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

#define MAX_JOBS 10

int jobs_pending = 0;
int shutdown_flag = 0;

pthread_mutex_t job_mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t job_available = PTHREAD_COND_INITIALIZER;

void *worker(void *arg) {
    int id = *(int *)arg;

    while (1) {
        pthread_mutex_lock(&job_mutex);

        // wait until there is a job OR shutdown is signalled
        while (jobs_pending == 0 && !shutdown_flag)
            pthread_cond_wait(&job_available, &job_mutex);

        if (shutdown_flag && jobs_pending == 0) {
            pthread_mutex_unlock(&job_mutex);
            printf("[Worker %d] No more jobs, shutting down.\n", id);
            break;
        }

        // "consume" one job
        jobs_pending--;
        int job_id = rand() % 1000;
        printf("[Worker %d] Processing job ID %d (Jobs left: %d)\n",
               id, job_id, jobs_pending);

        pthread_mutex_unlock(&job_mutex);

        usleep(150000);
    }

    return NULL;
}

int main() {
    pthread_t worker_thread;
    int worker_id = 1;

    pthread_create(&worker_thread, NULL, worker, &worker_id);

    // simulate incoming jobs
    for (int i = 1; i <= MAX_JOBS; i++) {
        pthread_mutex_lock(&job_mutex);

        jobs_pending++;
        printf("[Main] Added job %d (Jobs pending: %d)\n", i, jobs_pending);

        pthread_cond_signal(&job_available);
        pthread_mutex_unlock(&job_mutex);

        usleep(100000);
    }

    // signal shutdown
    pthread_mutex_lock(&job_mutex);
    shutdown_flag = 1;
    pthread_cond_signal(&job_available);  // wake up worker
    pthread_mutex_unlock(&job_mutex);

    pthread_join(worker_thread, NULL);

    pthread_mutex_destroy(&job_mutex);
    pthread_cond_destroy(&job_available);

    return 0;
}