"use client";
import {
useEffect,
useLayoutEffect,
useRef,
useState,
useSyncExternalStore,
type ReactNode,
} from "react";
import { useAnimationLoop, type Metrics } from "@/hooks/use-animation-loop";
import {
generate,
Search,
type Maze,
type PathfinderAlgorithm,
type PathfinderMaze,
} from "./pathfinder-engine";
export type { PathfinderAlgorithm, PathfinderMaze } from "./pathfinder-engine";
export interface PathfinderProps {
algorithm?: PathfinderAlgorithm;
maze?: PathfinderMaze;
diagonal?: boolean;
speed?: number;
cellSize?: number;
autoplay?: boolean;
searchColor?: string;
pathColor?: string;
boardColor?: string;
paused?: boolean;
reducedMotion?: boolean;
className?: string;
}
type Phase = "carve" | "search" | "trace" | "hold" | "fade" | "idle";
type Action = "new" | "run" | "clear";
type Rgb = [number, number, number];
interface Drag {
id: number;
kind: "start" | "goal" | "wall";
value: number;
last: number;
}
const CARVE_MIN = 1;
const CARVE_MAX = 1.4;
const TRACE = 0.45;
const HOLD = 1.6;
const FADE = 0.35;
const CHROME_MIN_HEIGHT = 280;
const CHROME_MIN_WIDTH = 260;
const PAD = 8;
const BAND_TOP = 40;
const BAND_BOTTOM = 46;
const LABELS: Record<PathfinderAlgorithm, string> = {
astar: "A*",
dijkstra: "Dijkstra",
bfs: "BFS",
greedy: "Greedy",
};
const REDUCED_QUERY = "(prefers-reduced-motion: reduce)";
const subscribeReduced = (onChange: () => void) => {
const mq = window.matchMedia(REDUCED_QUERY);
mq.addEventListener("change", onChange);
return () => mq.removeEventListener("change", onChange);
};
const readReduced = () => window.matchMedia(REDUCED_QUERY).matches;
const readReducedOnServer = () => false;
export default function Pathfinder({
algorithm = "astar",
maze = "backtracker",
diagonal = false,
speed = 1,
cellSize = 18,
autoplay = true,
searchColor = "#a855f7",
pathColor = "#f0abfc",
boardColor = "#0d0b12",
paused = false,
reducedMotion = false,
className = "",
}: PathfinderProps) {
const wrapRef = useRef<HTMLDivElement>(null);
const canvasRef = useRef<HTMLCanvasElement>(null);
const exploredRef = useRef<HTMLSpanElement>(null);
const stepsRef = useRef<HTMLSpanElement>(null);
const announceRef = useRef<HTMLParagraphElement>(null);
const drawRef = useRef<((dt: number) => void | false) | null>(null);
const measureRef = useRef<((m: Metrics) => void) | null>(null);
const actRef = useRef<((action: Action) => void) | null>(null);
const [chrome, setChrome] = useState(false);
const osReduced = useSyncExternalStore(subscribeReduced, readReduced, readReducedOnServer);
const reduce = reducedMotion || osReduced;
const live = useRef({
algorithm,
maze,
diagonal,
speed,
cellSize,
autoplay,
searchColor,
pathColor,
boardColor,
paused,
reduce,
});
useLayoutEffect(() => {
live.current = {
algorithm,
maze,
diagonal,
speed,
cellSize,
autoplay,
searchColor,
pathColor,
boardColor,
paused,
reduce,
};
});
const loop = useAnimationLoop({
target: wrapRef,
halted: paused || reduce,
dpr: "auto",
resizeDebounceMs: 120,
onResize: (m) => measureRef.current?.(m),
onFrame: ({ dt }) => (drawRef.current ? drawRef.current(dt) : false),
});
useEffect(() => {
const wrap = wrapRef.current;
const canvas = canvasRef.current;
if (!wrap || !canvas) return;
const ctx = canvas.getContext("2d");
if (!ctx) return;
let width = 0;
let height = 0;
let dpr = 1;
let cols = 0;
let rows = 0;
let cs = 0;
let ox = 0;
let oy = 0;
let ready = false;
let gridLines = new Path2D();
let walls: Uint8Array = new Uint8Array(0);
let shown: Uint8Array = new Uint8Array(0);
let build: Maze | null = null;
let next: Maze | null = null;
let revealed = 0;
let start = 0;
let goal = 0;
