/*
    This file is part of Magnum.

    Copyright © 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019,
                2020, 2021 Vladimír Vondruš <mosra@centrum.cz>

    Permission is hereby granted, free of charge, to any person obtaining a
    copy of this software and associated documentation files (the "Software"),
    to deal in the Software without restriction, including without limitation
    the rights to use, copy, modify, merge, publish, distribute, sublicense,
    and/or sell copies of the Software, and to permit persons to whom the
    Software is furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be included
    in all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
    DEALINGS IN THE SOFTWARE.
*/

#include "FlatGL.h"

#include <Corrade/Containers/EnumSet.hpp>
#include <Corrade/Containers/Reference.h>
#include <Corrade/Utility/Resource.h>

#include "Magnum/GL/Context.h"
#include "Magnum/GL/Extensions.h"
#include "Magnum/GL/Shader.h"
#include "Magnum/GL/Texture.h"
#include "Magnum/Math/Color.h"
#include "Magnum/Math/Matrix3.h"
#include "Magnum/Math/Matrix4.h"

#include "Magnum/Shaders/Implementation/CreateCompatibilityShader.h"

#ifndef MAGNUM_TARGET_GLES2
#include <Corrade/Utility/FormatStl.h>

#include "Magnum/GL/Buffer.h"
#endif

namespace Magnum { namespace Shaders {

namespace {
    enum: Int { TextureUnit = 0 };

    #ifndef MAGNUM_TARGET_GLES2
    enum: Int {
        /* Not using the zero binding to avoid conflicts with
           ProjectionBufferBinding from other shaders which can likely stay
           bound to the same buffer for the whole time */
        TransformationProjectionBufferBinding = 1,
        DrawBufferBinding = 2,
        TextureTransformationBufferBinding = 3
    };
    #endif
}

template<UnsignedInt dimensions> FlatGL<dimensions>::FlatGL(const Flags flags
    #ifndef MAGNUM_TARGET_GLES2
    , const UnsignedInt drawCount
    #endif
):
    _flags{flags}
    #ifndef MAGNUM_TARGET_GLES2
    , _drawCount{drawCount}
    #endif
{
    CORRADE_ASSERT(!(flags & Flag::TextureTransformation) || (flags & Flag::Textured),
        "Shaders::FlatGL: texture transformation enabled but the shader is not textured", );

    #ifndef MAGNUM_TARGET_GLES2
    CORRADE_ASSERT(!(flags >= Flag::UniformBuffers) || drawCount,
        "Shaders::FlatGL: draw count can't be zero", );
    #endif

    #ifndef MAGNUM_TARGET_GLES
    if(flags >= Flag::UniformBuffers)
        MAGNUM_ASSERT_GL_EXTENSION_SUPPORTED(GL::Extensions::ARB::uniform_buffer_object);
    #endif
    #ifndef MAGNUM_TARGET_GLES2
    if(flags >= Flag::MultiDraw) {
        #ifndef MAGNUM_TARGET_GLES
        MAGNUM_ASSERT_GL_EXTENSION_SUPPORTED(GL::Extensions::ARB::shader_draw_parameters);
        #elif !defined(MAGNUM_TARGET_WEBGL)
        MAGNUM_ASSERT_GL_EXTENSION_SUPPORTED(GL::Extensions::ANGLE::multi_draw);
        #else
        MAGNUM_ASSERT_GL_EXTENSION_SUPPORTED(GL::Extensions::WEBGL::multi_draw);
        #endif
    }
    #endif

    #ifdef MAGNUM_BUILD_STATIC
    /* Import resources on static build, if not already */
    if(!Utility::Resource::hasGroup("MagnumShadersGL"))
        importShaderResources();
    #endif
    Utility::Resource rs("MagnumShadersGL");

    const GL::Context& context = GL::Context::current();

    #ifndef MAGNUM_TARGET_GLES
    const GL::Version version = context.supportedVersion({GL::Version::GL320, GL::Version::GL310, GL::Version::GL300, GL::Version::GL210});
    #else
    const GL::Version version = context.supportedVersion({GL::Version::GLES300, GL::Version::GLES200});
    #endif

