package com.htmlism.mos6502.dsl

import scala.collection.immutable.ListSet
import scala.collection.mutable.ListBuffer

import cats.syntax.all.*

import com.htmlism.mos6502.model.*

object DslDemo extends App:
  val cpu =
    new CPU

  import registers.{A, X}

  // address demonstration
  withAssemblyContext { implicit ctx =>
    val payloadLocation =
      0x01.z

    cpu.A = 0x40

    A.add(payloadLocation)
  }

  // a becomes others
  withAssemblyContext { implicit ctx =>
    cpu.A = cpu.X
    cpu.A = cpu.Y
  }

  // demonstrate first example
  withAssemblyContext { implicit ctx =>
    cpu.A = 0xc0

    cpu.X = cpu.A

    X.incr

    A.add(0xc4)
  }

  def withAssemblyContext(f: AssemblyContext => Unit): Unit =
    val ctx: AssemblyContext =
      new AssemblyContext

    f(ctx)

    ctx.printOut()
    println()
    println()

object registers:
  sealed trait Register

  sealed trait DestinationA

  sealed trait IndexRegister

  case object A extends Register:
    def add[A](x: A)(using ctx: AssemblyContext, ev: Operand[A]): Unit =
      ev.operandType match
        case ValueLiteral =>
          ctx.push(ADC, x, s"add LITERAL to a")

        case MemoryLocation =>
          ctx.push(ADC, x, s"add ADDR to a")

  case object X extends Register with DestinationA with IndexRegister:
    def incr(using ctx: AssemblyContext): Unit =
      ctx.push(INX, "incr x")

    def loop(s: String, spec: RangeSpec)(f: AssemblyContext => Unit)(using ctx: AssemblyContext): Unit =
      val (start, stop, instruction) =
        spec match
          case Incrementing(from, to) =>
            (from, to, INX)

          case Decrementing(from, to) =>
            (from, to, DEX)

      ctx.push(LDX, start)

      label(s)

      f(ctx)

      ctx.push(instruction)
      ctx.push(CPX, stop)
      ctx.branch(BNE, s)

  case object Y extends Register with DestinationA with IndexRegister

class CPU:
  def A: registers.A.type =
    registers.A

  def A_=[A](x: A)(using ctx: AssemblyContext, ev: Operand[A]): Unit =
    ctx.push(LDA, x, "set A to " + ev.toShow(x))

  def A_=(reg: registers.DestinationA)(using ctx: AssemblyContext): Unit =
    reg match
      case registers.X =>
        ctx.push(TXA)
      case registers.Y =>
        ctx.push(TYA)

  def X: registers.X.type =
    registers.X

  def X_=(reg: registers.A.type)(using ctx: AssemblyContext): Unit =
    ctx.push(TAX, s"set x to register $reg")

  def Y: registers.Y.type =
    registers.Y

  def Y_=(reg: registers.A.type)(using ctx: AssemblyContext): Unit =
    ctx.push(TAY, s"set x to register $reg")

class AssemblyContext:
  private val xs: ListBuffer[Statement] =
    ListBuffer()

  private var jumps: ListSet[Subroutine] =
    ListSet()

  def push(instruction: Instruction): Unit =
    xs.append(UnaryInstruction(instruction, None))

  def push(instruction: Instruction, s: String): Unit =
    xs.append(UnaryInstruction(instruction, s.some))

  def label(s: String): Unit =
    xs.append(Label(s))

  def push[A: Operand](instruction: Instruction, x: A): Unit =
    xs.append(InstructionWithOperand(instruction, x, None))

  def push[A: Operand](instruction: Instruction, x: A, s: String): Unit =
    xs.append(InstructionWithOperand(instruction, x: A, s.some))

  def branch(instruction: Instruction, label: String): Unit =
    xs.append(BranchingInstruction(instruction, label))

  def addJump(subroutine: Subroutine): Unit =
    jumps = jumps + subroutine

  def printOut(): Unit =
    xs.map(_.toAsm)
      .foreach(println)

  def triplets: List[(String, Option[String], Option[String])] =
    xs.map(_.toTriplet).toList

  def toFragment: AsmFragment =
    AsmFragment(xs.toList)

  def getJumps: ListSet[Subroutine] =
    jumps