FrenoCorp/apps/api/src/services/spamshield/spamshield.service.ts

import { prisma, SpamRule, SpamFeedback, User } from '@shieldsai/shared-db';
import { spamShieldEnv, SpamDecision, ConfidenceLevel } from './spamshield.config';

// Number reputation service (Hiya API integration)
export class NumberReputationService {
  /**
   * Check number reputation using Hiya API
   */
  async checkReputation(phoneNumber: string): Promise<{
    isSpam: boolean;
    confidence: number;
    spamType?: string;
    reportCount: number;
  }> {
    try {
      // TODO: Integrate with Hiya API
      // const response = await fetch(`${spamShieldEnv.HIYA_API_URL}/lookup`, {
      //   headers: { 'X-API-Key': spamShieldEnv.HIYA_API_KEY },
      //   method: 'POST',
      //   body: JSON.stringify({ phone: phoneNumber }),
      // });
      
      // Simulated response for now
      return {
        isSpam: false,
        confidence: 0.1,
        spamType: undefined,
        reportCount: 0,
      };
    } catch (error) {
      console.error('Error checking number reputation:', error);
      return {
        isSpam: false,
        confidence: 0.0,
        reportCount: 0,
      };
    }
  }

  /**
   * Check number against multiple reputation sources
   */
  async checkMultiSource(phoneNumber: string): Promise<{
    hiya: { isSpam: boolean; confidence: number };
    truecaller: { isSpam: boolean; confidence: number } | null;
    combinedScore: number;
  }> {
    const hiyaResult = await this.checkReputation(phoneNumber);
    
    let truecallerResult: { isSpam: boolean; confidence: number } | null = null;
    if (spamShieldEnv.TRUECALLER_API_KEY) {
      // TODO: Integrate Truecaller
      truecallerResult = {
        isSpam: false,
        confidence: 0.0,
      };
    }

    // Weighted average: Hiya 70%, Truecaller 30%
    const combinedScore = hiyaResult.confidence * 0.7 + 
                         (truecallerResult?.confidence ?? 0) * 0.3;

    return {
      hiya: { isSpam: hiyaResult.isSpam, confidence: hiyaResult.confidence },
      truecaller: truecallerResult,
      combinedScore,
    };
  }
}

// SMS content classifier (BERT-based)
export class SMSClassifierService {
  private model: any = null; // BERT model placeholder

  /**
   * Initialize the BERT model
   */
  async initialize(): Promise<void> {
    // TODO: Load BERT model from path
    // this.model = await loadBERTModel(spamShieldEnv.BERT_MODEL_PATH);
    console.log('SMS classifier initialized');
  }

  /**
   * Classify SMS text as spam or ham
   */
  async classify(smsText: string): Promise<{
    isSpam: boolean;
    confidence: number;
    spamFeatures: string[];
  }> {
    if (!this.model) {
      await this.initialize();
    }

    // Extract features
    const features = this.extractFeatures(smsText);
    
    // TODO: Run through BERT model
    // const prediction = await this.model.predict(smsText);
    
    // Simulated prediction
    const confidence = this.calculateConfidence(features);
    const isSpam = confidence >= spamShieldEnv.SPAM_THRESHOLD_AUTO_BLOCK;

    return {
      isSpam,
      confidence,
      spamFeatures: features,
    };
  }

  private extractFeatures(text: string): string[] {
    const features: string[] = [];
    const lowerText = text.toLowerCase();

    // URL presence
    if (/(http|www)\./i.test(text)) {
      features.push('url_present');
    }

    // Emoji density
    const emojiCount = (text.match(/[\p{Emoji}]/gu) || []).length;
    if (emojiCount / text.length > 0.1) {
      features.push('high_emoji_density');
    }

    // Urgency keywords
    const urgencyWords = ['now', 'urgent', 'limited', 'act fast', 'today'];
    if (urgencyWords.some(word => lowerText.includes(word))) {
      features.push('urgency_keyword');
    }

    // Excessive capitalization
    if (/[A-Z]{3,}/.test(text)) {
      features.push('excessive_caps');
    }

    return features;
  }

  private calculateConfidence(features: string[]): number {
    const baseConfidence = 0.5;
    const featureWeights: Record<string, number> = {
      url_present: 0.1,
      high_emoji_density: 0.15,
      urgency_keyword: 0.2,
      excessive_caps: 0.15,
    };

    return Math.min(1.0, baseConfidence + 
      features.reduce((sum, f) => sum + (featureWeights[f] || 0), 0));
  }
}

