/**
 * Content Similarity Service
 * Analyzes semantic similarity between articles with market-aware adjustments
 */

const ClaudeAPIService = require('./ClaudeAPI.service');
const publicationConfig = require('../config/publication-targets.config');
const logger = require('../utils/logger.util');

class ContentSimilarityService {
  /**
   * Analyze semantic similarity between two articles
   * @param {Object} article1 - First article
   * @param {Object} article2 - Second article
   * @param {Object} context - Optional context (target publication, etc.)
   * @returns {Promise<Object>} Similarity analysis with market adjustments
   */
  async analyzeSimilarity(article1, article2, context = {}) {
    logger.info(`Analyzing similarity: "${article1.title}" vs "${article2.title}"`);

    try {
      const claudeAPI = ClaudeAPIService;

      // Build system prompt for similarity analysis
      const systemPrompt = `You are an expert content analyst evaluating semantic similarity between two articles.

Your task is to analyze:
1. **Core Argument Similarity**: Do they make the same fundamental argument?
2. **Evidence/Examples**: Do they use the same examples or evidence?
3. **Narrative/Framing**: Do they frame the issue the same way?
4. **Conclusions**: Do they reach the same conclusions?
5. **Unique Elements**: What makes each article distinct?

Return JSON:
{
  "semanticSimilarity": 0.0-1.0,
  "argumentSimilarity": 0.0-1.0,
  "evidenceSimilarity": 0.0-1.0,
  "framingSimilarity": 0.0-1.0,
  "conclusionSimilarity": 0.0-1.0,
  "uniqueElements": {
    "article1": ["Unique aspect 1", "Unique aspect 2"],
    "article2": ["Unique aspect 1", "Unique aspect 2"]
  },
  "reasoning": "Detailed explanation of similarity assessment",
  "verdict": "distinct|similar|very-similar|duplicate"
}

Similarity scale:
- 0.0-0.3: Distinct (different arguments)
- 0.3-0.5: Some overlap (related topics, different angles)
- 0.5-0.7: Similar (same argument, different execution)
- 0.7-0.9: Very similar (same argument and approach)
- 0.9-1.0: Duplicate (essentially the same article)`;

      const userPrompt = `Compare these two articles:

**Article 1: "${article1.title}"**
Word Count: ${article1.wordCount || 'unknown'}

${article1.content.substring(0, 3000)}${article1.content.length > 3000 ? '...' : ''}

---

**Article 2: "${article2.title}"**
Word Count: ${article2.wordCount || 'unknown'}

${article2.content.substring(0, 3000)}${article2.content.length > 3000 ? '...' : ''}

---

Analyze semantic similarity and provide detailed JSON response.`;

      const messages = [{ role: 'user', content: userPrompt }];

      const response = await claudeAPI.sendMessage(messages, {
        system: systemPrompt,
        max_tokens: 1500,
        temperature: 0.2  // Low temperature for consistent analysis
      });

      const baseSimilarity = claudeAPI.extractJSON(response);

      // Apply market-aware adjustments
      const adjusted = this._applyMarketAdjustments(
        baseSimilarity,
        article1,
        article2,
        context
      );

      logger.info(`Similarity analysis complete: ${adjusted.finalSimilarity.toFixed(2)}`);

      return adjusted;

    } catch (error) {
      logger.error('Similarity analysis error:', error);
      throw new Error(`Failed to analyze similarity: ${error.message}`);
    }
  }

  /**
   * Apply market-aware adjustments to similarity score
   * @private
   */
  _applyMarketAdjustments(baseSimilarity, article1, article2, context) {
    const adjustments = {
      differentLanguage: 0,
      differentRegion: 0,
      differentCultural: 0,
      differentAudience: 0,
      isAdaptation: 0
    };

    const reasoning = [];

    // Get publication market data
    const pub1 = context.targetPublication1
      ? publicationConfig.getPublicationById(context.targetPublication1)
      : null;
    const pub2 = context.targetPublication2
      ? publicationConfig.getPublicationById(context.targetPublication2)
      : null;

    // Different language modifier
    if (pub1?.market?.language && pub2?.market?.language) {
      if (pub1.market.language !== pub2.market.language) {
        adjustments.differentLanguage = -0.3;
        reasoning.push(`Different languages (${pub1.market.language} vs ${pub2.market.language}) - major adjustment`);
      }
    }

