/**
 * QUIXZOOM Object Identity Engine v2
 * 
 * Justerad för riktig data:
 * - Högre spatial vikt (objekt nära varandra i verkligheten)
 * - Lägre visual vikt (AI-attribut är osäkra)
 * - Kontext-vikt för att skilja liknande objekt
 * - Temporal vikt för förändring över tid
 */

const crypto = require('crypto');

class ObjectIdentityPipelineV2 {
  constructor(config = {}) {
    this.config = {
      // Justerade vikter baserat på Bangkok-test
      spatialWeight: config.spatialWeight || 0.50, // Högre — GPS är pålitlig
      visualWeight: config.visualWeight || 0.20,   // Lägre — AI-attribut är osäkra
      contextWeight: config.contextWeight || 0.20,  // Ny — vägtyp, närliggande objekt
      temporalWeight: config.temporalWeight || 0.10, // Samma — tid är sekundär
      
      // Justerade trösklar
      autoMergeThreshold: config.autoMergeThreshold || 0.75, // Högre — färre felaktiga merges
      waitThreshold: config.waitThreshold || 0.50,           // Lägre — mer konservativ
      
      // Spatiala parametrar
      gridSize: config.gridSize || 50, // meter
      maxSearchRadius: config.maxSearchRadius || 100, // meter
      
      ...config,
    };
    
    this.objects = new Map();
    this.spatialIndex = new Map();
    this.stats = {
      processed: 0,
      merged: 0,
      created: 0,
      uncertain: 0,
    };
  }

  /**
   * Processa observation
   */
  async process(observation) {
    this.stats.processed++;
    
    // 1. Hitta kandidater
    const candidates = this.findCandidates(observation);
    
    if (candidates.length === 0) {
      // Ingen kandidat — skapa nytt objekt
      return this.createObject(observation);
    }
    
    // 2. Beräkna matchnings-confidence för varje kandidat
    const matches = candidates.map(candidate => ({
      object: candidate,
      confidence: this.calculateConfidence(observation, candidate),
    }));
    
    // 3. Välj bästa match
    const bestMatch = matches.reduce((best, current) => 
      current.confidence > best.confidence ? current : best
    );
    
    // 4. Bestäm åtgärd baserat på confidence
    if (bestMatch.confidence >= this.config.autoMergeThreshold) {
      // Auto-merge
      return this.mergeObservation(bestMatch.object, observation, bestMatch.confidence);
    } else if (bestMatch.confidence >= this.config.waitThreshold) {
      // Osäker — vänta på mer data
      this.stats.uncertain++;
      return {
        action: 'wait',
        objectId: bestMatch.object.id,
        confidence: bestMatch.confidence,
        reason: 'confidence_below_auto_merge',
      };
    } else {
      // För låg confidence — nytt objekt
      return this.createObject(observation);
    }
  }

  /**
   * Hitta kandidater i spatialt index
   */
  findCandidates(observation) {
    const radius = this.calculateSearchRadius(observation);
    const gridKeys = this.getGridKeysInRadius(observation.location, radius);
    
    const candidates = [];
    const seen = new Set();
    
    for (const key of gridKeys) {
      const objectsInGrid = this.spatialIndex.get(key);
      if (!objectsInGrid) continue;
      
      for (const objectId of objectsInGrid) {
        if (seen.has(objectId)) continue;
        seen.add(objectId);
        
        const object = this.objects.get(objectId);
        if (!object) continue;
        
        // Snabb spatial check
        const distance = this.calculateDistance(observation.location, object.location);
        if (distance <= radius) {
          candidates.push(object);
        }
      }
    }
    
    return candidates;
  }

  /**
   * Beräkna matchnings-confidence
   */
  calculateConfidence(observation, object) {
    const spatial = this.calculateSpatialConfidence(observation, object);
    const visual = this.calculateVisualConfidence(observation, object);
    const context = this.calculateContextConfidence(observation, object);
    const temporal = this.calculateTemporalConfidence(observation, object);
    
    // Viktat medelvärde
    const confidence = 
      spatial * this.config.spatialWeight +
      visual * this.config.visualWeight +
      context * this.config.contextWeight +
      temporal * this.config.temporalWeight;
    
    return confidence;
  }

  /**
   * Spatial confidence — avstånd mellan observationer
   */
  calculateSpatialConfidence(observation, object) {
    const distance = this.calculateDistance(observation.location, object.location);
    const accuracy = Math.max(observation.gpsAccuracy || 3, object.gpsAccuracy || 3);
    
