import React, { useRef, useState } from 'react';
import './SwipeCell.css';

/* 与 CSS 的 --kole-m-swipecell-action-width 默认值保持一致：
   展开位移 = 操作区宽度 × 操作数量（规格 §5.8 明确该宽度无标准档位，这里是实现默认值） */
const ACTION_WIDTH = 72;

/* 滑动单元格（移动端）— 规格 §5；横向位移 > 10px 判定为滑动，
   纵向位移更大时取消滑动（让位给页面滚动）；松手按是否超过操作区宽度一半决定展开/回弹。 */
export default function SwipeCell({
  direction = 'left',
  actions = [],
  open = false,
  onAction,
  children,
}) {
  const [offset, setOffset] = useState(0);
  const [dragging, setDragging] = useState(false);
  const gestures = useRef({ startX: 0, startY: 0, dx: 0, width: ACTION_WIDTH, decided: false, dragging: false });
  const rootRef = useRef(null);

  /** 展开态位移：右侧操作向左滑（负），左侧操作向右滑（正） */
  const openOffset = (direction === 'right' ? 1 : -1) * ACTION_WIDTH * Math.max(1, actions.length);

  function measure() {
    const el = rootRef.current && rootRef.current.querySelector('.kole-m-swipecell__actions');
    return (el && el.offsetWidth) || ACTION_WIDTH;
  }

  function settle(isOpen) {
    const w = measure();
    setOffset(isOpen ? (direction === 'right' ? w : -w) : 0);
  }

  function onPointerDown(e) {
    const g = gestures.current;
    g.startX = e.clientX;
    g.startY = e.clientY;
    g.dx = 0;
    g.decided = false;
    g.dragging = false;
    g.width = measure();
  }

  function onPointerMove(e) {
    const g = gestures.current;
    g.dx = e.clientX - g.startX;
    const dy = e.clientY - g.startY;
    if (!g.decided) {
      if (Math.abs(g.dx) < 10 && Math.abs(dy) < 10) return;
      g.decided = true;
      if (Math.abs(dy) > Math.abs(g.dx)) return;
      g.dragging = true;
      setDragging(true);
    }
    if (!g.dragging) return;
    setOffset(Math.max(-g.width, Math.min(g.width, g.dx)));
  }

  function onPointerEnd() {
    const g = gestures.current;
    if (g.dragging) {
      g.dragging = false;
      setDragging(false);
      settle(Math.abs(g.dx) > g.width / 2);
    } else if (open) {
      settle(false);
    }
    g.decided = false;
  }

  const appliedOffset = dragging || offset !== 0 ? offset : open ? openOffset : 0;

  return (
    <div
      ref={rootRef}
      className={
        'kole-m-swipecell' +
        (direction === 'right' ? ' kole-m-swipecell--right' : '') +
        (dragging ? ' is-dragging' : '') +
        (open ? ' is-open' : '')
      }
      style={{ '--kole-m-swipecell-offset': appliedOffset + 'px' }}
      data-state={open ? 'open' : 'closed'}
      onPointerDown={onPointerDown}
      onPointerMove={onPointerMove}
      onPointerUp={onPointerEnd}
      onPointerCancel={onPointerEnd}
    >
      <div className="kole-m-swipecell__actions">
        {actions.map((a, i) => (
          <button
            key={a.key || i}
            className={
              'kole-m-swipecell__action' +
              (a.tone === 'danger' ? ' kole-m-swipecell__action--danger' : '')
            }
            type="button"
            aria-label={a.ariaLabel || a.label}
            onClick={() => onAction && onAction(a.key, a)}
          >
            {a.label}
          </button>
        ))}
      </div>
      <div className="kole-m-swipecell__content">{children}</div>
    </div>
  );
}