// SPDX-FileCopyrightText: Copyright 2024 shadPS4 Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later

#include <span>
#include <type_traits>
#include <utility>
#include <vector>
#include "common/func_traits.h"
#include "shader_recompiler/backend/spirv/emit_spirv.h"
#include "shader_recompiler/backend/spirv/emit_spirv_instructions.h"
#include "shader_recompiler/backend/spirv/spirv_emit_context.h"
#include "shader_recompiler/ir/basic_block.h"
#include "shader_recompiler/ir/program.h"

namespace Shader::Backend::SPIRV {
namespace {

template <auto func, typename... Args>
void SetDefinition(EmitContext& ctx, IR::Inst* inst, Args... args) {
    inst->SetDefinition<Id>(func(ctx, std::forward<Args>(args)...));
}

template <typename ArgType>
ArgType Arg(EmitContext& ctx, const IR::Value& arg) {
    if constexpr (std::is_same_v<ArgType, Id>) {
        return ctx.Def(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::Attribute>) {
        return arg.Attribute();
    } else if constexpr (std::is_same_v<ArgType, IR::ScalarReg>) {
        return arg.ScalarReg();
    } else if constexpr (std::is_same_v<ArgType, IR::VectorReg>) {
        return arg.VectorReg();
    }
}

template <auto func, bool is_first_arg_inst, size_t... I>
void Invoke(EmitContext& ctx, IR::Inst* inst, std::index_sequence<I...>) {
    using Traits = Common::FuncTraits<decltype(func)>;
    if constexpr (std::is_same_v<typename Traits::ReturnType, Id>) {
        if constexpr (is_first_arg_inst) {
            SetDefinition<func>(
                ctx, inst, inst,
                Arg<typename Traits::template ArgType<I + 2>>(ctx, inst->Arg(I))...);
        } else {
            SetDefinition<func>(
                ctx, inst, Arg<typename Traits::template ArgType<I + 1>>(ctx, inst->Arg(I))...);
        }
    } else {
        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 = Common::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/ir/opcodes.inc"
#undef OPCODE
    }
    throw LogicError("Invalid opcode {}", inst->GetOpcode());
}

Id TypeId(const EmitContext& ctx, IR::Type type) {
    switch (type) {
    case IR::Type::U1:
        return ctx.U1[1];
    case IR::Type::U32:
        return ctx.U32[1];
    default:
        throw NotImplementedException("Phi node type {}", type);
    }
}

void Traverse(EmitContext& ctx, IR::Program& program) {
    IR::Block* current_block{};
    for (const IR::AbstractSyntaxNode& node : program.syntax_list) {
        switch (node.type) {
        case IR::AbstractSyntaxNode::Type::Block: {
            const Id label{node.data.block->Definition<Id>()};
            if (current_block) {
                ctx.OpBranch(label);
            }
            current_block = node.data.block;
            ctx.AddLabel(label);
            for (IR::Inst& inst : node.data.block->Instructions()) {
                EmitInst(ctx, &inst);
            }
            break;
        }
        case IR::AbstractSyntaxNode::Type::If: {
            const Id if_label{node.data.if_node.body->Definition<Id>()};
            const Id endif_label{node.data.if_node.merge->Definition<Id>()};
            ctx.OpSelectionMerge(endif_label, spv::SelectionControlMask::MaskNone);
            ctx.OpBranchConditional(ctx.Def(node.data.if_node.cond), if_label, endif_label);
            break;
        }
        case IR::AbstractSyntaxNode::Type::Loop: {
            const Id body_label{node.data.loop.body->Definition<Id>()};
            const Id continue_label{node.data.loop.continue_block->Definition<Id>()};
            const Id endloop_label{node.data.loop.merge->Definition<Id>()};

            ctx.OpLoopMerge(endloop_label, continue_label, spv::LoopControlMask::MaskNone);
            ctx.OpBranch(body_label);
            break;
        }
        case IR::AbstractSyntaxNode::Type::Break: {
            const Id break_label{node.data.break_node.merge->Definition<Id>()};
            const Id skip_label{node.data.break_node.skip->Definition<Id>()};
            ctx.OpBranchConditional(ctx.Def(node.data.break_node.cond), break_label, skip_label);
            break;
        }
        case IR::AbstractSyntaxNode::Type::EndIf:
            if (current_block) {
                ctx.OpBranch(node.data.end_if.merge->Definition<Id>());
            }
            break;
        case IR::AbstractSyntaxNode::Type::Repeat: {
            Id cond{ctx.Def(node.data.repeat.cond)};
            const Id loop_header_label{node.data.repeat.loop_header->Definition<Id>()};
            const Id merge_label{node.data.repeat.merge->Definition<Id>()};
            ctx.OpBranchConditional(cond, loop_header_label, merge_label);
            break;
        }
        case IR::AbstractSyntaxNode::Type::Return:
            ctx.OpReturn();
            break;
        case IR::AbstractSyntaxNode::Type::Unreachable:
            ctx.OpUnreachable();
            break;
        }
        if (node.type != IR::AbstractSyntaxNode::Type::Block) {
            current_block = nullptr;
        }
    }
}

