/*
 * 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/GrGLInterface.h"
#include "gl/GrGLExtensions.h"
#include "../GrGLUtil.h"

#include <dlfcn.h>

// We get the proc addresss of all GL functions dynamically because we sometimes link against
// alternative GL implementations (e.g. MESA) in addition to the native GL implementation.
class GLLoader {
public:
    GLLoader() {
        fLibrary = dlopen(
                    "/System/Library/Frameworks/OpenGL.framework/Versions/A/Libraries/libGL.dylib",
                    RTLD_LAZY);
    }
    ~GLLoader() {
        if (NULL != fLibrary) {
            dlclose(fLibrary);
        }
    }
    void* handle() {
        return NULL == fLibrary ? RTLD_DEFAULT : fLibrary;
    }
private:
    void* fLibrary;
};

static void* GetProcAddress(const char* name) {
    static GLLoader gLoader;
    return dlsym(gLoader.handle(), name);
}

#define GET_PROC(name) (interface->f ## name = ((GrGL ## name ## Proc) GetProcAddress("gl" #name)))
#define GET_PROC_SUFFIX(name, suffix) (interface->f ## name = ((GrGL ## name ## Proc) GetProcAddress("gl" #name #suffix)))

const GrGLInterface* GrGLCreateNativeInterface() {
    // The gl functions are not context-specific so we create one global interface
    static SkAutoTUnref<GrGLInterface> glInterface;
    if (!glInterface.get()) {
        GrGLInterface* interface = new GrGLInterface;

        GrGLGetStringProc glGetString = (GrGLGetStringProc) GetProcAddress("glGetString");
        GrGLGetStringiProc glGetStringi = (GrGLGetStringiProc) GetProcAddress("glGetStringi");
        GrGLGetIntegervProc glGetIntegerv = (GrGLGetIntegervProc) GetProcAddress("glGetIntegerv");

        glInterface.reset(interface);
        const char* verStr = (const char*) glGetString(GR_GL_VERSION);
        GrGLVersion ver = GrGLGetVersionFromString(verStr);
        GrGLExtensions extensions;
        if (!extensions.init(kDesktop_GrGLBinding, glGetString, glGetStringi, glGetIntegerv)) {
            glInterface.reset(NULL);
            return NULL;
        }
        interface->fBindingsExported = kDesktop_GrGLBinding;

        GET_PROC(ActiveTexture);
        GET_PROC(AttachShader);
        GET_PROC(BeginQuery);
        GET_PROC(BindAttribLocation);
        GET_PROC(BindBuffer);
        if (ver >= GR_GL_VER(3,0)) {
            GET_PROC(BindFragDataLocation);
        }
        GET_PROC(BindTexture);
        GET_PROC(BlendFunc);

        if (ver >= GR_GL_VER(1,4) ||
            extensions.has("GL_ARB_imaging") ||
            extensions.has("GL_EXT_blend_color")) {
            GET_PROC(BlendColor);
        }

        GET_PROC(BufferData);
        GET_PROC(BufferSubData);
        GET_PROC(Clear);
        GET_PROC(ClearColor);
        GET_PROC(ClearStencil);
        GET_PROC(ClientActiveTexture);
        GET_PROC(ColorMask);
        GET_PROC(CompileShader);
        GET_PROC(CompressedTexImage2D);
        GET_PROC(CopyTexSubImage2D);
        GET_PROC(CreateProgram);
        GET_PROC(CreateShader);
        GET_PROC(CullFace);
        GET_PROC(DeleteBuffers);
        GET_PROC(DeleteProgram);
        GET_PROC(DeleteQueries);
        GET_PROC(DeleteShader);
        GET_PROC(DeleteTextures);
        GET_PROC(DepthMask);
        GET_PROC(Disable);
        GET_PROC(DisableClientState);
        GET_PROC(DisableVertexAttribArray);
        GET_PROC(DrawArrays);
        GET_PROC(DrawBuffer);
        GET_PROC(DrawBuffers);
        GET_PROC(DrawElements);
        GET_PROC(Enable);
        GET_PROC(EnableClientState);
        GET_PROC(EnableVertexAttribArray);
        GET_PROC(EndQuery);
        GET_PROC(Finish);
        GET_PROC(Flush);
        GET_PROC(FrontFace);
        GET_PROC(GenBuffers);
        GET_PROC(GenerateMipmap);
        GET_PROC(GenQueries);
        GET_PROC(GetBufferParameteriv);
        GET_PROC(GetError);
        GET_PROC(GetIntegerv);
        GET_PROC(GetProgramInfoLog);
        GET_PROC(GetProgramiv);
        GET_PROC(GetQueryiv);
        GET_PROC(GetQueryObjectiv);
        GET_PROC(GetQueryObjectuiv);
        GET_PROC(GetShaderInfoLog);
        GET_PROC(GetShaderiv);
        GET_PROC(GetString);
        GET_PROC(GetStringi);
        GET_PROC(GetTexLevelParameteriv);
        GET_PROC(GenTextures);
        GET_PROC(GetUniformLocation);
        GET_PROC(LineWidth);
        GET_PROC(LinkProgram);
        GET_PROC(LoadIdentity);
        GET_PROC(LoadMatrixf);
        GET_PROC(MapBuffer);
        GET_PROC(MatrixMode);
        GET_PROC(PixelStorei);
        GET_PROC(ReadBuffer);
        GET_PROC(ReadPixels);
        GET_PROC(Scissor);
        GET_PROC(ShaderSource);
        GET_PROC(StencilFunc);
        GET_PROC(StencilFuncSeparate);
        GET_PROC(StencilMask);
        GET_PROC(StencilMaskSeparate);
        GET_PROC(StencilOp);
        GET_PROC(StencilOpSeparate);
        GET_PROC(TexGenf);
        GET_PROC(TexGenfv);
        GET_PROC(TexGeni);
        GET_PROC(TexImage2D);
        GET_PROC(TexParameteri);
        GET_PROC(TexParameteriv);
        if (ver >= GR_GL_VER(4,2) || extensions.has("GL_ARB_texture_storage")) {
            GET_PROC(TexStorage2D);
        } else if (extensions.has("GL_EXT_texture_storage")) {
            GET_PROC_SUFFIX(TexStorage2D, EXT);
        }
        GET_PROC(TexSubImage2D);
        GET_PROC(Uniform1f);
        GET_PROC(Uniform1i);
        GET_PROC(Uniform1fv);
        GET_PROC(Uniform1iv);
        GET_PROC(Uniform2f);
        GET_PROC(Uniform2i);
        GET_PROC(Uniform2fv);
        GET_PROC(Uniform2iv);
        GET_PROC(Uniform3f);
        GET_PROC(Uniform3i);
        GET_PROC(Uniform3fv);
        GET_PROC(Uniform3iv);
        GET_PROC(Uniform4f);
        GET_PROC(Uniform4i);
        GET_PROC(Uniform4fv);
        GET_PROC(Uniform4iv);
        GET_PROC(Uniform4fv);
        GET_PROC(UniformMatrix2fv);
        GET_PROC(UniformMatrix3fv);
        GET_PROC(UniformMatrix4fv);
        GET_PROC(UnmapBuffer);
        GET_PROC(UseProgram);
        GET_PROC(VertexAttrib4fv);
        GET_PROC(VertexAttribPointer);
        GET_PROC(VertexPointer);
        GET_PROC(Viewport);

