nNowDistance[CurrentSubway], value.nSpeed[CurrentSubway]);
}

void Usage()
{
	printf("Usage %s:\n", pProgname);
	printf("%s filename\n", pProgname);
}