#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <unistd.h>

#define DEBUG 1
#define MAX_DATA 12
#define SUBWAYS 4

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

void ReadLine(int Line);
void StartThread(int Subway);
static void *GoSubwayGo(void *index);
void PrintList(int Subway);
void Usage();

FILE *file;

subway_t value;

pthread_t th[SUBWAYS];
pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t cond;

char *pProgname;
char *pFilename;
int GlobalSubway;

int main(int argc, char *argv[])
{
	char cBuffer[MAX_DATA];
	int nCount;
  	
	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 < SUBWAYS; nCount++)
	{
		ReadLine(nCount);
	}
	
#if DEBUG
	for(nCount = 0; nCount < SUBWAYS; nCount++) PrintList(nCount);	
#endif
	while((cBuffer[0] = getchar()) != 'S')
	{
		continue;
	}
	for(nCount = 0; nCount < SUBWAYS; nCount++)
	{
		GlobalSubway = nCount;
		StartThread(nCount);
	}
				
	for(nCount = 0; nCount < SUBWAYS; nCount++)
	{
		pthread_join(th[nCount], NULL);
	}

#if DEBUG
	for(nCount = 0; nCount < SUBWAYS; nCount++) PrintList(nCount);
#endif
	return EXIT_SUCCESS;	
}	

void ReadLine(int Line)
{
	char cBuffer[MAX_DATA];

	if(fgets(cBuffer, MAX_DATA -1, file) == NULL)
	{
		fprintf(stderr, "%s: invalid file layout %s\n", pProgname, pFilename);
		exit(EXIT_FAILURE);
	}
	sscanf(cBuffer,"%lf %lf", &value.nStartDistance[Line], &value.nSpeed[Line]);
	value.nNowDistance[Line] = value.nStartDistance[Line] * 1000;
	value.nSpeed[Line] = value.nSpeed[Line] / 3.6;
}

void StartThread(int Subway)
{
	char cBuffer[255];

	sprintf(cBuffer,"%d", Subway);
#if DEBUG
	printf("cBuffer: %s\n", cBuffer);
#endif
	if(pthread_create(&th[Subway], NULL, &GoSubwayGo, cBuffer) != 0)
	{
		fprintf(stderr, "%s: Error creating Thread\n", pProgname);
		exit(EXIT_FAILURE);	
	}
}

static void *GoSubwayGo(void *index)
{
	int Status;
	int Subway;
	int GotWhere = 1;

	printf("index: %s\n", (char *) index);
	Subway = (int) strtol((char *) index, NULL, 10);
	Subway = GlobalSubway;
	printf("Subway %d started\n", Subway);
   	while (GotWhere != 0)
   	{
#if DEBUG
		printf("Subway: %d\n", Subway);
#endif
	    	if((Status = pthread_mutex_lock(&mutex)) != 0);
		{
			fprintf(stderr,"%s: Error Mutex_Lock with Tread %ld\n", pProgname, pthread_self());
			exit(EXIT_FAILURE);
		}

		if(value.nNowDistance[Subway] >= value.nSpeed[Subway])
		{
			value.nNowDistance[Subway] = value.nNowDistance[Subway] - value.nSpeed[Subway];
		}
                else
                {
               		value.nNowDistance[Subway] = 0;	
                        pthread_cond_wait(&cond, &mutex);
		}

		GotWhere = value.nNowDistance[Subway];

		if((Status = pthread_mutex_unlock(&mutex)) != 0)
		{
			fprintf(stderr,"%s: Error Mutex_Unlock with Tread %ld\n", pProgname, pthread_self());
			exit(EXIT_FAILURE);
		}	
		sleep (1);		
	}
	pthread_exit((void *) 0);
}

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

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