// Copyright 2023 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "mpact/sim/decoder/instruction_set.h"

#include <memory>
#include <string>
#include <utility>
#include <variant>
#include <vector>

#include "absl/container/btree_set.h"
#include "absl/container/flat_hash_map.h"
#include "absl/log/log.h"
#include "absl/strings/string_view.h"
#include "mpact/sim/decoder/bundle.h"
#include "mpact/sim/decoder/format_name.h"
#include "mpact/sim/decoder/instruction.h"
#include "mpact/sim/decoder/opcode.h"
#include "mpact/sim/decoder/slot.h"

namespace mpact {
namespace sim {
namespace machine_description {
namespace instruction_set {

absl::btree_set<std::string> *InstructionSet::attribute_names_ = nullptr;

InstructionSet::InstructionSet(absl::string_view name)
    : opcode_factory_(std::make_unique<OpcodeFactory>()),
      resource_factory_(std::make_unique<ResourceFactory>()),
      name_(name),
      pascal_name_(ToPascalCase(name)) {}

InstructionSet::~InstructionSet() {
  delete bundle_;
  for (auto &[unused, bundle_ptr] : bundle_map_) {
    delete bundle_ptr;
  }
  for (auto &[unused, slot_ptr] : slot_map_) {
    delete slot_ptr;
  }
  bundle_map_.clear();
  slot_map_.clear();
}

void InstructionSet::AddBundle(Bundle *bundle) {
  bundle_map_.insert({bundle->name(), bundle});
}

void InstructionSet::AddSlot(Slot *slot) {
  slot_map_.insert({slot->name(), slot});
}

// Lookup bundle and slot by name.
Bundle *InstructionSet::GetBundle(absl::string_view bundle_name) const {
  auto iter = bundle_map_.find(bundle_name);
  if (iter == bundle_map_.end()) return nullptr;
  return iter->second;
}

Slot *InstructionSet::GetSlot(absl::string_view slot_name) const {
  auto iter = slot_map_.find(slot_name);
  if (iter == slot_map_.end()) return nullptr;
  return iter->second;
}

absl::Status InstructionSet::AnalyzeResourceUse() {
  for (auto const *slot : slot_order_) {
    for (auto &[unused, inst_ptr] : slot->instruction_map()) {
      for (auto const *def : inst_ptr->resource_acquire_vec()) {
        if (def->begin_expression != nullptr) {
          auto result = def->begin_expression->GetValue();
          if (!result.ok()) return result.status();
          if (std::get<int>(result.value()) != 0) {
            def->resource->set_is_simple(false);
          }
        }
        if (def->end_expression != nullptr) {
          auto result = def->end_expression->GetValue();
          if (!result.ok()) return result.status();
        }
      }
    }
  }
  return absl::OkStatus();
}

void InstructionSet::ComputeSlotAndBundleOrders() {
  // Compute order of slot definitions
  for (auto const &[unused, slot_ptr] : slot_map_) {
    if (slot_ptr->is_marked()) continue;
    AddToSlotOrder(slot_ptr);
  }

  // Compute order of bundle definitions
  for (auto const &[unused, bundle_ptr] : bundle_map_) {
    if (bundle_ptr->is_marked()) continue;
    AddToBundleOrder(bundle_ptr);
  }
}

void InstructionSet::AddToBundleOrder(Bundle *bundle) {
  if (bundle->is_marked()) return;
  for (auto const &bundle_name : bundle->bundle_names()) {
    Bundle *sub_bundle = bundle_map_[bundle_name];
    AddToBundleOrder(sub_bundle);
  }
  bundle_order_.push_back(bundle);
  bundle->set_is_marked(true);
}

void InstructionSet::AddToSlotOrder(Slot *slot) {
  if (slot->is_marked()) return;
  for (auto const &base_slot : slot->base_slots()) {
    AddToSlotOrder(slot_map_[base_slot.base->name()]);
  }
  slot->set_is_marked(true);
  slot_order_.push_back(slot);
}

void InstructionSet::AddAttributeName(const std::string &name) {
  if (attribute_names_ == nullptr) {
    attribute_names_ = new absl::btree_set<std::string>();
  }
  auto iter = attribute_names_->find(name);
  if (iter == attribute_names_->end()) {
    attribute_names_->insert(name);
  }
}

