import { tool } from '@langchain/core/tools';
import { z } from 'zod';
import { RunnableConfig } from '@langchain/core/runnables';
import { Document } from 'langchain/document';
import { Embeddings } from '@langchain/core/embeddings';
import {
  processFilesToDocuments,
  getRankedDocs,
} from '@/lib/utils/fileProcessing';

// Schema for file search tool input
const FileSearchToolSchema = z.object({
  query: z
    .string()
    .describe('The search query to find relevant content in files'),
  fileIds: z.array(z.string()).describe('Array of file IDs to search through'),
  maxResults: z
    .number()
    .optional()
    .default(12)
    .describe('Maximum number of results to return'),
  similarityThreshold: z
    .number()
    .optional()
    .default(0.3)
    .describe('Minimum similarity threshold for results'),
});

/**
 * FileSearchTool - Reimplementation of FileSearchAgent as a tool
 *
 * This tool handles:
 * 1. Processing uploaded files into searchable documents
 * 2. Performing similarity search across file content
 * 3. Ranking and filtering results by relevance
 * 4. Returning relevant file sections as documents
 */
export const fileSearchTool = tool(
  async (
    input: z.infer<typeof FileSearchToolSchema>,
    config?: RunnableConfig,
  ): Promise<{
    documents: Document[];
    processedFiles: number;
    relevantSections: number;
    relevantDocuments?: any[];
  }> => {
    try {
      const {
        query,
        fileIds,
        maxResults = 12,
        similarityThreshold = 0.3,
      } = input;

      console.log(
        `FileSearchTool: Processing ${fileIds.length} files for query: "${query}"`,
      );

      // Check if we have files to process
      if (!fileIds || fileIds.length === 0) {
        console.log('FileSearchTool: No files provided for search');
        return {
          documents: [],
          processedFiles: 0,
          relevantSections: 0,
        };
      }

      // Get embeddings from config
      if (!config?.configurable?.embeddings) {
        throw new Error('Embeddings not available in config');
      }

      const embeddings: Embeddings = config.configurable.embeddings;

      // Step 1: Process files to documents
      console.log('FileSearchTool: Processing files to documents...');
      const fileDocuments = await processFilesToDocuments(fileIds);

      if (fileDocuments.length === 0) {
        console.log('FileSearchTool: No processable content found in files');
        return {
          documents: [],
          processedFiles: fileIds.length,
          relevantSections: 0,
        };
      }

      console.log(
        `FileSearchTool: Processed ${fileDocuments.length} file sections`,
      );

      // Step 2: Generate query embedding for similarity search
      console.log('FileSearchTool: Generating query embedding...');
      const queryEmbedding = await embeddings.embedQuery(query);

      // Step 3: Perform similarity search and ranking
      console.log('FileSearchTool: Performing similarity search...');
      const rankedDocuments = getRankedDocs(
        queryEmbedding,
        fileDocuments,
        maxResults,
        similarityThreshold,
      );

      console.log(
        `FileSearchTool: Found ${rankedDocuments.length} relevant file sections`,
      );

      // Add search metadata to documents
      const documentsWithMetadata = rankedDocuments.map((doc) => {
        return new Document({
          pageContent: doc.pageContent,
          metadata: {
            ...doc.metadata,
            source: 'file_search',
            searchQuery: query,
            similarityScore: doc.metadata?.similarity || 0,
          },
        });
      });

      return {
        documents: documentsWithMetadata,
        processedFiles: fileIds.length,
        relevantSections: rankedDocuments.length,
      };
    } catch (error) {
      console.error('FileSearchTool: Error during file search:', error);
      const errorMessage =
        error instanceof Error ? error.message : 'Unknown error';

      // Return empty results on error, but don't throw to allow graceful handling
      return {
        documents: [],
        processedFiles: input.fileIds?.length || 0,
        relevantSections: 0,
      };
    }
  },
  {
    name: 'file_search',
    description:
      'Searches through uploaded files to find relevant content sections based on a query using semantic similarity',
    schema: FileSearchToolSchema,
  },
);