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

typedef struct {
    int* a_n;
    char marker;
} WorkerArgs;

void* worker(void* arg) {
    WorkerArgs* a_args = arg;
    int *a_x = a_args -> a_n;
    while(*a_x < 100) {
        (*a_x)++;
        fputc(a_args -> marker, stdout);  // print marker for this thread
        fflush(stdout);  // force it to print each character one at a time
    }
    printf("increment finished\n");
    return NULL;
}

// GOAL:  Increment x and y to 100, using only ++.  Yes, this is silly.

int main() {
    int x = 0, y = 0;
    printf("x: %d, y: %d\n", x, y);

    pthread_t t1;  // This is an "opaque" objects -- none of your biz
    WorkerArgs worker_args = { .a_n = &x, .marker='*' };
    int status = pthread_create(&t1, NULL, worker, &worker_args);
    // like calling worker(&x)
    if(status != 0) {
        return EXIT_FAILURE;
    }

    pthread_t t2;
    worker_args = (WorkerArgs) { .a_n = &y, .marker='&' };  // BUG!!!!
         // They each got the address of the same object.  Same spot in
         // memory.
    status = pthread_create(&t2, NULL, worker, &worker_args);
    if(status != 0) {
        return EXIT_FAILURE;
    }

    // Three threads are active now:  main thread, t1, and t2

    // Wait for t1 to finish, and then join (terminate the thread nicely)
    pthread_join(t1, NULL);

    /* // If t2 finished before t1 finished, then t2 is waiting now. */
    /* pthread_join(t2, NULL); */

    printf("x: %d, y: %d\n", x, y);
    return 0;
}
    /*
    // temporary:
    int num_threads = 2;
    pthread_t* threads = malloc(sizeof(*threads) * num_threads);
    pthread_create(&threads[0], NULL, worker, &y); // TODO: check if returns 0
    */