import { readFileSync } from 'node:fs';
import { DOMParser } from '@xmldom/xmldom';

/**
 * 读取 Game_Surface_3 风格的 Layer XML (UTF-8 编码), 解析 Layer + Spirit 字段.
 *
 * 协议来源: docs/protocol/ (服务器零改动). XML 结构与 save/Layer*.xml 一致:
 *   <Layer>
 *     <PropertyList><Property Name="ID" Value="2"/><Property Name="Name" Value="..."/></PropertyList>
 *     <SpiritList>
 *       <Spirit>
 *         <PropertyList><Property Name="SpiritType" Value="0"/>...</PropertyList>
 *       </Spirit>
 *     </SpiritList>
 *   </Layer>
 *
 * 数据源权威: 字段缺失/不存在一律返回 undefined (不上游兜底, 由下游显式判错).
 *
 * @param {string} path - 文件路径 (相对 cwd 或绝对)
 * @returns {{ layerId: string|undefined, layerName: string|undefined, spirits: Array<{ id, name, type, imgResID, x, y, w, h, group, indexOfLayer }> }}
 */
export function readLayerXml(path) {
  const text = readFileSync(path, 'utf8');
  const doc = new DOMParser().parseFromString(text, 'text/xml');

  const getProp = (el, name) => {
    const prop = Array.from(el.getElementsByTagName('Property'))
      .find(p => p.getAttribute('Name') === name);
    return prop?.getAttribute('Value');
  };

  const layerEl = doc.getElementsByTagName('Layer')[0];
  const layerPropList = layerEl.getElementsByTagName('PropertyList')[0];
  const layerId = getProp(layerPropList, 'ID');
  const layerName = getProp(layerPropList, 'Name');

  const spiritEls = doc.getElementsByTagName('Spirit');
  const spirits = Array.from(spiritEls).map(sp => {
    const propList = sp.getElementsByTagName('PropertyList')[0];
    return {
      id: getProp(propList, 'ID'),
      name: getProp(propList, 'Name'),
      type: getProp(propList, 'SpiritType'),
      imgResID: getProp(propList, 'ImgResID'),
      x: getProp(propList, 'X'),
      y: getProp(propList, 'Y'),
      w: getProp(propList, 'Width'),
      h: getProp(propList, 'Height'),
      group: getProp(propList, 'BelongGroupID'),
      indexOfLayer: getProp(propList, 'IndexOfLayer'),
    };
  });

  return { layerId, layerName, spirits };
}