#ifndef FOOT_EMULATOR
#define FOOT_EMULATOR

#include <array>
#include <cstdint>
#include <memory>
#include <vector>

namespace foot
{

struct Operand
{
  Operand(uint8_t bits);

  enum class AddressingMode
  {
    Immediate = 0,
    Direct,
    IndirectAutoIncrement,
    Indirect
  } addressing_mode;
  uint8_t register_index;
};

class Device
{
  friend class Emulator;
public:
  virtual ~Device() = default;

  virtual bool update() = 0;
  virtual uint16_t mapped_memory_size() const { return assigned_memory_size; }

protected:
  Device(uint16_t size);

  uint32_t& memory(uint16_t index);

private:
  uint32_t* assigned_memory_base;
  uint32_t  assigned_memory_size;
};

class Emulator
{
public:
  static constexpr uint8_t PC = 31;
  static constexpr uint8_t LC = 30;

  Emulator();

  void run(const std::vector<uint32_t>& program);
  void map_device(std::unique_ptr<Device>&& device);

  uint32_t& memory_at(uint16_t address);
  uint32_t& decode_operand(Operand operand);
  uint32_t& register_at(uint8_t index);

  void run_instruction();

private:
  std::array<uint32_t, 1 << 16> memory;
  std::array<uint32_t, 1 << 5> registers;
  enum class Status
  {
    Less,
    Equal,
    Greater
  } status_register;
  uint32_t instruction;
  uint32_t configuration;
  uint32_t dummy_value;
  std::vector<std::unique_ptr<Device>> devices;
  uint16_t mapped_base;
  bool keep_running;

  void read_instruction();

  void CNST();
  void CMPR();
  void BWNG();
  void ARNG();
  void LONG();
  void CONF();
  void BWOR();
  void BAND();
  void BXOR();
  void SRSH();
  void ZLSH();
  void CLSH();
  void ADDI();
  void SUBT();
  void MULT();
  void DIVI();
  void MODU();

  bool repeats() const;
  uint8_t simd_elements() const;
  uint8_t shift() const;

  uint32_t apply_many_unary(uint32_t a, uint32_t (Emulator::*fn)(uint32_t a) const) const;
  uint32_t apply_many_binary(uint32_t a, uint32_t b, uint32_t (Emulator::*fn)(uint32_t a, uint32_t b) const) const;

  uint32_t op_arithmetic_negate(uint32_t a) const;
  uint32_t op_logical_negate(uint32_t a) const;
  uint32_t op_signed_right_shift(uint32_t a, uint32_t b) const;
  uint32_t op_pad_zero_left_shift(uint32_t a, uint32_t b) const;
  uint32_t op_circular_left_shift(uint32_t a, uint32_t b) const;
  uint32_t op_add(uint32_t a, uint32_t b) const;
  uint32_t op_sub(uint32_t a, uint32_t b) const;
  uint32_t op_mul(uint32_t a, uint32_t b) const;
  uint32_t op_div(uint32_t a, uint32_t b) const;
  uint32_t op_mod(uint32_t a, uint32_t b) const;
};

}

#endif//FOOT_EMULATOR