/*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "../GLWindowContext.h"
#include "WindowContextFactory_unix.h"

#include <GL/gl.h>

using sk_app::window_context_factory::XlibWindowInfo;
using sk_app::DisplayParams;
using sk_app::GLWindowContext;

namespace {

class GLWindowContext_xlib : public GLWindowContext {
public:
    GLWindowContext_xlib(const XlibWindowInfo&, const DisplayParams&);
    ~GLWindowContext_xlib() override;

    void onSwapBuffers() override;

    void onDestroyContext() override;

protected:
    void onInitializeContext() override;

private:
    GLWindowContext_xlib(void*, const DisplayParams&);

    Display*     fDisplay;
    XWindow      fWindow;
    XVisualInfo* fVisualInfo;
    GLXContext   fGLContext;
};

GLWindowContext_xlib::GLWindowContext_xlib(const XlibWindowInfo& winInfo, const DisplayParams& params)
        : GLWindowContext(params)
        , fDisplay(winInfo.fDisplay)
        , fWindow(winInfo.fWindow)
        , fVisualInfo(winInfo.fVisualInfo)
        , fGLContext() {
    this->initializeContext();
}

void GLWindowContext_xlib::onInitializeContext() {
    // any config code here (particularly for msaa)?
    SkASSERT(fDisplay);
    fGLContext = glXCreateContext(fDisplay, fVisualInfo, nullptr, GL_TRUE);
    if (!fGLContext) {
        return;
    }

    if (glXMakeCurrent(fDisplay, fWindow, fGLContext)) {
        glClearStencil(0);
        glClearColor(0, 0, 0, 0);
        glStencilMask(0xffffffff);
        glClear(GL_STENCIL_BUFFER_BIT | GL_COLOR_BUFFER_BIT);

        glXGetConfig(fDisplay, fVisualInfo, GLX_STENCIL_SIZE, &fStencilBits);
        glXGetConfig(fDisplay, fVisualInfo, GLX_SAMPLES_ARB, &fSampleCount);

        XWindow root;
        int x, y;
        unsigned int border_width, depth;
        XGetGeometry(fDisplay, fWindow, &root, &x, &y,
                     (unsigned int*)&fWidth, (unsigned int*)&fHeight, &border_width, &depth);
        glViewport(0, 0, fWidth, fHeight);
    }
}

GLWindowContext_xlib::~GLWindowContext_xlib() {
    this->destroyContext();
}

void GLWindowContext_xlib::onDestroyContext() {
    if (!fDisplay || !fGLContext) {
        return;
    }
    glXMakeCurrent(fDisplay, None, nullptr);
    glXDestroyContext(fDisplay, fGLContext);
    fGLContext = nullptr;
}

void GLWindowContext_xlib::onSwapBuffers() {
    if (fDisplay && fGLContext) {
        glXSwapBuffers(fDisplay, fWindow);
    }
}

}  // anonymous namespace

namespace sk_app {

namespace window_context_factory {

WindowContext* NewGLForXlib(const XlibWindowInfo& winInfo, const DisplayParams& params) {
    WindowContext* ctx = new GLWindowContext_xlib(winInfo, params);
    if (!ctx->isValid()) {
        delete ctx;
        return nullptr;
    }
    return ctx;
}

}  // namespace window_context_factory

}  // namespace sk_app