search.ts

/**
 * Section 1: Backend Core - Search Integration
 * 
 * Integrates DuckDuckGo search API for "Search Online" mode
 * Provides web search results to augment LLM responses
 */

/**
 * Search result interface
 */
export interface SearchResult {
  title: string;
  url: string;
  snippet: string;
  source?: string;
}

/**
 * Search the web using DuckDuckGo API
 * 
 * @param query - Search query
 * @param maxResults - Maximum number of results to return
 * @returns Array of search results
 */
export async function searchOnline(
  query: string,
  maxResults: number = 5
): Promise<SearchResult[]> {
  try {
    if (!query || query.trim().length === 0) {
      return [];
    }

    console.log(`Searching for: "${query}"`);

    // Use DuckDuckGo search API (no authentication required for basic searches)
    // We'll use the instant answer API which is free and doesn't require authentication
    const searchUrl = new URL("https://api.duckduckgo.com/");
    searchUrl.searchParams.set("q", query);
    searchUrl.searchParams.set("format", "json");
    searchUrl.searchParams.set("no_html", "1");
    searchUrl.searchParams.set("skip_disambig", "1");

    const response = await fetch(searchUrl.toString(), {
      headers: {
        "User-Agent":
          "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36",
      },
    });

    if (!response.ok) {
      console.error(`DuckDuckGo API error: ${response.status}`);
      return [];
    }

    const data = (await response.json()) as any;

    // Parse DuckDuckGo response
    const results: SearchResult[] = [];

    // Add instant answer if available
    if (data.AbstractText) {
      results.push({
        title: data.AbstractTitle || "Answer",
        url: data.AbstractURL || "",
        snippet: data.AbstractText,
        source: "DuckDuckGo Instant Answer",
      });
    }

    // Add related topics
    if (data.RelatedTopics && Array.isArray(data.RelatedTopics)) {
      for (const topic of data.RelatedTopics.slice(0, maxResults - results.length)) {
        if (topic.FirstURL && topic.Text) {
          results.push({
            title: topic.FirstURL.split("/")[2] || "Result",
            url: topic.FirstURL,
            snippet: topic.Text.substring(0, 200),
            source: "DuckDuckGo",
          });
        }
      }
    }

    // If no results from instant answer, try fetching from search results
    if (results.length === 0) {
      return await searchDuckDuckGoWeb(query, maxResults);
    }

    return results.slice(0, maxResults);
  } catch (error) {
    console.error("Search error:", error);
    return [];
  }
}

/**
 * Fallback search using DuckDuckGo HTML scraping
 * (Limited by rate limiting and reliability)
 */
async function searchDuckDuckGoWeb(
  query: string,
  maxResults: number
): Promise<SearchResult[]> {
  try {
    // This is a simplified fallback - in production, consider using a dedicated search API
    const searchUrl = `https://html.duckduckgo.com/?q=${encodeURIComponent(query)}&t=h_&ia=web`;

    const response = await fetch(searchUrl, {
      headers: {
        "User-Agent":
          "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36",
      },
    });

    if (!response.ok) {
      return [];
    }

    // Basic HTML parsing (would need cheerio or similar in production)
    // For now, return empty to avoid complexity
    return [];
  } catch (error) {
    console.error("DuckDuckGo web search error:", error);
    return [];
  }
}

/**
 * Format search results into a context string for the LLM
 * 
 * @param results - Array of search results
 * @returns Formatted string for LLM context
 */
export function formatSearchResults(results: SearchResult[]): string {
  if (results.length === 0) {
    return "";
  }

  let formatted = "## Search Results\n\n";

  results.forEach((result, index) => {
    formatted += `${index + 1}. **${result.title}**\n`;
    formatted += `   URL: ${result.url}\n`;
    formatted += `   ${result.snippet}\n\n`;
  });

  formatted += "---\n";

  return formatted;
}

/**
 * Validate and sanitize search query
 * 
 * @param query - Raw search query
 * @returns Sanitized query
 */
export function sanitizeSearchQuery(query: string): string {
  // Remove potentially harmful characters
  return query
    .replace(/[<>]/g, "")
    .trim()
    .substring(0, 500); // Limit query length
}