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    <path fill="var(--stroke)" d="M98.3201 39.3222L89.7589 36.5462C88.2688 41.1416 90.6725 46.0937 95.2048 47.7659L98.3201 39.3222ZM71.6799 39.3222L74.7952 47.7659C79.3275 46.0937 81.7312 41.1416 80.2411 36.5462L71.6799 39.3222ZM54.2398 58V67C58.658 67 62.4228 63.7931 63.1253 59.4312L54.2398 58ZM23.8059 83.7931L32.42 81.1862L32.42 81.1862L23.8059 83.7931ZM34.7006 119.793L26.0864 122.4L26.0864 122.4L34.7006 119.793ZM45.4311 132.146L51.1198 139.12C53.5226 137.16 54.7472 134.101 54.3609 131.025C53.9746 127.948 52.0318 125.287 49.2191 123.982L45.4311 132.146ZM124.913 131.982L120.97 123.892C118.183 125.25 116.292 127.947 115.963 131.029C115.635 134.112 116.917 137.147 119.355 139.061L124.913 131.982ZM135.299 119.793L126.685 117.186L126.685 117.186L135.299 119.793ZM146.194 83.7932L137.58 81.1862L137.58 81.1862L146.194 83.7932ZM115.76 58L106.875 59.4312C107.577 63.7931 111.342 67 115.76 67V58ZM90 35C90 35.5543 89.9131 36.0707 89.7589 36.5462L106.881 42.0983C107.61 39.8513 108 37.4624 108 35H90ZM85 30C87.7614 30 90 32.2386 90 35H108C108 22.2975 97.7026 12 85 12V30ZM80 35C80 32.2386 82.2386 30 85 30V12C72.2975 12 62 22.2975 62 35H80ZM80.2411 36.5462C80.0869 36.0707 80 35.5543 80 35H62C62 37.4624 62.3902 39.8513 63.1188 42.0983L80.2411 36.5462ZM63.1253 59.4312C63.7988 55.2498 67.5604 50.4352 74.7952 47.7659L68.5647 30.8786C57.1112 35.1044 47.3444 44.2138 45.3544 56.5688L63.1253 59.4312ZM54.2398 49H42.9485V67H54.2398V49ZM42.9485 49C23.4932 49 9.55633 67.7789 15.1917 86.4001L32.42 81.1862C30.2825 74.123 35.5689 67 42.9485 67V49ZM15.1917 86.4001L26.0864 122.4L43.3148 117.186L32.42 81.1862L15.1917 86.4001ZM26.0864 122.4C28.5395 130.506 34.3182 136.911 41.643 140.31L49.2191 123.982C46.429 122.687 44.2438 120.256 43.3148 117.186L26.0864 122.4ZM39.7423 125.172C34.5896 129.375 31.2741 135.804 31.2741 143H49.2741C49.2741 141.44 49.978 140.051 51.1198 139.12L39.7423 125.172ZM31.2741 143C31.2741 155.703 41.5715 166 54.2741 166V148C51.5127 148 49.2741 145.761 49.2741 143H31.2741ZM54.2741 166H116.274V148H54.2741V166ZM116.274 166C128.977 166 139.274 155.703 139.274 143H121.274C121.274 145.761 119.036 148 116.274 148V166ZM139.274 143C139.274 135.648 135.815 129.099 130.471 124.904L119.355 139.061C120.54 139.991 121.274 141.407 121.274 143H139.274ZM128.856 140.073C135.943 136.619 141.516 130.321 143.914 122.4L126.685 117.186C125.777 120.186 123.67 122.576 120.97 123.892L128.856 140.073ZM143.914 122.4L154.808 86.4001L137.58 81.1862L126.685 117.186L143.914 122.4ZM154.808 86.4001C160.444 67.7789 146.507 49 127.052 49V67C134.431 67 139.718 74.123 137.58 81.1862L154.808 86.4001ZM127.052 49H115.76V67H127.052V49ZM95.2048 47.7659C102.44 50.4352 106.201 55.2498 106.875 59.4312L124.646 56.5688C122.656 44.2138 112.889 35.1044 101.435 30.8786L95.2048 47.7659Z" />
    <path fill-rule="evenodd" clip-rule="evenodd" d="M98.3201 39.3222C98.7615 37.961 99 36.5084 99 35C99 27.268 92.732 21 85 21C77.268 21 71 27.268 71 35C71 36.5084 71.2385 37.961 71.6799 39.3222C62.3358 42.7698 55.5716 49.7318 54.2398 58H42.9485C29.5311 58 19.9194 70.951 23.8059 83.7931L34.7006 119.793C36.3917 125.381 40.3736 129.799 45.4311 132.146C42.2838 134.713 40.2741 138.622 40.2741 143C40.2741 150.732 46.5421 157 54.2741 157H116.274C124.006 157 130.274 150.732 130.274 143C130.274 138.528 128.177 134.545 124.913 131.982C129.807 129.597 133.647 125.254 135.299 119.793L146.194 83.7932C150.081 70.951 140.469 58 127.052 58H115.76C114.428 49.7318 107.664 42.7698 98.3201 39.3222Z" />
  </g>
  
  <g id="king">
    <path fill="var(--stroke)" d="M71.3981 29V38C74.4851 38 77.3566 36.4179 79.0059 33.8085C80.6552 31.1991 80.8521 27.9265 79.5275 25.1382L71.3981 29ZM55.5392 47V56C59.196 56 62.4893 53.7874 63.8715 50.4019C65.2537 47.0165 64.4501 43.1312 61.8383 40.5718L55.5392 47ZM16.8101 72.5915L25.4512 70.0754L25.4512 70.0754L16.8101 72.5915ZM30.4959 119.592L39.137 117.075L39.137 117.075L30.4959 119.592ZM44.3251 133.266L50.7933 139.524C52.9992 137.244 53.8418 133.971 53.011 130.909C52.1801 127.848 49.7986 125.449 46.7427 124.597L44.3251 133.266ZM126.438 133.253L123.999 124.59C120.947 125.449 118.572 127.851 117.747 130.913C116.923 133.974 117.77 137.244 119.978 139.52L126.438 133.253ZM140.22 119.592L148.861 122.108L148.861 122.108L140.22 119.592ZM153.906 72.5915L145.265 70.0753L145.265 70.0753L153.906 72.5915ZM115.236 47L108.937 40.5718C106.325 43.1312 105.522 47.0165 106.904 50.4019C108.286 53.7874 111.579 56 115.236 56V47ZM99.3773 29L91.2479 25.1382C89.9233 27.9265 90.1202 31.1991 91.7695 33.8085C93.4188 36.4179 96.2903 38 99.3773 38V29ZM79.3877 24.5C79.3877 23.6716 80.0593 23 80.8877 23V5C70.1181 5 61.3877 13.7304 61.3877 24.5H79.3877ZM79.5275 25.1382C79.4407 24.9555 79.3877 24.7465 79.3877 24.5H61.3877C61.3877 27.4743 62.0598 30.3168 63.2688 32.8618L79.5275 25.1382ZM71.3981 20H62.8877V38H71.3981V20ZM62.8877 20C52.1181 20 43.3877 28.7304 43.3877 39.5H61.3877C61.3877 38.6716 62.0593 38 62.8877 38V20ZM43.3877 39.5C43.3877 44.9545 45.639 49.8994 49.2401 53.4282L61.8383 40.5718C61.5498 40.2891 61.3877 39.9216 61.3877 39.5H43.3877ZM55.5392 38H36.0125V56H55.5392V38ZM36.0125 38C16.6845 38 2.7653 56.5505 8.16895 75.1077L25.4512 70.0754C23.4015 63.0364 28.6812 56 36.0125 56V38ZM8.16895 75.1077L21.8548 122.108L39.137 117.075L25.4512 70.0754L8.16895 75.1077ZM21.8548 122.108C24.7108 131.916 32.4229 139.291 41.9074 141.936L46.7427 124.597C43.1399 123.592 40.2185 120.789 39.137 117.075L21.8548 122.108ZM37.8569 127.008C33.861 131.139 31.3877 136.79 31.3877 143H49.3877C49.3877 141.646 49.9143 140.433 50.7933 139.524L37.8569 127.008ZM31.3877 143C31.3877 155.703 41.6852 166 54.3877 166V148C51.6263 148 49.3877 145.761 49.3877 143H31.3877ZM54.3877 166H116.388V148H54.3877V166ZM116.388 166C129.09 166 139.388 155.703 139.388 143H121.388C121.388 145.761 119.149 148 116.388 148V166ZM139.388 143C139.388 136.779 136.906 131.119 132.898 126.987L119.978 139.52C120.859 140.429 121.388 141.643 121.388 143H139.388ZM128.876 141.917C138.33 139.256 146.012 131.893 148.861 122.108L131.579 117.075C130.5 120.781 127.59 123.579 123.999 124.59L128.876 141.917ZM148.861 122.108L162.547 75.1077L145.265 70.0753L131.579 117.075L148.861 122.108ZM162.547 75.1077C167.951 56.5504 154.032 38 134.704 38V56C142.035 56 147.315 63.0364 145.265 70.0753L162.547 75.1077ZM134.704 38H115.236V56H134.704V38ZM121.535 53.4282C125.136 49.8994 127.388 44.9545 127.388 39.5H109.388C109.388 39.9216 109.226 40.2891 108.937 40.5718L121.535 53.4282ZM127.388 39.5C127.388 28.7304 118.657 20 107.888 20V38C108.716 38 109.388 38.6716 109.388 39.5H127.388ZM107.888 20H99.3773V38H107.888V20ZM91.3877 24.5C91.3877 24.7465 91.3347 24.9555 91.2479 25.1382L107.507 32.8618C108.716 30.3168 109.388 27.4743 109.388 24.5H91.3877ZM89.8877 23C90.7161 23 91.3877 23.6716 91.3877 24.5H109.388C109.388 13.7304 100.657 5 89.8877 5V23ZM80.8877 23H89.8877V5H80.8877V23Z" />
    <path fill-rule="evenodd" clip-rule="evenodd" d="M80.8877 14C75.0887 14 70.3877 18.701 70.3877 24.5C70.3877 26.1104 70.7502 27.6361 71.3981 29H62.8877C57.0887 29 52.3877 33.701 52.3877 39.5C52.3877 42.438 53.5944 45.0942 55.5392 47H36.0125C22.6829 47 13.0834 59.7934 16.8101 72.5915L30.4959 119.592C32.4647 126.353 37.7814 131.441 44.3251 133.266C41.8876 135.786 40.3877 139.218 40.3877 143C40.3877 150.732 46.6557 157 54.3877 157H116.388C124.12 157 130.388 150.732 130.388 143C130.388 139.211 128.883 135.774 126.438 133.253C132.96 131.417 138.256 126.337 140.22 119.592L153.906 72.5915C157.633 59.7934 148.033 47 134.704 47H115.236C117.181 45.0942 118.388 42.438 118.388 39.5C118.388 33.701 113.687 29 107.888 29H99.3773C100.025 27.6361 100.388 26.1104 100.388 24.5C100.388 18.701 95.6867 14 89.8877 14H80.8877Z" />
  </g>
</svg>
              
