/**
 * A4 画布正文解析（配合 pages/hr/components/A4Preview.vue 使用）。
 *
 * 后端 documentContent 的字段口径：「A4画布正文JSON或HTML；变量统一使用双花括号编码占位，
 * 例如 {{EMPLOYEE_NAME}}」。这里统一解析成三种形态：
 *   - blocks：JSON 画布（{ blocks: [...] } 或 block 数组），拆成可渲染的块
 *   - html  ：HTML 正文，交给 rich-text 渲染
 *   - text  ：无法解析时按纯文本展示，保证历史数据也能看到内容
 */

const TITLE_TYPES = ["title", "heading", "h1", "h2", "header"];
const SIGN_TYPES = ["sign", "signature", "date", "footer"];

/** 把一段文本按 {{变量名}} 切成普通文本 / 变量片段，供预览高亮 */
export function splitVariableSegments(value) {
  const source = String(value == null ? "" : value);
  const pattern = /\{\{\s*([^{}]+?)\s*\}\}/g;
  const segments = [];
  let last = 0;
  let match = pattern.exec(source);
  while (match) {
    if (match.index > last) {
      segments.push({ text: source.slice(last, match.index), isVar: false });
    }
    segments.push({ text: match[1], isVar: true });
    last = match.index + match[0].length;
    match = pattern.exec(source);
  }
  if (last < source.length) segments.push({ text: source.slice(last), isVar: false });
  return segments;
}

function cellText(cell) {
  if (cell && typeof cell === "object") {
    return String(cell.text != null ? cell.text : cell.value != null ? cell.value : "");
  }
  return cell == null ? "" : String(cell);
}

function normalizeRows(block) {
  const rows = block.rows || block.cells || block.table;
  if (!Array.isArray(rows)) return [];
  const result = [];
  rows.forEach((rawRow) => {
    const rowArray = Array.isArray(rawRow) ? rawRow : [rawRow];
    // 每行的每个 cell 拆成 VariableSegment[]；空行丢弃
    const cells = rowArray.map((cell) => splitVariableSegments(cellText(cell)));
    if (cells.length) result.push(cells);
  });
  return result;
}

function normalizeBlocks(parsed) {
  const raw = Array.isArray(parsed) ? parsed : parsed && parsed.blocks;
  if (!Array.isArray(raw)) return [];
  return raw.reduce((blocks, item, index) => {
    const key = `block-${index}`;
    if (item == null) return blocks;
    if (typeof item !== "object") {
      const text = String(item);
      if (text.trim()) blocks.push({ key, kind: "para", segments: splitVariableSegments(text) });
      return blocks;
    }
    const block = item;
    const type = String(block.type || "").toLowerCase();
    if (type === "table") {
      const rows = normalizeRows(block);
      if (rows.length) blocks.push({ key, kind: "table", rows });
      return blocks;
    }
    const text = block.text != null ? block.text : block.content != null ? block.content : block.value != null ? block.value : "";
    if (!String(text).trim()) return blocks;
    const kind = TITLE_TYPES.indexOf(type) >= 0 ? "title" : SIGN_TYPES.indexOf(type) >= 0 ? "sign" : "para";
    blocks.push({ key, kind, segments: splitVariableSegments(text) });
    return blocks;
  }, []);
}

/** HTML 正文里去掉脚本与内联事件，避免画布内容带出可执行代码 */
function sanitizeHtml(html) {
  return String(html)
    .replace(/<script[\s\S]*?<\/script>/gi, "")
    .replace(/<script[^>]*>/gi, "")
    .replace(/\son\w+\s*=\s*("[^"]*"|'[^']*'|[^\s>]+)/gi, "");
}

/** 解析画布正文 */
export function parseA4Content(content = "") {
  const text = String(content == null ? "" : content).trim();
  if (!text) return { type: "empty", blocks: [], html: "", text: "" };
  if (text.charAt(0) === "<") return { type: "html", blocks: [], html: sanitizeHtml(text), text: "" };
  if (text.charAt(0) === "{" || text.charAt(0) === "[") {
    try {
      const blocks = normalizeBlocks(JSON.parse(text));
      if (blocks.length) return { type: "blocks", blocks, html: "", text: "" };
    } catch (error) {
      // 解析失败按纯文本展示
    }
  }
  return { type: "text", blocks: [], html: "", text };
}

export default { parseA4Content, splitVariableSegments };