    // Different region modifier
    if (pub1?.market && pub2?.market) {
      const overlap = this._calculateRegionOverlap(pub1.market.regions, pub2.market.regions);

      if (overlap === 0) {
        adjustments.differentRegion = -0.2;
        reasoning.push(`No regional overlap - content can be reused across markets`);
      } else if (overlap < 0.3) {
        adjustments.differentRegion = -0.1;
        reasoning.push(`Minimal regional overlap (${(overlap * 100).toFixed(0)}%) - slight adjustment`);
      } else if (overlap > 0.7) {
        reasoning.push(`High regional overlap (${(overlap * 100).toFixed(0)}%) - similarity matters`);
      }
    }

    // Different cultural context
    if (pub1?.market?.culturalContext && pub2?.market?.culturalContext) {
      if (pub1.market.culturalContext !== pub2.market.culturalContext &&
          pub1.market.culturalContext !== 'universal' &&
          pub2.market.culturalContext !== 'universal') {
        adjustments.differentCultural = -0.15;
        reasoning.push(`Different cultural contexts (${pub1.market.culturalContext} vs ${pub2.market.culturalContext})`);
      }
    }

    // Different audience sophistication
    if (pub1?.audience && pub2?.audience) {
      const audienceOverlap = this._calculateAudienceOverlap(pub1.audience, pub2.audience);
      if (audienceOverlap < 0.3) {
        adjustments.differentAudience = -0.1;
        reasoning.push(`Different target audiences - allows similar messaging with different framing`);
      }
    }

    // Check if intentional adaptation
    if (context.isAdaptation) {
      adjustments.isAdaptation = -0.4;
      reasoning.push(`Marked as intentional adaptation - high similarity expected and allowed`);
    }

    // Calculate final similarity
    const totalAdjustment = Object.values(adjustments).reduce((sum, val) => sum + val, 0);
    const finalSimilarity = Math.max(0, Math.min(1, baseSimilarity.semanticSimilarity + totalAdjustment));

    // Determine if allowed
    const threshold = context.similarityThreshold || 0.70;
    const allowed = finalSimilarity < threshold;

    return {
      baseSimilarity: baseSimilarity.semanticSimilarity,
      adjustments,
      totalAdjustment,
      finalSimilarity,
      threshold,
      allowed,
      verdict: baseSimilarity.verdict,
      reasoning: reasoning.join('; '),
      detailedAnalysis: baseSimilarity,
      recommendation: this._generateRecommendation(finalSimilarity, allowed, context)
    };
  }

  /**
   * Calculate regional overlap between two publication markets
   * @private
   */
  _calculateRegionOverlap(regions1, regions2) {
    if (!regions1 || !regions2) return 0.5; // Unknown, assume moderate overlap

    // Handle global reach specially
    if (regions1.includes('global') || regions2.includes('global')) {
      return 1.0; // Global publications overlap with everything
    }

    const set1 = new Set(regions1);
    const set2 = new Set(regions2);
    const intersection = new Set([...set1].filter(x => set2.has(x)));

    if (set1.size === 0 || set2.size === 0) return 0;

    return intersection.size / Math.max(set1.size, set2.size);
  }

  /**
   * Calculate audience overlap
   * @private
   */
  _calculateAudienceOverlap(audience1, audience2) {
    if (!audience1 || !audience2) return 0.5;

    const set1 = new Set(audience1);
    const set2 = new Set(audience2);
    const intersection = new Set([...set1].filter(x => set2.has(x)));

    if (set1.size === 0 || set2.size === 0) return 0;

    return intersection.size / Math.max(set1.size, set2.size);
  }

  /**
   * Generate human-readable recommendation
   * @private
   */
  _generateRecommendation(similarity, allowed, context) {
    if (similarity < 0.3) {
      return '✅ These articles are distinct. Safe to publish both.';
    } else if (similarity < 0.5) {
      return '✅ Some thematic overlap, but different enough for both markets.';
    } else if (similarity < 0.7) {
      return allowed
        ? '⚠️ Moderately similar. Acceptable for different markets, but consider revisions for same market.'
        : '⚠️ Moderately similar. Consider significant revisions to differentiate.';
    } else if (similarity < 0.85) {
      return allowed
        ? '⚠️ Very similar. Only acceptable due to different markets/languages. Ensure cultural adaptation.'
        : '🚫 Very similar. Revisions required before submitting to overlapping markets.';
    } else {
      return allowed
        ? '⚠️ Nearly identical. Only acceptable as intentional translation/adaptation.'
        : '🚫 Too similar. This would violate editorial standards and exclusivity requirements.';
    }
  }

  /**
   * Check for submission conflicts
   * @param {string} contentId - BlogPost ID
   * @param {string} targetPublicationId - Target publication
   * @param {Object} SubmissionTracking - Submission model
   * @returns {Promise<Object>} Conflict analysis
   */
  async checkSubmissionConflict(contentId, targetPublicationId, SubmissionTracking) {
    const targetPub = publicationConfig.getPublicationById(targetPublicationId);

    if (!targetPub) {
      throw new Error(`Publication not found: ${targetPublicationId}`);
    }

