import { Router, Request, Response } from 'express';
import { ApiContext, SearchResult, UnifiedSearchOptions } from '../../types';

/**
 * Configures and returns the search-related routes for the API.
 *
 * @param context - The API context containing dependencies such as the database, timer, and filter creation function.
 *
 * @returns An Express router with the following endpoints:
 *
 * ### POST `/`
 * Performs a nearest neighbor search using the provided query vector(s) and options.
 *
 * Request Body:
 * - `query` (array): The query vector(s) to search for. **Required**.
 * - `k` (number): The number of nearest neighbors to retrieve.
 * - `method` (string): The search method to use (`hnsw` or `clustered`).
 * - `partitionIds` (array): Optional array of partition IDs to restrict the search.
 * - `efSearch` (number): The efSearch parameter for HNSW search.
 * - `distanceMetric` (string): The distance metric to use for the search.
 * - `rerank` (boolean): Whether to apply reranking to the results.
 * - `rerankingMethod` (string): The method to use for reranking.
 * - `rerankLambda` (number): The lambda parameter for reranking.
 * - `filters` (object | array): Filters to apply to the search results.
 * - `includeMetadata` (boolean): Whether to include metadata in the results.
 * - `includeVectors` (boolean): Whether to include vectors in the results.
 * - `skipCache` (boolean): Whether to skip the cache for this search.
 * - `searchTimeoutMs` (number): Timeout for the search operation in milliseconds.
 *
 * Response:
 * - `results` (array): The search results.
 * - `count` (number): The number of results returned.
 * - `duration` (number): The time taken to perform the search in milliseconds.
 * - `searchOptions` (object): Details about the search options used.
 *
 * ### POST `/metadata`
 * Searches for metadata entries that match specific criteria across all loaded partitions.
 *
 * Request Body:
 * - `criteria` (string | array | object): The criteria to match. **Required**.
 * - `values` (any): Optional values to match (used with string/array criteria).
 * - `includeVectors` (boolean): Whether to include vectors in the response.
 * - `limit` (number): Optional limit on the number of results to return.
 *
 * Response:
 * - `results` (array): The metadata entries matching the criteria.
 * - `count` (number): The number of results returned.
 * - `duration` (number): The time taken to perform the search in milliseconds.
 *
 * Errors:
 * - Returns a 400 status code for invalid requests (e.g., missing or invalid `query` or `criteria`).
 * - Returns a 500 status code for internal server errors, with optional stack trace in development mode.
 *
 * ### POST `/relationships`
 * Finds relationships between vectors based on a distance threshold.
 *
 * Request Body:
 * - `threshold` (number): The maximum distance between vectors to consider them related. **Required**.
 * - `metric` (string): Distance metric to use (e.g., 'cosine', 'euclidean'). Default depends on database implementation.
 * - `partitionIds` (array): Optional array of partition IDs to restrict the relationship search.
 *
 * Response:
 * - `relationships` (array): Array of relationships between vectors.
 * - `count` (number): The number of relationships found.
 * - `duration` (number): The time taken to extract relationships in milliseconds.
 *
 * Errors:
 * - Returns a 400 status code for invalid requests (e.g., missing or invalid `threshold`).
 * - Returns a 500 status code for internal server errors, with optional stack trace in development mode.
 */
export function searchRoutes(context: ApiContext) {
  const router = Router();
  const { database, timer, createFilterFunction } = context;
  /**
   * Nearest neighbor search endpoint
   *
   * Searches for the k-nearest neighbors of a given query vector across all loaded partitions.
   *
   * Request body:
   * - query: Array of query vectors (required)
   * - k: Number of nearest neighbors to retrieve
   * - method: Search method to use (e.g., 'hnsw' or 'clustered')
   * - partitionIds: Optional array of partition IDs to restrict the search
   * - efSearch: efSearch parameter for HNSW search
   * - distanceMetric: Distance metric to use for the search
   * - rerank: Whether to apply reranking to the results
   * - rerankingMethod: Method to use for reranking
   * - rerankLambda: Lambda parameter for reranking
   * - filters: Filters to apply to the search results (optional)
   * - includeMetadata: Whether to include metadata in the results
   * - includeVectors: Whether to include vectors in the results
   * - skipCache: Whether to skip the cache for this search
   * - searchTimeoutMs: Timeout for the search operation in milliseconds
   * * Example:
   * ```json
   * {
   *   "query": [[0.1, 0.2, 0.3]],
   *  "k": 5,
   *  "method": "hnsw",
   *  "partitionIds": ["partition1", "partition2"],
   *  "efSearch": 200,
   * "distanceMetric": "euclidean",
   * "rerank": true,
   * "rerankingMethod": "cosine",
   * "rerankLambda": 0.5,
   * "filters": { "field": "value" },
   * "includeMetadata": true,
   * "includeVectors": false,
   * "skipCache": false,
   * "searchTimeoutMs": 5000
   * }
   * @returns Array of nearest neighbors with metadata and vector IDs
   * * Example response:
   * ```json
   * {
   *   "results": [
   *                {
   *                  "partitionId": "partition1",
   *                  "vectorId": 123,
   *                  "distance": 0.1,
   *                  "metadata": { "field": "value" }
   *                },
   *                {
   *                  "partitionId": "partition2",
   *                  "vectorId": 456,
   *                  "distance": 0.2,
   *                  "metadata": { "field": "value" }
   *                }
   *              ],
   *    "count": 2,
   *    "duration": 1234,
   *    "searchOptions": {
   *        "k": 5,
   *        "method": "hnsw",
   *        "partitionsSearched": ["partition1", "partition2"],
   *        "rerankApplied": true,
   *        "cacheUsed": true,
   *        "filtersApplied": true
   *     }
   *
   */
  router.post('/', async function (req: Request, res: Response) {
    timer.start('search');

