#include "VRBase.h"

#include <assert.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

static engine_t vr_engine;
int vr_initialized = 0;

const char* const requiredExtensionNames[] = {
		XR_KHR_OPENGL_ES_ENABLE_EXTENSION_NAME,
#ifdef OPENXR_HAS_PERFORMANCE_EXTENSION
		XR_EXT_PERFORMANCE_SETTINGS_EXTENSION_NAME,
		XR_KHR_ANDROID_THREAD_SETTINGS_EXTENSION_NAME,
#endif
		XR_KHR_COMPOSITION_LAYER_CYLINDER_EXTENSION_NAME};
const uint32_t numRequiredExtensions =
		sizeof(requiredExtensionNames) / sizeof(requiredExtensionNames[0]);

void VR_Init( ovrJava java ) {
	if (vr_initialized)
		return;

	ovrApp_Clear(&vr_engine.appState);

	PFN_xrInitializeLoaderKHR xrInitializeLoaderKHR;
	xrGetInstanceProcAddr(
			XR_NULL_HANDLE, "xrInitializeLoaderKHR", (PFN_xrVoidFunction*)&xrInitializeLoaderKHR);
	if (xrInitializeLoaderKHR != NULL) {
		XrLoaderInitInfoAndroidKHR loaderInitializeInfoAndroid;
		memset(&loaderInitializeInfoAndroid, 0, sizeof(loaderInitializeInfoAndroid));
		loaderInitializeInfoAndroid.type = XR_TYPE_LOADER_INIT_INFO_ANDROID_KHR;
		loaderInitializeInfoAndroid.next = NULL;
		loaderInitializeInfoAndroid.applicationVM = java.Vm;
		loaderInitializeInfoAndroid.applicationContext = java.ActivityObject;
		xrInitializeLoaderKHR((XrLoaderInitInfoBaseHeaderKHR*)&loaderInitializeInfoAndroid);
	}

	// Create the OpenXR instance.
	XrApplicationInfo appInfo;
	memset(&appInfo, 0, sizeof(appInfo));
	strcpy(appInfo.applicationName, java.AppName);
	strcpy(appInfo.engineName, java.AppName);
	appInfo.applicationVersion = java.AppVersion;
	appInfo.engineVersion = java.AppVersion;
	appInfo.apiVersion = XR_CURRENT_API_VERSION;

	XrInstanceCreateInfo instanceCreateInfo;
	memset(&instanceCreateInfo, 0, sizeof(instanceCreateInfo));
	instanceCreateInfo.type = XR_TYPE_INSTANCE_CREATE_INFO;
	instanceCreateInfo.next = NULL;
	instanceCreateInfo.createFlags = 0;
	instanceCreateInfo.applicationInfo = appInfo;
	instanceCreateInfo.enabledApiLayerCount = 0;
	instanceCreateInfo.enabledApiLayerNames = NULL;
	instanceCreateInfo.enabledExtensionCount = numRequiredExtensions;
	instanceCreateInfo.enabledExtensionNames = requiredExtensionNames;

	XrResult initResult;
	OXR(initResult = xrCreateInstance(&instanceCreateInfo, &vr_engine.appState.Instance));
	if (initResult != XR_SUCCESS) {
		ALOGE("Failed to create XR instance: %d.", initResult);
		exit(1);
	}

	XrInstanceProperties instanceInfo;
	instanceInfo.type = XR_TYPE_INSTANCE_PROPERTIES;
	instanceInfo.next = NULL;
	OXR(xrGetInstanceProperties(vr_engine.appState.Instance, &instanceInfo));
	ALOGV(
			"Runtime %s: Version : %u.%u.%u",
			instanceInfo.runtimeName,
			XR_VERSION_MAJOR(instanceInfo.runtimeVersion),
			XR_VERSION_MINOR(instanceInfo.runtimeVersion),
			XR_VERSION_PATCH(instanceInfo.runtimeVersion));

	XrSystemGetInfo systemGetInfo;
	memset(&systemGetInfo, 0, sizeof(systemGetInfo));
	systemGetInfo.type = XR_TYPE_SYSTEM_GET_INFO;
	systemGetInfo.next = NULL;
	systemGetInfo.formFactor = XR_FORM_FACTOR_HEAD_MOUNTED_DISPLAY;

