import React, { useState, useEffect, useRef } from "react";
import Button from '@material-ui/core/Button';
import Dialog from '@material-ui/core/Dialog';
import DialogActions from '@material-ui/core/DialogActions';
import DialogContent from '@material-ui/core/DialogContent';
import DialogContentText from '@material-ui/core/DialogContentText';
import DialogTitle from '@material-ui/core/DialogTitle';
import "./App.css";
let imdtRes;
let imdtResIdx;
let resArr = [];

function Addition() {
  const [input, setInput] = useState(""); // initial user input like 34+56.7
  const [result, setResult] = useState(0); // real result of calculation
  const [carryArr, setCarryArr] = useState([]); // array of carries [1","0"]
  const [commaIdx, setCommaIdx] = useState(0); // int: comma position
  const [numbers, setNumbers] = useState(0); // array of arrays with input numbers
  const [showAlert, setShowAlert] = useState(false);

  const handleInput = (e) => {
    setInput(e.target.value);
    // TODO: reset results, etc.
  }

  const handleResChange = (e, nosLeft) => {

    if(typeof e === "string"){
      imdtRes = e;
      let carryArrCopy = [...carryArr]
      carryArrCopy[nosLeft] = carryArrCopy[nosLeft+1]
      setCarryArr(carryArrCopy)
    }else{
      imdtRes = e.target.value;
    }

    if(imdtRes === ""){
      console.log(resArr, resArr.length)
      let no = resArr.shift();
      console.log(resArr, "n", no);
    }else{

    resArr.unshift(imdtRes);

      if(nosLeft === 0){
        console.log("set true")
        setShowAlert(true);

//      addResultToDiv(resArr);


        let resCalc = resArr.join("");
        resCalc = parseFloat(resCalc);

//      if(resCalc === result){
//        alert("success")
//        resCalc = 0;
//      }else{
//        alert("error")
//        resCalc = 0;
//      }
      }
    }
  }

  const handleCarryChange = (e, noOfDigits, idx) => {
    if(typeof carryArr === "undefined"){
       setCarryArr(Array(noOfDigits).fill("-"));
    }
    let carryArrCopy = [...carryArr]
    carryArrCopy[idx] = e.target.value
    setCarryArr(carryArrCopy);
  }

  const handleSubmit = (e) => {
    // setInput("1,3+22,450");
    startCalculation();
    e.preventDefault(); // avoid page reload
  }

  const afterCommaLen = (number) => {
    let noStrList = number.toString().split(".");
    if (noStrList.length > 1){
      return noStrList[1].length
    }
    return 0
  }

  const addNumbersToDiv = (numbers, noOfDigits) => {
    for (let idx in numbers){
      let no = numbers[idx].join("")
      if(idx===numbers.length-1){
        no = "+ " + no
      }
      let pNo = "<p>" + no + "</p>"
      document.getElementById("overview").innerHTML += pNo;
    }
    document.getElementById("overview").innerHTML += carryArr.join("");
    document.getElementById("overview").innerHTML += "<hr>";
  }

  const addResultToDiv = () => {
    let res = "<p>" + resArr.join("") + "</p>"
    document.getElementById("overview").innerHTML += res;
  }


  function numbersToArrOfArr(numbers) {
    let befComma = Math.max(...numbers).toString().split(".")[0].length;
    let afterComma = Math.max(...numbers.map(x => afterCommaLen(x)));
    let withComma = Math.max(...numbers.map(x => x.toString().indexOf(".")));

    let arrLength;
    if(withComma < 0){ // no comma found
      arrLength = befComma;
    }else{
      arrLength = befComma + afterComma + 1; // add comma and after comma len
    }

    let numbersArr = numbers.map(x => x.toString().split(""));
    for (let numArr of numbersArr){
      let commaIdx = numArr.indexOf(".");

