/* This file is part of the sirit project.
 * Copyright (c) 2019 sirit
 * This software may be used and distributed according to the terms of the
 * 3-Clause BSD License
 */

#include <cstdio>
#include <cstdlib>
#include <sirit/sirit.h>

using u32 = uint32_t;

class MyModule : public Sirit::Module {
public:
    MyModule() = default;
    ~MyModule() = default;

    void Generate() {
        AddCapability(spv::Capability::Shader);
        SetMemoryModel(spv::AddressingModel::Logical, spv::MemoryModel::GLSL450);

        const auto t_void = Name(TypeVoid(), "void");
        const auto t_uint = Name(TypeInt(32, false), "uint");
        const auto t_float = Name(TypeFloat(32), "float");

        const auto float4 = Name(TypeVector(t_float, 4), "float4");
        const auto in_float = Name(TypePointer(spv::StorageClass::Input, t_float), "in_float");
        const auto in_float4 = Name(TypePointer(spv::StorageClass::Input, float4), "in_float4");
        const auto out_float4 =
            Name(TypePointer(spv::StorageClass::Output, float4), "out_float4");

        const auto gl_per_vertex = Name(TypeStruct(float4), "gl_PerVertex");
        const auto gl_per_vertex_ptr =
            Name(TypePointer(spv::StorageClass::Output, gl_per_vertex), "out_gl_PerVertex");

        const auto in_pos = Name(OpVariable(in_float4, spv::StorageClass::Input), "in_pos");
        const auto per_vertex =
            Name(OpVariable(gl_per_vertex_ptr, spv::StorageClass::Output), "per_vertex");

        Decorate(in_pos, spv::Decoration::Location, 0);
        Decorate(gl_per_vertex, spv::Decoration::Block);
        Decorate(gl_per_vertex, spv::Decoration::Block);
        MemberDecorate(gl_per_vertex, 0, spv::Decoration::BuiltIn,
                       static_cast<u32>(spv::BuiltIn::Position));

        AddGlobalVariable(in_pos);
        AddGlobalVariable(per_vertex);

        const auto main_func = Emit(
            Name(OpFunction(t_void, spv::FunctionControlMask::MaskNone, TypeFunction(t_void)),
                 "main"));
        Emit(OpLabel());

        const auto ptr_pos_x = Emit(OpAccessChain(in_float, in_pos, Constant(t_uint, 0u)));
        const auto ptr_pos_y = Emit(OpAccessChain(in_float, in_pos, Constant(t_uint, 1u)));

        const auto pos_x = Emit(OpLoad(t_float, ptr_pos_x));
        const auto pos_y = Emit(OpLoad(t_float, ptr_pos_y));

        auto tmp_position = Emit(OpUndef(float4));
        Decorate(tmp_position, spv::Decoration::FPRoundingMode,
                 static_cast<u32>(spv::FPRoundingMode::RTE));
        tmp_position = Emit(OpCompositeInsert(float4, pos_x, tmp_position, 0));
        tmp_position = Emit(OpCompositeInsert(float4, pos_y, tmp_position, 1));
        tmp_position = Emit(OpCompositeInsert(float4, Constant(t_float, 0.f), tmp_position, 2));
        tmp_position = Emit(OpCompositeInsert(float4, Constant(t_float, 1.f), tmp_position, 3));

        const auto gl_position = Emit(OpAccessChain(out_float4, per_vertex, Constant(t_uint, 0u)));
        Emit(OpStore(gl_position, tmp_position));

        Emit(OpReturn());
        Emit(OpFunctionEnd());

        AddEntryPoint(spv::ExecutionModel::Vertex, main_func, "main", in_pos, per_vertex);
    }
};

int main(int argc, char** argv) {
    MyModule module;
    module.Generate();

    std::vector<std::uint8_t> code{module.Assemble()};

    FILE* file = fopen("sirit.spv", "wb");
    fwrite(code.data(), 1, code.size(), file);
    fclose(file);

    return 0;
}