#include <mbgl/platform/default/headless_display.hpp>

#include <cstring>
#include <stdexcept>

#if MBGL_USE_GLX
#include <GL/glx.h>
#endif

namespace mbgl {

HeadlessDisplay::HeadlessDisplay() {
#if MBGL_USE_CGL
    // TODO: test if OpenGL 4.1 with GL_ARB_ES2_compatibility is supported
    // If it is, use kCGLOGLPVersion_3_2_Core and enable that extension.
    CGLPixelFormatAttribute attributes[] = {
        kCGLPFAOpenGLProfile,
        static_cast<CGLPixelFormatAttribute>(kCGLOGLPVersion_Legacy),
        kCGLPFAAccelerated,
        static_cast<CGLPixelFormatAttribute>(0)
    };

    GLint num;
    CGLError error = CGLChoosePixelFormat(attributes, &pixelFormat, &num);
    if (error != kCGLNoError) {
        throw std::runtime_error(std::string("Error choosing pixel format:") + CGLErrorString(error) + "\n");
        return;
    }
    if (num <= 0) {
        throw std::runtime_error("No pixel formats found.");
        return;
    }
#endif

#if MBGL_USE_GLX
    if (!XInitThreads()) {
        throw std::runtime_error("Failed to XInitThreads.");
    }

    xDisplay = XOpenDisplay(nullptr);
    if (xDisplay == nullptr) {
        throw std::runtime_error("Failed to open X display.");
    }

    const char *extensions = reinterpret_cast<const char *>(glXQueryServerString(xDisplay, DefaultScreen(xDisplay), GLX_EXTENSIONS));
    if (!extensions) {
        throw std::runtime_error("Cannot read GLX extensions.");
    }
    if (!strstr(extensions,"GLX_SGIX_fbconfig")) {
        throw std::runtime_error("Extension GLX_SGIX_fbconfig was not found.");
    }
    if (!strstr(extensions, "GLX_SGIX_pbuffer")) {
        throw std::runtime_error("Cannot find glXCreateContextAttribsARB.");
    }

    // We're creating a dummy pbuffer anyway that we're not using.
    static int pixelFormat[] = {
        GLX_DRAWABLE_TYPE, GLX_PBUFFER_BIT,
        None
    };

    int configs = 0;
    fbConfigs = glXChooseFBConfig(xDisplay, DefaultScreen(xDisplay), pixelFormat, &configs);
    if (fbConfigs == nullptr) {
        throw std::runtime_error("Failed to glXChooseFBConfig.");
    }
    if (configs <= 0) {
        throw std::runtime_error("No Framebuffer configurations.");
    }
#endif
}

HeadlessDisplay::~HeadlessDisplay() {
#if MBGL_USE_CGL
    CGLDestroyPixelFormat(pixelFormat);
#endif

#if MBGL_USE_GLX
    XFree(fbConfigs);
    XCloseDisplay(xDisplay);
#endif
}

}