// Copyright 2021 yuzu Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.

#include <string>
#include <tuple>

#include "shader_recompiler/backend/bindings.h"
#include "shader_recompiler/backend/glasm/emit_context.h"
#include "shader_recompiler/backend/glasm/emit_glasm.h"
#include "shader_recompiler/backend/glasm/emit_glasm_instructions.h"
#include "shader_recompiler/frontend/ir/program.h"
#include "shader_recompiler/profile.h"

namespace Shader::Backend::GLASM {
namespace {
template <class Func>
struct FuncTraits {};

template <class ReturnType_, class... Args>
struct FuncTraits<ReturnType_ (*)(Args...)> {
    using ReturnType = ReturnType_;

    static constexpr size_t NUM_ARGS = sizeof...(Args);

    template <size_t I>
    using ArgType = std::tuple_element_t<I, std::tuple<Args...>>;
};

template <typename ArgType>
auto Arg(EmitContext& ctx, const IR::Value& arg) {
    if constexpr (std::is_same_v<ArgType, std::string_view>) {
        return ctx.reg_alloc.Consume(arg);
    } else if constexpr (std::is_same_v<ArgType, const IR::Value&>) {
        return arg;
    } else if constexpr (std::is_same_v<ArgType, u32>) {
        return arg.U32();
    } else if constexpr (std::is_same_v<ArgType, IR::Block*>) {
        return arg.Label();
    } else if constexpr (std::is_same_v<ArgType, IR::Attribute>) {
        return arg.Attribute();
    } else if constexpr (std::is_same_v<ArgType, IR::Patch>) {
        return arg.Patch();
    } else if constexpr (std::is_same_v<ArgType, IR::Reg>) {
        return arg.Reg();
    }
}

template <auto func, bool is_first_arg_inst, size_t... I>
void Invoke(EmitContext& ctx, IR::Inst* inst, std::index_sequence<I...>) {
    using Traits = FuncTraits<decltype(func)>;
    if constexpr (is_first_arg_inst) {
        func(ctx, *inst, Arg<typename Traits::template ArgType<I + 2>>(ctx, inst->Arg(I))...);
    } else {
        func(ctx, Arg<typename Traits::template ArgType<I + 1>>(ctx, inst->Arg(I))...);
    }
}

template <auto func>
void Invoke(EmitContext& ctx, IR::Inst* inst) {
    using Traits = FuncTraits<decltype(func)>;
    static_assert(Traits::NUM_ARGS >= 1, "Insufficient arguments");
    if constexpr (Traits::NUM_ARGS == 1) {
        Invoke<func, false>(ctx, inst, std::make_index_sequence<0>{});
    } else {
        using FirstArgType = typename Traits::template ArgType<1>;
        static constexpr bool is_first_arg_inst = std::is_same_v<FirstArgType, IR::Inst&>;
        using Indices = std::make_index_sequence<Traits::NUM_ARGS - (is_first_arg_inst ? 2 : 1)>;
        Invoke<func, is_first_arg_inst>(ctx, inst, Indices{});
    }
}

void EmitInst(EmitContext& ctx, IR::Inst* inst) {
    switch (inst->GetOpcode()) {
#define OPCODE(name, result_type, ...)                                                             \
    case IR::Opcode::name:                                                                         \
        return Invoke<&Emit##name>(ctx, inst);
#include "shader_recompiler/frontend/ir/opcodes.inc"
#undef OPCODE
    }
    throw LogicError("Invalid opcode {}", inst->GetOpcode());
}

void Identity(IR::Inst& inst, const IR::Value& value) {
    if (value.IsImmediate()) {
        return;
    }
    IR::Inst* const value_inst{value.InstRecursive()};
    if (inst.GetOpcode() == IR::Opcode::Identity) {
        value_inst->DestructiveAddUsage(inst.UseCount());
        value_inst->DestructiveRemoveUsage();
    }
    inst.SetDefinition(value_inst->Definition<Id>());
}
} // Anonymous namespace

std::string EmitGLASM(const Profile&, IR::Program& program, Bindings&) {
    EmitContext ctx{program};
    for (IR::Block* const block : program.blocks) {
        for (IR::Inst& inst : block->Instructions()) {
            EmitInst(ctx, &inst);
        }
    }
    std::string header = "!!NVcp5.0\n"
                         "OPTION NV_internal;";
    switch (program.stage) {
    case Stage::Compute:
        header += fmt::format("GROUP_SIZE {} {} {};", program.workgroup_size[0],
                              program.workgroup_size[1], program.workgroup_size[2]);
        break;
    default:
        break;
    }
    header += "TEMP ";
    for (size_t index = 0; index < ctx.reg_alloc.NumUsedRegisters(); ++index) {
        header += fmt::format("R{},", index);
    }
    header += "RC;";
    if (!program.info.storage_buffers_descriptors.empty()) {
        header += "LONG TEMP LC;";
    }
    ctx.code.insert(0, header);
    ctx.code += "END";
    return ctx.code;
}

void EmitIdentity(EmitContext& ctx, IR::Inst& inst, const IR::Value& value) {
    Identity(inst, value);
}

void EmitBitCastU16F16(EmitContext& ctx, IR::Inst& inst, const IR::Value& value) {
    Identity(inst, value);
}

void EmitBitCastU32F32(EmitContext& ctx, IR::Inst& inst, const IR::Value& value) {
    Identity(inst, value);
}

void EmitBitCastU64F64(EmitContext& ctx, IR::Inst& inst, const IR::Value& value) {
    Identity(inst, value);
}

void EmitBitCastF16U16(EmitContext& ctx, IR::Inst& inst, const IR::Value& value) {
    Identity(inst, value);
}

void EmitBitCastF32U32(EmitContext& ctx, IR::Inst& inst, const IR::Value& value) {
    Identity(inst, value);
}

void EmitBitCastF64U64(EmitContext& ctx, IR::Inst& inst, const IR::Value& value) {
    Identity(inst, value);
}

} // namespace Shader::Backend::GLASM