            
!

CSS

              
                :root {
  --border-width: calc(var(--diameter-tile) / 60);
  --diameter-board: min(85vw, 85vh);
  --diameter-tile: calc(1 / 8 * var(--diameter-board));
  --edge-width: calc((min(100vw, 100vh) - var(--diameter-board)) * 0.3);
  --color-danger: tomato;
  --color-success: #1d83e0;
  --color-white: #f0f0f0;
  --color-black: #222;
  --color-board-hue: 30;
  --color-board-sat: 40%;
  --color-shadow: hsl(var(--color-board-hue), var(--color-board-sat), 50%);
  --color-shadow-lighter: hsl(var(--color-board-hue), var(--color-board-sat), 55%);
  --transition-ease: cubic-bezier(0.25, 1, 0.5, 1);
  --color-background: var(--color-black);
}

aside {
  display: flex;
  justify-content: space-between;
  left: 0;
  position: absolute;
  top: calc(var(--edge-width) * -0.55);
  transform: translateY(-50%);
  width: 100%;
  z-index: 999;
}
aside div {
  align-items: center;
  color: white;
  display: flex;
}
aside div > * {
  align-items: center;
  display: flex;
}
aside div > * + * {
  margin-left: calc(var(--border-width) * 2);
}
aside div h3,
aside div label {
  font-size: calc(var(--edge-width) * 0.3);
  height: calc(var(--edge-width) * 0.3);
  line-height: 1;
  margin-bottom: 0;
  margin-top: 0;
  text-transform: uppercase;
}
aside div label {
  cursor: pointer;
}
aside div input {
  left: -99999px;
  position: absolute;
}

aside div input + * {
  opacity: 0.5;
}
aside div input:checked + * {
  font-weight: bold;
  opacity: 1;
}

aside div svg {
  height: calc(var(--edge-width) * 0.5);
  width: auto;
}

html,
body {
  height: 100%;
}

body {
  background: var(--color-background);
  overflow: hidden;
  transition: background-color 250ms ease-in-out;
}

#view {
  background: var(--color-shadow-lighter);
  box-shadow: 0 0 0 calc(var(--border-width) * 3) var(--color-shadow-lighter),
    0 0 0 var(--edge-width) var(--color-shadow);
  height: var(--diameter-board);
  margin: calc((100vh - var(--diameter-board)) * 0.5)
    calc((100vw - var(--diameter-board)) * 0.5);
  position: relative;
  width: var(--diameter-board);
}

.board {
  display: flex;
  flex-direction: column-reverse;
  height: 100%;
  width: 100%;
}

.board .row {
  display: flex;
  height: var(--diameter-tile);
  width: 100%;
}

.perspective-black .board .row {
  flex-direction: row-reverse;
}

.perspective-black .board {
  flex-direction: column;
}

.board .row .tile {
  background-color: currentcolor;
  border: none;
  box-shadow: inset 0 0 0 var(--border-width) var(--color-shadow-lighter);
  display: flex;
  flex-direction: column;
  height: var(--diameter-tile);
  justify-content: space-between;
  padding: 0;
  position: relative;
  transition: background-color 350ms var(--transition-ease);
  width: var(--diameter-tile);
}

.perspective-black .board .row:nth-child(even) .tile:nth-child(odd),
.perspective-black .board .row:nth-child(odd) .tile:nth-child(even),
.perspective-white .board .row:nth-child(even) .tile:nth-child(even),
.perspective-white .board .row:nth-child(odd) .tile:nth-child(odd) {
  color: hsl(var(--color-board-hue), var(--color-board-sat), 62%);
}

.perspective-black .board .row:nth-child(even) .tile:nth-child(even),
.perspective-black .board .row:nth-child(odd) .tile:nth-child(odd),
.perspective-white .board .row:nth-child(even) .tile:nth-child(odd),
.perspective-white .board .row:nth-child(odd) .tile:nth-child(even) {
  color: hsl(var(--color-board-hue), var(--color-board-sat), 70%);
}
.board .row .tile.highlight-active {}
.board .row .tile.highlight-capture {}
.board .row .tile.highlight-move {}

.board .row .tile .move,
.board .row .tile .moves,
.board .row .tile .captures {
  box-sizing: border-box;
  display: flex;
  flex-wrap: wrap;
  height: var(--diameter-tile);
  justify-content: center;
  left: 0;
  padding: calc(var(--diameter-tile) * 0.025);
  position: absolute;
  top: 0;
  width: var(--diameter-tile);
  z-index: 9;
}

.board .row .tile .move,
.board .row .tile .moves {
  align-content: center;
  align-items: center;
}
.board .row .tile .captures {
  align-items: flex-start;
  justify-content: space-between;
}
.board .row .tile:not(.occupied) .captures {
  align-items: center;
  justify-content: center;
}

.board .row .tile > div > svg {
  --stroke: transparent;
  box-sizing: border-box;
  height: var(--di);
  line-height: var(--di);
  width: var(--di);
}

.board .row .tile .move svg {
  --di: calc(var(--diameter-tile) / 4);
  --fill: var(--color-shadow);
}

.board .row .tile .moves svg,
.board .row .tile .captures svg {
  --di: calc(var(--diameter-tile) / 4);
  --fill: var(--color-shadow);
  opacity: 0.4;
}

.board .row .tile.occupied .captures svg { position: absolute; }
.board .row .tile.occupied .captures svg:nth-child(1) { top: 0; left: 0; }
.board .row .tile.occupied .captures svg:nth-child(2) { top: 0; right: 0; }
.board .row .tile.occupied .captures svg:nth-child(3) { bottom: calc(var(--di) * 0.1); left: 0; }
.board .row .tile.occupied .captures svg:nth-child(4) { bottom: calc(var(--di) * 0.1); right: 0; }
.board .row .tile.occupied .captures svg:nth-child(5) { top: calc(50% - var(--di) * 0.55); left: 0; }
.board .row .tile.occupied .captures svg:nth-child(6) { top: calc(50% - var(--di) * 0.55); right: 0; }
.board .row .tile.occupied .captures svg:nth-child(7) { top: 0; left: calc(50% - var(--di) * 0.5); }
.board .row .tile.occupied .captures svg:nth-child(8) { bottom: calc(var(--di) * 0.1); left: calc(50% - var(--di) * 0.5); }