let turn = -1;
let edited = false;
let search: Search | null = null;
let budget = 0;
let clock = 0;
let path: Int32Array = new Int32Array(0);
let pathLength = 0;
let progress = 0;
let phase: Phase = "idle";
let t = 0;
let carveFor = CARVE_MIN;
let announceRun = false;
let cursor = 0;
let focused = false;
let keyboard = false;
let drag: Drag | null = null;
let pointerLook = "";
const initial = live.current;
const applied = {
algorithm: initial.algorithm,
diagonal: initial.diagonal,
maze: initial.maze,
autoplay: initial.autoplay,
reduce: initial.reduce,
};
const cycling = () => {
const l = live.current;
return l.autoplay && !edited && !l.reduce;
};
const still = () => live.current.paused || live.current.reduce;
const rate = () => Math.max(0.05, live.current.speed) * Math.max(60, (cols * rows) / 3.2);
const pal = {
key: "",
board: "",
wall: "",
lip: "",
grid: "",
age: ["", "", ""],
glow: ["", "", ""],
front: "",
path: "",
core: "",
ink: "",
halo: "",
};
const palette = () => {
const l = live.current;
const key = `${l.boardColor}|${l.searchColor}|${l.pathColor}`;
if (key === pal.key) return pal;
const board = toRgb(ctx, l.boardColor, [13, 11, 18]);
const seek = toRgb(ctx, l.searchColor, [168, 85, 247]);
const route = toRgb(ctx, l.pathColor, [240, 171, 252]);
const dark = luminance(board) < 0.5;
pal.key = key;
pal.board = rgba(board, 1);
pal.wall = rgba(mix(board, dark ? [255, 255, 255] : [0, 0, 0], dark ? 0.1 : 0.13), 1);
pal.lip = dark
? rgba(mix(board, [255, 255, 255], 0.2), 1)
: rgba(mix(board, [255, 255, 255], 0.55), 1);
pal.grid = dark ? "rgba(255,255,255,0.05)" : "rgba(0,0,0,0.06)";
pal.age = [rgba(seek, 0.66), rgba(seek, 0.42), rgba(seek, 0.25)];
const spark = dark
? mix([255, 255, 255], seek, 0.28)
: mix(mix(board, [0, 0, 0], 0.7), seek, 0.28);
pal.glow = [rgba(spark, 0.55), rgba(spark, 0.32), rgba(spark, 0.17)];
pal.front = dark
? rgba(mix(seek, [255, 255, 255], 0.5), 0.92)
: rgba(mix(seek, [0, 0, 0], 0.25), 0.92);
pal.path = rgba(route, 1);
pal.core = rgba(mix(route, [255, 255, 255], 0.65), 0.95);
pal.ink = dark ? "rgba(255,255,255,0.96)" : "rgba(18,16,24,0.92)";
pal.halo = rgba(board, 0.72);
return pal;
};
const cx = (cell: number) => ox + ((cell % cols) + 0.5) * cs;
const cy = (cell: number) => oy + (Math.floor(cell / cols) + 0.5) * cs;
const lengthOf = (route: Int32Array) => {
let total = 0;
for (let i = 1; i < route.length; i++) {
const a = route[i - 1];
const b = route[i];
total += a % cols !== b % cols && Math.floor(a / cols) !== Math.floor(b / cols) ? Math.SQRT2 : 1;
}
return total;
};
const fresh = (): Maze => {
turn++;
const seed = (Math.imul(turn + 1, 0x9e3779b1) ^ 0x5eed) >>> 0;
return generate(cols, rows, live.current.maze, seed, turn);
};
const adopt = (m: Maze) => {
build = m;
walls = m.walls.slice();
start = m.start;
goal = m.goal;
search = null;
path = new Int32Array(0);
pathLength = 0;
progress = 0;
};
const say = (message: string) => {
const el = announceRef.current;
if (!el) return;
el.textContent = el.textContent === message ? message + String.fromCharCode(160) : message;
};
const finishSearch = () => {
const s = search;
path = s && s.found ? s.path() : new Int32Array(0);
pathLength = lengthOf(path);
if (announceRun && s) {
announceRun = false;
say(
s.found
? `Path found: ${path.length - 1} steps, ${s.visited} cells explored.`
: `No path found. ${s.visited} cells explored.`,
);
}
};
const solveNow = () => {
const l = live.current;
search = new Search(walls, cols, rows, start, goal, l.algorithm, l.diagonal).solve();
budget = 0;
clock = Infinity;
finishSearch();
progress = search.found ? 1 : 0;
};
