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

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

// Shared resources
char buffer;
sem_t empty;  // Tracks empty slots
sem_t full;   // Tracks filled slots

void cleanup_resources() {
    sem_destroy(&empty);
    sem_destroy(&full);
}

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

    // Initialize semaphores
    // first 0 is for shared between threads, second 0 is for the initial value
    // first 1 would mean that the semaphore is shared between processes
    sem_init(&empty, 0, 1);  // Initially, buffer is empty (1 empty slot)
    sem_init(&full, 0, 0);   // Initially, buffer is not full (0 filled slots)
    pthread_attr_init(&attr);

    pthread_create(&reader, &attr, reader_function, 0);

    writer_function();

    pthread_join(reader, 0);

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

void writer_function(void) {
    char a = 0;

    while (a != 'q') {
        sem_wait(&empty);

        a = make_new_item();
        buffer = a;
        printf("Thread 1: buffer: '%c'\n", a);

        // Signal that the buffer is full
        sem_post(&full);
    }
}

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

    while (a != 'q') {
        sem_wait(&full);

        a = buffer;
        if (a != 'q') {
            consume_item(a, 0);
        }

        sem_post(&empty);
    }

    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'\n", a);
}