    const { query, k, method, partitionIds, efSearch, distanceMetric, rerank, rerankingMethod, rerankLambda, filters = {}, includeMetadata, includeVectors, skipCache, searchTimeoutMs } = req.body;

    if (!query || !Array.isArray(query)) {
      res.status(400).json({
        error: 'Invalid request: query vector array is required',
      });
      return;
    }

    try {
      const hasFilters = Array.isArray(filters) ? filters.length > 0 : Object.keys(filters).length > 0;

      // Build comprehensive search options
      const searchOptions: UnifiedSearchOptions = {
        k,
        useHNSW: method === 'hnsw',
        // Only include filter if filters are present
        filter: hasFilters ? createFilterFunction(filters) : undefined,
        includeMetadata,
        includeVectors,
        skipCache,
        partitionIds,
        efSearch,
        distanceMetric,
        rerank,
        rerankingMethod,
        rerankLambda,
        searchTimeoutMs,
      };

      // Remove undefined options to avoid overriding defaults
      Object.keys(searchOptions).forEach((key) => {
        if (searchOptions[key as keyof UnifiedSearchOptions] === undefined) {
          delete searchOptions[key as keyof UnifiedSearchOptions];
        }
      });

      const results: SearchResult[] = await database.findNearest(query, k, searchOptions);

      const duration = timer.stop('search').total;

      // Return enhanced response with details
      res.json({
        results,
        count: results.length,
        duration,
        searchOptions: {
          k,
          method: method === 'hnsw' ? 'hnsw' : 'clustered',
          partitionsSearched: partitionIds?.length || 'all',
          rerankApplied: rerank,
          cacheUsed: !skipCache,
          filtersApplied: hasFilters,
        },
      });
      return;
    } catch (error) {
      const duration = timer.stop('search').total;
      console.error('Search error:', error);