	XrSystemId systemId;
	OXR(initResult = xrGetSystem(vr_engine.appState.Instance, &systemGetInfo, &systemId));
	if (initResult != XR_SUCCESS) {
		ALOGE("Failed to get system.");
		exit(1);
	}

	// Get the graphics requirements.
	PFN_xrGetOpenGLESGraphicsRequirementsKHR pfnGetOpenGLESGraphicsRequirementsKHR = NULL;
	OXR(xrGetInstanceProcAddr(
			vr_engine.appState.Instance,
			"xrGetOpenGLESGraphicsRequirementsKHR",
			(PFN_xrVoidFunction*)(&pfnGetOpenGLESGraphicsRequirementsKHR)));

	XrGraphicsRequirementsOpenGLESKHR graphicsRequirements = {};
	graphicsRequirements.type = XR_TYPE_GRAPHICS_REQUIREMENTS_OPENGL_ES_KHR;
	OXR(pfnGetOpenGLESGraphicsRequirementsKHR(vr_engine.appState.Instance, systemId, &graphicsRequirements));

	vr_engine.appState.MainThreadTid = gettid();
	vr_engine.appState.SystemId = systemId;

	vr_engine.java = java;
	vr_initialized = 1;
}

void VR_Destroy( engine_t* engine ) {
	if (engine == &vr_engine) {
		xrDestroyInstance(engine->appState.Instance);
		ovrApp_Destroy(&engine->appState);
	}
}

void VR_EnterVR( engine_t* engine ) {

	if (engine->appState.Session) {
		ALOGE("VR_EnterVR called with existing session");
		return;
	}

	// Create the OpenXR Session.
	XrGraphicsBindingOpenGLESAndroidKHR graphicsBindingAndroidGLES = {};
	graphicsBindingAndroidGLES.type = XR_TYPE_GRAPHICS_BINDING_OPENGL_ES_ANDROID_KHR;
	graphicsBindingAndroidGLES.next = NULL;
	graphicsBindingAndroidGLES.display = eglGetCurrentDisplay();
	graphicsBindingAndroidGLES.config = eglGetCurrentSurface(EGL_DRAW);
	graphicsBindingAndroidGLES.context = eglGetCurrentContext();

	XrSessionCreateInfo sessionCreateInfo = {};
	memset(&sessionCreateInfo, 0, sizeof(sessionCreateInfo));
	sessionCreateInfo.type = XR_TYPE_SESSION_CREATE_INFO;
	sessionCreateInfo.next = &graphicsBindingAndroidGLES;
	sessionCreateInfo.createFlags = 0;
	sessionCreateInfo.systemId = engine->appState.SystemId;

	XrResult initResult;
	OXR(initResult = xrCreateSession(engine->appState.Instance, &sessionCreateInfo, &engine->appState.Session));
	if (initResult != XR_SUCCESS) {
		ALOGE("Failed to create XR session: %d.", initResult);
		exit(1);
	}

	// Create a space to the first path
	XrReferenceSpaceCreateInfo spaceCreateInfo = {};
	spaceCreateInfo.type = XR_TYPE_REFERENCE_SPACE_CREATE_INFO;
	spaceCreateInfo.referenceSpaceType = XR_REFERENCE_SPACE_TYPE_VIEW;
	spaceCreateInfo.poseInReferenceSpace.orientation.w = 1.0f;
	OXR(xrCreateReferenceSpace(engine->appState.Session, &spaceCreateInfo, &engine->appState.HeadSpace));
}

void VR_LeaveVR( engine_t* engine ) {
	if (engine->appState.Session) {
		OXR(xrDestroySpace(engine->appState.HeadSpace));
		// StageSpace is optional.
		if (engine->appState.StageSpace != XR_NULL_HANDLE) {
			OXR(xrDestroySpace(engine->appState.StageSpace));
		}
		OXR(xrDestroySpace(engine->appState.FakeStageSpace));
		engine->appState.CurrentSpace = XR_NULL_HANDLE;
		OXR(xrDestroySession(engine->appState.Session));
		engine->appState.Session = NULL;
	}
}

engine_t* VR_GetEngine( void ) {
	return &vr_engine;
}