支持直连google\baidu搜索引擎 (#30)

* 支持直连google\baidu搜索引擎

* 删除无用参数

app/api/langchain-tools/google_search.ts

@@ -0,0 +1,80 @@
+import { decode } from "html-entities";
+import { convert as htmlToText } from "html-to-text";
+import { Tool } from "langchain/tools";
+import * as cheerio from "cheerio";
+import { getRandomUserAgent } from "./ua_tools";
+
+interface SearchResults {
+  /** The web results of the search. */
+  results: SearchResult[];
+}
+
+interface SearchResult {
+  /** The URL of the result. */
+  url: string;
+  /** The title of the result. */
+  title: string;
+  /**
+   * The sanitized description of the result.
+   * Bold tags will still be present in this string.
+   */
+  description: string;
+}
+
+async function search(
+  input: string,
+  maxResults: number,
+): Promise<SearchResults> {
+  const results: SearchResults = {
+    results: [],
+  };
+  const headers = new Headers();
+  headers.append("User-Agent", getRandomUserAgent());
+  const resp = await fetch(
+    `https://www.google.com/search?nfpr=1&num=${maxResults}&pws=0&q=${encodeURIComponent(
+      input,
+    )}`,
+    {
+      headers: headers,
+    },
+  );
+  const respCheerio = cheerio.load(await resp.text());
+  respCheerio("div.g").each((i, elem) => {
+    const item = cheerio.load(elem);
+    const linkElement = item("a");
+    const url = (linkElement.attr("href") ?? "").trim();
+    if (url !== "" && url !== "#") {
+      const title = decode(item("h3").text());
+      const description = item(`div[data-sncf~="1"]`).text().trim();
+      results.results.push({
+        url,
+        title,
+        description,
+      });
+    }
+  });
+  return results;
+}
+
+export class GoogleSearch extends Tool {
+  name = "google_search";
+  maxResults = 6;
+
+  /** @ignore */
+  async _call(input: string) {
+    const searchResults = await search(input, this.maxResults);
+
+    if (searchResults.results.length === 0) {
+      return "No good search result found";
+    }
+
+    const results = searchResults.results
+      .slice(0, this.maxResults)
+      .map(({ title, description, url }) => htmlToText(description))
+      .join("\n\n");
+    return results;
+  }
+
+  description =
+    "a search engine. useful for when you need to answer questions about current events. input should be a search query.";
+}