#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <pthread.h>

#include "debug.h"
#include "memory.h"
#include "args.h"

void *task(void *arg);

#define NUM_THREADS 200
#define NUM_INCREMENTOS 1000

typedef struct thread_params_t
{
    pthread_mutex_t mutex;
}thread_params_t;

int G_shared_counter;

int main(int argc, char *argv[]){

    (void)argc; (void)argv;

    G_shared_counter = 0;

    pthread_t tids[NUM_THREADS];
    thread_params_t thread_params;

    // Mutex: inicializa o mutex antes de criar a(s) thread(s)
    if ((errno = pthread_mutex_init(&thread_params.mutex, NULL)) != 0)
        ERROR(12, "pthread_mutex_init() failed");

    // Criação das threads + passagem de parâmetro
    for (int i = 0; i < NUM_THREADS; i++){
        if ((errno = pthread_create(&tids[i], NULL, task, &thread_params)) != 0)
            ERROR(10, "Erro no pthread_create()!");
    }

    // Espera que todas as threads terminem
    for (int i = 0; i < NUM_THREADS; i++){
        if ((errno = pthread_join(tids[i], NULL)) != 0)
            ERROR(11, "Erro no pthread_join()!\n");
    }

    // Mutex: liberta recurso
    if ((errno = pthread_mutex_destroy(&thread_params.mutex)) != 0)
        ERROR(13, "pthread_mutex_destroy() failed");

    printf("G_shared_counter = %d\n", G_shared_counter);

    return 0;
}

void *task(void *arg)
{
    // cast para o tipo de dados enviado pela 'main thread'
    struct thread_params_t *params = (struct thread_params_t *) arg;
    int local;

    // Mutex: entra na secção crítica
    if ((errno = pthread_mutex_lock(&params->mutex)) != 0){
        WARNING("pthread_mutex_lock() failed");
        return NULL;
    }

    for (int i = 0; i < NUM_INCREMENTOS; ++i)
    {
        local = G_shared_counter;
        sched_yield();
        local = local + 1;
        G_shared_counter = local;
    }

    if ((errno = pthread_mutex_unlock(&params->mutex)) != 0){
        WARNING("pthread_mutex_unlock() failed");
        return NULL;
    }

    return NULL;
}