/****************************/
/*	Subway.c	    */
/*Ubahn Simulations Programm*/
/* von Philipp Klenkhart    */
/*	V 1.0 21.5.05	    */
/****************************/

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

#define LINE_LEN 255

pthread_cond_t cond;
pthread_mutex_t mutex;

typedef struct timetable{
	double distance;
	double speed;
	double time;	
	}timetable_t;

timetable_t line[4];

double position[4];
int stopit = 0;
int counter;

/*Funktion zum starten der Threads*/
void *subwaytohell(void *arg)
{
	int status;
	int index = counter; /**(int *)arg*/;
	
	counter++;
	fprintf(stdout, "Subway %d: goin to work: %ld\n", index+1, pthread_self());
	fprintf(stdout, "speed before mutex %lf: workin\n", line[index].speed);	
	while(position[index] <= 500)
	{
		if(stopit == 0)
		{				
			status = pthread_mutex_lock(&mutex);

   

   			if (status != 0)

   			{

       				fprintf (stdout, "Error on mutex_unlock with Thread%ld\n", pthread_self());

       				exit (EXIT_FAILURE);

       			}    
			
			position[index] = position[index] + line[index].speed;
			fprintf(stdout, "Subway %lf: workin %ld\n", line[index].speed, pthread_self());	
			status = pthread_mutex_unlock(&mutex);
			
			if (status != 0)

   			{

       				fprintf (stdout, "Error on mutex_unlock with Thread%ld\n", pthread_self());

       				exit (EXIT_FAILURE);

       			}  
			
			sleep(1);
			}
		else
		{
			fprintf(stdout, "Subway %d: waitin\n", index);
			pthread_cond_wait(&cond, &mutex);
			}
		
		}	

	if(position[index] >= 500 && position[index] < line[index].distance)
	{
		fprintf(stdout, "Subway %d: reached critical section\n", index);
		stopit = 1;
		   
			
		while(position [index] <= 700)
		{
			status = pthread_mutex_lock(&mutex);

   

   			if (status != 0)

   			{

       				fprintf (stdout, "Error on mutex_unlock with Thread%ld\n", pthread_self());

       				exit (EXIT_FAILURE);

       				}
				
			position[index] += line[index].speed;
			
			status = pthread_mutex_unlock(&mutex);
	
			if (status != 0)

   			{

       				fprintf (stdout, "Error on mutex_unlock with Thread%ld\n", pthread_self());

       				exit (EXIT_FAILURE);

       				}
			sleep(1);
			}
		 
		stopit = 0;
		pthread_cond_signal(&cond);	
		}

	while(position[index] <= line[index].distance)
	{
		pthread_mutex_lock(&mutex);

		position[index] += line[index].speed;

		pthread_mutex_unlock(&mutex);
		sleep(1);
		}
	
	if(position[index] == line[index].distance)
	{
		fprintf(stdout, "Destination Reached\n");
		
		pthread_exit((void *)0);line[index].time = line[index].distance / line[index].speed;
		}
return (0);
}

int thread_start()
{
	pthread_t th[4];
	int i;
	counter=0;
	for (i = 0; i < 4; i++) 
	{fprintf(stdout, "i: %d\n",i);	
		
		if(pthread_create(&th[i], NULL, subwaytohell, NULL) != 0) 
		{
			fprintf (stderr, "Error creating Thread %d ...\n",i+1);
			return EXIT_FAILURE;
			}
		
	}   
	/*Es wird für jeden Thread gewartet bis er beendet hat*/
	for( i=0; i <= 3; i++)
	{
		pthread_join(th[i], NULL);
		}
	
	fprintf(stdout, "All Subways reached their Destinatons!\n");

	return (0);
} 

int main(int argc, char *argv[])
{
	FILE *fp;
	char buffer[LINE_LEN];
	int i;

	if(argc < 1){
		
		/*usage();*/
		return EXIT_FAILURE;
		
		}

	if( (fp=fopen(argv[1], "r")) == NULL){
		
		fprintf(stdout, "File couldn't be opened!\n");
		return EXIT_FAILURE;
		
		}
	fprintf(stdout, "reading file\n");

	for(i = 0; i < 3; i++)
        {
        	if(fgets(buffer, LINE_LEN -1, fp) == NULL)
        	{
        		fprintf(stderr, "%s: invalid file layout %s\n", argv[0], argv[1]);
        		return EXIT_FAILURE;
        	}
      
		sscanf(buffer,"%lf %lf", &line[i].distance, &line[i].speed);
       		fprintf(stdout, "speed read: %lf\n", line[i].speed);
		line[i].speed = line[i].speed/3.6;
		fprintf(stdout, "speed math: %lf\n", line[i].speed);
       		line[i].time = line[i].distance / line[i].speed;
		
	}
	
	
	
	thread_start();

return (0);

}