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

/**
 * Aurora Admin Slider（React）
 * 对齐 组件7.txt SliderInput 规范：单/双滑块、刻度、输入框联动
 *
 * props:
 *  - value / defaultValue : number | [lo, hi]
 *  - min / max / step
 *  - range     : 双滑块
 *  - showTicks : 刻度
 *  - showInput : 数值输入框联动
 *  - disabled
 *  - onChange(value)
 */
export default function Slider({
  value,
  defaultValue = 0,
  min = 0,
  max = 100,
  step = 1,
  range = false,
  showTicks = false,
  showInput = false,
  disabled = false,
  onChange
}) {
  const trackRef = useRef(null);
  const [dragIndex, setDragIndex] = useState(-1);
  const current = value !== undefined ? value : defaultValue;

  const pct = (v) => ((v - min) / (max - min)) * 100;
  const clamp = (v) => {
    const snapped = Math.round((v - min) / step) * step + min;
    return Math.max(min, Math.min(max, snapped));
  };
  const valueFromClientX = (x) => {
    const rect = trackRef.current.getBoundingClientRect();
    return clamp(min + (x - rect.left) / rect.width * (max - min));
  };

  const setVal = (next) => {
    if (value === undefined) onChange && onChange(next);
    else onChange && onChange(next);
  };

  const onMove = (e) => {
    if (dragIndex < 0) return;
    const nv = valueFromClientX(e.clientX);
    if (range) {
      const arr = [...current]; arr[dragIndex] = nv; arr.sort((a, b) => a - b);
      setVal(arr);
    } else {
      setVal(nv);
    }
  };
  const onUp = () => {
    setDragIndex(-1);
    window.removeEventListener('pointermove', onMove);
    window.removeEventListener('pointerup', onUp);
  };
  const onHandleDown = (i, e) => {
    if (disabled) return;
    e.preventDefault();
    setDragIndex(i);
    window.addEventListener('pointermove', onMove);
    window.addEventListener('pointerup', onUp);
  };
  const onTrackDown = (e) => {
    if (disabled || e.target.classList.contains('aa-slider-handle')) return;
    const nv = valueFromClientX(e.clientX);
    if (range) {
      const i = Math.abs(nv - current[0]) <= Math.abs(nv - current[1]) ? 0 : 1;
      const arr = [...current]; arr[i] = nv; arr.sort((a, b) => a - b);
      setVal(arr);
    } else {
      setVal(nv);
    }
  };
  const onInput = (i, e) => {
    const v = +e.target.value;
    if (range) {
      const arr = [...current]; arr[i] = v; arr.sort((a, b) => a - b);
      setVal(arr);
    } else {
      setVal(v);
    }
  };

  useEffect(() => () => onUp(), []); // eslint-disable-line

  const handlePercents = range ? [pct(current[0]), pct(current[1])] : [pct(current)];
  const fillStyle = range
    ? { left: pct(current[0]) + '%', width: (pct(current[1]) - pct(current[0])) + '%' }
    : { left: '0%', width: pct(current) + '%' };
  const tickPercents = Array.from(
    { length: Math.floor((max - min) / step) + 1 },
    (_, i) => pct(min + i * step)
  );

  return (
    <div className={`aa-slider${disabled ? ' is-disabled' : ''}`}>
      <div className="aa-slider-track" ref={trackRef} onPointerDown={onTrackDown}>
        <div className="aa-slider-rail"></div>
        <div className="aa-slider-fill" style={fillStyle}></div>
        {showTicks && (
          <div className="aa-slider-ticks">
            {tickPercents.map((t, i) => (
              <div key={i} className="aa-slider-tick" style={{ left: t + '%' }}></div>
            ))}
          </div>
        )}
        {handlePercents.map((h, i) => (
          <div
            key={i}
            className="aa-slider-handle"
            style={{ left: h + '%' }}
            onPointerDown={(e) => onHandleDown(i, e)}
          ></div>
        ))}
      </div>
      {showInput && (
        <div className="aa-slider-value">
          {range ? (
            <>
              <input type="number" value={current[0]} onChange={(e) => onInput(0, e)} />
              <span>—</span>
              <input type="number" value={current[1]} onChange={(e) => onInput(1, e)} />
            </>
          ) : (
            <input type="number" value={current} onChange={(e) => onInput(null, e)} />
          )}
        </div>
      )}
    </div>
  );
}

/*
用法示例：
import Slider from './Slider';
<Slider min={0} max={100} defaultValue={30} showInput onChange={setV} />
<Slider range min={0} max={100} defaultValue={[20, 60]} onChange={setRange} />
*/