const startSearch = () => {
const l = live.current;
search = new Search(walls, cols, rows, start, goal, l.algorithm, l.diagonal);
budget = 0;
clock = 0;
path = new Int32Array(0);
pathLength = 0;
progress = 0;
phase = "search";
t = 0;
};
const beginCarve = (m: Maze) => {
adopt(m);
shown = new Uint8Array(cols * rows).fill(m.solid ? 1 : 0);
revealed = 0;
carveFor = CARVE_MIN + (CARVE_MAX - CARVE_MIN) * Math.min(1, m.order.length / 1200);
phase = "carve";
t = 0;
};
const settle = (m: Maze) => {
next = null;
adopt(m);
solveNow();
phase = cycling() ? "hold" : "idle";
t = 0;
};
const beginFade = () => {
next = fresh();
if (phase === "fade") return;
phase = "fade";
t = 0;
};
const completeBuild = () => {
if (phase === "carve" && build) revealed = build.order.length;
next = null;
};
const beginEdit = () => {
completeBuild();
edited = true;
announceRun = false;
phase = "idle";
t = 0;
};
const newMaze = () => {
edited = false;
announceRun = false;
if (still()) settle(fresh());
else beginFade();
};
const run = () => {
completeBuild();
announceRun = true;
if (still()) {
solveNow();
phase = cycling() ? "hold" : "idle";
t = 0;
} else {
startSearch();
}
};
const clear = () => {
beginEdit();
walls.fill(0);
solveNow();
};
const restart = () => {
next = null;
shown = new Uint8Array(cols * rows);
cursor = (rows >> 1) * cols + (cols >> 1);
const m = fresh();
if (still() || !live.current.autoplay) settle(m);
else beginCarve(m);
};
const refit = (pc: number, pr: number, pw: Uint8Array, ps: number, pg: number, pcur: number) => {
const n = cols * rows;
const nw = new Uint8Array(n);
const dx = Math.floor((cols - pc) / 2);
const dy = Math.floor((rows - pr) / 2);
for (let y = 0; y < rows; y++) {
const sy = y - dy;
if (sy < 0 || sy >= pr) continue;
for (let x = 0; x < cols; x++) {
const sx = x - dx;
if (sx >= 0 && sx < pc) nw[y * cols + x] = pw[sy * pc + sx];
}
}
const carry = (cell: number) => {
const x = Math.min(cols - 1, Math.max(0, (cell % pc) + dx));
const y = Math.min(rows - 1, Math.max(0, Math.floor(cell / pc) + dy));
return y * cols + x;
};
walls = nw;
start = carry(ps);
goal = carry(pg);
if (goal === start) goal = start + 1 < n ? start + 1 : start - 1;
walls[start] = 0;
walls[goal] = 0;
cursor = carry(pcur);
build = null;
next = null;
shown = new Uint8Array(n);
solveNow();
phase = "idle";
t = 0;
};
const syncProps = () => {
const l = live.current;
if (l.reduce !== applied.reduce) {
applied.reduce = l.reduce;
if (l.reduce) {
if (phase !== "idle") {
completeBuild();
if (!search || !search.done) solveNow();
else {
clock = Infinity;
progress = search.found ? 1 : 0;
}
phase = "idle";
t = 0;
}
} else if (cycling() && phase === "idle") {
phase = "hold";
t = HOLD;
}
}
if (l.autoplay !== applied.autoplay) {
applied.autoplay = l.autoplay;
edited = false;
if (l.autoplay && !l.reduce && phase === "idle") {
phase = "hold";
t = HOLD;
}
}
if (l.maze !== applied.maze) {
applied.maze = l.maze;
if (!edited) newMaze();
}
if (l.algorithm !== applied.algorithm || l.diagonal !== applied.diagonal) {
applied.algorithm = l.algorithm;
applied.diagonal = l.diagonal;
if (phase === "carve" || phase === "fade") {
} else if (phase === "idle" || still()) {
solveNow();
if (phase !== "idle") {
phase = cycling() ? "hold" : "idle";
t = 0;
}
} else {
startSearch();
}
}
};
const advance = (dt: number) => {
switch (phase) {
case "carve": {
t += dt;
if (!build) {
phase = "idle";
break;
}
const total = build.order.length;
const k = t >= carveFor ? total : Math.floor((total * t) / carveFor);
while (revealed < k) {
const cell = build.order[revealed++];
shown[cell] = build.walls[cell];
}
