import { requireAuth } from '~/server/utils/auth';
import { getNocoDbConfiguration } from '~/server/utils/nocodb';

export default defineEventHandler(async (event) => {
  console.log('[DUPLICATES] Find duplicates request');

  try {
    // Require authentication (any authenticated user with interest access)
    await requireAuth(event);

    const query = getQuery(event);
    const threshold = query.threshold ? parseFloat(query.threshold as string) : 0.8;

    // Get all interests from NocoDB
    const config = getNocoDbConfiguration();
    const interestTableId = "mbs9hjauug4eseo"; // Interest table ID from nocodb.ts
    const response = await $fetch(`${config.url}/api/v2/tables/${interestTableId}/records`, {
      headers: {
        'xc-token': config.token
      },
      params: {
        limit: 5000 // Get a large batch for duplicate detection
      }
    }) as any;

    const interests = response.list || [];
    console.log('[ADMIN] Analyzing', interests.length, 'interests for duplicates');

    // Find potential duplicates
    const duplicateGroups = findDuplicateInterests(interests, threshold);

    console.log('[ADMIN] Found', duplicateGroups.length, 'duplicate groups');

    return {
      success: true,
      data: {
        duplicateGroups,
        totalInterests: interests.length,
        duplicateCount: duplicateGroups.reduce((sum, group) => sum + group.interests.length, 0),
        threshold
      }
    };

  } catch (error: any) {
    console.error('[ADMIN] Failed to find duplicates:', error);
    
    if (error.statusCode === 403) {
      return {
        success: false,
        error: 'Insufficient permissions. Admin access required.'
      };
    }

    return {
      success: false,
      error: 'Failed to find duplicates'
    };
  }
});

/**
 * Find duplicate interests based on multiple criteria
 */
function findDuplicateInterests(interests: any[], threshold: number = 0.8) {
  const duplicateGroups: Array<{
    id: string;
    interests: any[];
    matchReason: string;
    confidence: number;
    masterCandidate: any;
  }> = [];

  const processedIds = new Set<number>();

  for (let i = 0; i < interests.length; i++) {
    const interest1 = interests[i];
    
    if (processedIds.has(interest1.Id)) continue;

    const matches = [interest1];
    
    for (let j = i + 1; j < interests.length; j++) {
      const interest2 = interests[j];
      
      if (processedIds.has(interest2.Id)) continue;

      const similarity = calculateSimilarity(interest1, interest2);
      
      if (similarity.score >= threshold) {
        matches.push(interest2);
        processedIds.add(interest2.Id);
      }
    }

    if (matches.length > 1) {
      // Mark all as processed
      matches.forEach(match => processedIds.add(match.Id));

      // Determine the best master candidate (most complete record)
      const masterCandidate = selectMasterCandidate(matches);
      
      duplicateGroups.push({
        id: `group_${duplicateGroups.length + 1}`,
        interests: matches,
        matchReason: 'Multiple matching criteria',
        confidence: Math.max(...matches.slice(1).map(match => 
          calculateSimilarity(masterCandidate, match).score
        )),
        masterCandidate
      });
    }
  }

  return duplicateGroups;
}

/**
 * Calculate similarity between two interests
 */
function calculateSimilarity(interest1: any, interest2: any) {
  const scores: Array<{ type: string; score: number; weight: number }> = [];

  // Email similarity (highest weight)
  if (interest1.Email && interest2.Email) {
    const emailScore = interest1.Email.toLowerCase() === interest2.Email.toLowerCase() ? 1.0 : 0.0;
    scores.push({ type: 'email', score: emailScore, weight: 0.4 });
  }

  // Phone similarity
  if (interest1.Phone && interest2.Phone) {
    const phone1 = normalizePhone(interest1.Phone);
    const phone2 = normalizePhone(interest2.Phone);
    const phoneScore = phone1 === phone2 ? 1.0 : 0.0;
    scores.push({ type: 'phone', score: phoneScore, weight: 0.3 });
  }

