#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_ANDROID_CREATE_INSTANCE_EXTENSION_NAME,
        XR_KHR_OPENGL_ES_ENABLE_EXTENSION_NAME,
        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);

    // Create the EGL Context
    ovrEgl_CreateContext(&vr_engine.appState.Egl, NULL);

    XrInstanceCreateInfoAndroidKHR instanceCreateInfoAndroid = {XR_TYPE_INSTANCE_CREATE_INFO_ANDROID_KHR};
    instanceCreateInfoAndroid.applicationVM = java.Vm;
    instanceCreateInfoAndroid.applicationActivity = java.ActivityObject;

    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, "PPSSPP");
    appInfo.applicationVersion = 0;
    strcpy(appInfo.engineName, "PPSSPP");
    appInfo.engineVersion = 0;
    appInfo.apiVersion = XR_CURRENT_API_VERSION;

    XrInstanceCreateInfo instanceCreateInfo;
    memset(&instanceCreateInfo, 0, sizeof(instanceCreateInfo));
    instanceCreateInfo.type = XR_TYPE_INSTANCE_CREATE_INFO;
    instanceCreateInfo.next = (XrBaseInStructure*)&instanceCreateInfoAndroid;
    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);
        ovrEgl_DestroyContext(&engine->appState.Egl);
        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 = engine->appState.Egl.Display;
    graphicsBindingAndroidGLES.config = engine->appState.Egl.Config;
    graphicsBindingAndroidGLES.context = engine->appState.Egl.Context;

    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;
}