/*
 * Copyright 2011 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
#include "gl/SkNativeGLContext.h"

SkNativeGLContext::AutoContextRestore::AutoContextRestore() {
    fOldEGLContext = eglGetCurrentContext();
    fOldDisplay = eglGetCurrentDisplay();
    fOldSurface = eglGetCurrentSurface(EGL_DRAW);

}

SkNativeGLContext::AutoContextRestore::~AutoContextRestore() {
    if (NULL != fOldDisplay) {
        eglMakeCurrent(fOldDisplay, fOldSurface, fOldSurface, fOldEGLContext);
    }
}

///////////////////////////////////////////////////////////////////////////////

SkNativeGLContext::SkNativeGLContext()
    : fContext(EGL_NO_CONTEXT)
    , fDisplay(EGL_NO_DISPLAY)
    , fSurface(EGL_NO_SURFACE) {
}

SkNativeGLContext::~SkNativeGLContext() {
    this->destroyGLContext();
}

void SkNativeGLContext::destroyGLContext() {
    if (fDisplay) {
        eglMakeCurrent(fDisplay, 0, 0, 0);

        if (fContext) {
            eglDestroyContext(fDisplay, fContext);
            fContext = EGL_NO_CONTEXT;
        }

        if (fSurface) {
            eglDestroySurface(fDisplay, fSurface);
            fSurface = EGL_NO_SURFACE;
        }

        //TODO should we close the display?
        fDisplay = EGL_NO_DISPLAY;
    }
}

const GrGLInterface* SkNativeGLContext::createGLContext(GrGLStandard forcedGpuAPI) {
    static const EGLint kEGLContextAttribsForOpenGL[] = {
        EGL_NONE
    };

    static const EGLint kEGLContextAttribsForOpenGLES[] = {
        EGL_CONTEXT_CLIENT_VERSION, 2,
        EGL_NONE
    };

    static const struct {
        const EGLint* fContextAttribs;
        EGLenum fAPI;
        EGLint  fRenderableTypeBit;
        GrGLStandard fStandard;
    } kAPIs[] = {
        {   // OpenGL
            kEGLContextAttribsForOpenGL,
            EGL_OPENGL_API,
            EGL_OPENGL_BIT,
            kGL_GrGLStandard
        },
        {   // OpenGL ES. This seems to work for both ES2 and 3 (when available).
            kEGLContextAttribsForOpenGLES,
            EGL_OPENGL_ES_API,
            EGL_OPENGL_ES2_BIT,
            kGLES_GrGLStandard
        },
    };

    size_t apiLimit = SK_ARRAY_COUNT(kAPIs);
    size_t api = 0;
    if (forcedGpuAPI == kGL_GrGLStandard) {
        apiLimit = 1;
    } else if (forcedGpuAPI == kGLES_GrGLStandard) {
        api = 1;
    }
    SkASSERT(forcedGpuAPI == kNone_GrGLStandard || kAPIs[api].fStandard == forcedGpuAPI);

    const GrGLInterface* interface = NULL;

    for (size_t i = 0; NULL == interface && i < apiLimit; ++api) {
        fDisplay = eglGetDisplay(EGL_DEFAULT_DISPLAY);

        EGLint majorVersion;
        EGLint minorVersion;
        eglInitialize(fDisplay, &majorVersion, &minorVersion);

#if 0
        SkDebugf("VENDOR: %s\n", eglQueryString(fDisplay, EGL_VENDOR));
        SkDebugf("APIS: %s\n", eglQueryString(fDisplay, EGL_CLIENT_APIS));
        SkDebugf("VERSION: %s\n", eglQueryString(fDisplay, EGL_VERSION));
        SkDebugf("EXTENSIONS %s\n", eglQueryString(fDisplay, EGL_EXTENSIONS));
#endif

        if (!eglBindAPI(kAPIs[api].fAPI)) {
            continue;
        }

        EGLint numConfigs;
        const EGLint configAttribs[] = {
            EGL_SURFACE_TYPE, EGL_PBUFFER_BIT,
            EGL_RENDERABLE_TYPE, kAPIs[api].fRenderableTypeBit,
            EGL_RED_SIZE, 8,
            EGL_GREEN_SIZE, 8,
            EGL_BLUE_SIZE, 8,
            EGL_ALPHA_SIZE, 8,
            EGL_NONE
        };

        EGLConfig surfaceConfig;
        if (!eglChooseConfig(fDisplay, configAttribs, &surfaceConfig, 1, &numConfigs)) {
            SkDebugf("eglChooseConfig failed. EGL Error: 0x%08x\n", eglGetError());
            continue;
        }

        fContext = eglCreateContext(fDisplay, surfaceConfig, NULL, kAPIs[api].fContextAttribs);
        if (EGL_NO_CONTEXT == fContext) {
            SkDebugf("eglCreateContext failed.  EGL Error: 0x%08x\n", eglGetError());
            continue;
        }

        static const EGLint kSurfaceAttribs[] = {
            EGL_WIDTH, 1,
            EGL_HEIGHT, 1,
            EGL_NONE
        };

        fSurface = eglCreatePbufferSurface(fDisplay, surfaceConfig, kSurfaceAttribs);
        if (EGL_NO_SURFACE == fSurface) {
            SkDebugf("eglCreatePbufferSurface failed. EGL Error: 0x%08x\n", eglGetError());
            this->destroyGLContext();
            continue;
        }

        if (!eglMakeCurrent(fDisplay, fSurface, fSurface, fContext)) {
            SkDebugf("eglMakeCurrent failed.  EGL Error: 0x%08x\n", eglGetError());
            this->destroyGLContext();
            continue;
        }

        interface = GrGLCreateNativeInterface();
        if (NULL == interface) {
            SkDebugf("Failed to create gl interface.\n");
            this->destroyGLContext();
            continue;
        }

        if (!interface->validate()) {
            interface->unref();
            interface = NULL;
            this->destroyGLContext();
        }
    }

    return interface;
}

void SkNativeGLContext::makeCurrent() const {
    if (!eglMakeCurrent(fDisplay, fSurface, fSurface, fContext)) {
        SkDebugf("Could not set the context.\n");
    }
}

void SkNativeGLContext::swapBuffers() const {
    if (!eglSwapBuffers(fDisplay, fSurface)) {
        SkDebugf("Could not complete eglSwapBuffers.\n");
    }
}