// Return a string containing class header file, for all bundles and slots.
// As an example the following shows an abbreviated example of code that is
// generated.
//
// class MyEncodingType {
//  public:
//   virtual ~MyEncodingType() = default;
//
//   virtual OpcodeEnum GetOpcode(SlotEnum slot, int entry) = 0;
//   virtual ResourceOperandInterface *GetSimpleResource(
//               SlotEnum slot,
//               int entry,
//               OpcodeEnum opcode,
//               SimpleResourceEnum resource) = 0;
//   virtual ResourceOperandInterface *GetComplexResource(
//               SlotEnum slot,
//               int entry,
//               OpcodeEnum opcode,
//               ComplexResourceEnum) = 0;
//   virtual PredicateOperandInterface *GetPredicate(SlotEnum slot,
//                                                   int entry,
//                                                   OpcodeEnum opcode,
//                                                   PredOpEnum pred) = 0;
//   virtual SourceOperandInterface *GetSource(SlotEnum slot,
//                                             int entry,
//                                             OpcodeEnum opcode,
//                                             SourceOpEnum source,
//                                             int source_no) = 0;
//   virtual DestinationOperandInterface *GetDestination(int latency,
//                                                       SlotEnum slot,
//                                                       int entry,
//                                                       OpcodeEnum opcode,
//                                                       DestOpEnum dest,
//                                                       int dest_no) = 0;
//   virtual int GetLatency(SlotEnum slot, int entry, OpcodeEnum opcode,
//                          DestOpEnum dest) = 0;
//   virtual ResourceOperandInterface *GetSimpleResourceOperand(
//               SlotEnum slot,
//               int entry,
//               OpcodeEnum opcode,
//               SimpleResourceVector resource_vec,
//               int end) = 0;
//   virtual ResourceOperandInterface *GetComplexResourceOperand(
//               SlotEnum slot,
//               int entry,
//               OpcodeEnum opcode,
//               ComplexResourceEnum resource,
//               int begin,
//               int end) = 0;
// };
//
//  // Alu0 Slot class.
//  class ScalarAlu0Slot {
//   public:
//    explicit ScalarAlu0Slot(ArchState *arch_state);
//    virtual ~ScalarAlu0Slot() = default;
//    virtual SemFunc GetNopSemFunc() = 0;
//    virtual SemFunc GetSvctS32F32SemFunc() = 0;
//    virtual SemFunc GetScvtF32S32SemFunc() = 0;
//    ...
//    Instruction *Decode(uint64_t address, MyEncodingType* isa_encoding,
//                        MyEncodingType::SlotEnum, int entry);
//
//   private:
//    ArchState *arch_state_;
//    SemFuncGetters semantic_function_getter_;
//    OperandSetters set_operands_;
//    static constexpr MyEncodingType::SlotEnum slot_ =
//        MyEncodingType::SlotEnum::kScalarAlu0;
//  };
//
//  class ScalarBundleDecoder {
//   public:
//    explicit ScalarBundleDecoder(ArchState *arch_state);
//    virtual ~ScalarBundleDecoder() = default;
//    virtual Instruction *Decode(uint64_t address, MyEncodingType *encoding);
//    virtual SemFunc GetSemanticFunction() = 0;
//
//    ScalarAlu0Slot *scalar_alu_0_decoder() {
//      return scalar_alu_0_decoder_.get();
//    }
//    ScalarAlu1Slot *scalar_alu_1_decoder() {
//      return scalar_alu_1_decoder_.get();
//    }
//
//   private:
//    std::unique_ptr<ScalarAlu0Slot> scalar_alu_0_decoder_;
//    std::unique_ptr<ScalarAlu1Slot> scalar_alu_1_decoder_;
//    ArchState *arch_state_;
//  };
//
//  class InstructionSetFactory{
//   public:
//    InstructionSetFactory() = default;
//    virtual ~InstructionSetFactory() = default;
//    virtual std::unique_ptr<ScalarBundleDecoder> CreateScalarBundleDecoder(
//                                                     ArchState *) = 0;
//    virtual std::unique_ptr<ScalarAlu0Slot> CreateScalarAlu0Slot(
//                                                     ArchState *) = 0;
//    virtual std::unique_ptr<ScalarAlu1Slot> CreateScalarAlu1Slot(
//                                                     ArchState *) = 0;
//  };
//
//  class InstructionSet {
//   public:
//    InstructionSet(ArchState *arch_state, InstructionSetFactory *factory);
//    Instruction *Decode(uint64_t address, MyEncodingType *encoding);
//
//   private:
//    std::unique_ptr<ScalarBundleDecoder> scalar_bundle_decoder_;
//    ArchState *arch_state_;
//  };

std::string InstructionSet::GenerateClassDeclarations(
    absl::string_view file_name, absl::string_view opcode_file_name,
    absl::string_view encoding_type) const {
  std::string output;

