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

#include <CoreFoundation/CoreFoundation.h>

namespace mbgl {

gl::glProc HeadlessView::initializeExtension(const char* name) {
    static CFBundleRef framework = CFBundleGetBundleWithIdentifier(CFSTR("com.apple.opengl"));
    if (!framework) {
        throw std::runtime_error("Failed to load OpenGL framework.");
    }

    CFStringRef str = CFStringCreateWithCString(kCFAllocatorDefault, name, kCFStringEncodingASCII);
    void* symbol = CFBundleGetFunctionPointerForName(framework, str);
    CFRelease(str);

    return reinterpret_cast<gl::glProc>(symbol);
}

void HeadlessView::createContext() {
    CGLError error = CGLCreateContext(display->pixelFormat, nullptr, &glContext);
    if (error != kCGLNoError) {
        throw std::runtime_error(std::string("Error creating GL context object:") + CGLErrorString(error) + "\n");
    }

    error = CGLEnable(glContext, kCGLCEMPEngine);
    if (error != kCGLNoError) {
        throw std::runtime_error(std::string("Error enabling OpenGL multithreading:") + CGLErrorString(error) + "\n");
    }
}

void HeadlessView::destroyContext() {
    CGLDestroyContext(glContext);
}

void HeadlessView::resizeFramebuffer() {
    const unsigned int w = dimensions[0] * pixelRatio;
    const unsigned int h = dimensions[1] * pixelRatio;

    // Create depth/stencil buffer
    MBGL_CHECK_ERROR(glGenRenderbuffersEXT(1, &fboDepthStencil));
    MBGL_CHECK_ERROR(glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, fboDepthStencil));
    MBGL_CHECK_ERROR(glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_DEPTH24_STENCIL8_EXT, w, h));
    MBGL_CHECK_ERROR(glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, 0));

    MBGL_CHECK_ERROR(glGenRenderbuffersEXT(1, &fboColor));
    MBGL_CHECK_ERROR(glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, fboColor));
    MBGL_CHECK_ERROR(glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_RGBA8, w, h));
    MBGL_CHECK_ERROR(glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, 0));

    MBGL_CHECK_ERROR(glGenFramebuffersEXT(1, &fbo));
    MBGL_CHECK_ERROR(glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo));

    MBGL_CHECK_ERROR(glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_RENDERBUFFER_EXT, fboColor));
    MBGL_CHECK_ERROR(glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER_EXT, fboDepthStencil));

    GLenum status = MBGL_CHECK_ERROR(glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT));

    if (status != GL_FRAMEBUFFER_COMPLETE_EXT) {
        std::string error("Couldn't create framebuffer: ");
        switch (status) {
            case GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT_EXT: (error += "incomplete attachment"); break;
            case GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT_EXT: error += "incomplete missing attachment"; break;
            case GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS_EXT: error += "incomplete dimensions"; break;
            case GL_FRAMEBUFFER_INCOMPLETE_FORMATS_EXT: error += "incomplete formats"; break;
            case GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER_EXT: error += "incomplete draw buffer"; break;
            case GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER_EXT: error += "incomplete read buffer"; break;
            case GL_FRAMEBUFFER_UNSUPPORTED: error += "unsupported"; break;
            default: error += "other"; break;
        }
        throw std::runtime_error(error);
    }

    MBGL_CHECK_ERROR(glViewport(0, 0, w, h));
}

void HeadlessView::clearBuffers() {
    assert(active);

    MBGL_CHECK_ERROR(glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0));

    if (fbo) {
        MBGL_CHECK_ERROR(glDeleteFramebuffersEXT(1, &fbo));
        fbo = 0;
    }

    if (fboColor) {
        MBGL_CHECK_ERROR(glDeleteRenderbuffersEXT(1, &fboColor));
        fboColor = 0;
    }

    if (fboDepthStencil) {
        MBGL_CHECK_ERROR(glDeleteRenderbuffersEXT(1, &fboDepthStencil));
        fboDepthStencil = 0;
    }
}

void HeadlessView::activateContext() {
    CGLError error = CGLSetCurrentContext(glContext);
    if (error != kCGLNoError) {
        throw std::runtime_error(std::string("Switching OpenGL context failed:") + CGLErrorString(error) + "\n");
    }
}

void HeadlessView::deactivateContext() {
    CGLError error = CGLSetCurrentContext(nullptr);
    if (error != kCGLNoError) {
        throw std::runtime_error(std::string("Removing OpenGL context failed:") + CGLErrorString(error) + "\n");
    }
}

} // namespace mbgl