  // Name similarity
  if (interest1.Name && interest2.Name) {
    const nameScore = calculateNameSimilarity(interest1.Name, interest2.Name);
    scores.push({ type: 'name', score: nameScore, weight: 0.2 });
  }

  // Address similarity
  if (interest1.Address && interest2.Address) {
    const addressScore = calculateStringSimilarity(interest1.Address, interest2.Address);
    scores.push({ type: 'address', score: addressScore, weight: 0.1 });
  }

  // Calculate weighted average
  const totalWeight = scores.reduce((sum, s) => sum + s.weight, 0);
  const weightedScore = scores.reduce((sum, s) => sum + (s.score * s.weight), 0) / (totalWeight || 1);

  return {
    score: weightedScore,
    details: scores
  };
}

/**
 * Normalize phone number for comparison
 */
function normalizePhone(phone: string): string {
  return phone.replace(/\D/g, ''); // Remove all non-digits
}

/**
 * Calculate name similarity using Levenshtein distance
 */
function calculateNameSimilarity(name1: string, name2: string): number {
  const str1 = name1.toLowerCase().trim();
  const str2 = name2.toLowerCase().trim();
  
  if (str1 === str2) return 1.0;
  
  const distance = levenshteinDistance(str1, str2);
  const maxLength = Math.max(str1.length, str2.length);
  
  return maxLength > 0 ? 1 - (distance / maxLength) : 0;
}

/**
 * Calculate string similarity using Levenshtein distance
 */
function calculateStringSimilarity(str1: string, str2: string): number {
  const s1 = str1.toLowerCase().trim();
  const s2 = str2.toLowerCase().trim();
  
  if (s1 === s2) return 1.0;
  
  const distance = levenshteinDistance(s1, s2);
  const maxLength = Math.max(s1.length, s2.length);
  
  return maxLength > 0 ? 1 - (distance / maxLength) : 0;
}

/**
 * Calculate Levenshtein distance between two strings
 */
function levenshteinDistance(str1: string, str2: string): number {
  const matrix = Array(str2.length + 1).fill(null).map(() => Array(str1.length + 1).fill(null));

  for (let i = 0; i <= str1.length; i += 1) {
    matrix[0][i] = i;
  }

  for (let j = 0; j <= str2.length; j += 1) {
    matrix[j][0] = j;
  }

  for (let j = 1; j <= str2.length; j += 1) {
    for (let i = 1; i <= str1.length; i += 1) {
      const indicator = str1[i - 1] === str2[j - 1] ? 0 : 1;
      matrix[j][i] = Math.min(
        matrix[j][i - 1] + 1, // deletion
        matrix[j - 1][i] + 1, // insertion
        matrix[j - 1][i - 1] + indicator // substitution
      );
    }
  }

  return matrix[str2.length][str1.length];
}

/**
 * Select the best master candidate from a group of duplicates
 */
function selectMasterCandidate(interests: any[]) {
  return interests.reduce((best, current) => {
    const bestScore = calculateCompletenessScore(best);
    const currentScore = calculateCompletenessScore(current);
    
    return currentScore > bestScore ? current : best;
  });
}

/**
 * Calculate completeness score for an interest record
 */
function calculateCompletenessScore(interest: any): number {
  const fields = ['Name', 'Email', 'Phone', 'Address', 'Comments', 'BerthRequirements'];
  const filledFields = fields.filter(field => 
    interest[field] && interest[field].toString().trim().length > 0
  );
  
  let score = filledFields.length / fields.length;
  
  // Bonus for recent creation
  if (interest.CreatedAt) {
    const created = new Date(interest.CreatedAt);
    const now = new Date();
    const daysOld = (now.getTime() - created.getTime()) / (1000 * 60 * 60 * 24);
    
    // More recent records get a small bonus
    if (daysOld < 30) score += 0.1;
    else if (daysOld < 90) score += 0.05;
  }
  
  return score;
}
