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FIX:Reflect the Latest values of states in handleKeydown event handler #4

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FIX:Reflect the Latest values of states in handleKeydown event handler #4

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26 changes: 18 additions & 8 deletions src/Board/Board.jsx
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
import React, {useEffect, useState} from 'react';
import React, {useEffect, useState, useRef} from 'react';
import {
randomIntFromInterval,
reverseLinkedList,
Expand Down Expand Up @@ -58,12 +58,26 @@ const Board = () => {
const [snake, setSnake] = useState(
new LinkedList(getStartingSnakeLLValue(board)),
);
const [snakeCells, setSnakeCells] = useState(

const [snakeCells, _setSnakeCells] = useState(
new Set([snake.head.value.cell]),
);
const snakeCellsHookRef = useRef(snakeCells);
const setSnakeCells = newSnakeCells => {
snakeCellsHookRef.current = newSnakeCells;
_setSnakeCells(newSnakeCells);
}

// Naively set the starting food cell 5 cells away from the starting snake cell.
const [foodCell, setFoodCell] = useState(snake.head.value.cell + 5);
const [direction, setDirection] = useState(Direction.RIGHT);

const [direction, _setDirection] = useState(Direction.RIGHT);
const directionHookRef = useRef(direction);
const setDirection = direction => {
directionHookRef.current = direction;
_setDirection(direction);
}

const [foodShouldReverseDirection, setFoodShouldReverseDirection] = useState(
false,
);
Expand All @@ -86,11 +100,7 @@ const Board = () => {
const isValidDirection = newDirection !== '';
if (!isValidDirection) return;
const snakeWillRunIntoItself =
getOppositeDirection(newDirection) === direction && snakeCells.size > 1;
// Note: this functionality is currently broken, for the same reason that
// `useInterval` is needed. Specifically, the `direction` and `snakeCells`
// will currently never reflect their "latest version" when `handleKeydown`
// is called. I leave it as an exercise to the viewer to fix this :P
getOppositeDirection(newDirection) === directionHookRef.current && snakeCellsHookRef.current.size > 1;
if (snakeWillRunIntoItself) return;
setDirection(newDirection);
};
Expand Down