/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */

#include "pch.h"
#include "OpenGLES.h"

using namespace Platform;
using namespace Windows::UI::Xaml::Controls;
using namespace Windows::Foundation;
using namespace Windows::Foundation::Collections;

OpenGLES::OpenGLES()
    : mEglConfig(nullptr)
    , mEglDisplay(EGL_NO_DISPLAY)
    , mEglContext(EGL_NO_CONTEXT)
{
    Initialize();
}

OpenGLES::~OpenGLES()
{
    Cleanup();
}

void OpenGLES::Initialize()
{
    const EGLint configAttributes[] = {
        EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
        EGL_RED_SIZE, 8,
        EGL_GREEN_SIZE, 8,
        EGL_BLUE_SIZE, 8,
        EGL_ALPHA_SIZE, 8,
        EGL_DEPTH_SIZE, 24,
        EGL_STENCIL_SIZE, 8,
        EGL_NONE
    };

    const EGLint contextAttributes[] = {
        EGL_CONTEXT_CLIENT_VERSION, 3,
        EGL_NONE
    };

    // Based on Angle MS template.

    const EGLint defaultDisplayAttributes[] = {
        // These are the default display attributes, used to request ANGLE's D3D11 renderer.
        // eglInitialize will only succeed with these attributes if the hardware supports D3D11 Feature Level 10_0+.
        EGL_PLATFORM_ANGLE_TYPE_ANGLE,
        EGL_PLATFORM_ANGLE_TYPE_D3D11_ANGLE,

        // EGL_ANGLE_DISPLAY_ALLOW_RENDER_TO_BACK_BUFFER is an optimization that can have large performance benefits on
        // mobile devices. Its syntax is subject to change, though. Please update your Visual Studio templates if you
        // experience compilation issues with it.
        EGL_ANGLE_DISPLAY_ALLOW_RENDER_TO_BACK_BUFFER,
        EGL_TRUE,

        // EGL_PLATFORM_ANGLE_ENABLE_AUTOMATIC_TRIM_ANGLE is an option that enables ANGLE to automatically call
        // the IDXGIDevice3::Trim method on behalf of the application when it gets suspended.
        // Calling IDXGIDevice3::Trim when an application is suspended is a Windows Store application certification
        // requirement.
        EGL_PLATFORM_ANGLE_ENABLE_AUTOMATIC_TRIM_ANGLE,
        EGL_TRUE,
        EGL_NONE,
    };

    const EGLint fl9_3DisplayAttributes[] = {
        // These can be used to request ANGLE's D3D11 renderer, with D3D11 Feature Level 9_3.
        // These attributes are used if the call to eglInitialize fails with the default display attributes.
        EGL_PLATFORM_ANGLE_TYPE_ANGLE,
        EGL_PLATFORM_ANGLE_TYPE_D3D11_ANGLE,
        EGL_PLATFORM_ANGLE_MAX_VERSION_MAJOR_ANGLE,
        9,
        EGL_PLATFORM_ANGLE_MAX_VERSION_MINOR_ANGLE,
        3,
        EGL_ANGLE_DISPLAY_ALLOW_RENDER_TO_BACK_BUFFER,
        EGL_TRUE,
        EGL_PLATFORM_ANGLE_ENABLE_AUTOMATIC_TRIM_ANGLE,
        EGL_TRUE,
        EGL_NONE,
    };

    const EGLint warpDisplayAttributes[] = {
        // These attributes can be used to request D3D11 WARP.
        // They are used if eglInitialize fails with both the default display attributes and the 9_3 display attributes.
        EGL_PLATFORM_ANGLE_TYPE_ANGLE,
        EGL_PLATFORM_ANGLE_TYPE_D3D11_ANGLE,
        EGL_PLATFORM_ANGLE_DEVICE_TYPE_ANGLE,
        EGL_PLATFORM_ANGLE_DEVICE_TYPE_WARP_ANGLE,
        EGL_ANGLE_DISPLAY_ALLOW_RENDER_TO_BACK_BUFFER,
        EGL_TRUE,
        EGL_PLATFORM_ANGLE_ENABLE_AUTOMATIC_TRIM_ANGLE,
        EGL_TRUE,
        EGL_NONE,
    };

    EGLConfig config = NULL;

    // eglGetPlatformDisplayEXT is an alternative to eglGetDisplay.
    // It allows us to pass in display attributes, used to configure D3D11.
    PFNEGLGETPLATFORMDISPLAYEXTPROC eglGetPlatformDisplayEXT =
      reinterpret_cast<PFNEGLGETPLATFORMDISPLAYEXTPROC>(eglGetProcAddress("eglGetPlatformDisplayEXT"));
    if (!eglGetPlatformDisplayEXT) {
        throw Exception::CreateException(E_FAIL, L"Failed to get function eglGetPlatformDisplayEXT");
    }

    //
    // To initialize the display, we make three sets of calls to eglGetPlatformDisplayEXT and eglInitialize,
    // with varying parameters passed to eglGetPlatformDisplayEXT:
    // 1) The first calls uses "defaultDisplayAttributes" as a parameter. This corresponds to D3D11 Feature Level 10_0+.
    // 2) If eglInitialize fails for step 1 (e.g. because 10_0+ isn't supported by the default GPU), then we try again
    //    using "fl9_3DisplayAttributes". This corresponds to D3D11 Feature Level 9_3.
    // 3) If eglInitialize fails for step 2 (e.g. because 9_3+ isn't supported by the default GPU), then we try again
    //    using "warpDisplayAttributes".  This corresponds to D3D11 Feature Level 11_0 on WARP, a D3D11 software
    //    rasterizer.
    //