      // Provide detailed error response
      res.status(500).json({
        error: (error as Error).message,
        stack: process.env.NODE_ENV === 'development' ? (error as Error).stack : undefined,
        duration,
      });
      return;
    }
  });
  /**
   * Metadata search endpoint
   *
   * Searches for metadata entries that match specific criteria across all loaded partitions.
   *
   * Request body:
   * - criteria: String, array of strings, or object with field-value pairs
   * - values: Optional values to match (used with string/array criteria)
   * - includeVectors: Whether to include vectors in the response
   * - limit: Optional limit on the number of results to return
   * Example
   * - Get all metadata entries with 'category' field across partitions
   * POST body
   * ```json
   * {
   *   "criteria":"category"
   * }
   * ```
   *
   * - Get entries where 'status' equals 'active' across partitions
   * POST body
   * ```json
   * {
   *   "criteria":"category",
   *   "values":"active"
   * }
   * ```
   *
   * - Get entries with both 'author' and 'title' fields across partitions
   * POST body

   * ```json
   * {
   *   "criteria":["author", "title"]
   * }
   * ```
   * - Get entries where 'type' is 'book' AND 'published' is true across partitions
   * POST body
   * ```json
   * {
   *   "criteria":["type", "published"],
   *   "values": ["book", true]
   * }
   * - Using object syntax (recommended): type='book' AND published=true
   * const publishedBooks = await db.getMetadataWithFieldAcrossPartitions({ type: 'book', published: true });
   * POST body
   * ```json
   * {
   *   "criteria":{ "type": "book", "published": true },
   * }
   * @returns Array of metadata entries matching the criteria with partition and vector IDs
   */
  router.post('/metadata', async function (req: Request, res: Response) {
    timer.start('metadata_search');

    const { criteria, values, includeVectors = false, limit } = req.body;

    // Validate that criteria is provided and is of the right type
    if (criteria === undefined || (typeof criteria !== 'string' && !Array.isArray(criteria) && (typeof criteria !== 'object' || criteria === null))) {
      res.status(400).json({
        error: 'Invalid request: criteria must be a string, array of strings, or object with field-value pairs',
      });
      return;
    }

    try {
      // Call the database method to get metadata with matching fields
      const results = await database.getMetadataWithField(criteria, values, { limit });

      // If includeVectors is true, fetch vectors for each result
      if (includeVectors) {
        const resultsWithVectors = await Promise.all(
          results.map(async (item: { partitionId: string; vectorId: number | string; metadata: Record<string, any> }) => {
            const vectorData = await database.getVector(item.vectorId);
            return {
              ...item,
              vector: vectorData ? vectorData.vector : null,
            };
          })
        );

        const duration = timer.stop('metadata_search').total;
        res.json({
          results: resultsWithVectors,
          count: resultsWithVectors.length,
          duration,
        });
        return;
      }

      const duration = timer.stop('metadata_search').total;
      res.json({
        results,
        count: results.length,
        duration,
      });
    } catch (error) {
      const duration = timer.stop('metadata_search').total;
      console.error('Metadata search error:', error);

      res.status(500).json({
        error: (error as Error).message,
        stack: process.env.NODE_ENV === 'development' ? (error as Error).stack : undefined,
        duration,
      });
    }
  });

  /**
   * Vector relationships extraction endpoint
   *
   * Finds relationships between vectors based on a distance threshold.
   *
   * Request body:
   * - threshold: The maximum distance between vectors to consider them related (required)
   * - metric: Distance metric to use (e.g., 'cosine', 'euclidean')
   * - partitionIds: Optional array of partition IDs to restrict the relationship search
   * - `includeMetadata` (boolean): Whether to include metadata for each vector in the results.
   *
   * Example:
   * ```json
   * {
   *   "threshold": 0.3,
   *   "metric": "cosine",
   *   "partitionIds": ["partition1", "partition2"]
   *   "includeMetadata": true
   * }
   * ```
   * @returns Array of relationships between vectors
   *
   * Example response:
   * ```json
   * {
   *   "relationships": [
   *     {
   *       "vector1": { "id": 123, "partitionId": "partition1" },
   *       "vector2": { "id": 456, "partitionId": "partition1" },
   *       "distance": 0.25
   *     },
   *     {
   *       "vector1": { "id": 789, "partitionId": "partition2" },
   *       "vector2": { "id": 101, "partitionId": "partition2" },
   *       "distance": 0.15
   *     }
   *   ],
   *   "count": 2,
   *   "duration": 345
   * }
   * ```
   */
  router.post('/relationships', async function (req: Request, res: Response) {
    timer.start('extract_relationships');