      // without comma, add before
      while(commaIdx===-1 && numArr.length < befComma){
        numArr.unshift("&nbsp;"); // add " " before comma
      }
      // without comma, add after
      while(commaIdx===-1 && numArr.length < arrLength){
        numArr.push("&nbsp;"); // add " " after comma
      }
      // with comma, add before
      while(commaIdx>-1 && commaIdx!==befComma){
        numArr.unshift("&nbsp;"); // add " " before comma
        commaIdx = numArr.indexOf(".");
      }
      // with comma, add after
      while(numArr.length < arrLength){
        numArr.push("&nbsp;"); // add " " after comma
      }
      numArr.unshift("&nbsp;"); // for carry
    }

    document.getElementById("overview").innerHTML = "";
    setNumbers(numbersArr);
    setCommaIdx(befComma+1);
    addNumbersToDiv(numbersArr, arrLength);

    // TODO: assert all have same length and comma at same index?

    return [numbersArr, befComma]
  }



  const startCalculation = () => {
    if (input.includes("+")){
      let numbers = input.split("+").map(x => parseFloat(x.replace(",",".")));
      let commaIdx = -1;
      setResult(numbers.reduce((x,y) => x+y, 0));
      [numbers, commaIdx] = numbersToArrOfArr(numbers);
    }
  }

  const ResultCarryForm = ({handleResChange, handleCarryChange}) => {
    let resInputField = useRef(null);
    let carryInputField = useRef(null);

    // focus the input field
    useEffect(()=>{
      if(resInputField.current && resInputField.current.value === ""){
        resInputField.current.focus();
      }
    },[])


    let labelText = "";
    let nosLeft = imdtResIdx;
    let noOfDigits = 0;
    let carryText = "Übertrag = ";

    if(typeof numbers === "object" && imdtResIdx !== -1){
      if(typeof imdtResIdx === "undefined"){
        noOfDigits = Math.min(...numbers.map(n => n.length));
        imdtResIdx = noOfDigits-1;
      }

      if(imdtResIdx === commaIdx){
        handleResChange(".", nosLeft)
        imdtResIdx = imdtResIdx - 1;
      }
      for (let n in numbers){ // iterate numbers
        if(nosLeft === 1 && carryArr[1] === "0"){
          nosLeft = 0;
          imdtResIdx = -1;
          handleResChange("&nbsp;", 0)
          return <></>
        }
        let no = numbers[parseInt(n)][imdtResIdx];
        if(no === "" || no === "&nbsp;"){
          no = 0;
        }
        labelText += no;

        if (parseInt(n) === numbers.length - 1){
          if(carryArr[imdtResIdx+1]!=="undefind" && carryArr[imdtResIdx+1] > 0){
            labelText += " + " + carryArr[imdtResIdx+1].toString();
          }
          labelText += " = ";
        }else{
          labelText += " + "; // TODO: replace with -/* etc.
        }
      }

      if(carryArr[imdtResIdx] > -1){
        imdtRes = -1;
        imdtResIdx = imdtResIdx - 1;
        nosLeft = nosLeft - 1;
      }

      return (
        <form>
          <label htmlFor="input_result" id="input_result_label">
            {labelText}
          </label>
          <input
            onChange={(e) => handleResChange(e, nosLeft)}
            type="text" id="input_result" size="2" tabIndex={1}
            aria-labelledby="input_result_label" aria-required="true"
            ref={resInputField}/>
          <br/>
          <label htmlFor="input_carry" id="input_carry_label">
            {carryText}
          </label>
          <input
            onChange={(e) => handleCarryChange(e, noOfDigits, imdtResIdx)}
            type="text" id="input_carry" size="2" tabIndex={2}
            aria-labelledby="input_carry_label" aria-required="true"
            ref={carryInputField}/>
        </form>
      );
    }else{
      return (
        <>
        </>
      );
    }
  }


  const showIdmtResults = () => {
    setShowAlert(false);
    let realResArr = result.toString().split("");
    while(realResArr.length < resArr.length){
      realResArr.unshift("&nbsp;"); // add " " before
    }