  std::string factory_class_name = pascal_name() + "InstructionSetFactory";

  absl::StrAppend(&output, "class ", factory_class_name, ";\n");
  for (auto const *slot : slot_order_) {
    absl::StrAppend(&output, slot->GenerateClassDeclaration(encoding_type));
  }

  for (auto const *bundle : bundle_order_) {
    absl::StrAppend(&output, bundle->GenerateClassDeclaration(encoding_type));
  }
  // Generate factory class.
  absl::StrAppend(&output, "class ", factory_class_name,
                  "{\n"
                  " public:\n"
                  "  ",
                  factory_class_name,
                  "() = default;\n"
                  "  virtual ~",
                  factory_class_name, "() = default;\n");
  for (auto const bundle : bundle_order_) {
    if (bundle->is_marked()) {
      std::string bundle_class = bundle->pascal_name() + "Decoder";
      absl::StrAppend(&output, "  virtual std::unique_ptr<", bundle_class,
                      "> Create", bundle_class, "(ArchState *) = 0;\n");
    }
  }
  for (auto const slot : slot_order_) {
    if (slot->is_referenced()) {
      std::string slot_class = slot->pascal_name() + "Slot";
      absl::StrAppend(&output, "  virtual std::unique_ptr<", slot_class,
                      "> Create", slot_class, "(ArchState *) = 0;\n");
    }
  }
  absl::StrAppend(&output,
                  "};\n"
                  "\n");
  // Generate InstructionSet class.
  absl::StrAppend(&output, "class ", pascal_name(),
                  "InstructionSet {\n"
                  " public:\n"
                  "  ",
                  pascal_name(), "InstructionSet(ArchState *arch_state,\n",
                  Indent(absl::StrCat("  ", pascal_name(), "InstructionSet(")),
                  factory_class_name,
                  " *factory);\n"
                  "  Instruction *Decode(uint64_t address, ",
                  encoding_type,
                  " *encoding);\n"
                  "\n"
                  " private:\n");
  for (auto const &bundle_name : bundle_->bundle_names()) {
    absl::StrAppend(&output, "  std::unique_ptr<", ToPascalCase(bundle_name),
                    "Decoder> ", bundle_name, "_decoder_;\n");
  }
  for (auto const &[slot_name, unused] : bundle_->slot_uses()) {
    absl::StrAppend(&output, "  std::unique_ptr<", ToPascalCase(slot_name),
                    "Slot> ", slot_name, "_decoder_;\n");
  }
  absl::StrAppend(&output,
                  "  ArchState *arch_state_;\n"
                  "};\n"
                  "\n");
  return output;
}

// Return string containing .cc file for all bundles and slots.
std::string InstructionSet::GenerateClassDefinitions(
    absl::string_view include_file, absl::string_view encoding_type) const {
  std::string output;