Id DefineMain(EmitContext& ctx, IR::Program& program) {
    const Id void_function{ctx.TypeFunction(ctx.void_id)};
    const Id main{ctx.OpFunction(ctx.void_id, spv::FunctionControlMask::MaskNone, void_function)};
    for (IR::Block* const block : program.blocks) {
        block->SetDefinition(ctx.OpLabel());
    }
    Traverse(ctx, program);
    ctx.OpFunctionEnd();
    return main;
}

void DefineEntryPoint(const IR::Program& program, EmitContext& ctx, Id main) {
    const std::span interfaces(ctx.interfaces.data(), ctx.interfaces.size());
    spv::ExecutionModel execution_model{};
    switch (program.info.stage) {
    case Stage::Compute: {
        // const std::array<u32, 3> workgroup_size{program.workgroup_size};
        // execution_model = spv::ExecutionModel::GLCompute;
        // ctx.AddExecutionMode(main, spv::ExecutionMode::LocalSize, workgroup_size[0],
        //                      workgroup_size[1], workgroup_size[2]);
        break;
    }
    case Stage::Vertex:
        execution_model = spv::ExecutionModel::Vertex;
        break;
    case Stage::Fragment:
        execution_model = spv::ExecutionModel::Fragment;
        if (ctx.profile.lower_left_origin_mode) {
            ctx.AddExecutionMode(main, spv::ExecutionMode::OriginLowerLeft);
        } else {
            ctx.AddExecutionMode(main, spv::ExecutionMode::OriginUpperLeft);
        }
        // if (program.info.stores_frag_depth) {
        //     ctx.AddExecutionMode(main, spv::ExecutionMode::DepthReplacing);
        // }
        break;
    default:
        throw NotImplementedException("Stage {}", u32(program.info.stage));
    }
    ctx.AddEntryPoint(execution_model, main, "main", interfaces);
}

void PatchPhiNodes(IR::Program& program, EmitContext& ctx) {
    auto inst{program.blocks.front()->begin()};
    size_t block_index{0};
    ctx.PatchDeferredPhi([&](size_t phi_arg) {
        if (phi_arg == 0) {
            ++inst;
            if (inst == program.blocks[block_index]->end() ||
                inst->GetOpcode() != IR::Opcode::Phi) {
                do {
                    ++block_index;
                    inst = program.blocks[block_index]->begin();
                } while (inst->GetOpcode() != IR::Opcode::Phi);
            }
        }
        return ctx.Def(inst->Arg(phi_arg));
    });
}
} // Anonymous namespace

std::vector<u32> EmitSPIRV(const Profile& profile, IR::Program& program, Bindings& bindings) {
    EmitContext ctx{profile, program, bindings};
    const Id main{DefineMain(ctx, program)};
    DefineEntryPoint(program, ctx, main);
    if (program.info.stage == Stage::Vertex) {
        ctx.AddExtension("SPV_KHR_shader_draw_parameters");
        ctx.AddCapability(spv::Capability::DrawParameters);
    }
    PatchPhiNodes(program, ctx);
    return ctx.Assemble();
}

Id EmitPhi(EmitContext& ctx, IR::Inst* inst) {
    const size_t num_args{inst->NumArgs()};
    boost::container::small_vector<Id, 32> blocks;
    blocks.reserve(num_args);
    for (size_t index = 0; index < num_args; ++index) {
        blocks.push_back(inst->PhiBlock(index)->Definition<Id>());
    }
    // The type of a phi instruction is stored in its flags
    const Id result_type{TypeId(ctx, inst->Flags<IR::Type>())};
    return ctx.DeferredOpPhi(result_type, std::span(blocks.data(), blocks.size()));
}

void EmitVoid(EmitContext&) {}

Id EmitIdentity(EmitContext& ctx, const IR::Value& value) {
    throw NotImplementedException("Forward identity declaration");
}

Id EmitConditionRef(EmitContext& ctx, const IR::Value& value) {
    throw NotImplementedException("Forward identity declaration");
}

void EmitReference(EmitContext&) {}

void EmitPhiMove(EmitContext&) {
    throw LogicError("Unreachable instruction");
}

void EmitGetZeroFromOp(EmitContext&) {
    throw LogicError("Unreachable instruction");
}

void EmitGetSignFromOp(EmitContext&) {
    throw LogicError("Unreachable instruction");
}

void EmitGetCarryFromOp(EmitContext&) {
    throw LogicError("Unreachable instruction");
}

void EmitGetOverflowFromOp(EmitContext&) {
    throw LogicError("Unreachable instruction");
}

void EmitSetVcc(EmitContext& ctx) {
    throw LogicError("Unreachable instruction");
}

void EmitGetVcc(EmitContext& ctx) {
    throw LogicError("Unreachable instruction");
}

} // namespace Shader::Backend::SPIRV