package mtmc.asm.instructions

import mtmc.asm.Assembler
import mtmc.emulator.Register
import mtmc.emulator.Register.Companion.fromInteger
import mtmc.emulator.Register.Companion.toInteger
import mtmc.tokenizer.MTMCToken
import mtmc.util.BinaryUtils

class LoadStoreRegisterInstruction(
  type: InstructionType,
  label: List<MTMCToken>,
  instructionToken: MTMCToken
) : Instruction(type, label, instructionToken) {
  private var targetToken: MTMCToken? = null
  private var pointerToken: MTMCToken? = null
  private var offsetToken: MTMCToken? = null

  fun setTargetToken(targetToken: MTMCToken) {
    this.targetToken = targetToken
  }

  fun setPointerToken(pointerToken: MTMCToken) {
    this.pointerToken = pointerToken
  }

  fun setOffsetToken(offsetToken: MTMCToken?) {
    this.offsetToken = offsetToken
  }

  override fun genCode(output: ByteArray, assembler: Assembler) {
    var opcode = 0
    when (type) {
      InstructionType.LWR -> opcode = 4
      InstructionType.LBR -> opcode = 5
      InstructionType.SWR -> opcode = 6
      InstructionType.SBR -> opcode = 7
      else -> println("Invalid instruction type")
    }
    val target = toInteger(targetToken!!.stringValue)
    val pointer = toInteger(pointerToken!!.stringValue)
    var offset = Register.PC.ordinal
    if (offsetToken != null) {
      offset = toInteger(offsetToken!!.stringValue)
    }
    output[location] = (opcode shl 4 or target).toByte()
    output[location + 1] = (pointer shl 4 or offset).toByte()
  }

  companion object {
    fun disassemble(instruction: Short): String? {
      if (BinaryUtils.getBits(16, 2, instruction).toInt() == 1) {
        val builder = StringBuilder()
        val type = BinaryUtils.getBits(14, 2, instruction)
        if (type.toInt() == 0) {
          builder.append("lwr ")
        } else if (type.toInt() == 1) {
          builder.append("lbr ")
        } else if (type.toInt() == 2) {
          builder.append("swr ")
        } else if (type.toInt() == 3) {
          builder.append("sbr ")
        }
        val srcDestReg = BinaryUtils.getBits(12, 4, instruction)
        val addrReg = BinaryUtils.getBits(8, 4, instruction)
        val offsetReg = BinaryUtils.getBits(4, 4, instruction)
        builder.append(fromInteger(srcDestReg.toInt())).append(" ")
        builder.append(fromInteger(addrReg.toInt())).append(" ")
        builder.append(fromInteger(offsetReg.toInt()))
        return builder.toString()
      }
      return null
    }
  }
}