  std::string class_name = pascal_name() + "InstructionSet";
  std::string factory_class_name = class_name + "Factory";
  for (auto const *slot : slot_order_) {
    absl::StrAppend(&output, slot->GenerateClassDefinition(encoding_type));
  }
  // Constructor.
  absl::StrAppend(&output, class_name, "::", class_name,
                  "(ArchState *arch_state, ", factory_class_name,
                  "*factory) : \n"
                  "  arch_state_(arch_state) {\n");
  for (auto const &bundle_name : bundle_->bundle_names()) {
    absl::StrAppend(&output, "  ", bundle_name, "_decoder_ = factory->Create",
                    ToPascalCase(bundle_name), "Decoder(arch_state_);\n");
  }
  for (auto const &[slot_name, unused] : bundle_->slot_uses()) {
    absl::StrAppend(&output, "  ", slot_name, "_decoder_ = factory->Create",
                    ToPascalCase(slot_name), "Slot(arch_state_);\n");
  }
  absl::StrAppend(&output, "}\n");
  // Generate the top level decode function body.
  absl::StrAppend(&output, "Instruction *", class_name,
                  "::Decode(uint64_t address, ", encoding_type,
                  " *encoding) {\n"
                  "  Instruction *inst = nullptr;"
                  "  Instruction *tmp_inst;\n"
                  "  bool success = false;\n"
                  "  int size = 0;\n");
  if (!bundle_->bundle_names().empty()) {
    // If there are bundles, then a "parent instruction" is created. Bundles
    // are added as children of this parent instruction. The parent instruction
    // is responsible for controlling issue of the bundles.
    absl::StrAppend(&output,
                    "  inst = new Instruction(address, arch_state_);\n");
    // Generate calls to each of the top level bundle Decode methods.
    for (auto const &bundle_name : bundle_->bundle_names()) {
      absl::StrAppend(&output, "  tmp_inst = ", bundle_name,
                      "_decoder_->Decode(address, encoding);\n"
                      "  inst->AppendChild(tmp_inst);\n"
                      "  size += tmp_inst->size();\n"
                      "  tmp_inst->DecRef();\n"
                      "  success |= (nullptr != tmp_inst);\n");
    }
  }
  // Generate calls to each of the top level slot Decode methods.
  for (auto const &[slot_name, instance_vec] : bundle_->slot_uses()) {
    std::string enum_name =
        absl::StrCat("SlotEnum::", "k", ToPascalCase(slot_name));
    if (instance_vec.empty()) {
      absl::StrAppend(&output, "  tmp_inst = ", slot_name,
                      "_decoder_->Decode(address, encoding, ", enum_name,
                      ", 0);\n"
                      "  if (tmp_inst != nullptr) size += tmp_inst->size();\n"
                      "  if (inst == nullptr) {\n"
                      "    inst = tmp_inst;\n"
                      "  } else {\n"
                      "    inst->Append(tmp_inst);\n"
                      "    tmp_inst->DecRef();\n"
                      "  }\n"
                      "  success |= (nullptr != tmp_inst);\n");
    } else {
      for (auto const index : instance_vec) {
        absl::StrAppend(&output, "  tmp_inst = ", slot_name,
                        "_decoder_->Decode(address, encoding, , ", enum_name,
                        ", ", index,
                        ");\n"
                        "  if (tmp_inst != nullptr) size += tmp_inst->size();\n"
                        "  if (inst == nullptr) {\n"
                        "    inst = tmp_inst;\n"
                        "  } else {\n"
                        "    inst->Append(tmp_inst);\n"
                        "    tmp_inst->DecRef();\n"
                        "  }\n"
                        "  success |= (nullptr != tmp_inst);\n");
      }
    }
  }
  // If the decode failed, DecRef the instruction and return nullptr.
  absl::StrAppend(&output,
                  "  inst->set_size(size);\n"
                  "  if (!success) {\n"
                  "    inst->DecRef();\n"
                  "    inst = nullptr;\n"
                  "  }\n"
                  "  return inst;\n"
                  "}\n");
  return output;
}

InstructionSet::StringPair InstructionSet::GenerateEnums(
    absl::string_view file_name) const {
  std::string h_output;
  std::string cc_output;

  // Emit slot enumeration type.
  absl::StrAppend(&h_output,
                  "  enum class SlotEnum {\n"
                  "    kNone = 0,\n");
  absl::btree_set<std::string> name_set;
  for (auto const *slot : slot_order_) {
    if (slot->is_referenced()) name_set.insert(slot->pascal_name());
  }
  for (auto const &name : name_set) {
    absl::StrAppend(&h_output, "    k", name, ",\n");
  }
  absl::StrAppend(&h_output, "  };\n\n");

  // Btree sets to sort by name.
  absl::btree_set<std::string> predicate_operands;
  absl::btree_set<std::string> source_operands;
  absl::btree_set<std::string> dest_operands;
  absl::btree_set<std::string> dest_latency;
  // Insert PascalCase operand names into the sets to select unique names.
  for (auto const *slot : slot_order_) {
    if (!slot->is_referenced()) continue;
    for (auto const &[unused, inst_ptr] : slot->instruction_map()) {
      auto *inst = inst_ptr;
      while (inst != nullptr) {
        auto *opcode = inst->opcode();
        if (!opcode->predicate_op_name().empty()) {
          predicate_operands.insert(ToPascalCase(opcode->predicate_op_name()));
        }
        for (auto const &source_op_name : opcode->source_op_name_vec()) {
          source_operands.insert(ToPascalCase(source_op_name));
        }
        for (auto const *dest_op : opcode->dest_op_vec()) {
          dest_operands.insert(dest_op->pascal_case_name());
          if (dest_op->expression() == nullptr) {
            dest_latency.insert(dest_op->pascal_case_name());
          }
        }
        inst = inst->child();
      }
    }
  }
  // Create enum for predicate operands.
  absl::StrAppend(&h_output, "  enum class PredOpEnum {\n");
  int pred_count = 0;
  absl::StrAppend(&h_output, "    kNone = ", pred_count++, ",\n");
  for (auto const &pred_name : predicate_operands) {
    absl::StrAppend(&h_output, "    k", pred_name, " = ", pred_count++, ",\n");
  }
  absl::StrAppend(&h_output, "    kPastMaxValue = ", pred_count,
                  ",\n"
                  "  };\n\n");
  // Create enum for source operands.
  absl::StrAppend(&h_output, "  enum class SourceOpEnum {\n");
  int src_count = 0;
  absl::StrAppend(&h_output, "    kNone = ", src_count++, ",\n");
  for (auto const &source_name : source_operands) {
    absl::StrAppend(&h_output, "    k", source_name, " = ", src_count++, ",\n");
  }
  absl::StrAppend(&h_output, "    kPastMaxValue = ", src_count,
                  ",\n"
                  "  };\n\n");
  // Create enum for destination operands.
  absl::StrAppend(&h_output, "  enum class DestOpEnum {\n");
  int dst_count = 0;
  absl::StrAppend(&h_output, "    kNone = ", dst_count++, ",\n");
  for (auto const &dest_name : dest_operands) {
    absl::StrAppend(&h_output, "    k", dest_name, " = ", dst_count++, ",\n");
  }
  absl::StrAppend(&h_output, "    kPastMaxValue = ", dst_count,
                  ",\n"
                  "  };\n\n");