    GL::Shader vert = Implementation::createCompatibilityShader(rs, version, GL::Shader::Type::Vertex);
    GL::Shader frag = Implementation::createCompatibilityShader(rs, version, GL::Shader::Type::Fragment);

    vert.addSource(flags & Flag::Textured ? "#define TEXTURED\n" : "")
        .addSource(flags & Flag::VertexColor ? "#define VERTEX_COLOR\n" : "")
        .addSource(flags & Flag::TextureTransformation ? "#define TEXTURE_TRANSFORMATION\n" : "")
        .addSource(dimensions == 2 ? "#define TWO_DIMENSIONS\n" : "#define THREE_DIMENSIONS\n")
        #ifndef MAGNUM_TARGET_GLES2
        .addSource(flags >= Flag::InstancedObjectId ? "#define INSTANCED_OBJECT_ID\n" : "")
        #endif
        .addSource(flags & Flag::InstancedTransformation ? "#define INSTANCED_TRANSFORMATION\n" : "")
        .addSource(flags >= Flag::InstancedTextureOffset ? "#define INSTANCED_TEXTURE_OFFSET\n" : "");
    #ifndef MAGNUM_TARGET_GLES2
    if(flags >= Flag::UniformBuffers) {
        vert.addSource(Utility::formatString(
            "#define UNIFORM_BUFFERS\n"
            "#define DRAW_COUNT {}\n",
            drawCount));
        vert.addSource(flags >= Flag::MultiDraw ? "#define MULTI_DRAW\n" : "");
    }
    #endif
    vert.addSource(rs.get("generic.glsl"))
        .addSource(rs.get("Flat.vert"));
    frag.addSource(flags & Flag::Textured ? "#define TEXTURED\n" : "")
        .addSource(flags & Flag::AlphaMask ? "#define ALPHA_MASK\n" : "")
        .addSource(flags & Flag::VertexColor ? "#define VERTEX_COLOR\n" : "")
        #ifndef MAGNUM_TARGET_GLES2
        .addSource(flags & Flag::ObjectId ? "#define OBJECT_ID\n" : "")
        .addSource(flags >= Flag::InstancedObjectId ? "#define INSTANCED_OBJECT_ID\n" : "")
        #endif
        ;
    #ifndef MAGNUM_TARGET_GLES2
    if(flags >= Flag::UniformBuffers) {
        frag.addSource(Utility::formatString(
            "#define UNIFORM_BUFFERS\n"
            "#define DRAW_COUNT {}\n",
            drawCount));
        frag.addSource(flags >= Flag::MultiDraw ? "#define MULTI_DRAW\n" : "");
    }
    #endif
    frag.addSource(rs.get("generic.glsl"))
        .addSource(rs.get("Flat.frag"));

    CORRADE_INTERNAL_ASSERT_OUTPUT(GL::Shader::compile({vert, frag}));

    attachShaders({vert, frag});

    /* ES3 has this done in the shader directly and doesn't even provide
       bindFragmentDataLocation() */
    #if !defined(MAGNUM_TARGET_GLES) || defined(MAGNUM_TARGET_GLES2)
    #ifndef MAGNUM_TARGET_GLES
    if(!context.isExtensionSupported<GL::Extensions::ARB::explicit_attrib_location>(version))
    #endif
    {
        bindAttributeLocation(Position::Location, "position");
        if(flags & Flag::Textured)
            bindAttributeLocation(TextureCoordinates::Location, "textureCoordinates");
        if(flags & Flag::VertexColor)
            bindAttributeLocation(Color3::Location, "vertexColor"); /* Color4 is the same */
        #ifndef MAGNUM_TARGET_GLES2
        if(flags & Flag::ObjectId) {
            bindFragmentDataLocation(ColorOutput, "color");
            bindFragmentDataLocation(ObjectIdOutput, "objectId");
        }
        if(flags >= Flag::InstancedObjectId)
            bindAttributeLocation(ObjectId::Location, "instanceObjectId");
        #endif
        if(flags & Flag::InstancedTransformation)
            bindAttributeLocation(TransformationMatrix::Location, "instancedTransformationMatrix");
        if(flags >= Flag::InstancedTextureOffset)
            bindAttributeLocation(TextureOffset::Location, "instancedTextureOffset");
    }
    #endif