.touching .board .row .tile .moves,
.touching .board .row .tile .captures,
.turn-black .board .row .tile .moves .white,
.turn-black .board .row .tile .captures .white,
.turn-white .board .row .tile .moves .black,
.turn-white .board .row .tile .captures .black {
  display: none;
}

.board .row .tile[class*="highlight-"] .moves,
.board .row .tile[class*="highlight-"] .captures {
  display: none;  
}

button:focus {
  outline: none;
  position: relative;
  z-index: 9;
}

svg {
  --fill: var(--color-black);
  --stroke: var(--color-shadow);
  fill: var(--fill);
}

svg.white { --fill: var(--color-white); }
svg.black { --fill: var(--color-black); }

.pieces {
  display: block;
  height: var(--diameter-board);
  left: 0;
  pointer-events: none;
  position: absolute;
  top: 0;
  width: var(--diameter-board);
  z-index: 99;
}

.pieces .piece.white {
  --pos-row: -1;
}
.pieces .piece.black {
  --pos-row: 8;
}
.pieces .piece {
  --pos-col: 3.5;
  --scale: 0;
  --transition-delay: 0ms;
  --transition-duration: 200ms;
  bottom: 0;
  display: block;
  height: var(--diameter-tile);
  position: absolute;
  left: 0;
  transform: translate(
      calc(var(--pos-col) * 100%),
      calc(var(--pos-row) * -100%)
    )
    translateZ(0);
  transform-origin: 50% 50%;
  transition: all var(--transition-duration) var(--transition-ease)
    var(--transition-delay);
  width: var(--diameter-tile);
}
.perspective-black .pieces .piece {
  transform: translate(
      calc((7 - var(--pos-col)) * 100%),
      calc((7 - var(--pos-row)) * -100%)
    )
    translateZ(0);
}
.pieces .piece svg {
  display: block;
  left: 50%;
  opacity: 1;
  position: absolute;
  top: 50%;
  transform: translate(-50%, -50%) translateZ(0) scale(var(--scale));
  transform-origin: 50% 50%;
  transition: transform var(--transition-duration) var(--transition-ease),
    fill var(--transition-duration) var(--transition-ease),
    opacity var(--transition-duration) var(--transition-ease);
}
.turn-white .pieces .piece:not(.highlight-capture) svg.black,
.turn-black .pieces .piece:not(.highlight-capture) svg.white,
.turn-black .pieces .piece:not(.can-move):not(.can-capture) svg.black,
.turn-white .pieces .piece:not(.can-move):not(.can-capture) svg.white {
  --stroke: transparent;
  opacity: 0.8;
}

@keyframes wobble {
  0%, 50%, 100% { transform: translate(-50%, -50%) translateZ(0) scale(1) rotate(0deg); }
  25% { transform: translate(-50%, -50%) translateZ(0) scale(1.1) rotate(-2deg); }
  75% { transform: translate(-50%, -50%) translateZ(0) scale(1.1) rotate(2deg); }
}
.pieces .piece.highlight-active svg {
  animation: wobble 500ms linear infinite;
  --stroke: var(--color-success);
}

.pieces .piece.highlight-capture svg {
  --stroke: var(--color-danger);
}

.piece svg {
  --svg-di: calc(var(--diameter-tile) * 0.666);
  display: block;
  font-weight: bold;
  height: var(--svg-di);
  left: 50%;
  line-height: var(--svg-di);
  position: absolute;
  stroke-linejoin: round;
  text-align: center;
  top: 50%;
  transform: translate(-50%, -50%);
  width: var(--svg-di);
}

.support-link {
  text-decoration: none;
  color: #747474;
  font-weight: bold;
  font-family: roboto;
  margin: 2rem;
}
              
            
!

JS

              
                console.clear();

// TODO: url based

type MoveType = "CANCEL" | "CAPTURE" | "INVALID" | "MOVE" | "TOUCH";
// prettier-ignore
type PieceIdBlack = "A8" | "B8" | "C8" | "D8" | "E8" | "F8" | "G8" | "H8" |
                    "A7" | "B7" | "C7" | "D7" | "E7" | "F7" | "G7" | "H7";
// prettier-ignore
type PieceIdWhite = "A2" | "B2" | "C2" | "D2" | "E2" | "F2" | "G2" | "H2" |
                    "A1" | "B1" | "C1" | "D1" | "E1" | "F1" | "G1" | "H1";
type PieceId = PieceIdWhite | PieceIdBlack;
type PieceType = "PAWN" | "ROOK" | "KNIGHT" | "BISHOP" | "QUEEN" | "KING";
type PlayerId = "WHITE" | "BLACK";
type PositionColumn = "A" | "B" | "C" | "D" | "E" | "F" | "G" | "H";
type PositionRow = "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8";

interface ActivateResponse {
  activePieceId?: PieceId;
  capturedPieceId?: PieceId;
  captures?: Position[];
  castledId?: PieceId;
  moves?: Position[];
  type: MoveType;
}
interface Options {
  captures: Position[];
  moves: Position[];
}
interface PieceData {
  id: PieceId;
  type: PieceType;
  player: PlayerId;
}
interface PiecePositionOnBoard extends Position {
  active: true;
}
interface PiecePositionOffBoard {
  active: false;
  row?: undefined;
  col?: undefined;
}
interface Position {
  row: PositionRow;
  col: PositionColumn;
  capture?: Position;
  castles?: PositionColumn;
  _moves?: number;
  _promoted?: boolean;
}

type BoardPieces = { [K in PieceId]: HTMLElement };
type BoardState = { [K in PositionRow]?: { [K in PositionColumn]?: PieceId } };
type BoardTiles = {
  [K in PositionRow]: { [K in PositionColumn]: HTMLElement };
};
type PiecePosition = PiecePositionOnBoard | PiecePositionOffBoard;
type Pieces = { [K in PieceId]: Piece };
type PieceDirResponse = Position | undefined;
type PiecePositions = { [K in PieceId]: PiecePosition };
type PiecesToTiles = { [K in PieceId]?: Position[] };
type TilesToPieces = {
  [K in PositionRow]: { [K in PositionColumn]: PieceId[] };
};
type TileRelation = "FRIEND" | "ENEMY" | "BLANK";

type ConstraintArguments = {
  moveIndex: number;
  piece: Piece;
  pieces: Pieces;
  piecePositions: PiecePositions;
  state: BoardState;
  kingCastles?: (king: Piece) => Position[];
};

type ResultingChecksArguments = {
  piece: Piece;
  location: Position;
  capture: boolean;
  moveIndex: number;
};

let PIECE_DIR_CALC = 0;

class Utils {
  static colToInt(col: PositionColumn): number {
    return Board.COLS.indexOf(col);
  }
  static rowToInt(row: PositionRow): number {
    return Board.ROWS.indexOf(row);
  }
  static intToCol(int: number): PositionColumn {
    return Board.COLS[int];
  }
  static intToRow(int: number): PositionRow {
    return Board.ROWS[int];
  }

  static getPositionsFromShortCode(shortCode: string): PiecePositions {
    const positions = Utils.getInitialPiecePositions();
    const overrides = {};
    const defaultPositionMode = shortCode.charAt(0) === "X";
    if (defaultPositionMode) {
      shortCode = shortCode.slice(1);
    }
    shortCode.split(",").forEach((string) => {
      const promoted = string.charAt(0) === "P";
      if (promoted) {
        string = string.slice(1);
      }
      if (defaultPositionMode) {
        const inactive = string.length === 3;
        const id = string.slice(0, 2);
        const col = inactive ? undefined : string.charAt(2);
        const row = inactive ? undefined : string.charAt(3);
        const moves = string.charAt(4) || "1";
        overrides[id] = {
          col,
          row,
          active: !inactive,
          _moves: parseInt(moves),
          _promoted: promoted,
        };
      } else {
        const moved = string.length >= 4;
        const id = string.slice(0, 2);
        const col = string.charAt(moved ? 2 : 0);
        const row = string.charAt(moved ? 3 : 1);
        const moves = string.charAt(4) || moved ? "1" : "0";
        overrides[id] = { col, row, active: true, _moves: parseInt(moves), _promoted: promoted };
      }
    });
    for (let id in positions) {
      if (overrides[id]) {
        positions[id] = overrides[id];
      } else {
        positions[id] = defaultPositionMode ? positions[id] : { active: false };
      }
    }
    return positions;
  }

