const FENCE = /(```[\s\S]*?```)/;
const DEFINITION_LINE = /^(.{2,80}?)[：:](.+)$/u;

function isSkippableLine(line: string): boolean {
  return /^(#{1,6}\s|>\s|[-*+]\s|\d+[.)]\s|\|)/.test(line) || line.startsWith("```");
}

function isDefinitionLine(block: string): boolean {
  const trimmed = block.trim();
  if (!trimmed || trimmed.includes("\n") || isSkippableLine(trimmed)) return false;
  const match = DEFINITION_LINE.exec(trimmed);
  if (!match) return false;
  const body = match[2]?.trim() ?? "";
  return body.length >= 4;
}

function toListItem(block: string): string {
  const trimmed = block.trim();
  const match = DEFINITION_LINE.exec(trimmed);
  if (!match) return trimmed;
  return `- **${match[1].trim()}**：${match[2].trim()}`;
}

function promoteProse(text: string): string {
  const blocks = text.split(/\n{2,}/);
  const out: string[] = [];
  let index = 0;
  while (index < blocks.length) {
    if (isDefinitionLine(blocks[index] ?? "")) {
      let end = index;
      while (end < blocks.length && isDefinitionLine(blocks[end] ?? "")) end += 1;
      if (end - index >= 2) {
        out.push(blocks.slice(index, end).map((block) => toListItem(block)).join("\n"));
        index = end;
        continue;
      }
    }
    const lines = (blocks[index] ?? "").split("\n").map((line) => line.trim()).filter(Boolean);
    if (lines.length >= 2 && lines.every(isDefinitionLine)) {
      out.push(lines.map((line) => toListItem(line)).join("\n"));
    } else {
      out.push(blocks[index] ?? "");
    }
    index += 1;
  }
  return out.join("\n\n");
}

export function promoteDefinitionLists(text: string): string {
  if (!text.includes("：") && !text.includes(":")) return text;
  return text.split(FENCE).map((chunk, index) => (
    index % 2 === 1 ? chunk : promoteProse(chunk)
  )).join("");
}