// Compiler call:		cc -o aufgabe1 aufgabe1.c -lpthread
#include <pthread.h>
#include <stdio.h>
//#include <stdlib.h>
#include <unistd.h>

int		make_new_item(void);
void 	consume_item(char a, int count);
void*	reader_function(void*);
void	writer_function(void);

char 			buffer;
int 			buffer_has_item = 0;
pthread_mutex_t mutex;

void cleanup_resources() {
    pthread_mutex_destroy(&mutex);
}

int main(int argc, char *argv[]){
	pthread_mutexattr_t	mutex_attr;
	pthread_attr_t		attr;
	pthread_t 			reader;
    int ret;

    // Initialize mutex attributes
    if ((ret = pthread_mutexattr_init(&mutex_attr)) != 0) {
        fprintf(stderr, "Error initializing mutex attributes: %d\n", ret);
        return 1;
    }

    // Initialize mutex
    if ((ret = pthread_mutex_init(&mutex, &mutex_attr)) != 0) {
        fprintf(stderr, "Error initializing mutex: %d\n", ret);
        return 1;
    }

    // Initialize thread attributes
    if ((ret = pthread_attr_init(&attr)) != 0) {
        fprintf(stderr, "Error initializing thread attributes: %d\n", ret);
        cleanup_resources();
        return 1;
    }

    // Create reader thread
    if ((ret = pthread_create(&reader, &attr, reader_function, 0)) != 0) {
        fprintf(stderr, "Error creating thread: %d\n", ret);
        cleanup_resources();
        return 1;
    }

    writer_function();

    // Wait for reader thread to finish
    if ((ret = pthread_join(reader, 0)) != 0) {
        fprintf(stderr, "Error joining thread: %d\n", ret);
        cleanup_resources();
        return 1;
    }

    cleanup_resources();
    printf("Main thread finished!\n");
    return 0;
}

void writer_function(void){
	char	a=0;
	int		count=0;

	while( a != 'q' ){	
		pthread_mutex_lock( &mutex );

		if ( !buffer_has_item ){
			a = make_new_item();
			buffer=a;
			buffer_has_item = 1;
			printf("Thread 1: buffer: '%c', loop count=%d\n", a, count);
			count=0;
		}
		else
			count++;

		pthread_mutex_unlock( &mutex );
	}
}

void* reader_function(void *ptr){
	char	a=0;
	int		count=0;

	while(a != 'q'){
		pthread_mutex_lock( &mutex );

		if ( buffer_has_item ){	
            a=buffer;
			if ( a != 'q' )
				consume_item(a,count);
			buffer_has_item = 0;
			count=0;
		}
		else
			count++;

		pthread_mutex_unlock(&mutex);
	}
	printf("Reader thread finished\n");
	return 0;
}

int make_new_item(){
	static int buffer='a';
	return buffer++;
}

void consume_item(char a, int count){
	printf("Thread 2: buffer read with '%c', loop count=%d\n", a, count);
}