#include "JoglCommon.h"

#include <assert.h>
#include <KHR/khrplatform.h>

static const char * const ClazzNameRuntimeException = "java/lang/RuntimeException";
static jclass    runtimeExceptionClz=NULL;

static JavaVM *_jvmHandle = NULL;
static int _jvmVersion = 0;

void JoglCommon_init(JNIEnv *env) {
    if(NULL==runtimeExceptionClz) {
        jclass c = (*env)->FindClass(env, ClazzNameRuntimeException);
        if(NULL==c) {
            JoglCommon_FatalError(env, "JOGL: can't find %s", ClazzNameRuntimeException);
        }
        runtimeExceptionClz = (jclass)(*env)->NewGlobalRef(env, c);
        (*env)->DeleteLocalRef(env, c);
        if(NULL==runtimeExceptionClz) {
            JoglCommon_FatalError(env, "JOGL: can't use %s", ClazzNameRuntimeException);
        }
    }
    if(0 != (*env)->GetJavaVM(env, &_jvmHandle)) {
        JoglCommon_FatalError(env, "JOGL: can't fetch JavaVM handle");
    } else {
        _jvmVersion = (*env)->GetVersion(env);
    }
}

void JoglCommon_FatalError(JNIEnv *env, const char* msg, ...)
{
    char buffer[512];
    va_list ap;
    int shallBeDetached = 0;

    if(NULL == env) {
        env = JoglCommon_GetJNIEnv (&shallBeDetached);
    }

    va_start(ap, msg);
    vsnprintf(buffer, sizeof(buffer), msg, ap);
    va_end(ap);

    fprintf(stderr, "%s\n", buffer);
    if(NULL != env) {
        (*env)->FatalError(env, buffer);
        JoglCommon_ReleaseJNIEnv (shallBeDetached);
    }
}

void JoglCommon_throwNewRuntimeException(JNIEnv *env, const char* msg, ...)
{
    char buffer[512];
    va_list ap;
    int shallBeDetached = 0;

    if(NULL == env) {
        env = JoglCommon_GetJNIEnv (&shallBeDetached);
    }

    va_start(ap, msg);
    vsnprintf(buffer, sizeof(buffer), msg, ap);
    va_end(ap);

    if(NULL != env) {
        (*env)->ThrowNew(env, runtimeExceptionClz, buffer);
        JoglCommon_ReleaseJNIEnv (shallBeDetached);
    }
}

JavaVM *JoglCommon_GetJVMHandle() {
    return _jvmHandle;
}

int JoglCommon_GetJVMVersion() {
    return _jvmVersion;
}

jchar* JoglCommon_GetNullTerminatedStringChars(JNIEnv* env, jstring str)
{
    jchar* strChars = NULL;
    strChars = calloc((*env)->GetStringLength(env, str) + 1, sizeof(jchar));
    if (strChars != NULL) {
        (*env)->GetStringRegion(env, str, 0, (*env)->GetStringLength(env, str), strChars);
    }
    return strChars;
}

JNIEnv* JoglCommon_GetJNIEnv (int * shallBeDetached)
{
    JNIEnv* curEnv = NULL;
    JNIEnv* newEnv = NULL;
    int envRes;

    if(NULL == _jvmHandle) {
        fprintf(stderr, "JOGL: No JavaVM handle registered, call JoglCommon_init(..) 1st");
        return NULL;
    }

    // retrieve this thread's JNIEnv curEnv - or detect it's detached
    envRes = (*_jvmHandle)->GetEnv(_jvmHandle, (void **) &curEnv, _jvmVersion) ;
    if( JNI_EDETACHED == envRes ) {
        // detached thread - attach to JVM
        if( JNI_OK != ( envRes = (*_jvmHandle)->AttachCurrentThread(_jvmHandle, (void**) &newEnv, NULL) ) ) {
            fprintf(stderr, "JNIEnv: can't attach thread: %d\n", envRes);
            return NULL;
        }
        curEnv = newEnv;
    } else if( JNI_OK != envRes ) {
        // oops ..
        fprintf(stderr, "can't GetEnv: %d\n", envRes);
        return NULL;
    }
    if (curEnv==NULL) {
        fprintf(stderr, "env is NULL\n");
        return NULL;
    }
    *shallBeDetached = NULL != newEnv;
    return curEnv;
}

void JoglCommon_ReleaseJNIEnv (int shallBeDetached) {
    if(NULL == _jvmHandle) {
        fprintf(stderr, "JOGL: No JavaVM handle registered, call JoglCommon_init(..) 1st");
    }

    if(shallBeDetached) {
        (*_jvmHandle)->DetachCurrentThread(_jvmHandle);
    }
}