    const { threshold, metric, partitionIds, includeMetadata = true } = req.body;

    if (threshold === undefined || typeof threshold !== 'number' || threshold <= 0) {
      res.status(400).json({
        error: 'Invalid request: threshold must be a positive number',
      });
      return;
    }

    try {
      const relationships = await database.extractRelationships(threshold, {
        metric,
        partitionIds,
        includeMetadata,
      });

      const duration = timer.stop('extract_relationships').total;

      res.json({
        relationships,
        count: relationships.length,
        duration,
      });
    } catch (error) {
      const duration = timer.stop('extract_relationships').total;
      console.error('Relationship extraction error:', error);

      res.status(500).json({
        error: (error as Error).message,
        stack: process.env.NODE_ENV === 'development' ? (error as Error).stack : undefined,
        duration,
      });
    }
  });

  /**
   * Vector communities extraction endpoint
   *
   * Finds communities (clusters) of vectors based on a distance threshold across loaded partitions.
   * A community is a group of vectors where each vector is related to at least one other vector in the group.
   *
   * Request body:
   * - `threshold` (number): The maximum distance between vectors to consider them related. **Required**.
   * - `metric` (string): Distance metric to use (e.g., 'cosine', 'euclidean'). Default depends on database implementation.
   * - `partitionIds` (array): Optional array of partition IDs to restrict the community extraction.
   * - `includeMetadata` (boolean): Whether to include metadata for each vector in the results.
   *
   * Example:
   * ```json
   * {
   *   "threshold": 0.3,
   *   "metric": "cosine",
   *   "partitionIds": ["partition1", "partition2"],
   *   "includeMetadata": true
   * }
   * ```
   * @returns Array of communities, where each community is an array of related vectors
   *
   * Example response:
   * ```json
   * {
   *   "communities": [
   *     [
   *       { "id": 123, "partitionId": "partition1", "metadata": { "label": "doc1" } },
   *       { "id": 456, "partitionId": "partition1", "metadata": { "label": "doc2" } }
   *     ],
   *     [
   *       { "id": 789, "partitionId": "partition2", "metadata": { "label": "doc3" } },
   *       { "id": 101, "partitionId": "partition2", "metadata": { "label": "doc4" } },
   *       { "id": 102, "partitionId": "partition2", "metadata": { "label": "doc5" } }
   *     ]
   *   ],
   *   "count": 2,
   *   "totalVectors": 5,
   *   "duration": 345
   * }
   * ```
   */
  router.post('/communities', async function (req: Request, res: Response) {
    timer.start('extract_communities');

    const { threshold, metric, partitionIds, includeMetadata = true } = req.body;

    if (threshold === undefined || typeof threshold !== 'number' || threshold <= 0) {
      res.status(400).json({
        error: 'Invalid request: threshold must be a positive number',
      });
      return;
    }

    try {
      const communities = await database.extractCommunities(threshold, {
        metric,
        partitionIds,
        includeMetadata,
      });

      const duration = timer.stop('extract_communities').total;

      res.json({
        communities,
        count: communities.length,
        totalVectors: communities.reduce((sum, community) => sum + community.length, 0),
        duration,
      });
    } catch (error) {
      const duration = timer.stop('extract_communities').total;
      console.error('Community extraction error:', error);

      res.status(500).json({
        error: (error as Error).message,
        stack: process.env.NODE_ENV === 'development' ? (error as Error).stack : undefined,
        duration,
      });
    }
  });

  return router;
}