import TurndownService from "turndown";

const turndown = new TurndownService({
  headingStyle: "atx",
  codeBlockStyle: "fenced",
  bulletListMarker: "-",
});

export type ParseMode = "raw" | "markdown" | "json";

export interface ParseResult {
  content: unknown;
  contentType: "text" | "markdown" | "json";
  degraded?: boolean;
  note?: string;
}

export function parseResponse(
  body: string,
  mode: ParseMode,
  contentTypeHeader?: string,
): ParseResult {
  switch (mode) {
    case "raw":
      return { content: body, contentType: "text" };

    case "json": {
      try {
        const parsed = JSON.parse(body);
        return { content: parsed, contentType: "json" };
      } catch {
        return {
          content: body,
          contentType: "text",
          degraded: true,
          note: "JSON 解析失败，返回原始文本",
        };
      }
    }

    case "markdown": {
      const isHtml =
        contentTypeHeader?.includes("text/html") ||
        /^\s*<(?:!doctype|html|body|div|p|h[1-6]|ul|ol|table|span|a)\b/i.test(body);
      if (isHtml) {
        const md = turndown.turndown(body);
        return { content: md, contentType: "markdown" };
      }
      return { content: body, contentType: "text" };
    }

    default:
      return { content: body, contentType: "text" };
  }
}