  static getInitialBoardPieces(parent: HTMLElement, pieces: Pieces): BoardPieces {
    const boardPieces = {};
    const container = document.createElement("div");
    container.className = "pieces";
    parent.appendChild(container);
    for (let pieceId in pieces) {
      const boardPiece = document.createElement("div");
      boardPiece.className = `piece ${pieces[pieceId].data.player.toLowerCase()}`;
      boardPiece.innerHTML = pieces[pieceId].shape();
      container.appendChild(boardPiece);
      boardPieces[pieceId] = boardPiece;
    }
    return boardPieces as BoardPieces;
  }

  static getInitialBoardTiles(parent: HTMLElement, handler: (params: Position) => void): BoardTiles {
    const tiles = { 1: {}, 2: {}, 3: {}, 4: {}, 5: {}, 6: {}, 7: {}, 8: {} };
    const board = document.createElement("div");
    board.className = "board";
    parent.appendChild(board);
    for (let i = 0; i < 8; i++) {
      const row = document.createElement("div");
      row.className = "row";
      board.appendChild(row);
      for (let j = 0; j < 8; j++) {
        const tile = document.createElement("button");
        tile.className = "tile";
        const r = Utils.intToRow(i);
        const c = Utils.intToCol(j);
        tile.addEventListener("click", () => handler({ row: r, col: c }));
        row.appendChild(tile);
        tiles[r][c] = tile;
      }
    }
    return tiles as BoardTiles;
  }

  static getInitialBoardState(construct = () => undefined): any {
    const blankRow = () => ({
      A: construct(),
      B: construct(),
      C: construct(),
      D: construct(),
      E: construct(),
      F: construct(),
      G: construct(),
      H: construct(),
    });
    return {
      1: { ...blankRow() },
      2: { ...blankRow() },
      3: { ...blankRow() },
      4: { ...blankRow() },
      5: { ...blankRow() },
      6: { ...blankRow() },
      7: { ...blankRow() },
      8: { ...blankRow() },
    };
  }

  static getInitialPiecePositions(): PiecePositions {
    return {
      A8: { active: true, row: "8", col: "A" },
      B8: { active: true, row: "8", col: "B" },
      C8: { active: true, row: "8", col: "C" },
      D8: { active: true, row: "8", col: "D" },
      E8: { active: true, row: "8", col: "E" },
      F8: { active: true, row: "8", col: "F" },
      G8: { active: true, row: "8", col: "G" },
      H8: { active: true, row: "8", col: "H" },
      A7: { active: true, row: "7", col: "A" },
      B7: { active: true, row: "7", col: "B" },
      C7: { active: true, row: "7", col: "C" },
      D7: { active: true, row: "7", col: "D" },
      E7: { active: true, row: "7", col: "E" },
      F7: { active: true, row: "7", col: "F" },
      G7: { active: true, row: "7", col: "G" },
      H7: { active: true, row: "7", col: "H" },
      A2: { active: true, row: "2", col: "A" },
      B2: { active: true, row: "2", col: "B" },
      C2: { active: true, row: "2", col: "C" },
      D2: { active: true, row: "2", col: "D" },
      E2: { active: true, row: "2", col: "E" },
      F2: { active: true, row: "2", col: "F" },
      G2: { active: true, row: "2", col: "G" },
      H2: { active: true, row: "2", col: "H" },
      A1: { active: true, row: "1", col: "A" },
      B1: { active: true, row: "1", col: "B" },
      C1: { active: true, row: "1", col: "C" },
      D1: { active: true, row: "1", col: "D" },
      E1: { active: true, row: "1", col: "E" },
      F1: { active: true, row: "1", col: "F" },
      G1: { active: true, row: "1", col: "G" },
      H1: { active: true, row: "1", col: "H" },
    };
  }

  static getInitialPieces(): Pieces {
    return {
      A8: new Piece({ id: "A8", player: "BLACK", type: "ROOK" }),
      B8: new Piece({ id: "B8", player: "BLACK", type: "KNIGHT" }),
      C8: new Piece({ id: "C8", player: "BLACK", type: "BISHOP" }),
      D8: new Piece({ id: "D8", player: "BLACK", type: "QUEEN" }),
      E8: new Piece({ id: "E8", player: "BLACK", type: "KING" }),
      F8: new Piece({ id: "F8", player: "BLACK", type: "BISHOP" }),
      G8: new Piece({ id: "G8", player: "BLACK", type: "KNIGHT" }),
      H8: new Piece({ id: "H8", player: "BLACK", type: "ROOK" }),
      A7: new Piece({ id: "A7", player: "BLACK", type: "PAWN" }),
      B7: new Piece({ id: "B7", player: "BLACK", type: "PAWN" }),
      C7: new Piece({ id: "C7", player: "BLACK", type: "PAWN" }),
      D7: new Piece({ id: "D7", player: "BLACK", type: "PAWN" }),
      E7: new Piece({ id: "E7", player: "BLACK", type: "PAWN" }),
      F7: new Piece({ id: "F7", player: "BLACK", type: "PAWN" }),
      G7: new Piece({ id: "G7", player: "BLACK", type: "PAWN" }),
      H7: new Piece({ id: "H7", player: "BLACK", type: "PAWN" }),
      A2: new Piece({ id: "A2", player: "WHITE", type: "PAWN" }),
      B2: new Piece({ id: "B2", player: "WHITE", type: "PAWN" }),
      C2: new Piece({ id: "C2", player: "WHITE", type: "PAWN" }),
      D2: new Piece({ id: "D2", player: "WHITE", type: "PAWN" }),
      E2: new Piece({ id: "E2", player: "WHITE", type: "PAWN" }),
      F2: new Piece({ id: "F2", player: "WHITE", type: "PAWN" }),
      G2: new Piece({ id: "G2", player: "WHITE", type: "PAWN" }),
      H2: new Piece({ id: "H2", player: "WHITE", type: "PAWN" }),
      A1: new Piece({ id: "A1", player: "WHITE", type: "ROOK" }),
      B1: new Piece({ id: "B1", player: "WHITE", type: "KNIGHT" }),
      C1: new Piece({ id: "C1", player: "WHITE", type: "BISHOP" }),
      D1: new Piece({ id: "D1", player: "WHITE", type: "QUEEN" }),
      E1: new Piece({ id: "E1", player: "WHITE", type: "KING" }),
      F1: new Piece({ id: "F1", player: "WHITE", type: "BISHOP" }),
      G1: new Piece({ id: "G1", player: "WHITE", type: "KNIGHT" }),
      H1: new Piece({ id: "H1", player: "WHITE", type: "ROOK" }),
    };
  }
}

class Shape {
  static shape(player: string, piece: string) {
    return `<svg class="${player}" width="170" height="170" viewBox="0 0 170 170" fill="none" xmlns="http://www.w3.org/2000/svg">
      <use href="#${piece}" />
    </svg>`;
  }
  static shapeBishop(player: string) {
    return Shape.shape(player, "bishop");
  }
  static shapeKing(player: string) {
    return Shape.shape(player, "king");
  }
  static shapeKnight(player: string) {
    return Shape.shape(player, "knight");
  }
  static shapePawn(player: string) {
    return Shape.shape(player, "pawn");
  }
  static shapeQueen(player: string) {
    return Shape.shape(player, "queen");
  }
  static shapeRook(player: string) {
    return Shape.shape(player, "rook");
  }
}

class Constraints {
  static generate(args: ConstraintArguments, resultingChecks?: (args: ResultingChecksArguments) => PiecePosition[]): Options {
    let method;
    const { piecePositions, piece } = args;
    if (piecePositions[piece.data.id].active) {
      switch (piece.data.type) {
        case "BISHOP":
          method = Constraints.constraintsBishop;
          break;
        case "KING":
          method = Constraints.constraintsKing;
          break;
        case "KNIGHT":
          method = Constraints.constraintsKnight;
          break;
        case "PAWN":
          method = Constraints.constraintsPawn;
          break;
        case "QUEEN":
          method = Constraints.constraintsQueen;
          break;
        case "ROOK":
          method = Constraints.constraintsRook;
          break;
      }
    }
    const result = method ? method(args) : { moves: [], captures: [] };
    if (resultingChecks) {
      const moveIndex = args.moveIndex + 1;
      result.moves = result.moves.filter((location) => !resultingChecks({ piece, location, capture: false, moveIndex }).length);
      result.captures = result.captures.filter((location) => !resultingChecks({ piece, location, capture: true, moveIndex }).length);
    }
    return result;
  }

  static constraintsBishop(args: ConstraintArguments): Options {
    return Constraints.constraintsDiagonal(args);
  }

  static constraintsDiagonal(args: ConstraintArguments): Options {
    const response = { moves: [], captures: [] };
    const { piece } = args;