// Call analysis service
export class CallAnalysisService {
  /**
   * Analyze incoming call for spam indicators
   */
  async analyzeCall(callData: {
    phoneNumber: string;
    duration?: number;
    callTime: Date;
    isVoip?: boolean;
  }): Promise<{
    decision: SpamDecision;
    confidence: number;
    reasons: string[];
  }> {
    const reasons: string[] = [];
    let spamScore = 0.0;

    // Number reputation check
    const reputationService = new NumberReputationService();
    const reputation = await reputationService.checkMultiSource(callData.phoneNumber);
    
    if (reputation.combinedScore > 0.7) {
      spamScore += reputation.combinedScore * 0.4;
      reasons.push('high_spam_reputation');
    }

    // Behavioral analysis
    if (callData.duration && callData.duration < 10) {
      spamScore += 0.2;
      reasons.push('short_duration');
    }

    if (callData.isVoip) {
      spamScore += 0.15;
      reasons.push('voip_number');
    }

    // Time-of-day anomaly (simplified)
    const hour = callData.callTime.getHours();
    if (hour < 6 || hour > 22) {
      spamScore += 0.1;
      reasons.push('unusual_hours');
    }

    // Determine decision
    let decision: SpamDecision;
    if (spamScore >= spamShieldEnv.SPAM_THRESHOLD_AUTO_BLOCK) {
      decision = SpamDecision.BLOCK;
    } else if (spamScore >= spamShieldEnv.SPAM_THRESHOLD_FLAG) {
      decision = SpamDecision.FLAG;
    } else {
      decision = SpamDecision.ALLOW;
    }

    return {
      decision,
      confidence: spamScore,
      reasons,
    };
  }
}

// User feedback service
export class SpamFeedbackService {
  /**
   * Record user feedback on spam detection
   */
  async recordFeedback(
    userId: string,
    phoneNumber: string,
    isSpam: boolean,
    confidence?: number,
    metadata?: Record<string, any>
  ): Promise<SpamFeedback> {
    const phoneNumberHash = this.hashPhoneNumber(phoneNumber);

    const feedback = await prisma.spamFeedback.create({
      data: {
        userId,
        phoneNumber,
        phoneNumberHash,
        isSpam,
        confidence,
        feedbackType: 'user_confirmation',
        metadata,
      },
    });

    return feedback;
  }

  /**
   * Get spam history for a user
   */
  async getSpamHistory(
    userId: string,
    options?: {
      limit?: number;
      isSpam?: boolean;
      startDate?: Date;
    }
  ): Promise<SpamFeedback[]> {
    return prisma.spamFeedback.findMany({
      where: {
        userId,
        ...(options?.isSpam !== undefined && { isSpam: options.isSpam }),
        ...(options?.startDate && { createdAt: { gte: options.startDate } }),
      },
      orderBy: { createdAt: 'desc' },
      take: options?.limit ?? 100,
    });
  }

  /**
   * Get statistics for a user
   */
  async getStatistics(userId: string): Promise<{
    totalAnalyses: number;
    spamCount: number;
    hamCount: number;
    spamPercentage: number;
  }> {
    const [total, spam] = await Promise.all([
      prisma.spamFeedback.count({ where: { userId } }),
      prisma.spamFeedback.count({ where: { userId, isSpam: true } }),
    ]);

    return {
      totalAnalyses: total,
      spamCount: spam,
      hamCount: total - spam,
      spamPercentage: total > 0 ? (spam / total) * 100 : 0,
    };
  }

  private hashPhoneNumber(phoneNumber: string): string {
    // Simple hash for demonstration
    let hash = 0;
    for (let i = 0; i < phoneNumber.length; i++) {
      hash = ((hash << 5) - hash) + phoneNumber.charCodeAt(i);
      hash |= 0;
    }
    return `hash_${Math.abs(hash)}`;
  }
}

// Export instances
export const numberReputationService = new NumberReputationService();
export const smsClassifierService = new SMSClassifierService();
export const callAnalysisService = new CallAnalysisService();
export const spamFeedbackService = new SpamFeedbackService();