if (t >= carveFor) startSearch();
break;
}
case "search": {
const s = search;
if (!s) {
phase = "idle";
break;
}
const r = rate();
budget += r * dt;
clock += r * dt;
const n = Math.floor(budget);
if (n > 0) {
s.step(n);
budget -= n;
}
if (s.done) {
finishSearch();
phase = s.found ? "trace" : "hold";
t = 0;
}
break;
}
case "trace": {
t += dt;
clock += rate() * dt;
const k = Math.min(1, t / TRACE);
progress = 1 - (1 - k) * (1 - k) * (1 - k);
if (t >= TRACE) {
progress = 1;
phase = "hold";
t = 0;
}
break;
}
case "hold": {
t += dt;
clock += rate() * dt;
if (t >= HOLD) {
if (cycling()) beginFade();
else {
clock = Infinity;
phase = "idle";
t = 0;
}
}
break;
}
case "fade": {
t += dt;
if (t >= FADE) {
const m = next;
next = null;
if (m) beginCarve(m);
else phase = "idle";
}
break;
}
default:
break;
}
};
const drawWalls = (P: typeof pal, src: Uint8Array) => {
const body = new Path2D();
const lip = new Path2D();
for (let y = 0; y < rows; y++) {
const row = y * cols;
let x = 0;
while (x < cols) {
if (!src[row + x]) {
x++;
continue;
}
const x0 = x;
while (x < cols && src[row + x]) x++;
body.rect(ox + x0 * cs, oy + y * cs, (x - x0) * cs, cs);
}
x = 0;
while (x < cols) {
const i = row + x;
if (!src[i] || (y > 0 && src[i - cols])) {
x++;
continue;
}
const x0 = x;
x++;
while (x < cols && src[row + x] && !(y > 0 && src[row + x - cols])) x++;
lip.rect(ox + x0 * cs, oy + y * cs, (x - x0) * cs, 1);
}
}
ctx.fillStyle = P.wall;
ctx.fill(body);
ctx.fillStyle = P.lip;
ctx.fill(lip);
};
const drawExplored = (P: typeof pal, s: Search) => {
const { state, closedAt } = s;
const r = rate();
const hot = r * 0.16;
const warm = r * 0.55;
const layers = [new Path2D(), new Path2D(), new Path2D()];
for (let y = 0; y < rows; y++) {
const row = y * cols;
let x = 0;
while (x < cols) {
const i = row + x;
if (state[i] !== 2) {
x++;
continue;
}
const age = clock - closedAt[i];
const b = age < hot ? 0 : age < warm ? 1 : 2;
const x0 = x;
x++;
while (x < cols) {
const j = row + x;
if (state[j] !== 2) break;
const a = clock - closedAt[j];
if ((a < hot ? 0 : a < warm ? 1 : 2) !== b) break;
x++;
}
layers[b].rect(ox + x0 * cs, oy + y * cs, (x - x0) * cs, cs);
}
}
for (let b = 2; b >= 0; b--) {
ctx.fillStyle = P.age[b];
ctx.fill(layers[b]);
}
const inset = Math.max(1, Math.round(cs * 0.31));
const side = cs - inset * 2;
if (side <= 0) return;
const front = new Path2D();
let any = false;
for (let i = 0; i < state.length; i++) {
if (state[i] !== 1) continue;
front.rect(ox + (i % cols) * cs + inset, oy + Math.floor(i / cols) * cs + inset, side, side);
any = true;
}
if (any) {
ctx.fillStyle = P.front;
ctx.fill(front);
}
};
const drawCarveGlow = (P: typeof pal) => {
if (!build || revealed === 0 || revealed >= build.order.length) return;
const span = Math.min(42, Math.max(3, Math.ceil((build.order.length * 0.14) / carveFor)));
const from = Math.max(0, revealed - span);
const layers = [new Path2D(), new Path2D(), new Path2D()];
for (let i = from; i < revealed; i++) {
const cell = build.order[i];
const b = Math.min(2, Math.floor(((revealed - 1 - i) / span) * 3));
layers[b].rect(ox + (cell % cols) * cs, oy + Math.floor(cell / cols) * cs, cs, cs);
}
for (let b = 2; b >= 0; b--) {
ctx.fillStyle = P.glow[b];
ctx.fill(layers[b]);
}
};
const drawPath = (P: typeof pal, glow: number) => {
if (path.length < 2 || progress <= 0) return;
let left = progress * pathLength;
let px = cx(path[0]);
let py = cy(path[0]);
let tipX = px;
let tipY = py;
ctx.beginPath();
ctx.moveTo(px, py);
for (let i = 1; i < path.length; i++) {
const nx = cx(path[i]);
const ny = cy(path[i]);
const seg = nx !== px && ny !== py ? Math.SQRT2 : 1;
