package wacc

import cats.data.Chain
import wacc.assemblyIR._

sealed trait RuntimeError {
  val name: String
  protected val errStr: String

  protected def getErrLabel(using labelGenerator: LabelGenerator): LabelArg =
    labelGenerator.getLabelArg(errStr, name = name)

  protected def generateHandler(using labelGenerator: LabelGenerator): Chain[AsmLine]

  def generate(using labelGenerator: LabelGenerator): Chain[AsmLine] =
    labelGenerator.getLabelDef(this) +: generateHandler
}

object RuntimeError {

  // TODO: Refactor to mitigate imports and redeclared vals perhaps

  import wacc.asmGenerator.stackAlign
  import assemblyIR.Size._
  import assemblyIR.RegName._

  // private val RAX = Register(Q64, AX)
  // private val EAX = Register(D32, AX)
  private val RDI = Register(Q64, DI)
  private val RIP = Register(Q64, IP)
  // private val RBP = Register(Q64, BP)
  private val RSI = Register(Q64, SI)
  // private val RDX = Register(Q64, DX)
  // private val RCX = Register(Q64, CX)

  case object ZeroDivError extends RuntimeError {
    val name = "errDivZero"
    protected val errStr = "fatal error: division or modulo by zero"

    protected def generateHandler(using labelGenerator: LabelGenerator): Chain[AsmLine] = Chain(
      stackAlign,
      Load(RDI, IndexAddress(RIP, getErrLabel)),
      assemblyIR.Call(CLibFunc.PrintF),
      Move(RDI, ImmediateVal(-1)),
      assemblyIR.Call(CLibFunc.Exit)
    )

  }

  case object BadChrError extends RuntimeError {
    val name = "errBadChr"
    protected val errStr = "fatal error: int %d is not an ASCII character 0-127"

    protected def generateHandler(using labelGenerator: LabelGenerator): Chain[AsmLine] = Chain(
      Pop(RSI),
      stackAlign,
      Load(RDI, IndexAddress(RIP, getErrLabel)),
      assemblyIR.Call(CLibFunc.PrintF),
      Move(RDI, ImmediateVal(255)),
      assemblyIR.Call(CLibFunc.Exit)
    )

  }

  case object NullPtrError extends RuntimeError {
    val name = "errNullPtr"
    protected val errStr = "fatal error: null pair dereferenced or freed"

    protected def generateHandler(using labelGenerator: LabelGenerator): Chain[AsmLine] = Chain(
      stackAlign,
      Load(RDI, IndexAddress(RIP, getErrLabel)),
      assemblyIR.Call(CLibFunc.PrintF),
      Move(RDI, ImmediateVal(255)),
      assemblyIR.Call(CLibFunc.Exit)
    )

  }

  case object OverflowError extends RuntimeError {
    val name = "errOverflow"
    protected val errStr = "fatal error: integer overflow or underflow occurred"

    protected def generateHandler(using labelGenerator: LabelGenerator): Chain[AsmLine] = Chain(
      stackAlign,
      Load(RDI, IndexAddress(RIP, getErrLabel)),
      assemblyIR.Call(CLibFunc.PrintF),
      Move(RDI, ImmediateVal(255)),
      assemblyIR.Call(CLibFunc.Exit)
    )

  }

  case object OutOfBoundsError extends RuntimeError {
    val name = "errOutOfBounds"
    protected val errStr = "fatal error: array index %d out of bounds"

    protected def generateHandler(using labelGenerator: LabelGenerator): Chain[AsmLine] = Chain(
      Move(RSI, Register(Q64, CX)),
      stackAlign,
      Load(RDI, IndexAddress(RIP, getErrLabel)),
      assemblyIR.Call(CLibFunc.PrintF),
      Move(RDI, ImmediateVal(255)),
      assemblyIR.Call(CLibFunc.Exit)
    )
  }

  val all: Chain[RuntimeError] =
    Chain(ZeroDivError, BadChrError, NullPtrError, OverflowError, OutOfBoundsError)
}