    Constraints.runUntil(piece.dirNW.bind(piece), response, args);
    Constraints.runUntil(piece.dirNE.bind(piece), response, args);
    Constraints.runUntil(piece.dirSW.bind(piece), response, args);
    Constraints.runUntil(piece.dirSE.bind(piece), response, args);

    return response;
  }

  static constraintsKing(args: ConstraintArguments): Options {
    const { piece, kingCastles, piecePositions } = args;
    const moves = [];
    const captures = [];
    const locations = [
      piece.dirN(1, piecePositions),
      piece.dirNE(1, piecePositions),
      piece.dirE(1, piecePositions),
      piece.dirSE(1, piecePositions),
      piece.dirS(1, piecePositions),
      piece.dirSW(1, piecePositions),
      piece.dirW(1, piecePositions),
      piece.dirNW(1, piecePositions),
    ];
    if (kingCastles) {
      const castles = kingCastles(piece);
      castles.forEach((position) => moves.push(position));
    }
    locations.forEach((location) => {
      const value = Constraints.relationshipToTile(location, args);
      if (value === "BLANK") {
        moves.push(location);
      } else if (value === "ENEMY") {
        captures.push(location);
      }
    });
    return { moves, captures };
  }

  static constraintsKnight(args: ConstraintArguments): Options {
    const { piece, piecePositions } = args;
    const moves = [];
    const captures = [];
    const locations = [
      piece.dir(1, 2, piecePositions),
      piece.dir(1, -2, piecePositions),
      piece.dir(2, 1, piecePositions),
      piece.dir(2, -1, piecePositions),
      piece.dir(-1, 2, piecePositions),
      piece.dir(-1, -2, piecePositions),
      piece.dir(-2, 1, piecePositions),
      piece.dir(-2, -1, piecePositions),
    ];
    locations.forEach((location) => {
      const value = Constraints.relationshipToTile(location, args);
      if (value === "BLANK") {
        moves.push(location);
      } else if (value === "ENEMY") {
        captures.push(location);
      }
    });
    return { moves, captures };
  }

  static constraintsOrthangonal(args: ConstraintArguments): Options {
    const { piece } = args;
    const response = { moves: [], captures: [] };

    Constraints.runUntil(piece.dirN.bind(piece), response, args);
    Constraints.runUntil(piece.dirE.bind(piece), response, args);
    Constraints.runUntil(piece.dirS.bind(piece), response, args);
    Constraints.runUntil(piece.dirW.bind(piece), response, args);

    return response;
  }

  static constraintsPawn(args: ConstraintArguments): Options {
    const { piece, piecePositions } = args;
    const moves = [];
    const captures = [];
    const locationN1 = piece.dirN(1, piecePositions);
    const locationN2 = piece.dirN(2, piecePositions);

    if (Constraints.relationshipToTile(locationN1, args) === "BLANK") {
      moves.push(locationN1);
      if (!piece.moves.length && Constraints.relationshipToTile(locationN2, args) === "BLANK") {
        moves.push(locationN2);
      }
    }

    [
      [piece.dirNW(1, piecePositions), piece.dirW(1, piecePositions)],
      [piece.dirNE(1, piecePositions), piece.dirE(1, piecePositions)],
    ].forEach(([location, enPassant]) => {
      const standardCaptureRelationship = Constraints.relationshipToTile(location, args);
      const enPassantCaptureRelationship = Constraints.relationshipToTile(enPassant, args);
      if (standardCaptureRelationship === "ENEMY") {
        captures.push(location);
      } else if (piece.moves.length > 0 && enPassantCaptureRelationship === "ENEMY") {
        const enPassantRow = enPassant.row === (piece.playerWhite() ? "5" : "4");
        const other = Constraints.locationToPiece(enPassant, args);
        if (enPassantRow && other && other.data.type === "PAWN") {
          if (other.moves.length === 1 && other.moves[0] === args.moveIndex - 1) {
            location.capture = { ...enPassant };
            captures.push(location);
          }
        }
      }
    });
    return { moves, captures };
  }

  static constraintsQueen(args: ConstraintArguments): Options {
    const diagonal = Constraints.constraintsDiagonal(args);
    const orthagonal = Constraints.constraintsOrthangonal(args);
    return {
      moves: diagonal.moves.concat(orthagonal.moves),
      captures: diagonal.captures.concat(orthagonal.captures),
    };
  }

  static constraintsRook(args: ConstraintArguments): Options {
    return Constraints.constraintsOrthangonal(args);
  }

  static locationToPiece(location: Position, args: ConstraintArguments): Piece | undefined {
    if (!location) {
      return undefined;
    }
    const { state, pieces } = args;
    const row = state[location.row];
    const occupyingId = row === undefined ? undefined : row[location.col];
    return pieces[occupyingId];
  }

  static relationshipToTile(location: Position, args: ConstraintArguments): TileRelation | undefined {
    if (!location) {
      return undefined;
    }
    const { piece } = args;
    const occupying = Constraints.locationToPiece(location, args);
    if (occupying) {
      return occupying.data.player === piece.data.player ? "FRIEND" : "ENEMY";
    } else {
      return "BLANK";
    }
  }

  static runUntil(locationFunction: (integer: number, positions: PiecePositions) => PieceDirResponse, response: Options, args: ConstraintArguments) {
    const { piecePositions } = args;

    let inc = 1;
    let location = locationFunction(inc++, piecePositions);
    while (location) {
      let abort = false;
      const relations = Constraints.relationshipToTile(location, args);
      if (relations === "ENEMY") {
        response.captures.push(location);
        abort = true;
      } else if (relations === "FRIEND") {
        abort = true;
      } else {
        response.moves.push(location);
      }
      if (abort) {
        location = undefined;
      } else {
        location = locationFunction(inc++, piecePositions);
      }
    }
  }
}

class Piece {
  data: PieceData;
  moves = [];
  promoted = false;
  updateShape = false;

  constructor(data: PieceData) {
    this.data = data;
  }

  get orientation() {
    return this.data.player === "BLACK" ? -1 : 1;
  }

  dirN(steps: number, positions: PiecePositions): PieceDirResponse {
    return this.dir(steps, 0, positions);
  }
  dirS(steps: number, positions: PiecePositions): PieceDirResponse {
    return this.dir(-steps, 0, positions);
  }
  dirW(steps: number, positions: PiecePositions): PieceDirResponse {
    return this.dir(0, -steps, positions);
  }
  dirE(steps: number, positions: PiecePositions): PieceDirResponse {
    return this.dir(0, steps, positions);
  }
  dirNW(steps: number, positions: PiecePositions): PieceDirResponse {
    return this.dir(steps, -steps, positions);
  }
  dirNE(steps: number, positions: PiecePositions): PieceDirResponse {
    return this.dir(steps, steps, positions);
  }
  dirSW(steps: number, positions: PiecePositions): PieceDirResponse {
    return this.dir(-steps, -steps, positions);
  }
  dirSE(steps: number, positions: PiecePositions): PieceDirResponse {
    return this.dir(-steps, steps, positions);
  }
  dir(stepsRow: number, stepsColumn: number, positions: PiecePositions): PieceDirResponse {
    PIECE_DIR_CALC++;
    const row = Utils.rowToInt(positions[this.data.id].row) + this.orientation * stepsRow;
    const col = Utils.colToInt(positions[this.data.id].col) + this.orientation * stepsColumn;
    if (row >= 0 && row <= 7 && col >= 0 && col <= 7) {
      return { row: Utils.intToRow(row), col: Utils.intToCol(col) };
    }
    return undefined;
  }

  move(moveIndex: number) {
    this.moves.push(moveIndex);
  }

  options(
    moveIndex: number,
    state: BoardState,
    pieces: Pieces,
    piecePositions: PiecePositions,
    resultingChecks?: (args: ResultingChecksArguments) => PiecePosition[],
    kingCastles?: (king: Piece) => Position[]
  ): Options {
    return Constraints.generate({ moveIndex, state, piece: this, pieces, piecePositions, kingCastles }, resultingChecks);
  }

  playerBlack() {
    return this.data.player === "BLACK";
  }
  playerWhite() {
    return this.data.player === "WHITE";
  }

  promote(type: PieceType = "QUEEN") {
    this.data.type = type;
    this.promoted = true;
    this.updateShape = true;
  }

  shape() {
    const player = this.data.player.toLowerCase();
    switch (this.data.type) {
      case "BISHOP":
        return Shape.shapeBishop(player);
      case "KING":
        return Shape.shapeKing(player);
      case "KNIGHT":
        return Shape.shapeKnight(player);
      case "PAWN":
        return Shape.shapePawn(player);
      case "QUEEN":
        return Shape.shapeQueen(player);
      case "ROOK":
        return Shape.shapeRook(player);
    }
  }
}