if (left >= seg) {
ctx.lineTo(nx, ny);
left -= seg;
tipX = nx;
tipY = ny;
} else {
const f = left / seg;
tipX = px + (nx - px) * f;
tipY = py + (ny - py) * f;
ctx.lineTo(tipX, tipY);
break;
}
px = nx;
py = ny;
}
ctx.lineJoin = "round";
ctx.lineCap = "round";
ctx.lineWidth = cs * 0.32;
ctx.strokeStyle = P.path;
ctx.shadowColor = P.path;
ctx.shadowBlur = cs * 0.75 * glow * dpr;
ctx.stroke();
ctx.shadowBlur = 0;
ctx.shadowColor = "transparent";
ctx.lineWidth = Math.max(1, cs * 0.09);
ctx.strokeStyle = P.core;
ctx.stroke();
if (progress < 1) {
ctx.fillStyle = P.ink;
ctx.beginPath();
ctx.arc(tipX, tipY, cs * 0.17, 0, Math.PI * 2);
ctx.fill();
}
};
const drawMarker = (P: typeof pal, cell: number, isGoal: boolean, alpha: number) => {
if (alpha <= 0) return;
const x = cx(cell);
const y = cy(cell);
ctx.globalAlpha = alpha;
ctx.fillStyle = P.halo;
ctx.beginPath();
ctx.arc(x, y, cs * 0.45, 0, Math.PI * 2);
ctx.fill();
ctx.fillStyle = P.ink;
ctx.strokeStyle = P.ink;
ctx.beginPath();
if (isGoal) {
ctx.lineWidth = Math.max(1.25, cs * 0.1);
ctx.arc(x, y, cs * 0.27, 0, Math.PI * 2);
ctx.stroke();
ctx.beginPath();
ctx.arc(x, y, cs * 0.09, 0, Math.PI * 2);
ctx.fill();
} else {
ctx.arc(x, y, cs * 0.27, 0, Math.PI * 2);
ctx.fill();
}
ctx.globalAlpha = 1;
};
const drawGrid = (P: typeof pal) => {
ctx.strokeStyle = P.grid;
ctx.lineWidth = 1;
ctx.stroke(gridLines);
};
const drawScene = (P: typeof pal) => {
ctx.fillStyle = P.board;
ctx.fillRect(0, 0, width, height);
if (!ready) return;
const carving = phase === "carve";
if (search && !carving) drawExplored(P, search);
drawGrid(P);
drawWalls(P, carving ? shown : walls);
if (carving) drawCarveGlow(P);
const pulse = phase === "hold" ? 0.5 - 0.5 * Math.cos((t / HOLD) * Math.PI * 4) : 0;
drawPath(P, 1 + 0.8 * pulse);
const alpha = carving ? Math.min(1, t / 0.3) : 1;
drawMarker(P, start, false, alpha);
drawMarker(P, goal, true, alpha);
};
const drawBaseOver = (P: typeof pal, m: Maze, alpha: number) => {
if (alpha <= 0) return;
ctx.globalAlpha = alpha;
const gw = cols * cs;
const gh = rows * cs;
if (m.solid) {
const around = new Path2D();
around.rect(0, 0, width, height);
around.rect(ox, oy, gw, gh);
ctx.fillStyle = P.board;
ctx.fill(around, "evenodd");
ctx.fillStyle = P.lip;
ctx.fillRect(ox, oy, gw, 1);
ctx.fillStyle = P.wall;
ctx.fillRect(ox, oy + 1, gw, gh - 1);
} else {
ctx.fillStyle = P.board;
ctx.fillRect(0, 0, width, height);
drawGrid(P);
}
ctx.globalAlpha = 1;
};
const drawCursor = () => {
if (!focused || !keyboard || !ready) return;
const x = ox + (cursor % cols) * cs;
const y = oy + Math.floor(cursor / cols) * cs;
ctx.strokeStyle = "rgba(255,255,255,0.92)";
ctx.lineWidth = 1.5;
ctx.strokeRect(x + 1.25, y + 1.25, cs - 2.5, cs - 2.5);
ctx.strokeStyle = "rgba(0,0,0,0.55)";
ctx.lineWidth = 1;
ctx.strokeRect(x + 2.5, y + 2.5, cs - 5, cs - 5);
};
const render = () => {
const P = palette();
drawScene(P);
if (phase === "fade" && next) {
const k = Math.min(1, t / FADE);
drawBaseOver(P, next, k * k * (3 - 2 * k));
}
drawCursor();
};
const hud = () => {
const explored = exploredRef.current;
const steps = stepsRef.current;
if (!explored || !steps) return;
const s = phase === "carve" ? null : search;
const e = s ? String(s.visited) : "0";
const p = !s || !s.done ? "…" : s.found ? String(path.length - 1) : "none";
if (explored.textContent !== e) explored.textContent = e;
if (steps.textContent !== p) steps.textContent = p;
};
drawRef.current = (dt) => {
if (!ready) return false;
syncProps();
advance(dt);
render();
hud();
return phase === "idle" ? false : undefined;
};
