#include <jni.h>
#include <unistd.h>
#include <stdlib.h>

static inline const char **to_string_array(JNIEnv *env, jobjectArray ja) {
  const int len = (*env)->GetArrayLength(env, ja);
  const char **ca = calloc((size_t) len + 1, sizeof(char *));

  for (int i = 0; i < len; ++i) {
    jstring jstr = (jstring) (*env)->GetObjectArrayElement(env, ja, i);
    ca[i] = (*env)->GetStringUTFChars(env, jstr, NULL);
  }

  ca[len] = NULL;
  return ca;
}

static inline void exec(const char **argcv) {
  execv(argcv[0], (char *const *) argcv);
  exit(1);
}

JNIEXPORT jint JNICALL
Java_org_pacien_tincapp_commands_Executor_forkExec(JNIEnv *env, jclass class, jobjectArray argcv) {
  pid_t pid = fork();
  switch (pid) {
    case 0:
      exec(to_string_array(env, argcv));
      return 0;

    default:
      return pid;
  }
}