    CORRADE_INTERNAL_ASSERT_OUTPUT(link());

    #ifndef MAGNUM_TARGET_GLES
    if(!context.isExtensionSupported<GL::Extensions::ARB::explicit_uniform_location>(version))
    #endif
    {
        #ifndef MAGNUM_TARGET_GLES2
        if(flags >= Flag::UniformBuffers) {
            _drawOffsetUniform = uniformLocation("drawOffset");
        } else
        #endif
        {
            _transformationProjectionMatrixUniform = uniformLocation("transformationProjectionMatrix");
            if(flags & Flag::TextureTransformation)
                _textureMatrixUniform = uniformLocation("textureMatrix");
            _colorUniform = uniformLocation("color");
            if(flags & Flag::AlphaMask) _alphaMaskUniform = uniformLocation("alphaMask");
            #ifndef MAGNUM_TARGET_GLES2
            if(flags & Flag::ObjectId) _objectIdUniform = uniformLocation("objectId");
            #endif
        }
    }

    #ifndef MAGNUM_TARGET_GLES
    if(!context.isExtensionSupported<GL::Extensions::ARB::shading_language_420pack>(version))
    #endif
    {
        if(flags & Flag::Textured) setUniform(uniformLocation("textureData"), TextureUnit);
        #ifndef MAGNUM_TARGET_GLES2
        if(flags >= Flag::UniformBuffers) {
            setUniformBlockBinding(uniformBlockIndex("TransformationProjection"), TransformationProjectionBufferBinding);
            setUniformBlockBinding(uniformBlockIndex("Draw"), DrawBufferBinding);
            if(flags & Flag::TextureTransformation)
                setUniformBlockBinding(uniformBlockIndex("TextureTransformation"), TextureTransformationBufferBinding);
        }
        #endif
    }

    /* Set defaults in OpenGL ES (for desktop they are set in shader code itself) */
    #ifdef MAGNUM_TARGET_GLES
    #ifndef MAGNUM_TARGET_GLES2
    if(flags >= Flag::UniformBuffers) {
        /* Draw offset is zero by default */
    } else
    #endif
    {
        setTransformationProjectionMatrix(MatrixTypeFor<dimensions, Float>{Math::IdentityInit});
        if(flags & Flag::TextureTransformation)
            setTextureMatrix(Matrix3{Math::IdentityInit});
        setColor(Magnum::Color4{1.0f});
        if(flags & Flag::AlphaMask) setAlphaMask(0.5f);
        /* Object ID is zero by default */
    }
    #endif
}

#ifndef MAGNUM_TARGET_GLES2
template<UnsignedInt dimensions> FlatGL<dimensions>::FlatGL(const Flags flags): FlatGL{flags, 1} {}
#endif

template<UnsignedInt dimensions> FlatGL<dimensions>& FlatGL<dimensions>::setTransformationProjectionMatrix(const MatrixTypeFor<dimensions, Float>& matrix) {
    #ifndef MAGNUM_TARGET_GLES2
    CORRADE_ASSERT(!(_flags >= Flag::UniformBuffers),
        "Shaders::FlatGL::setTransformationProjectionMatrix(): the shader was created with uniform buffers enabled", *this);
    #endif
    setUniform(_transformationProjectionMatrixUniform, matrix);
    return *this;
}

template<UnsignedInt dimensions> FlatGL<dimensions>& FlatGL<dimensions>::setTextureMatrix(const Matrix3& matrix) {
    #ifndef MAGNUM_TARGET_GLES2
    CORRADE_ASSERT(!(_flags >= Flag::UniformBuffers),
        "Shaders::FlatGL::setTextureMatrix(): the shader was created with uniform buffers enabled", *this);
    #endif
    CORRADE_ASSERT(_flags & Flag::TextureTransformation,
        "Shaders::FlatGL::setTextureMatrix(): the shader was not created with texture transformation enabled", *this);
    setUniform(_textureMatrixUniform, matrix);
    return *this;
}