measureRef.current = ({ width: w, height: h, dpr: d, bufferWidth, bufferHeight }) => {
if (w <= 0 || h <= 0) return;
width = w;
height = h;
dpr = d;
if (canvas.width !== bufferWidth) canvas.width = bufferWidth;
if (canvas.height !== bufferHeight) canvas.height = bufferHeight;
ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
const withChrome = h >= CHROME_MIN_HEIGHT && w >= CHROME_MIN_WIDTH;
setChrome(withChrome);
const top = withChrome ? BAND_TOP : PAD;
const bottom = withChrome ? BAND_BOTTOM : PAD;
const availW = w - PAD * 2;
const availH = h - top - bottom;
let size = Math.max(4, Math.round(live.current.cellSize));
let c = Math.floor(availW / size);
let r = Math.floor(availH / size);
if (c < 5 || r < 5) {
size = Math.max(4, Math.floor(Math.min(availW, availH) / 5));
c = Math.floor(availW / size);
r = Math.floor(availH / size);
}
if (c % 2 === 0) c--;
if (r % 2 === 0) r--;
if (c < 3 || r < 3) {
ready = false;
return;
}
ox = PAD + Math.floor((availW - c * size) / 2);
oy = top + Math.floor((availH - r * size) / 2);
wrap.style.setProperty("--pf-x", `${ox}px`);
wrap.style.setProperty("--pf-top", `${oy}px`);
wrap.style.setProperty("--pf-bottom", `${h - oy - r * size}px`);
const changed = c !== cols || r !== rows || size !== cs;
const pc = cols;
const pr = rows;
cols = c;
rows = r;
cs = size;
gridLines = new Path2D();
for (let x = 0; x <= cols; x++) {
const at = ox + x * cs + (x === cols ? -0.5 : 0.5);
gridLines.moveTo(at, oy);
gridLines.lineTo(at, oy + rows * cs);
}
for (let y = 0; y <= rows; y++) {
const at = oy + y * cs + (y === rows ? -0.5 : 0.5);
gridLines.moveTo(ox, at);
gridLines.lineTo(ox + cols * cs, at);
}
if (ready && !changed) return;
if (edited && pc > 0 && walls.length === pc * pr) refit(pc, pr, walls, start, goal, cursor);
else restart();
ready = true;
};
const cellAt = (e: PointerEvent, clamp: boolean) => {
const box = canvas.getBoundingClientRect();
const sx = box.width > 0 ? width / box.width : 1;
const sy = box.height > 0 ? height / box.height : 1;
let x = Math.floor(((e.clientX - box.left) * sx - ox) / cs);
let y = Math.floor(((e.clientY - box.top) * sy - oy) / cs);
if (clamp) {
x = Math.min(cols - 1, Math.max(0, x));
y = Math.min(rows - 1, Math.max(0, y));
} else if (x < 0 || y < 0 || x >= cols || y >= rows) {
return -1;
}
return y * cols + x;
};
const look = (value: string) => {
if (value === pointerLook) return;
pointerLook = value;
canvas.style.cursor = value;
};
const onDown = (e: PointerEvent) => {
if (!ready || drag) return;
if (e.pointerType === "mouse" && e.button !== 0) return;
const cell = cellAt(e, false);
if (cell < 0) return;
keyboard = false;
try {
canvas.setPointerCapture(e.pointerId);
} catch {
}
beginEdit();
if (cell === start || cell === goal) {
drag = { id: e.pointerId, kind: cell === start ? "start" : "goal", value: 0, last: cell };
look("grabbing");
} else {
const value = walls[cell] ? 0 : 1;
drag = { id: e.pointerId, kind: "wall", value, last: cell };
walls[cell] = value;
}
solveNow();
loop.paint();
};
const onMove = (e: PointerEvent) => {
if (!ready) return;
if (!drag || e.pointerId !== drag.id) {
if (drag || e.pointerType !== "mouse") return;
const cell = cellAt(e, false);
look(cell < 0 ? "" : cell === start || cell === goal ? "grab" : "crosshair");
return;
}
const cell = cellAt(e, true);
if (cell === drag.last) return;
let changed = false;
if (drag.kind === "wall") {
const value = drag.value;
trace(drag.last, cell, cols, (c) => {
if (c === start || c === goal || walls[c] === value) return;
walls[c] = value;
changed = true;
});
} else if (!walls[cell] && cell !== start && cell !== goal) {
if (drag.kind === "start") start = cell;
