/**
 * usePersonSearch Hook
 * 
 * Provides semantic search functionality for person profiles using
 * the RAG API's Qdrant vector database backend.
 * 
 * Features:
 * - Semantic vector search across all profiles
 * - Filter by field type (name, email, domain, birth_year)
 * - Debounced queries to prevent API overload
 * - Caching of search results
 */

import { useState, useEffect, useCallback, useRef } from 'react';

export type SearchField = 'all' | 'name' | 'email' | 'domain' | 'birth_year';

export interface PersonSearchResult {
  ppid?: string;
  name: string;
  headline?: string | null;
  custodian_name?: string | null;
  custodian_slug?: string | null;
  linkedin_url?: string | null;
  heritage_relevant?: boolean | null;
  heritage_type?: string | null;
  location?: string | null;
  email?: string | null;
  email_domain?: string | null;
  birth_year?: number | null;
  score?: number | null;
}

export interface PersonSearchResponse {
  query: string;
  results: PersonSearchResult[];
  result_count: number;
  query_time_ms: number;
  collection_stats?: Record<string, unknown> | null;
  embedding_model_used?: string | null;
}

interface UsePersonSearchOptions {
  debounceMs?: number;
  minQueryLength?: number;
  maxResults?: number;
}

interface UsePersonSearchReturn {
  // Search state
  query: string;
  setQuery: (query: string) => void;
  searchField: SearchField;
  setSearchField: (field: SearchField) => void;
  
  // Results
  results: PersonSearchResult[];
  isSearching: boolean;
  error: string | null;
  
  // Metadata
  queryTimeMs: number | null;
  resultCount: number;
  embeddingModelUsed: string | null;
  
  // Actions
  clearSearch: () => void;
  search: (query: string, field?: SearchField) => Promise<void>;
}

const API_BASE = '/api/rag';

export function usePersonSearch(options: UsePersonSearchOptions = {}): UsePersonSearchReturn {
  const {
    debounceMs = 300,
    minQueryLength = 2,
    maxResults = 50,
  } = options;

  // State
  const [query, setQuery] = useState('');
  const [searchField, setSearchField] = useState<SearchField>('all');
  const [results, setResults] = useState<PersonSearchResult[]>([]);
  const [isSearching, setIsSearching] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const [queryTimeMs, setQueryTimeMs] = useState<number | null>(null);
  const [resultCount, setResultCount] = useState(0);
  const [embeddingModelUsed, setEmbeddingModelUsed] = useState<string | null>(null);

  // Refs for debouncing
  const debounceTimerRef = useRef<NodeJS.Timeout | null>(null);
  const abortControllerRef = useRef<AbortController | null>(null);

  // Build the search query based on field selection
  const buildSearchQuery = useCallback((rawQuery: string, field: SearchField): string => {
    const trimmedQuery = rawQuery.trim();
    if (!trimmedQuery) return '';

    switch (field) {
      case 'name':
        return `person named ${trimmedQuery}`;
      case 'email':
        return `email address ${trimmedQuery}`;
      case 'domain':
        return `working at domain ${trimmedQuery}`;
      case 'birth_year':
        return `born in ${trimmedQuery}`;
      case 'all':
      default:
        return trimmedQuery;
    }
  }, []);

  // Perform the actual search
  const performSearch = useCallback(async (searchQuery: string, field: SearchField) => {
    if (searchQuery.trim().length < minQueryLength) {
      setResults([]);
      setResultCount(0);
      setQueryTimeMs(null);
      return;
    }

    // Cancel any pending request
    if (abortControllerRef.current) {
      abortControllerRef.current.abort();
    }
    abortControllerRef.current = new AbortController();

    setIsSearching(true);
    setError(null);

    try {
      const enhancedQuery = buildSearchQuery(searchQuery, field);
      
      const response = await fetch(`${API_BASE}/persons/search`, {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json',
        },
        body: JSON.stringify({
          query: enhancedQuery,
          k: maxResults,
          only_heritage_relevant: false,
        }),
        signal: abortControllerRef.current.signal,
      });

      if (!response.ok) {
        throw new Error(`Search failed: ${response.statusText}`);
      }

      const data: PersonSearchResponse = await response.json();
      
      // Deduplicate results by name (Qdrant may return multiple embeddings per person)
      const seen = new Map<string, PersonSearchResult>();
      for (const result of data.results) {
        const key = result.name.toLowerCase().trim();
        const existing = seen.get(key);
        // Keep the one with higher score, or the first if no scores
        if (!existing || (result.score && existing.score && result.score > existing.score)) {
          seen.set(key, result);
        }
      }
      const dedupedResults = Array.from(seen.values());
      
      setResults(dedupedResults);
      setResultCount(dedupedResults.length);
      setQueryTimeMs(data.query_time_ms);
      setEmbeddingModelUsed(data.embedding_model_used || null);
    } catch (err) {
      if (err instanceof Error && err.name === 'AbortError') {
        // Request was cancelled, ignore
        return;
      }
      console.error('Person search error:', err);
      setError(err instanceof Error ? err.message : 'Search failed');
      setResults([]);
    } finally {
      setIsSearching(false);
    }
  }, [buildSearchQuery, maxResults, minQueryLength]);

  // Debounced search effect
  useEffect(() => {
    if (debounceTimerRef.current) {
      clearTimeout(debounceTimerRef.current);
    }

    if (!query.trim()) {
      setResults([]);
      setResultCount(0);
      setQueryTimeMs(null);
      return;
    }

    debounceTimerRef.current = setTimeout(() => {
      performSearch(query, searchField);
    }, debounceMs);

    return () => {
      if (debounceTimerRef.current) {
        clearTimeout(debounceTimerRef.current);
      }
    };
  }, [query, searchField, debounceMs, performSearch]);

  // Manual search function (bypasses debounce)
  const search = useCallback(async (searchQuery: string, field?: SearchField) => {
    await performSearch(searchQuery, field || searchField);
  }, [performSearch, searchField]);

  // Clear search
  const clearSearch = useCallback(() => {
    setQuery('');
    setResults([]);
    setResultCount(0);
    setQueryTimeMs(null);
    setError(null);
    if (abortControllerRef.current) {
      abortControllerRef.current.abort();
    }
  }, []);

  // Cleanup on unmount
  useEffect(() => {
    return () => {
      if (debounceTimerRef.current) {
        clearTimeout(debounceTimerRef.current);
      }
      if (abortControllerRef.current) {
        abortControllerRef.current.abort();
      }
    };
  }, []);

  return {
    query,
    setQuery,
    searchField,
    setSearchField,
    results,
    isSearching,
    error,
    queryTimeMs,
    resultCount,
    embeddingModelUsed,
    clearSearch,
    search,
  };
}