        if (ver >= GR_GL_VER(3,0) || extensions.has("GL_ARB_vertex_array_object")) {
            // no ARB suffix for GL_ARB_vertex_array_object
            GET_PROC(BindVertexArray);
            GET_PROC(DeleteVertexArrays);
            GET_PROC(GenVertexArrays);
        }

        if (ver >= GR_GL_VER(3,3) || extensions.has("GL_ARB_timer_query")) {
            // ARB extension doesn't use the ARB suffix on the function name
            GET_PROC(QueryCounter);
            GET_PROC(GetQueryObjecti64v);
            GET_PROC(GetQueryObjectui64v);
        } else if (extensions.has("GL_EXT_timer_query")) {
            GET_PROC_SUFFIX(GetQueryObjecti64v, EXT);
            GET_PROC_SUFFIX(GetQueryObjectui64v, EXT);
        }

        if (ver >= GR_GL_VER(3,0) || extensions.has("GL_ARB_framebuffer_object")) {
            // ARB extension doesn't use the ARB suffix on the function names
                GET_PROC(GenFramebuffers);
                GET_PROC(GetFramebufferAttachmentParameteriv);
                GET_PROC(GetRenderbufferParameteriv);
                GET_PROC(BindFramebuffer);
                GET_PROC(FramebufferTexture2D);
                GET_PROC(CheckFramebufferStatus);
                GET_PROC(DeleteFramebuffers);
                GET_PROC(RenderbufferStorage);
                GET_PROC(GenRenderbuffers);
                GET_PROC(DeleteRenderbuffers);
                GET_PROC(FramebufferRenderbuffer);
                GET_PROC(BindRenderbuffer);
                GET_PROC(RenderbufferStorageMultisample);
                GET_PROC(BlitFramebuffer);
        } else {
            if (extensions.has("GL_EXT_framebuffer_object")) {
                GET_PROC_SUFFIX(GenFramebuffers, EXT);
                GET_PROC_SUFFIX(GetFramebufferAttachmentParameteriv, EXT);
                GET_PROC_SUFFIX(GetRenderbufferParameteriv, EXT);
                GET_PROC_SUFFIX(BindFramebuffer, EXT);
                GET_PROC_SUFFIX(FramebufferTexture2D, EXT);
                GET_PROC_SUFFIX(CheckFramebufferStatus, EXT);
                GET_PROC_SUFFIX(DeleteFramebuffers, EXT);
                GET_PROC_SUFFIX(RenderbufferStorage, EXT);
                GET_PROC_SUFFIX(GenRenderbuffers, EXT);
                GET_PROC_SUFFIX(DeleteRenderbuffers, EXT);
                GET_PROC_SUFFIX(FramebufferRenderbuffer, EXT);
                GET_PROC_SUFFIX(BindRenderbuffer, EXT);
            }
            if (extensions.has("GL_EXT_framebuffer_multisample")) {
                GET_PROC_SUFFIX(RenderbufferStorageMultisample, EXT);
            }
            if (extensions.has("GL_EXT_framebuffer_blit")) {
                GET_PROC_SUFFIX(BlitFramebuffer, EXT);
            }
        }
        if (ver >= GR_GL_VER(3,3) || extensions.has("GL_ARB_blend_func_extended")) {
            // ARB extension doesn't use the ARB suffix on the function name
            GET_PROC(BindFragDataLocationIndexed);
        }
    }
    glInterface.get()->ref();
    return glInterface.get();
}