import { useCallback, useRef } from 'react';
import { DEFAULT_ACTIVITY_POSTER_QR_SLOT, type ActivityPosterQrSlot } from '@dukang/shared-types';

type Props = {
  imageUrl?: string;
  value?: ActivityPosterQrSlot;
  onChange?: (slot: ActivityPosterQrSlot) => void;
};

export default function ActivityPosterQrSlotEditor({ imageUrl, value, onChange }: Props) {
  const boxRef = useRef<HTMLDivElement>(null);
  const dragRef = useRef<{
    mode: 'move' | 'resize';
    startX: number;
    startY: number;
    start: ActivityPosterQrSlot;
  } | null>(null);
  const slot = value ?? DEFAULT_ACTIVITY_POSTER_QR_SLOT;

  const apply = useCallback((next: ActivityPosterQrSlot) => {
    const size = Math.min(50, Math.max(5, next.qrSizePct));
    const box = boxRef.current;
    const ratio = box && box.clientHeight > 0 ? box.clientWidth / box.clientHeight : 1;
    const heightPct = size * ratio;
    const x = Math.min(100 - size, Math.max(0, next.qrXPct));
    const y = Math.min(Math.max(0, 100 - heightPct), Math.max(0, next.qrYPct));
    onChange?.({
      qrXPct: Number(x.toFixed(2)),
      qrYPct: Number(y.toFixed(2)),
      qrSizePct: Number(size.toFixed(2)),
    });
  }, [onChange]);

  function onPointerDown(mode: 'move' | 'resize', e: React.PointerEvent) {
    e.preventDefault();
    e.stopPropagation();
    (e.currentTarget as HTMLElement).setPointerCapture(e.pointerId);
    dragRef.current = { mode, startX: e.clientX, startY: e.clientY, start: { ...slot } };
  }

  function onPointerMove(e: React.PointerEvent) {
    const drag = dragRef.current;
    const box = boxRef.current;
    if (!drag || !box) return;
    const dx = ((e.clientX - drag.startX) / box.clientWidth) * 100;
    const dy = ((e.clientY - drag.startY) / box.clientHeight) * 100;
    if (drag.mode === 'move') {
      apply({
        ...drag.start,
        qrXPct: drag.start.qrXPct + dx,
        qrYPct: drag.start.qrYPct + dy,
      });
    } else {
      apply({ ...drag.start, qrSizePct: drag.start.qrSizePct + dx });
    }
  }

  function endDrag() {
    dragRef.current = null;
  }

  if (!imageUrl) {
    return <div style={{ color: 'rgba(0,0,0,0.45)' }}>请先上传活动图，再拖拽定位方形码栏</div>;
  }

  return (
    <div>
      <div
        ref={boxRef}
        style={{ position: 'relative', width: '100%', maxWidth: 420, userSelect: 'none', touchAction: 'none' }}
        onPointerMove={onPointerMove}
        onPointerUp={endDrag}
        onPointerCancel={endDrag}
      >
        <img src={imageUrl} alt="活动图预览" style={{ width: '100%', display: 'block' }} draggable={false} />
        <div
          style={{
            position: 'absolute',
            left: `${slot.qrXPct}%`,
            top: `${slot.qrYPct}%`,
            width: `${slot.qrSizePct}%`,
            aspectRatio: '1',
            border: '2px dashed #1677ff',
            background: 'rgba(22,119,255,0.14)',
            cursor: 'move',
            boxSizing: 'border-box',
          }}
          onPointerDown={(e) => onPointerDown('move', e)}
        >
          <div
            style={{
              position: 'absolute',
              right: -6,
              bottom: -6,
              width: 14,
              height: 14,
              background: '#1677ff',
              borderRadius: 2,
              cursor: 'nwse-resize',
            }}
            onPointerDown={(e) => onPointerDown('resize', e)}
          />
        </div>
      </div>
      <div style={{ marginTop: 8, color: 'rgba(0,0,0,0.45)', fontSize: 12 }}>
        拖拽移动码栏，拉右下角调整大小（边长相对图宽 {slot.qrSizePct}%）
      </div>
    </div>
  );
}