/* Copyright 2022 - 2026 R. Thomas
 *
 * 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
 *
 *     http://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.
 */
#ifndef LIEF_ASM_INST_H
#define LIEF_ASM_INST_H
#include "LIEF/compiler_attributes.hpp"
#include "LIEF/errors.hpp"
#include "LIEF/iterators.hpp"
#include "LIEF/visibility.h"

#include <memory>
#include <ostream>
#include <string>

namespace llvm {
class MCInst;
}


namespace LIEF::assembly {

namespace details {
class Instruction;
class InstructionIt;
}

/// This class represents an assembly instruction
class LIEF_API Instruction {
  public:
  /// **Lazy-forward** iterator that disassembles instructions on demand.
  class Iterator final
    : public iterator_facade_base<Iterator, std::forward_iterator_tag, Instruction,
                                  std::ptrdiff_t, const Instruction*,
                                  const Instruction&> {
    public:
    using implementation = details::InstructionIt;
    using iterator_facade_base::operator++;

    LIEF_API Iterator();

    LIEF_API Iterator(std::unique_ptr<details::InstructionIt> impl);
    LIEF_API Iterator(const Iterator&);
    LIEF_API Iterator& operator=(const Iterator&);

    LIEF_API Iterator(Iterator&&) noexcept;
    LIEF_API Iterator& operator=(Iterator&&) noexcept;

    LIEF_API ~Iterator();

    // NOLINTNEXTLINE(bugprone-derived-method-shadowing-base-method)
    LIEF_API Iterator& operator++();

    friend LIEF_API bool operator==(const Iterator& LHS, const Iterator& RHS);

    friend bool operator!=(const Iterator& LHS, const Iterator& RHS) {
      return !(LHS == RHS);
    }

    LIEF_API const Instruction& operator*() const LIEF_LIFETIMEBOUND;

    // NOLINTNEXTLINE(bugprone-derived-method-shadowing-base-method)
    LIEF_API const Instruction* operator->() const LIEF_LIFETIMEBOUND;

    /// Transfer ownership of the instruction at the current position to the
    /// caller. Returns `nullptr` if the iterator is past-the-end.
    LIEF_API std::unique_ptr<Instruction> yield();

    private:
    void load() const;

    std::unique_ptr<details::InstructionIt> impl_;
    mutable std::unique_ptr<Instruction> cached_;
  };

  public:
  /// Memory operation flags
  enum class MemoryAccess : uint8_t {
    NONE = 0,
    READ = 1 << 0,
    WRITE = 1 << 1,
    READ_WRITE = READ | WRITE,
  };

  /// Address of the instruction
  uint64_t address() const;

  /// Size of the instruction in bytes
  size_t size() const;

  /// Raw bytes of the current instruction
  const std::vector<uint8_t>& raw() const LIEF_LIFETIMEBOUND;

  /// Instruction mnemonic (e.g. `br`)
  std::string mnemonic() const;

  /// Representation of the current instruction in a pretty assembly way
  std::string to_string(bool with_address = true) const;

  /// True if the instruction is a call
  bool is_call() const;

  /// True if the instruction marks the end of a basic block
  bool is_terminator() const;

  /// True if the instruction is a branch
  bool is_branch() const;

  /// True if the instruction is a syscall
  bool is_syscall() const;

  /// True if the instruction performs a memory access
  bool is_memory_access() const;

  /// True if the instruction is a register to register move.
  bool is_move_reg() const;

  /// True if the instruction performs an arithmetic addition.
  bool is_add() const;

  /// True if the instruction is a trap.
  ///
  /// - On `x86/x86-64` this includes the `ud1/ud2` instructions
  /// - On `AArch64` this includes the `brk/udf` instructions
  bool is_trap() const;

  /// True if the instruction prevents executing the instruction
  /// that immediately follows the current. This includes return
  /// or unconditional branch instructions
  bool is_barrier() const;

  /// True if the instruction is a return
  bool is_return() const;

  /// True if the instruction is an indirect branch.
  ///
  /// This includes instructions that branch through a register (e.g. `jmp rax`,
  /// `br x1`).
  bool is_indirect_branch() const;

  /// True if the instruction is **conditionally** jumping to the next
  /// instruction **or** an instruction into some other basic block.
  bool is_conditional_branch() const;

  /// True if the instruction is jumping (**unconditionally**) to some other
  /// basic block.
  bool is_unconditional_branch() const;

  /// True if the instruction is a comparison
  bool is_compare() const;

  /// True if the instruction is moving an immediate
  bool is_move_immediate() const;

  /// True if the instruction is doing a bitcast
  bool is_bitcast() const;

  /// Memory access flags
  MemoryAccess memory_access() const;

  /// Given a is_branch() instruction, try to evaluate the address of the
  /// destination.
  result<uint64_t> branch_target() const;

  /// Return the underlying llvm::MCInst implementation.
  ///
  /// @warning Because of ABI compatibility, this MCInst can **only be used**
  ///          with the **same** version of LLVM used by LIEF (see documentation)
  const llvm::MCInst& mcinst() const LIEF_LIFETIMEBOUND;

  /// This function can be used to **down cast** an Instruction instance:
  ///
  /// ```cpp
  /// std::unique_ptr<assembly::Instruction> inst = get_inst();
  /// if (const auto* arm = inst->as<assembly::arm::Instruction>()) {
  ///   const arm::OPCODE op = arm->opcode();
  /// }
  /// ```
  template<class T>
  const T* as() const LIEF_LIFETIMEBOUND {
    static_assert(std::is_base_of_v<Instruction, T>,
                  "Require Instruction inheritance");
    if (T::classof(this)) {
      return static_cast<const T*>(this);
    }
    return nullptr;
  }

  friend LIEF_API std::ostream& operator<<(std::ostream& os,
                                           const Instruction& inst) {
    os << inst.to_string();
    return os;
  }

  virtual ~Instruction();

  /// @private
  static LIEF_LOCAL std::unique_ptr<Instruction>
      create(std::unique_ptr<details::Instruction> impl);

  /// @private
  LIEF_LOCAL const details::Instruction& impl() const LIEF_LIFETIMEBOUND {
    assert(impl_ != nullptr);
    return *impl_;
  }

  /// @private
  LIEF_LOCAL details::Instruction& impl() LIEF_LIFETIMEBOUND {
    assert(impl_ != nullptr);
    return *impl_;
  }

  protected:
  LIEF_LOCAL Instruction(std::unique_ptr<details::Instruction> impl);
  std::unique_ptr<details::Instruction> impl_;
};
}

#endif