    // Find active submissions for this content
    const activeSubmissions = await SubmissionTracking.find({
      blogPostId: contentId,
      status: { $in: ['submitted', 'under_review', 'revision_requested', 'revised'] }
    });

    const conflicts = [];

    for (const submission of activeSubmissions) {
      const submittedPub = publicationConfig.getPublicationById(submission.publicationId);

      if (!submittedPub) continue;

      // Check for market overlap
      const hasOverlap = this._checkMarketConflict(targetPub, submittedPub);

      if (hasOverlap) {
        conflicts.push({
          publication: submittedPub.name,
          status: submission.status,
          submittedAt: submission.submittedAt,
          reason: 'Overlapping market/readership',
          severity: 'high'
        });
      }
    }

    return {
      hasConflict: conflicts.length > 0,
      conflicts,
      allowed: conflicts.length === 0,
      message: conflicts.length > 0
        ? `Cannot submit: Active submission to ${conflicts[0].publication} (${conflicts[0].status})`
        : 'No conflicts - safe to submit'
    };
  }

  /**
   * Check if two publications have conflicting markets
   * @private
   */
  _checkMarketConflict(pub1, pub2) {
    // Same publication = definite conflict
    if (pub1.id === pub2.id) return true;

    // Check readership overlap list
    if (pub1.market?.readershipOverlap?.includes(pub2.id)) return true;
    if (pub2.market?.readershipOverlap?.includes(pub1.id)) return true;

    // Global publications conflict with everything
    if (pub1.market?.reach === 'global' || pub2.market?.reach === 'global') {
      return true;
    }

    // Check regional overlap
    if (pub1.market?.regions && pub2.market?.regions) {
      const overlap = this._calculateRegionOverlap(pub1.market.regions, pub2.market.regions);
      return overlap > 0.5; // More than 50% overlap = conflict
    }

    // Unknown - assume conflict for safety
    return true;
  }

  /**
   * Check title similarity between two articles
   * @param {string} title1 - First title
   * @param {string} title2 - Second title
   * @returns {Object} Title similarity result
   */
  analyzeTitleSimilarity(title1, title2) {
    const normalize = str => str.toLowerCase().replace(/[^a-z0-9\s]/g, '').trim();

    const t1 = normalize(title1);
    const t2 = normalize(title2);

    // Exact match
    if (t1 === t2) {
      return {
        similarity: 1.0,
        pass: false,
        message: '🚫 Identical titles - one must be changed'
      };
    }

    // Calculate word overlap
    const words1 = new Set(t1.split(/\s+/));
    const words2 = new Set(t2.split(/\s+/));

    // Remove common stop words
    const stopWords = new Set(['the', 'a', 'an', 'and', 'or', 'but', 'in', 'on', 'at', 'to', 'for', 'of', 'with', 'by']);
    const meaningfulWords1 = new Set([...words1].filter(w => !stopWords.has(w)));
    const meaningfulWords2 = new Set([...words2].filter(w => !stopWords.has(w)));

    const intersection = new Set([...meaningfulWords1].filter(x => meaningfulWords2.has(x)));
    const union = new Set([...meaningfulWords1, ...meaningfulWords2]);

    const jaccardSimilarity = union.size > 0 ? intersection.size / union.size : 0;

    // Check for substring containment
    const containment = t1.includes(t2) || t2.includes(t1) ? 0.3 : 0;

    const finalSimilarity = Math.max(jaccardSimilarity, containment);

    // Threshold: 60% similarity is too high for high-profile publications
    const threshold = 0.6;
    const pass = finalSimilarity < threshold;

    let message;
    if (finalSimilarity >= 0.9) {
      message = '🚫 Nearly identical titles - change required';
    } else if (finalSimilarity >= threshold) {
      message = '⚠️  Titles too similar for same-market publications - change one';
    } else if (finalSimilarity >= 0.4) {
      message = '⚠️  Some title overlap - acceptable but consider variation';
    } else {
      message = '✅ Titles sufficiently distinct';
    }

    return {
      similarity: Math.round(finalSimilarity * 100) / 100,
      pass,
      threshold,
      sharedWords: [...intersection],
      message
    };
  }
}

// Singleton instance
let instance = null;

module.exports = {
  getInstance: () => {
    if (!instance) {
      instance = new ContentSimilarityService();
    }
    return instance;
  },
  ContentSimilarityService
};