  // Emit opcode enumeration type.
  absl::StrAppend(&h_output,
                  "  enum class OpcodeEnum {\n"
                  "    kNone = 0,\n");
  name_set.clear();
  for (auto const *opcode : opcode_factory_->opcode_vec()) {
    name_set.insert(opcode->pascal_name());
  }
  int opcode_value = 1;
  for (auto const &name : name_set) {
    absl::StrAppend(&h_output, "    k", name, " = ", opcode_value++, ",\n");
  }
  absl::StrAppend(&h_output, "    kPastMaxValue = ", opcode_value, "\n");
  absl::StrAppend(&h_output, "  };\n\n");

  // Emit array of opcode names.
  absl::StrAppend(&cc_output,
                  "const char *kOpcodeNames[static_cast<int>("
                  "OpcodeEnum::kPastMaxValue)] = {\n"
                  "  kNoneName,\n");
  absl::StrAppend(&h_output, "  constexpr char kNoneName[] = \"none\";\n");
  for (auto const &name : name_set) {
    absl::StrAppend(&h_output, "  constexpr char k", name, "Name[] = \"", name,
                    "\";\n");
    absl::StrAppend(&cc_output, "  k", name, "Name,\n");
  }
  absl::StrAppend(&cc_output, "};\n\n");
  absl::StrAppend(&h_output,
                  "  extern const char *kOpcodeNames[static_cast<int>(\n"
                  "      OpcodeEnum::kPastMaxValue)];\n\n");
  // Emit resource enumeration types.
  absl::StrAppend(&h_output,
                  "  enum class SimpleResourceEnum {\n"
                  "    kNone = 0,\n");
  int resource_count = 1;
  name_set.clear();
  for (auto const &[unused, resource_ptr] : resource_factory_->resource_map()) {
    if (resource_ptr->is_simple()) {
      name_set.insert(resource_ptr->pascal_name());
    }
  }
  for (auto const &name : name_set) {
    absl::StrAppend(&h_output, "    k", name, " = ", resource_count++, ",\n");
  }
  absl::StrAppend(&h_output, "    kPastMaxValue = ", resource_count,
                  "\n  };\n\n");

  absl::StrAppend(&h_output,
                  "  enum class ComplexResourceEnum {\n"
                  "    kNone = 0,\n");
  resource_count = 1;
  name_set.clear();
  for (auto const &[unused, resource_ptr] : resource_factory_->resource_map()) {
    if (!resource_ptr->is_simple()) {
      name_set.insert(resource_ptr->pascal_name());
    }
  }
  for (auto const &name : name_set) {
    absl::StrAppend(&h_output, "    k", name, " = ", resource_count++, ",\n");
  }
  absl::StrAppend(&h_output, "    kPastMaxValue = ", resource_count,
                  "\n  };\n\n");

  // Emit instruction attribute types.
  absl::StrAppend(&h_output, "  enum class AttributeEnum {\n");
  int attribute_count = 0;
  if (InstructionSet::attribute_names_ != nullptr) {
    for (auto const &name : *InstructionSet::attribute_names_) {
      absl::StrAppend(&h_output, "    k", ToPascalCase(name), " = ",
                      attribute_count++, ",\n");
    }
  }
  absl::StrAppend(&h_output, "    kPastMaxValue = ", attribute_count,
                  "\n  };\n\n");

  return {h_output, cc_output};
}

}  // namespace instruction_set
}  // namespace machine_description
}  // namespace sim
}  // namespace mpact