class Board {
  checksBlack: PiecePosition[] = [];
  checksWhite: PiecePosition[] = [];
  piecesTilesCaptures: PiecesToTiles = {};
  piecesTilesMoves: PiecesToTiles = {};
  tilesPiecesBlackCaptures: TilesToPieces = Utils.getInitialBoardState(() => []);
  tilesPiecesBlackMoves: TilesToPieces = Utils.getInitialBoardState(() => []);
  tilesPiecesWhiteCaptures: TilesToPieces = Utils.getInitialBoardState(() => []);
  tilesPiecesWhiteMoves: TilesToPieces = Utils.getInitialBoardState(() => []);

  pieceIdsBlack: PieceIdBlack[] = [];
  pieceIdsWhite: PieceIdWhite[] = [];
  piecePositions: PiecePositions;
  pieces: Pieces;
  state: BoardState = Utils.getInitialBoardState() as BoardState;

  static COLS: PositionColumn[] = ["A", "B", "C", "D", "E", "F", "G", "H"];
  static ROWS: PositionRow[] = ["1", "2", "3", "4", "5", "6", "7", "8"];

  constructor(pieces: Pieces, piecePositions: PiecePositions) {
    this.pieces = pieces;
    for (let id in pieces) {
      if (pieces[id].playerWhite()) {
        this.pieceIdsWhite.push(id as PieceIdWhite);
      } else {
        this.pieceIdsBlack.push(id as PieceIdBlack);
      }
    }
    this.initializePositions(piecePositions);
  }

  initializePositions(piecePositions: PiecePositions) {
    this.piecePositions = piecePositions;
    this.initializeState();
    this.piecesUpdate(0);
  }

  initializeState() {
    for (let pieceId in this.pieces) {
      const { row, col, active, _moves, _promoted } = this.piecePositions[pieceId];
      if (_moves) {
        delete this.piecePositions[pieceId]._moves;
        // TODO: come back to this
        // this.pieces[pieceId].moves = new Array(_moves);
      }
      if (_promoted) {
        delete this.piecePositions[pieceId]._promoted;
        this.pieces[pieceId].promote();
      }
      if (active) {
        this.state[row] = this.state[row] || [];
        this.state[row][col] = pieceId;
      }
    }
  }

  kingCastles(king: Piece): Position[] {
    const castles = [];
    // king has to not have moved
    if (king.moves.length) {
      return castles;
    }
    const kingIsWhite = king.playerWhite();
    const moves = kingIsWhite ? this.tilesPiecesBlackMoves : this.tilesPiecesWhiteMoves;
    const checkPositions = (row: PositionRow, rookCol: PositionColumn, castles: Position[]) => {
      const cols: PositionColumn[] = rookCol === "A" ? ["D", "C", "B"] : ["F", "G"];
      // rook has to not have moved
      const rookId = `${rookCol}${row}`;
      const rook = this.pieces[rookId];
      const { active } = this.piecePositions[rookId];
      if (active && rook.moves.length === 0) {
        let canCastle = true;
        cols.forEach((col) => {
          // each tile has to be empty
          if (this.state[row][col]) {
            canCastle = false;
            // each tile cant be in the path of the other team
          } else if (moves[row][col].length) {
            canCastle = false;
          }
        });
        if (canCastle) {
          castles.push({ col: cols[1], row, castles: rookCol });
        }
      }
    };
    const row = kingIsWhite ? "1" : "8";
    if (!this.pieces[`A${row}`].moves.length) {
      checkPositions(row, "A", castles);
    }
    if (!this.pieces[`H${row}`].moves.length) {
      checkPositions(row, "H", castles);
    }
    return castles;
  }

  kingCheckStates(kingPosition: PiecePosition, captures: TilesToPieces, piecePositions: PiecePositions): PiecePosition[] {
    const { col, row } = kingPosition;
    return captures[row][col].map((id) => piecePositions[id]).filter((pos) => pos.active);
  }

  pieceCalculateMoves(
    pieceId: PieceId,
    moveIndex: number,
    state: BoardState,
    piecePositions: PiecePositions,
    piecesTilesCaptures: PiecesToTiles,
    piecesTilesMoves: PiecesToTiles,
    tilesPiecesCaptures: TilesToPieces,
    tilesPiecesMoves: TilesToPieces,
    resultingChecks?: (args: ResultingChecksArguments) => PiecePosition[],
    kingCastles?: (king: Piece) => Position[]
  ) {
    const { captures, moves } = this.pieces[pieceId].options(moveIndex, state, this.pieces, piecePositions, resultingChecks, kingCastles);
    piecesTilesCaptures[pieceId] = Array.from(captures);
    piecesTilesMoves[pieceId] = Array.from(moves);
    captures.forEach(({ col, row }) => tilesPiecesCaptures[row][col].push(pieceId));
    moves.forEach(({ col, row }) => tilesPiecesMoves[row][col].push(pieceId));
  }

  pieceCapture(piece: Piece) {
    const pieceId = piece.data.id;
    const { col, row } = this.piecePositions[pieceId];
    this.state[row][col] = undefined;
    delete this.piecePositions[pieceId].col;
    delete this.piecePositions[pieceId].row;
    this.piecePositions[pieceId].active = false;
  }

  pieceMove(piece: Piece, location: Position) {
    const pieceId = piece.data.id;
    const { row, col } = this.piecePositions[pieceId];
    this.state[row][col] = undefined;
    this.state[location.row][location.col] = pieceId;
    this.piecePositions[pieceId].row = location.row;
    this.piecePositions[pieceId].col = location.col;
    if (piece.data.type === "PAWN" && (location.row === "8" || location.row === "1")) {
      piece.promote();
    }
  }

  piecesUpdate(moveIndex: number) {
    this.tilesPiecesBlackCaptures = Utils.getInitialBoardState(() => []);
    this.tilesPiecesBlackMoves = Utils.getInitialBoardState(() => []);
    this.tilesPiecesWhiteCaptures = Utils.getInitialBoardState(() => []);
    this.tilesPiecesWhiteMoves = Utils.getInitialBoardState(() => []);

    this.pieceIdsBlack.forEach((id) =>
      this.pieceCalculateMoves(
        id,
        moveIndex,
        this.state,
        this.piecePositions,
        this.piecesTilesCaptures,
        this.piecesTilesMoves,
        this.tilesPiecesBlackCaptures,
        this.tilesPiecesBlackMoves,
        this.resultingChecks.bind(this),
        this.kingCastles.bind(this)
      )
    );
    this.pieceIdsWhite.forEach((id) =>
      this.pieceCalculateMoves(
        id,
        moveIndex,
        this.state,
        this.piecePositions,
        this.piecesTilesCaptures,
        this.piecesTilesMoves,
        this.tilesPiecesWhiteCaptures,
        this.tilesPiecesWhiteMoves,
        this.resultingChecks.bind(this),
        this.kingCastles.bind(this)
      )
    );

    this.checksBlack = this.kingCheckStates(this.piecePositions.E1, this.tilesPiecesBlackCaptures, this.piecePositions);
    this.checksWhite = this.kingCheckStates(this.piecePositions.E8, this.tilesPiecesWhiteCaptures, this.piecePositions);
  }

  resultingChecks({ piece, location, capture, moveIndex }: ResultingChecksArguments) {
    const tilesPiecesCaptures = Utils.getInitialBoardState(() => []);
    const tilesPiecesMoves = Utils.getInitialBoardState(() => []);
    const piecesTilesCaptures = {};
    const piecesTilesMoves = {};
    const state = JSON.parse(JSON.stringify(this.state));
    const piecePositions = JSON.parse(JSON.stringify(this.piecePositions));
    if (capture) {
      const loc = location.capture || location;
      const capturedId = state[loc.row][loc.col];
      if (this.pieces[capturedId].data.type === "KING") {
        // this is a checking move
      } else {
        delete piecePositions[capturedId].col;
        delete piecePositions[capturedId].row;
        piecePositions[capturedId].active = false;
      }
    }
    const pieceId = piece.data.id;
    const { row, col } = piecePositions[pieceId];
    state[row][col] = undefined;
    state[location.row][location.col] = pieceId;
    piecePositions[pieceId].row = location.row;
    piecePositions[pieceId].col = location.col;

    const ids = piece.playerWhite() ? this.pieceIdsBlack : this.pieceIdsWhite;
    const king = piece.playerWhite() ? piecePositions.E1 : piecePositions.E8;
    ids.forEach((id) =>
      this.pieceCalculateMoves(id, moveIndex, state, piecePositions, piecesTilesCaptures, piecesTilesMoves, tilesPiecesCaptures, tilesPiecesMoves)
    );
    return this.kingCheckStates(king, tilesPiecesCaptures, piecePositions);
  }