    let carries = carryArr.map(x => x || "0")
    carries.push("0");
    while(carries.length < resArr.length){
      carries.unshift("0"); // add "0" before
    }

    let foundComma = false;
    for (let i=0; i<resArr.length-1; i++) {
      let text = "";
      let trueNumbers = false;
      let idxNumbers = resArr.length - i - 1;
      let idxCarry = carries.length - i - 1;
      let realSum = 0;
      for (let j=0; j<numbers.length; j++) {
        let no = numbers[j][idxNumbers];
        if (no!=="." && no!=="&nbsp;"){
          trueNumbers = true;
          realSum += parseInt(no);
        }
        text += no
        if (j<numbers.length-1){
          text += " + "
        }
      }

      // ignore indexes without real digits
      if (resArr[idxNumbers]!=="&nbsp;" || carries[idxCarry]!=="&nbsp;"){
        trueNumbers = true;
      }

      // carry array has no "."
      if (resArr[idxNumbers] === "."){
        foundComma = true;
        trueNumbers = false;
      }
      if (foundComma){
        idxCarry += 1;
      }

      // add carry only if > 0
      if (carries[idxCarry]!=="0"){
        realSum += parseInt(carries[idxCarry]);
        text += " + " + carries[idxCarry] + " Übertrag"
      }

      let realCarry = parseInt(realSum/10).toString()
      realSum = (realSum % 10).toString()
      text += " = "

      if (trueNumbers){
        text += resArr[idxNumbers]
        text = text.replace("&nbsp;", "0")
        text += resArr[idxNumbers]===realSum && carries[idxCarry-1]===realCarry ? "\t\tRichtig" : "\t\tFalsch";

        let paragraph = document.createElement("p");
        paragraph.innerHTML = text
        document.getElementById("idmtResultSteps").appendChild(paragraph);

        let btn = document.createElement("button");
        btn.innerHTML = "bearbeiten: " + text;
        btn.addEventListener("click", () => startOver(i));
        document.getElementById("idmtResultSteps").appendChild(btn);
      }
    }

    let btnSubmit = document.createElement("button");
    btnSubmit.innerHTML = "submit result";
    btnSubmit.addEventListener("click", () => console.log("end"));
    document.getElementById("idmtResultSteps").appendChild(btnSubmit);

  }

  const startOver = (idx) => {
    console.log("clicked at " + idx)
  }



  const handleClose = () => {
    setShowAlert(false);
  };

  const Alert = () => {
    return(
    <div>
      <Dialog
        open={showAlert}
        onClose={handleClose}
        aria-labelledby="alert-dialog-title"
        aria-describedby="alert-dialog-description"
      >
        <DialogTitle id="alert-dialog-title">{"Ergebnis überprüfen oder abgeben?"}</DialogTitle>

        <DialogContent>
          <DialogContentText id="alert-dialog-description">
            Willst du dein Ergebnis nochmal überprüfen oder gleich abgeben?
          </DialogContentText>
        </DialogContent>

        <DialogActions>
          <Button onClick={showIdmtResults} color="primary" autoFocus>
            Prüfen
          </Button>
          <Button onClick={handleClose} color="primary">
            Abgeben
          </Button>
        </DialogActions>

      </Dialog>
    </div>
  )};


  return (
    <div id="content">

      <h1>Addition</h1>

      <form onSubmit={(e) => handleSubmit(e)}>
        <label for="calculationInput">
          Rechnung:
        </label>
        <input
          type="text"
          id="calculationInput"
          onChange={(e) => handleInput(e)}
          aria-label="Rechnung"
          aria-required="true"/>
        <input type="submit" value="berechnen"/>
      </form>

      <div id="overview"></div>

      <div id="calculation">
        <ResultCarryForm
          handleResChange={handleResChange}
          handleCarryChange={handleCarryChange}/>
      </div>

      <div id="idmtResultSteps"></div>

      <Alert/>

    </div>
  );
}

export default Addition;