    // This tries to initialize EGL to D3D11 Feature Level 10_0+. See above comment for details.
    mEglDisplay = eglGetPlatformDisplayEXT(EGL_PLATFORM_ANGLE_ANGLE, EGL_DEFAULT_DISPLAY, defaultDisplayAttributes);
    if (mEglDisplay == EGL_NO_DISPLAY) {
        throw Exception::CreateException(E_FAIL, L"Failed to get EGL display");
    }

    if (eglInitialize(mEglDisplay, NULL, NULL) == EGL_FALSE) {
        // This tries to initialize EGL to D3D11 Feature Level 9_3, if 10_0+ is unavailable (e.g. on some mobile
        // devices).
        mEglDisplay = eglGetPlatformDisplayEXT(EGL_PLATFORM_ANGLE_ANGLE, EGL_DEFAULT_DISPLAY, fl9_3DisplayAttributes);
        if (mEglDisplay == EGL_NO_DISPLAY) {
            throw Exception::CreateException(E_FAIL, L"Failed to get EGL display");
        }

        if (eglInitialize(mEglDisplay, NULL, NULL) == EGL_FALSE) {
            // This initializes EGL to D3D11 Feature Level 11_0 on WARP, if 9_3+ is unavailable on the default GPU.
            mEglDisplay = eglGetPlatformDisplayEXT(EGL_PLATFORM_ANGLE_ANGLE, EGL_DEFAULT_DISPLAY,
                warpDisplayAttributes);
            if (mEglDisplay == EGL_NO_DISPLAY) {
                throw Exception::CreateException(E_FAIL, L"Failed to get EGL display");
            }

            if (eglInitialize(mEglDisplay, NULL, NULL) == EGL_FALSE) {
                // If all of the calls to eglInitialize returned EGL_FALSE then an error has occurred.
                throw Exception::CreateException(E_FAIL, L"Failed to initialize EGL");
            }
        }
    }

    EGLint numConfigs = 0;
    if ((eglChooseConfig(mEglDisplay, configAttributes, &mEglConfig, 1, &numConfigs) == EGL_FALSE) ||
        (numConfigs == 0)) {
        throw Exception::CreateException(E_FAIL, L"Failed to choose first EGLConfig");
    }

    mEglContext = eglCreateContext(mEglDisplay, mEglConfig, EGL_NO_CONTEXT, contextAttributes);
    if (mEglContext == EGL_NO_CONTEXT) {
        throw Exception::CreateException(E_FAIL, L"Failed to create EGL context");
    }
}

void OpenGLES::Cleanup()
{
    if (mEglDisplay != EGL_NO_DISPLAY && mEglContext != EGL_NO_CONTEXT) {
        eglDestroyContext(mEglDisplay, mEglContext);
        mEglContext = EGL_NO_CONTEXT;
    }

    if (mEglDisplay != EGL_NO_DISPLAY) {
        eglTerminate(mEglDisplay);
        mEglDisplay = EGL_NO_DISPLAY;
    }
}

void OpenGLES::Reset()
{
    Cleanup();
    Initialize();
}

EGLSurface OpenGLES::CreateSurface(SwapChainPanel ^ panel)
{
    if (!panel) {
        throw Exception::CreateException(E_INVALIDARG, L"SwapChainPanel parameter is invalid");
    }

    EGLSurface surface = EGL_NO_SURFACE;

    const EGLint surfaceAttributes[] = {
        EGL_ANGLE_SURFACE_RENDER_TO_BACK_BUFFER, EGL_TRUE,
        EGL_NONE
    };

    PropertySet ^ surfaceCreationProperties = ref new PropertySet();
    surfaceCreationProperties->Insert(ref new String(EGLNativeWindowTypeProperty), panel);

    // How to set size and or scale:
    // surfaceCreationProperties->Insert(ref new String(EGLRenderSurfaceSizeProperty),
    //  PropertyValue::CreateSize(*renderSurfaceSize));
    // surfaceCreationProperties->Insert(ref new String(EGLRenderResolutionScaleProperty),
    //  PropertyValue::CreateSingle(*resolutionScale));

    surface = eglCreateWindowSurface(mEglDisplay, mEglConfig,
        reinterpret_cast<IInspectable*>(surfaceCreationProperties), surfaceAttributes);
    if (surface == EGL_NO_SURFACE) {
        throw Exception::CreateException(E_FAIL, L"Failed to create EGL surface");
    }

    return surface;
}

void OpenGLES::GetSurfaceDimensions(const EGLSurface surface, EGLint* width, EGLint* height)
{
    eglQuerySurface(mEglDisplay, surface, EGL_WIDTH, width);
    eglQuerySurface(mEglDisplay, surface, EGL_HEIGHT, height);
}

void OpenGLES::DestroySurface(const EGLSurface surface)
{
    if (mEglDisplay != EGL_NO_DISPLAY && surface != EGL_NO_SURFACE) {
        eglDestroySurface(mEglDisplay, surface);
    }
}

void OpenGLES::MakeCurrent(const EGLSurface surface)
{
    if (eglMakeCurrent(mEglDisplay, surface, surface, mEglContext) == EGL_FALSE) {
        throw Exception::CreateException(E_FAIL, L"Failed to make EGLSurface current");
    }
}

EGLBoolean OpenGLES::SwapBuffers(const EGLSurface surface)
{
    return (eglSwapBuffers(mEglDisplay, surface));
}