else goal = cell;
changed = true;
}
drag.last = cell;
if (changed) {
solveNow();
loop.paint();
}
};
const onUp = (e: PointerEvent) => {
if (!drag || e.pointerId !== drag.id) return;
if (canvas.hasPointerCapture(e.pointerId)) canvas.releasePointerCapture(e.pointerId);
drag = null;
look("");
loop.paint();
};
const onMenu = (e: Event) => e.preventDefault();
const moveCursor = (x: number, y: number) => {
cursor = Math.min(rows - 1, Math.max(0, y)) * cols + Math.min(cols - 1, Math.max(0, x));
};
const place = (isGoal: boolean) => {
if (cursor === (isGoal ? start : goal)) return;
beginEdit();
walls[cursor] = 0;
if (isGoal) goal = cursor;
else start = cursor;
solveNow();
};
const onKey = (e: KeyboardEvent) => {
if (e.target !== wrap || !ready) return;
if (e.altKey || e.ctrlKey || e.metaKey) return;
const x = cursor % cols;
const y = Math.floor(cursor / cols);
const by = e.shiftKey ? 5 : 1;
switch (e.key) {
case "ArrowLeft":
moveCursor(x - by, y);
break;
case "ArrowRight":
moveCursor(x + by, y);
break;
case "ArrowUp":
moveCursor(x, y - by);
break;
case "ArrowDown":
moveCursor(x, y + by);
break;
case " ":
case "Spacebar":
if (!e.repeat && cursor !== start && cursor !== goal) {
beginEdit();
walls[cursor] = walls[cursor] ? 0 : 1;
solveNow();
}
break;
case "s":
case "S":
if (!e.repeat) place(false);
break;
case "g":
case "G":
if (!e.repeat) place(true);
break;
case "Enter":
if (!e.repeat) run();
break;
case "m":
case "M":
if (!e.repeat) newMaze();
break;
case "c":
case "C":
if (!e.repeat) clear();
break;
default:
return;
}
e.preventDefault();
keyboard = true;
loop.paint();
};
const onFocus = () => {
focused = true;
try {
keyboard = wrap.matches(":focus-visible");
} catch {
keyboard = false;
}
loop.paint();
};
const onBlur = () => {
focused = false;
keyboard = false;
loop.paint();
};
actRef.current = (action) => {
if (!ready) return;
if (action === "new") newMaze();
else if (action === "run") run();
else clear();
loop.paint();
};
canvas.addEventListener("pointerdown", onDown);
canvas.addEventListener("pointermove", onMove);
canvas.addEventListener("pointerup", onUp);
canvas.addEventListener("pointercancel", onUp);
canvas.addEventListener("lostpointercapture", onUp);
canvas.addEventListener("contextmenu", onMenu);
wrap.addEventListener("keydown", onKey);
wrap.addEventListener("focus", onFocus);
wrap.addEventListener("blur", onBlur);
loop.resize();
loop.start();
return () => {
drawRef.current = null;
measureRef.current = null;
actRef.current = null;
canvas.removeEventListener("pointerdown", onDown);
canvas.removeEventListener("pointermove", onMove);
canvas.removeEventListener("pointerup", onUp);
canvas.removeEventListener("pointercancel", onUp);
canvas.removeEventListener("lostpointercapture", onUp);
canvas.removeEventListener("contextmenu", onMenu);
wrap.removeEventListener("keydown", onKey);
wrap.removeEventListener("focus", onFocus);
wrap.removeEventListener("blur", onBlur);
};
}, [loop]);
useEffect(() => {
loop.start();
}, [paused, reduce, autoplay, algorithm, maze, diagonal, loop]);
useEffect(() => {
loop.paint();
}, [searchColor, pathColor, boardColor, chrome, loop]);
useEffect(() => {
loop.resize();
}, [cellSize, loop]);
return (
<div className={`relative flex h-full w-full flex-col overflow-hidden ${className}`.trim()}>
<div
ref={wrapRef}
tabIndex={0}
role="application"
aria-roledescription="pathfinding grid"
aria-label="Pathfinding grid. Arrow keys move the cursor, and Shift moves it five cells. Space adds or removes a wall. S sets the start and G sets the goal. Enter runs the search, M builds a new maze and C clears the board."
