/*
 * Copyright 2017 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "GrContext.h"
#include "SkRefCnt.h"
#include "gl/GrGLFunctions.h"
#include "gl/GrGLInterface.h"

#include <EGL/egl.h>
#include <GLES2/gl2.h>

#include <sstream>

static const EGLint configAttribs[] = {
    EGL_SURFACE_TYPE, EGL_PBUFFER_BIT,
    EGL_BLUE_SIZE, 8,
    EGL_GREEN_SIZE, 8,
    EGL_RED_SIZE, 8,
    EGL_DEPTH_SIZE, 8,
    EGL_RENDERABLE_TYPE, EGL_OPENGL_BIT,
    EGL_NONE
};

static const int pbufferWidth = 9;
static const int pbufferHeight = 9;

static const EGLint pbufferAttribs[] = {
    EGL_WIDTH, pbufferWidth,
    EGL_HEIGHT, pbufferHeight,
    EGL_NONE,
};

// create_grcontext implementation for EGL.
sk_sp<GrContext> create_grcontext(std::ostringstream &driverinfo) {
    EGLDisplay eglDpy = eglGetDisplay(EGL_DEFAULT_DISPLAY);
    if (EGL_NO_DISPLAY == eglDpy) {
        return nullptr;
    }

    EGLint major, minor;
    if (EGL_TRUE != eglInitialize(eglDpy, &major, &minor)) {
        return nullptr;
    }

    EGLint numConfigs;
    EGLConfig eglCfg;
    if (EGL_TRUE != eglChooseConfig(eglDpy, configAttribs, &eglCfg, 1, &numConfigs)) {
        return nullptr;
    }

    EGLSurface eglSurf = eglCreatePbufferSurface(eglDpy, eglCfg, pbufferAttribs);
    if (EGL_NO_SURFACE == eglSurf) {
        return nullptr;
    }

    if (EGL_TRUE != eglBindAPI(EGL_OPENGL_API)) {
        return nullptr;
    }

    EGLContext eglCtx = eglCreateContext(eglDpy, eglCfg, EGL_NO_CONTEXT, nullptr);
    if (EGL_NO_CONTEXT == eglCtx) {
        return nullptr;
    }
    if (EGL_FALSE == eglMakeCurrent(eglDpy, eglSurf, eglSurf, eglCtx)) {
        return nullptr;
    }

    driverinfo << "EGL " << major << "." << minor << "\n";
    GrGLGetStringProc getString = (GrGLGetStringProc )eglGetProcAddress("glGetString");
    driverinfo << "GL Versionr: " << getString(GL_VERSION) << "\n";
    driverinfo << "GL Vendor: " << getString(GL_VENDOR) << "\n";
    driverinfo << "GL Renderer: " << getString(GL_RENDERER) << "\n";
    driverinfo << "GL Extensions: " << getString(GL_EXTENSIONS) << "\n";

    auto interface = GrGLMakeNativeInterface();
    if (!interface) {
        return nullptr;
    }
    eglTerminate(eglDpy);

    return sk_sp<GrContext>(GrContext::MakeGL(interface));
}