#include "ExecutorCases.h"

#include "Instruction.h"
#include "Bus.h"

#include <bitset>
#include <iostream>

CPUContext::CPUContext(Instruction& i, uint32_t& ip, uint32_t& flags, uint32_t* reg, std::shared_ptr<Bus>& bus, bool& isHalted) : m_Instruction(i), m_InstructionPointer(ip), m_Flags(flags), m_Registers(reg), m_Bus(bus), m_IsHalted(isHalted) { }

CPUContext::~CPUContext() = default;

// NO SIB SUPPORT YET
namespace executor_cases {
  void Nop(CPUContext& cc){
    std::cout << "No op" << std::endl;
  }

  void Hlt(CPUContext& cc){
    std::cout << "Program halted!" << std::endl;
    exit(0);
  }

  void Mov_r32_imm32(CPUContext& cc){
    cc.m_Registers[cc.m_Instruction.m_Operand1] = cc.m_Instruction.m_Operand2;
  }
  
  void Add_rm32_r32(CPUContext& cc){
    x86::ModRM modrm = cc.m_Instruction.optional.m_ModRM;

    switch(modrm.m_State) {
    case x86::ModRMState::R:
    {
      cc.m_Registers[modrm.m_Rm] += cc.m_Registers[modrm.m_Reg];
      break;
    }
    case x86::ModRMState::LR:
    {
      uint32_t dstPrevValue = cc.m_Bus->AccessX<uint32_t>(cc.m_Registers[modrm.m_Rm]);
      uint32_t currRegValue = cc.m_Registers[modrm.m_Reg];
      uint32_t result = dstPrevValue + currRegValue;
      cc.m_Bus->WriteX<uint32_t>(cc.m_Registers[modrm.m_Rm], result);
      break;
    }
    case x86::ModRMState::LR_DISP8:
    {
      uint32_t dstAddress = cc.m_Registers[modrm.m_Rm] + cc.m_Instruction.m_Operand2;
      uint32_t dstPrevValue = cc.m_Bus->AccessX<uint32_t>(dstAddress);
      uint32_t currRegValue = cc.m_Registers[modrm.m_Reg];
      uint32_t result = dstPrevValue + currRegValue;
      cc.m_Bus->WriteX<uint32_t>(dstAddress, result);
      break;
    }
    default:
    {
      throw std::runtime_error("Invalid ModRM State encountered during Add_rm32_r32");
    }
    }
  }
}
 
constexpr std::array<ExecutorCase, 255> GenerateExecutorTable(){
  std::array<ExecutorCase, 255> table{};
  table[Opcode::NOP] = executor_cases::Nop;
  table[Opcode::HLT] = executor_cases::Hlt;
  table[Opcode::MOV_R_IMM32] = executor_cases::Mov_r32_imm32;
  table[Opcode::ADD_RM32_R32] = executor_cases::Add_rm32_r32;
  return table;
}

static constexpr std::array<ExecutorCase, 255> s_ExecutorTable = GenerateExecutorTable();

const std::array<ExecutorCase, 255>& GetExecutorTable() {
  return s_ExecutorTable;
}