  tileEach(callback: (position: Position, piece?: Piece, pieceMoves?: Position[], pieceCaptures?: Position[]) => void) {
    Board.ROWS.forEach((row) => {
      Board.COLS.forEach((col) => {
        const piece = this.tileFind({ row, col });
        const moves = piece ? this.piecesTilesMoves[piece.data.id] : undefined;
        const captures = piece ? this.piecesTilesCaptures[piece.data.id] : undefined;
        callback({ row, col }, piece, moves, captures);
      });
    });
  }

  tileFind({ row, col }: Position): Piece | undefined {
    const id = this.state[row][col];
    return this.pieces[id];
  }

  toShortCode() {
    const positionsAbsolute = [];
    const positionsDefaults = [];
    for (let id in this.piecePositions) {
      const { active, col, row } = this.piecePositions[id];
      const pos = `${col}${row}`;
      const moves = this.pieces[id].moves;
      const promotedCode = this.pieces[id].promoted ? "P" : "";
      const movesCode = moves > 9 ? "9" : moves > 1 ? moves.toString() : "";
      if (active) {
        positionsAbsolute.push(`${promotedCode}${id}${id === pos ? "" : pos}${movesCode}`);
        if (id !== pos || moves > 0) {
          positionsDefaults.push(`${promotedCode}${id}${pos}${movesCode}`);
        }
      } else {
        if (id !== "BQ" && id !== "WQ") {
          positionsDefaults.push(`${promotedCode}${id}X`);
        }
      }
    }
    const pA = positionsAbsolute.join(",");
    const pD = positionsDefaults.join(",");
    return pA.length > pD.length ? `X${pD}` : pA;
  }
}

class Game {
  active: Piece | null = null;
  activePieceOptions: Position[] = [];
  board: Board;
  moveIndex = 0;
  moves = [];
  turn: PlayerId;

  constructor(pieces: Pieces, piecePositions: PiecePositions, turn: PlayerId = "WHITE") {
    this.turn = turn;
    this.board = new Board(pieces, piecePositions);
  }

  activate(location: Position): ActivateResponse {
    const tilePiece = this.board.tileFind(location);
    if (tilePiece && !this.active && tilePiece.data.player !== this.turn) {
      this.active = null;
      return { type: "INVALID" };
      // a piece is active rn
    } else if (this.active) {
      const activePieceId = this.active.data.id;
      this.active = null;
      const validatedPosition = this.activePieceOptions.find((option) => option.col === location.col && option.row === location.row);
      const positionIsValid = !!validatedPosition;
      this.activePieceOptions = [];
      const capturePiece: Piece | undefined = validatedPosition?.capture ? this.board.tileFind(validatedPosition.capture) : tilePiece;

      // a piece is on the tile
      if (capturePiece) {
        const capturedPieceId = capturePiece.data.id;
        // cancelling the selected piece on invalid location
        if (capturedPieceId === activePieceId) {
          return { type: "CANCEL" };
        } else if (positionIsValid) {
          // capturing the selected piece
          this.capture(activePieceId, capturedPieceId, location);
          return {
            type: "CAPTURE",
            activePieceId,
            capturedPieceId,
            captures: [location],
          };
          // cancel
        } else if (capturePiece.data.player !== this.turn) {
          return { type: "CANCEL" };
        } else {
          // proceed to TOUCH or CANCEL
        }
      } else if (positionIsValid) {
        // moving will return castled if that happens (only two move)
        const castledId = this.move(activePieceId, location);
        return { type: "MOVE", activePieceId, moves: [location], castledId };
        // invalid spot. cancel.
      } else {
        return { type: "CANCEL" };
      }
    }

    // no piece selected or new CANCEL + TOUCH
    if (tilePiece) {
      const tilePieceId = tilePiece.data.id;
      const moves = this.board.piecesTilesMoves[tilePieceId];
      const captures = this.board.piecesTilesCaptures[tilePieceId];
      if (!moves.length && !captures.length) {
        return { type: "INVALID" };
      }
      this.active = tilePiece;
      this.activePieceOptions = moves.concat(captures);
      return { type: "TOUCH", captures, moves, activePieceId: tilePieceId };
      // cancelling
    } else {
      this.activePieceOptions = [];
      return { type: "CANCEL" };
    }
  }

  capture(capturingPieceId: PieceId, capturedPieceId: PieceId, location: Position) {
    const captured = this.board.pieces[capturedPieceId];
    this.board.pieceCapture(captured);
    this.move(capturingPieceId, location, true);
  }

  handleCastling(piece: Piece, location: Position): PieceId | undefined {
    if (
      piece.data.type !== "KING" ||
      piece.moves.length ||
      location.row !== (piece.playerWhite() ? "1" : "8") ||
      (location.col !== "C" && location.col !== "G")
    ) {
      return;
    }

    return `${location.col === "C" ? "A" : "H"}${location.row}` as PieceId;
  }

  move(pieceId: PieceId, location: Position, capture = false): PieceId | undefined {
    const piece = this.board.pieces[pieceId];
    const castledId = this.handleCastling(piece, location);
    piece.move(this.moveIndex);
    if (castledId) {
      const castled = this.board.pieces[castledId];
      castled.move(this.moveIndex);
      this.board.pieceMove(castled, { col: location.col === "C" ? "D" : "F", row: location.row });
      this.moves.push(`${pieceId}O${location.col}${location.row}`);
    } else {
      this.moves.push(`${pieceId}${capture ? "x" : ""}${location.col}${location.row}`);
    }
    this.moveIndex++;
    this.board.pieceMove(piece, location);
    this.turn = this.turn === "WHITE" ? "BLACK" : "WHITE";
    this.board.piecesUpdate(this.moveIndex);
    const state = this.moveResultState();
    console.log(state);
    if (!state.moves && !state.captures) {
      alert(state.stalemate ? "Stalemate!" : `${this.turn === "WHITE" ? "Black" : "White"} Wins!`);
    }
    return castledId;
  }

  moveResultState() {
    let movesWhite = 0;
    let capturesWhite = 0;
    let movesBlack = 0;
    let capturesBlack = 0;
    this.board.tileEach(({ row, col }) => {
      movesWhite += this.board.tilesPiecesWhiteMoves[row][col].length;
      capturesWhite += this.board.tilesPiecesWhiteCaptures[row][col].length;
      movesBlack += this.board.tilesPiecesBlackMoves[row][col].length;
      capturesBlack += this.board.tilesPiecesBlackCaptures[row][col].length;
    });
    const activeBlack = this.board.pieceIdsBlack.filter((pieceId) => this.board.piecePositions[pieceId].active).length;
    const activeWhite = this.board.pieceIdsWhite.filter((pieceId) => this.board.piecePositions[pieceId].active).length;
    const moves = this.turn === "WHITE" ? movesWhite : movesBlack;
    const captures = this.turn === "WHITE" ? capturesWhite : capturesBlack;
    const noMoves =  movesWhite + capturesWhite + movesBlack + capturesBlack === 0;
    const checked = !!this.board[this.turn === "WHITE" ? "checksBlack" : "checksWhite"].length;
    const onlyKings = activeBlack === 1 && activeWhite === 1;
    const stalemate =  onlyKings || noMoves || ((moves + captures === 0) && !checked);
    const code = this.board.toShortCode();
    return { turn: this.turn, checked, moves, captures, code, stalemate };
  }
  
  randomMove(): Position {
    if (this.active) {
      if (this.activePieceOptions.length) {
        const { col, row } = this.activePieceOptions[Math.floor(Math.random() * this.activePieceOptions.length)];
        return { col, row };
      } else {
        const {col, row} = this.board.piecePositions[this.active.data.id];
        return { col, row };
      }
    } else {
      const ids: PieceId[] = this.turn === "WHITE" ? this.board.pieceIdsWhite : this.board.pieceIdsBlack;
      const positions = ids.map((pieceId: PieceId) => {
        const moves = this.board.piecesTilesMoves[pieceId];
        const captures = this.board.piecesTilesCaptures[pieceId];
        return (moves.length || captures.length) ? this.board.piecePositions[pieceId] : undefined; 
      }).filter((position) => position?.active);
      const remaining = positions[Math.floor(Math.random() * positions.length)];
      const { col, row } = remaining || { col: "E", row: "1" };
      return { col, row };
    }
  }
}

class View {
  element: HTMLElement;
  game: Game;
  pieces: BoardPieces;
  tiles: BoardTiles;

