export interface MarkdownNormalization {
  markdown: string;
  convertedTables: number;
}

function splitTableRow(line: string): string[] {
  const trimmed = line.trim().replace(/^\|/, "").replace(/\|$/, "");
  return trimmed.split(/(?<!\\)\|/).map((cell) => cell.trim().replace(/\\\|/g, "|"));
}

function isTableSeparator(line: string): boolean {
  const cells = splitTableRow(line);
  return cells.length > 0 && cells.every((cell) => /^:?-{3,}:?$/.test(cell));
}

function formatTableRow(headers: string[], cells: string[]): string {
  const values = headers.map((header, index) => {
    const value = cells[index] ?? "";
    return header ? `**${header}**：${value || "–"}` : value;
  }).filter(Boolean);
  return `- ${values.join("；")}`;
}

/** Convert GFM tables to readable paragraphs so word_create never creates a table by default. */
export function normalizeMarkdownWithoutTables(markdown: string): MarkdownNormalization {
  const lines = markdown.replace(/\r\n?/g, "\n").split("\n");
  const output: string[] = [];
  let convertedTables = 0;

  for (let index = 0; index < lines.length; index += 1) {
    const headerLine = lines[index] ?? "";
    const separatorLine = lines[index + 1] ?? "";
    if (!headerLine.includes("|") || !separatorLine.includes("|") || !isTableSeparator(separatorLine)) {
      output.push(headerLine);
      continue;
    }

    const headers = splitTableRow(headerLine);
    const rows: string[][] = [];
    index += 2;
    while (index < lines.length && (lines[index] ?? "").includes("|") && (lines[index] ?? "").trim() !== "") {
      rows.push(splitTableRow(lines[index] ?? ""));
      index += 1;
    }
    index -= 1;

    convertedTables += 1;
    if (rows.length === 0) output.push(`- ${headers.join("；")}`);
    else output.push(...rows.map((row) => formatTableRow(headers, row)));
  }

  return { markdown: output.join("\n"), convertedTables };
}