//
//  Created by Bradley Austin Davis on 2016/05/15
//  Copyright 2013-2016 High Fidelity, Inc.
//
//  Distributed under the Apache License, Version 2.0.
//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
//
#ifndef hifi_gpu_gl_GLShader_h
#define hifi_gpu_gl_GLShader_h

#include "GLShared.h"

namespace gpu { namespace gl {

struct ShaderObject {
    GLuint glshader { 0 };
    GLuint glprogram { 0 };
    GLint transformCameraSlot { -1 };
    GLint transformObjectSlot { -1 };

    GLint resourceTextureTableSlot0 { -1 };
    GLint resourceTextureTableSlot1 { -1 };
};

int makeUniformSlots(GLuint glprogram, const Shader::BindingSet& slotBindings,
    Shader::SlotSet& uniforms, Shader::SlotSet& textures, Shader::SlotSet& textureTables, Shader::SlotSet& samplers);
int makeUniformBlockSlots(GLuint glprogram, const Shader::BindingSet& slotBindings, Shader::SlotSet& buffers);
int makeInputSlots(GLuint glprogram, const Shader::BindingSet& slotBindings, Shader::SlotSet& inputs);
int makeOutputSlots(GLuint glprogram, const Shader::BindingSet& slotBindings, Shader::SlotSet& outputs);
void makeProgramBindings(ShaderObject& shaderObject);


class GLShader : public GPUObject {
public:
    static GLShader* sync(GLBackend& backend, const Shader& shader, const Shader::CompilationHandler& handler = nullptr);
    static bool makeProgram(GLBackend& backend, Shader& shader, const Shader::BindingSet& slotBindings, const Shader::CompilationHandler& handler);

    enum Version {
        Mono = 0,
        Stereo,

        NumVersions
    };

    using ShaderObject = gpu::gl::ShaderObject;
    using ShaderObjects = std::array< ShaderObject, NumVersions >;

    using UniformMapping = std::map<GLint, GLint>;
    using UniformMappingVersions = std::vector<UniformMapping>;

    GLShader(const std::weak_ptr<GLBackend>& backend);
    ~GLShader();

    ShaderObjects _shaderObjects;
    UniformMappingVersions _uniformMappings;

    GLuint getProgram(Version version = Mono) const {
        return _shaderObjects[version].glprogram;
    }

    GLint getUniformLocation(GLint srcLoc, Version version = Mono) const {
        // This check protect against potential invalid src location for this shader, if unknown then return -1.
        const auto& mapping = _uniformMappings[version];
        auto found = mapping.find(srcLoc);
        if (found == mapping.end()) {
            return -1;
        }
        return found->second;
    }

    const std::weak_ptr<GLBackend> _backend;
};

} }


#endif