template<UnsignedInt dimensions> FlatGL<dimensions>& FlatGL<dimensions>::setColor(const Magnum::Color4& color) {
    #ifndef MAGNUM_TARGET_GLES2
    CORRADE_ASSERT(!(_flags >= Flag::UniformBuffers),
        "Shaders::FlatGL::setColor(): the shader was created with uniform buffers enabled", *this);
    #endif
    setUniform(_colorUniform, color);
    return *this;
}

template<UnsignedInt dimensions> FlatGL<dimensions>& FlatGL<dimensions>::setAlphaMask(Float mask) {
    #ifndef MAGNUM_TARGET_GLES2
    CORRADE_ASSERT(!(_flags >= Flag::UniformBuffers),
        "Shaders::FlatGL::setAlphaMask(): the shader was created with uniform buffers enabled", *this);
    #endif
    CORRADE_ASSERT(_flags & Flag::AlphaMask,
        "Shaders::FlatGL::setAlphaMask(): the shader was not created with alpha mask enabled", *this);
    setUniform(_alphaMaskUniform, mask);
    return *this;
}

#ifndef MAGNUM_TARGET_GLES2
template<UnsignedInt dimensions> FlatGL<dimensions>& FlatGL<dimensions>::setObjectId(UnsignedInt id) {
    CORRADE_ASSERT(!(_flags >= Flag::UniformBuffers),
        "Shaders::FlatGL::setObjectId(): the shader was created with uniform buffers enabled", *this);
    CORRADE_ASSERT(_flags & Flag::ObjectId,
        "Shaders::FlatGL::setObjectId(): the shader was not created with object ID enabled", *this);
    setUniform(_objectIdUniform, id);
    return *this;
}
#endif

#ifndef MAGNUM_TARGET_GLES2
template<UnsignedInt dimensions> FlatGL<dimensions>& FlatGL<dimensions>::setDrawOffset(const UnsignedInt offset) {
    CORRADE_ASSERT(_flags >= Flag::UniformBuffers,
        "Shaders::FlatGL::setDrawOffset(): the shader was not created with uniform buffers enabled", *this);
    CORRADE_ASSERT(offset < _drawCount,
        "Shaders::FlatGL::setDrawOffset(): draw offset" << offset << "is out of bounds for" << _drawCount << "draws", *this);
    setUniform(_drawOffsetUniform, offset);
    return *this;
}

template<UnsignedInt dimensions> FlatGL<dimensions>& FlatGL<dimensions>::bindTransformationProjectionBuffer(GL::Buffer& buffer) {
    CORRADE_ASSERT(_flags >= Flag::UniformBuffers,
        "Shaders::FlatGL::bindTransformationProjectionBuffer(): the shader was not created with uniform buffers enabled", *this);
    buffer.bind(GL::Buffer::Target::Uniform, TransformationProjectionBufferBinding);
    return *this;
}

template<UnsignedInt dimensions> FlatGL<dimensions>& FlatGL<dimensions>::bindTransformationProjectionBuffer(GL::Buffer& buffer, const GLintptr offset, const GLsizeiptr size) {
    CORRADE_ASSERT(_flags >= Flag::UniformBuffers,
        "Shaders::FlatGL::bindTransformationProjectionBuffer(): the shader was not created with uniform buffers enabled", *this);
    buffer.bind(GL::Buffer::Target::Uniform, TransformationProjectionBufferBinding, offset, size);
    return *this;
}

template<UnsignedInt dimensions> FlatGL<dimensions>& FlatGL<dimensions>::bindDrawBuffer(GL::Buffer& buffer) {
    CORRADE_ASSERT(_flags >= Flag::UniformBuffers,
        "Shaders::FlatGL::bindDrawBuffer(): the shader was not created with uniform buffers enabled", *this);
    buffer.bind(GL::Buffer::Target::Uniform, DrawBufferBinding);
    return *this;
}

