import bit from "./bit";
import { memory } from "./memory";
import { Ram, ram } from "./ram";
import { Word, emptyWord, wordFromNumber, wordFromString } from "./word";

const bank1GeneralAddressesStart = wordFromString("0010") as Word<4>
const bank2GeneralAddressesStart = wordFromString("0101") as Word<4>

const addressRegisterAddress = wordFromString("0000") as Word<4>
const extendedAddressRegisterAddress = wordFromString("0001") as Word<4>

const programCounterAddress = wordFromString("0010") as Word<4>
const overflowFlagAddress = wordFromString("0011") as Word<4>
const inputPinAddress = wordFromString("0100") as Word<4>


export function minecraftMachine(initialBank1Values: Word<4>[], initialBank2Values: Word<4>[], instructions: Word<4>[]) {

    const bank1Ram = ram({ size: 16, width: 4 })
    const bank2Ram = ram({ size: 16, width: 4 })
    const stack = ram({ size: 4, width: 4 })
    const stackPointer = memory(wordFromString("00"))
    const instructionPointer = memory(wordFromString("0"))

    initialBank1Values.forEach((value, index) => bank1Ram.write(value, wordFromNumber(index).plus(bank1GeneralAddressesStart).sum))
    initialBank2Values.forEach((value, index) => bank2Ram.write(value, wordFromNumber(index).plus(bank2GeneralAddressesStart).sum))

    const addressRegister = bank1Ram.get(addressRegisterAddress)
    const extendedAddressRegister = bank1Ram.get(extendedAddressRegisterAddress)
    addressRegister.set(wordFromNumber(2, 4) as Word<4>)

    bank2Ram.write(addressRegister.value(), addressRegisterAddress)
    bank2Ram.write(extendedAddressRegister.value(), extendedAddressRegisterAddress)


    const programCounter = bank2Ram.get(programCounterAddress)
    const overflowFlag = bank2Ram.get(overflowFlagAddress)
    const inputPin = bank2Ram.get(inputPinAddress)

    function tick() {
        incrementInstruction()
        stack.write(readCurrent(), stackPointer.value())

        if (!stackPointer.value().equals(wordFromString("11"))) {
            stackPointer.set(stackPointer.value().plus(wordFromString("01")).sum)
        }
        
        addressRegister.set(addressRegister.value().plus(wordFromNumber(1, 4)).sum)
    }

    function incrementInstruction() {
        if (instructionPointer.value().equals(wordFromString("1"))) {
            programCounter.set(programCounter.value().plus(wordFromNumber(1, 4)).sum)
        }

        instructionPointer.set(instructionPointer.value().plus(wordFromString("1")).sum)
    }

    function readCurrent() {
        const currentBank = extendedAddressRegister.value().toString() === "0000" ? bank1Ram : bank2Ram
        return currentBank.read(addressRegister.value())
    }

    return { programCounter, instructionPointer, addressRegister, extendedAddressRegister, stack, stackPointer, tick, bank1Ram, bank2Ram }
}