  constructor(element: HTMLElement, game: Game, perspective?: PlayerId) {
    this.element = element;
    this.game = game;
    this.setPerspective(perspective || this.game.turn);
    this.tiles = Utils.getInitialBoardTiles(this.element, this.handleTileClick.bind(this));
    this.pieces = Utils.getInitialBoardPieces(this.element, this.game.board.pieces);
    this.drawPiecePositions();
  }

  drawActivePiece(activePieceId: PieceId) {
    const { row, col } = this.game.board.piecePositions[activePieceId];
    this.tiles[row][col].classList.add("highlight-active");
    this.pieces[activePieceId].classList.add("highlight-active");
  }

  drawCapturedPiece(capturedPieceId: PieceId) {
    const piece = this.pieces[capturedPieceId];
    piece.style.setProperty("--transition-delay", "var(--transition-duration)");
    piece.style.removeProperty("--pos-col");
    piece.style.removeProperty("--pos-row");
    piece.style.setProperty("--scale", "0");
  }

  drawPiecePositions(moves: Position[] = [], moveInner: string = "") {
    document.body.style.setProperty("--color-background", `var(--color-${this.game.turn.toLowerCase()}`);
    const other = this.game.turn === "WHITE" ? "turn-black" : "turn-white";
    const current = this.game.turn === "WHITE" ? "turn-white" : "turn-black";
    this.element.classList.add(current);
    this.element.classList.remove(other);
    if (moves.length) {
      this.element.classList.add("touching");
    } else {
      this.element.classList.remove("touching");
    }

    const key = (row, col) => `${row}-${col}`;
    const moveKeys = moves.map(({ row, col }) => key(row, col));
    this.game.board.tileEach(({ row, col }, piece, pieceMoves, pieceCaptures) => {
      const tileElement = this.tiles[row][col];
      const move = moveKeys.includes(key(row, col)) ? moveInner : "";
      const format = (id, className) => this.game.board.pieces[id].shape();
      tileElement.innerHTML = `
        <div class="move">${move}</div>
        <div class="moves">
          ${this.game.board.tilesPiecesBlackMoves[row][col].map((id) => format(id, "black")).join("")}
          ${this.game.board.tilesPiecesWhiteMoves[row][col].map((id) => format(id, "white")).join("")}
        </div>
        <div class="captures">
          ${this.game.board.tilesPiecesBlackCaptures[row][col].map((id) => format(id, "black")).join("")}
          ${this.game.board.tilesPiecesWhiteCaptures[row][col].map((id) => format(id, "white")).join("")}
        </div>
      `;
      if (piece) {
        tileElement.classList.add("occupied");
        const pieceElement = this.pieces[piece.data.id];
        pieceElement.style.setProperty("--pos-col", Utils.colToInt(col).toString());
        pieceElement.style.setProperty("--pos-row", Utils.rowToInt(row).toString());
        pieceElement.style.setProperty("--scale", "1");
        pieceElement.classList[pieceMoves?.length ? "add" : "remove"]("can-move");
        pieceElement.classList[pieceCaptures?.length ? "add" : "remove"]("can-capture");
        if (piece.updateShape) {
          piece.updateShape = false;
          pieceElement.innerHTML = piece.shape();
        }
      } else {
        tileElement.classList.remove("occupied");
      }
    });
  }

  drawPositions(moves: Position[], captures: Position[]) {
    moves?.forEach(({ row, col }) => {
      this.tiles[row][col].classList.add("highlight-move");
      this.pieces[this.game.board.tileFind({ row, col })?.data.id]?.classList.add("highlight-move");
    });
    captures?.forEach(({ row, col, capture }) => {
      if (capture) {
        row = capture.row;
        col = capture.col;
      }
      this.tiles[row][col].classList.add("highlight-capture");
      this.pieces[this.game.board.tileFind({ row, col })?.data.id]?.classList.add("highlight-capture");
    });
  }

  drawResetClassNames() {
    document.querySelectorAll(".highlight-active").forEach((element) => element.classList.remove("highlight-active"));
    document.querySelectorAll(".highlight-capture").forEach((element) => element.classList.remove("highlight-capture"));
    document.querySelectorAll(".highlight-move").forEach((element) => element.classList.remove("highlight-move"));
  }

  handleTileClick(location: Position) {
    const { activePieceId, capturedPieceId, moves = [], captures = [], type } = this.game.activate(location);

    this.drawResetClassNames();
    if (type === "TOUCH") {
      const enPassant = captures.find((capture) => !!capture.capture);
      const passingMoves = enPassant ? moves.concat([enPassant]) : moves;
      this.drawPiecePositions(passingMoves, this.game.board.pieces[activePieceId].shape());
    } else {
      this.drawPiecePositions();
    }

    if (type === "CANCEL" || type === "INVALID") {
      return;
    }

    if (type === "MOVE" || type === "CAPTURE") {
    } else {
      this.drawActivePiece(activePieceId);
    }
    if (type === "TOUCH") {
      this.drawPositions(moves, captures);
    } else if (type === "CAPTURE") {
      this.drawCapturedPiece(capturedPieceId);
    }
    // crazy town
    // this.setPerspective(this.game.turn);
  }

  setPerspective(perspective: PlayerId) {
    const other = perspective === "WHITE" ? "perspective-black" : "perspective-white";
    const current = perspective === "WHITE" ? "perspective-white" : "perspective-black";
    this.element.classList.add(current);
    this.element.classList.remove(other);
  }
}

class Control {
  game: Game;
  inputSpeedAsap: HTMLInputElement = document.getElementById("speed-asap") as HTMLInputElement;
  inputSpeedFast: HTMLInputElement = document.getElementById("speed-fast") as HTMLInputElement;
  inputSpeedMedium: HTMLInputElement = document.getElementById("speed-medium") as HTMLInputElement;
  inputSpeedSlow: HTMLInputElement = document.getElementById("speed-slow") as HTMLInputElement;
  inputRandomBlack: HTMLInputElement = document.getElementById("black-random") as HTMLInputElement;
  inputRandomWhite: HTMLInputElement = document.getElementById("white-random") as HTMLInputElement;
  inputPerspectiveBlack: HTMLInputElement = document.getElementById("black-perspective") as HTMLInputElement;
  inputPerspectiveWhite: HTMLInputElement = document.getElementById("white-perspective") as HTMLInputElement;
  view: View;

  constructor(game: Game, view: View) {
    this.game = game;
    this.view = view;
    this.inputPerspectiveBlack.addEventListener("change", this.updateViewPerspective.bind(this));
    this.inputPerspectiveWhite.addEventListener("change", this.updateViewPerspective.bind(this));
    this.updateViewPerspective();
  }
  
  get speed() {
    if (this.inputSpeedAsap.checked) {
      return 50;
    }
    if (this.inputSpeedFast.checked) {
      return 250;
    }
    if (this.inputSpeedMedium.checked) {
      return 500;
    }
    if (this.inputSpeedSlow.checked) {
      return 1000;
    }
  }

  autoplay() {
    const input = this.game.turn === "WHITE" ? this.inputRandomWhite : this.inputRandomBlack;
    if (!input.checked) {
      setTimeout(this.autoplay.bind(this), this.speed);
      return;
    }
    const position = this.game.randomMove();
    this.view.handleTileClick(position);
    setTimeout(this.autoplay.bind(this), this.speed);
  }

  updateViewPerspective() {
    this.view.setPerspective(this.inputPerspectiveBlack.checked ? "BLACK" : "WHITE");
  }
}

const DEMOS = {
  castle1: "XD8B3,B1X,C1X,D1X,F1X,G1X",
  castle2: "XD8B3,B1X,C1X,C2X,D1X,F1X,G1X",
  castle3: "XD8E3,B1X,C1X,F2X,D1X,F1X,G1X",
  promote1: "E1,E8,C2C7",
  promote2: "E1,E8E7,PC2C8",
  start: "XE7E6,F7F5,D2D4,E2E5",
  test2: "C8E2,E8,G8H1,D7E4,H7H3,PA2H7,PB2G7,D2D6,E2E39,A1H2,E1B3",
  test: "C8E2,E8,G8H1,D7E4,H7H3,D1H7,PB2G7,D2D6,E2E39,A1H2,E1B3",
};

const initialPositions = Utils.getInitialPiecePositions();
// const initialPositions = Utils.getPositionsFromShortCode(DEMOS.castle1);
const initialTurn = "WHITE";
const perspective = "WHITE";
const game = new Game(Utils.getInitialPieces(), initialPositions, initialTurn);
const view = new View(document.getElementById("board"), game, perspective);
const control = new Control(game, view);

control.autoplay();
              
            
!
999px

Console