| 1 | import { useRef, useState } from 'react'; |
| 2 | import type { Tile } from '../game/tiles'; |
| 3 | import { TileView } from './TileView'; |
| 4 | |
| 5 | interface Props { |
| 6 | tiles: Tile[]; |
| 7 | /** Index of the tile held apart from the rest, if any. */ |
| 8 | drawnIndex: number | null; |
| 9 | selected: number | null; |
| 10 | canDiscard: boolean; |
| 11 | onSelect: (i: number) => void; |
| 12 | onDiscard: (i: number) => void; |
| 13 | onMove: (from: number, to: number) => void; |
| 14 | } |
| 15 | |
| 16 | /** How far a pointer must travel before a tap becomes a drag. */ |
| 17 | const DRAG_SLOP = 12; |
| 18 | |
| 19 | /** |
| 20 | * Finds the tile nearest the pointer. Works whatever the seat's rotation: |
| 21 | * bounding rects are always screen-axis-aligned, so we read the row's direction |
| 22 | * off the first two tiles rather than assuming it runs left-to-right. |
| 23 | */ |
| 24 | function nearestIndex(container: HTMLElement, x: number, y: number): number | null { |
| 25 | const els = Array.from(container.querySelectorAll<HTMLElement>('[data-idx]')); |
| 26 | if (els.length < 2) return null; |
| 27 | const centers = els.map((el) => { |
| 28 | const r = el.getBoundingClientRect(); |
| 29 | return { x: r.left + r.width / 2, y: r.top + r.height / 2 }; |
| 30 | }); |
| 31 | const horizontal = Math.abs(centers[1].x - centers[0].x) >= Math.abs(centers[1].y - centers[0].y); |
| 32 | const along = (p: { x: number; y: number }) => (horizontal ? p.x : p.y); |
| 33 | const p = along({ x, y }); |
| 34 | |
| 35 | let best = 0; |
| 36 | let bestD = Infinity; |
| 37 | centers.forEach((c, i) => { |
| 38 | const d = Math.abs(along(c) - p); |
| 39 | if (d < bestD) { |
| 40 | bestD = d; |
| 41 | best = i; |
| 42 | } |
| 43 | }); |
| 44 | return best; |
| 45 | } |
| 46 | |
| 47 | export function Hand({ |
| 48 | tiles, |
| 49 | drawnIndex, |
| 50 | selected, |
| 51 | canDiscard, |
| 52 | onSelect, |
| 53 | onDiscard, |
| 54 | onMove, |
| 55 | }: Props) { |
| 56 | const ref = useRef<HTMLDivElement>(null); |
| 57 | const drag = useRef<{ from: number; cur: number; x: number; y: number; moved: boolean } | null>(null); |
| 58 | const [dragging, setDragging] = useState<number | null>(null); |
| 59 | |
| 60 | const down = (e: React.PointerEvent, i: number) => { |
| 61 | (e.currentTarget as HTMLElement).setPointerCapture?.(e.pointerId); |
| 62 | drag.current = { from: i, cur: i, x: e.clientX, y: e.clientY, moved: false }; |
| 63 | }; |
| 64 | |
| 65 | const move = (e: React.PointerEvent) => { |
| 66 | const d = drag.current; |
| 67 | if (!d || !ref.current) return; |
| 68 | if (!d.moved && Math.hypot(e.clientX - d.x, e.clientY - d.y) < DRAG_SLOP) return; |
| 69 | if (!d.moved) { |
| 70 | d.moved = true; |
| 71 | setDragging(d.cur); |
| 72 | } |
| 73 | const to = nearestIndex(ref.current, e.clientX, e.clientY); |
| 74 | if (to !== null && to !== d.cur) { |
| 75 | onMove(d.cur, to); |
| 76 | d.cur = to; |
| 77 | setDragging(to); |
| 78 | } |
| 79 | }; |
| 80 | |
| 81 | const up = () => { |
| 82 | const d = drag.current; |
| 83 | drag.current = null; |
| 84 | setDragging(null); |
| 85 | if (!d || d.moved || !canDiscard) return; |
| 86 | if (selected === d.from) onDiscard(d.from); |
| 87 | else onSelect(d.from); |
| 88 | }; |
| 89 | |
| 90 | return ( |
| 91 | <div className="hand" ref={ref} onPointerMove={move} onPointerUp={up} onPointerCancel={up}> |
| 92 | {tiles.map((t, i) => ( |
| 93 | <div |
| 94 | key={i} |
| 95 | data-idx={i} |
| 96 | className={ |
| 97 | 'hand-cell' + |
| 98 | (i === drawnIndex ? ' drawn-slot' : '') + |
| 99 | (i === dragging ? ' dragging' : '') |
| 100 | } |
| 101 | onPointerDown={(e) => down(e, i)} |
| 102 | > |
| 103 | {i === drawnIndex && <span className="drawn-tag">摸 Drew</span>} |
| 104 | <TileView tile={t} raised={selected === i} /> |
| 105 | </div> |
| 106 | ))} |
| 107 | </div> |
| 108 | ); |
| 109 | } |