className="@container relative min-h-0 flex-1 touch-none select-none outline-none focus-visible:outline-2 focus-visible:-outline-offset-2"
style={{ backgroundColor: boardColor, outlineColor: searchColor }}
>
<canvas ref={canvasRef} aria-hidden="true" className="absolute inset-0 block size-full" />
{chrome && (
<>
<div
aria-hidden="true"
className="pointer-events-none absolute flex h-6 items-center gap-1.5 whitespace-nowrap rounded-md bg-black/45 px-2 font-mono text-[11px] leading-none tabular-nums text-white/85 backdrop-blur-sm"
style={{
left: "var(--pf-x, 8px)",
bottom: "calc(100% - var(--pf-top, 40px) + 6px)",
}}
>
<span className="font-semibold text-white">{LABELS[algorithm]}</span>
<span className="text-white/30">·</span>
<span className="text-white/50">explored</span>
<span ref={exploredRef} />
<span className="text-white/30">·</span>
<span className="text-white/50">path</span>
<span ref={stepsRef} />
</div>
<div
className="absolute flex items-center gap-0.5 rounded-md bg-black/45 p-0.5 text-white/85 backdrop-blur-sm"
style={{
left: "var(--pf-x, 8px)",
top: "calc(100% - var(--pf-bottom, 46px) + 6px)",
}}
>
<ToolButton label="New maze" shortcut="M" onPress={() => actRef.current?.("new")}>
<svg {...ICON}>
<path d="M4 9V4h16v11" />
<path d="M20 20H4v-7" />
<path d="M8 8h8v4" />
<path d="M8 12v4h4" />
</svg>
</ToolButton>
<ToolButton label="Run" shortcut="Enter" onPress={() => actRef.current?.("run")}>
<svg {...ICON}>
<path d="M8 5.5v13l10-6.5z" fill="currentColor" />
</svg>
</ToolButton>
<ToolButton label="Clear" shortcut="C" onPress={() => actRef.current?.("clear")}>
<svg {...ICON}>
<path d="M17.5 13.5 11 20H8l-4-4 9.5-9.5a2 2 0 0 1 2.8 0l1.2 1.2a2 2 0 0 1 0 2.8z" />
<path d="M8.5 11.5 14 17" />
<path d="M12 20h8" />
</svg>
</ToolButton>
</div>
</>
)}
</div>
<p ref={announceRef} aria-live="polite" className="sr-only" />
</div>
);
}
const ICON = {
viewBox: "0 0 24 24",
width: 14,
height: 14,
fill: "none",
stroke: "currentColor",
strokeWidth: 2,
strokeLinecap: "round",
strokeLinejoin: "round",
"aria-hidden": true,
} as const;
function ToolButton({
label,
shortcut,
onPress,
children,
}: {
label: string;
shortcut: string;
onPress: () => void;
children: ReactNode;
}) {
return (
<button
type="button"
aria-label={label}
title={`${label} (${shortcut})`}
onClick={onPress}
className="inline-flex h-7 items-center gap-1.5 rounded px-2 text-[11px] font-medium text-white/80 transition-colors hover:bg-white/10 hover:text-white focus-visible:outline-2 focus-visible:outline-white/70"
>
{children}
<span className="hidden @min-[480px]:inline">{label}</span>
</button>
);
}
function trace(from: number, to: number, width: number, visit: (cell: number) => void) {
let x0 = from % width;
let y0 = Math.floor(from / width);
const x1 = to % width;
const y1 = Math.floor(to / width);
const dx = Math.abs(x1 - x0);
const dy = -Math.abs(y1 - y0);
const sx = x0 < x1 ? 1 : -1;
const sy = y0 < y1 ? 1 : -1;
let err = dx + dy;
for (;;) {
visit(y0 * width + x0);
if (x0 === x1 && y0 === y1) break;
const e2 = 2 * err;
if (e2 >= dy) {
err += dy;
x0 += sx;
}
if (e2 <= dx) {
err += dx;
y0 += sy;
}
}
}
function toRgb(ctx: CanvasRenderingContext2D, color: string, fallback: Rgb): Rgb {
ctx.fillStyle = `rgb(${fallback[0]},${fallback[1]},${fallback[2]})`;
ctx.fillStyle = color;
const s = String(ctx.fillStyle);
if (s.startsWith("#") && s.length === 7) {
return [parseInt(s.slice(1, 3), 16), parseInt(s.slice(3, 5), 16), parseInt(s.slice(5, 7), 16)];
}
const m = /rgba?\(([^)]+)\)/.exec(s);
if (m) {
const [r, g, b] = m[1].split(",").map((v) => Number.parseFloat(v));
if ([r, g, b].every(Number.isFinite)) return [r, g, b];
}
return fallback;
}
function mix(a: Rgb, b: Rgb, k: number): Rgb {
return [a[0] + (b[0] - a[0]) * k, a[1] + (b[1] - a[1]) * k, a[2] + (b[2] - a[2]) * k];
}
function rgba(c: Rgb, alpha: number) {
return `rgba(${Math.round(c[0])},${Math.round(c[1])},${Math.round(c[2])},${alpha})`;
}
function luminance(c: Rgb) {
return (0.2126 * c[0] + 0.7152 * c[1] + 0.0722 * c[2]) / 255;
}