template<UnsignedInt dimensions> FlatGL<dimensions>& FlatGL<dimensions>::bindDrawBuffer(GL::Buffer& buffer, const GLintptr offset, const GLsizeiptr size) {
    CORRADE_ASSERT(_flags >= Flag::UniformBuffers,
        "Shaders::FlatGL::bindDrawBuffer(): the shader was not created with uniform buffers enabled", *this);
    buffer.bind(GL::Buffer::Target::Uniform, DrawBufferBinding, offset, size);
    return *this;
}

template<UnsignedInt dimensions> FlatGL<dimensions>& FlatGL<dimensions>::bindTextureTransformationBuffer(GL::Buffer& buffer) {
    CORRADE_ASSERT(_flags >= Flag::UniformBuffers,
        "Shaders::FlatGL::bindTextureTransformationBuffer(): the shader was not created with uniform buffers enabled", *this);
    CORRADE_ASSERT(_flags & Flag::TextureTransformation,
        "Shaders::FlatGL::bindTextureTransformationBuffer(): the shader was not created with texture transformation enabled", *this);
    buffer.bind(GL::Buffer::Target::Uniform, TextureTransformationBufferBinding);
    return *this;
}

template<UnsignedInt dimensions> FlatGL<dimensions>& FlatGL<dimensions>::bindTextureTransformationBuffer(GL::Buffer& buffer, const GLintptr offset, const GLsizeiptr size) {
    CORRADE_ASSERT(_flags >= Flag::UniformBuffers,
        "Shaders::FlatGL::bindTextureTransformationBuffer(): the shader was not created with uniform buffers enabled", *this);
    CORRADE_ASSERT(_flags & Flag::TextureTransformation,
        "Shaders::FlatGL::bindTextureTransformationBuffer(): the shader was not created with texture transformation enabled", *this);
    buffer.bind(GL::Buffer::Target::Uniform, TextureTransformationBufferBinding, offset, size);
    return *this;
}
#endif

template<UnsignedInt dimensions> FlatGL<dimensions>& FlatGL<dimensions>::bindTexture(GL::Texture2D& texture) {
    CORRADE_ASSERT(_flags & Flag::Textured,
        "Shaders::FlatGL::bindTexture(): the shader was not created with texturing enabled", *this);
    texture.bind(TextureUnit);
    return *this;
}

template class MAGNUM_SHADERS_EXPORT FlatGL<2>;
template class MAGNUM_SHADERS_EXPORT FlatGL<3>;

namespace Implementation {

Debug& operator<<(Debug& debug, const FlatGLFlag value) {
    debug << "Shaders::FlatGL::Flag" << Debug::nospace;

    switch(value) {
        /* LCOV_EXCL_START */
        #define _c(v) case FlatGLFlag::v: return debug << "::" #v;
        _c(Textured)
        _c(AlphaMask)
        _c(VertexColor)
        _c(TextureTransformation)
        #ifndef MAGNUM_TARGET_GLES2
        _c(ObjectId)
        _c(InstancedObjectId)
        #endif
        _c(InstancedTransformation)
        _c(InstancedTextureOffset)
        #ifndef MAGNUM_TARGET_GLES2
        _c(UniformBuffers)
        _c(MultiDraw)
        #endif
        #undef _c
        /* LCOV_EXCL_STOP */
    }

    return debug << "(" << Debug::nospace << reinterpret_cast<void*>(UnsignedShort(value)) << Debug::nospace << ")";
}

Debug& operator<<(Debug& debug, const FlatGLFlags value) {
    return Containers::enumSetDebugOutput(debug, value, "Shaders::FlatGL::Flags{}", {
        FlatGLFlag::Textured,
        FlatGLFlag::AlphaMask,
        FlatGLFlag::VertexColor,
        FlatGLFlag::InstancedTextureOffset, /* Superset of TextureTransformation */
        FlatGLFlag::TextureTransformation,
        #ifndef MAGNUM_TARGET_GLES2
        FlatGLFlag::InstancedObjectId, /* Superset of ObjectId */
        FlatGLFlag::ObjectId,
        #endif
        FlatGLFlag::InstancedTransformation,
        #ifndef MAGNUM_TARGET_GLES2
        FlatGLFlag::MultiDraw, /* Superset of UniformBuffers */
        FlatGLFlag::UniformBuffers
        #endif
    });
}

}

}}