    // Confidence minskar med avståndet
    // Max confidence vid 0m, 0 vid 3*accuracy
    const maxDistance = accuracy * 3;
    const confidence = Math.max(0, 1 - (distance / maxDistance));
    
    return confidence;
  }

  /**
   * Visual confidence — attribut-matchning
   */
  calculateVisualConfidence(observation, object) {
    const obsAttrs = observation.attributes || {};
    const objAttrs = object.attributes || {};
    
    const keys = Object.keys(obsAttrs);
    if (keys.length === 0) return 0.5;
    
    let matches = 0;
    let totalWeight = 0;
    
    for (const key of keys) {
      const weight = this.getAttributeWeight(key);
      totalWeight += weight;
      
      if (obsAttrs[key] === objAttrs[key]) {
        matches += weight;
      } else if (this.areAttributesSimilar(key, obsAttrs[key], objAttrs[key])) {
        matches += weight * 0.5;
      }
    }
    
    return totalWeight > 0 ? matches / totalWeight : 0.5;
  }

  /**
   * Context confidence — vägtyp, närliggande objekt
   */
  calculateContextConfidence(observation, object) {
    let confidence = 0.5;
    
    // Samma objekttyp
    if (observation.objectType === object.type) {
      confidence += 0.3;
    }
    
    // Närliggande objekt (om tillgängligt)
    if (observation.nearbyObjects && object.nearbyObjects) {
      const common = observation.nearbyObjects.filter(o => 
        object.nearbyObjects.includes(o)
      );
      confidence += Math.min(0.2, common.length * 0.05);
    }
    
    return Math.min(1, confidence);
  }

  /**
   * Temporal confidence — rimlighet över tid
   */
  calculateTemporalConfidence(observation, object) {
    if (!observation.timestamp || !object.lastSeen) return 0.5;
    
    const timeDiff = Math.abs(new Date(observation.timestamp) - new Date(object.lastSeen));
    const daysDiff = timeDiff / (1000 * 60 * 60 * 24);
    
    // Mindre confidence ju längre tid som gått
    if (daysDiff < 1) return 1.0;
    if (daysDiff < 7) return 0.9;
    if (daysDiff < 30) return 0.8;
    if (daysDiff < 90) return 0.7;
    return 0.6;
  }

  /**
   * Hjälpmetoder
   */
  calculateDistance(loc1, loc2) {
    const R = 6371000; // Jordens radie i meter
    const dLat = (loc2.lat - loc1.lat) * Math.PI / 180;
    const dLon = (loc2.lng - loc1.lng) * Math.PI / 180;
    const a = Math.sin(dLat/2) * Math.sin(dLat/2) +
              Math.cos(loc1.lat * Math.PI / 180) * Math.cos(loc2.lat * Math.PI / 180) *
              Math.sin(dLon/2) * Math.sin(dLon/2);
    const c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
    return R * c;
  }

  calculateSearchRadius(observation) {
    return Math.min(
      this.config.maxSearchRadius,
      (observation.gpsAccuracy || 3) * 5
    );
  }

  getGridKey(location) {
    const lat = Math.floor(location.lat * 1000 / this.config.gridSize);
    const lng = Math.floor(location.lng * 1000 / this.config.gridSize);
    return `${lat},${lng}`;
  }

  getGridKeysInRadius(location, radius) {
    const keys = [];
    const latDelta = radius / 111000; // grader
    const lngDelta = radius / (111000 * Math.cos(location.lat * Math.PI / 180));
    
    const latSteps = Math.ceil(latDelta * 1000 / this.config.gridSize);
    const lngSteps = Math.ceil(lngDelta * 1000 / this.config.gridSize);
    
    const centerLat = Math.floor(location.lat * 1000 / this.config.gridSize);
    const centerLng = Math.floor(location.lng * 1000 / this.config.gridSize);
    
    for (let lat = centerLat - latSteps; lat <= centerLat + latSteps; lat++) {
      for (let lng = centerLng - lngSteps; lng <= centerLng + lngSteps; lng++) {
        keys.push(`${lat},${lng}`);
      }
    }
    
    return keys;
  }

  getAttributeWeight(key) {
    const weights = {
      height: 0.8,
      material: 0.7,
      paint: 0.5,
      light: 0.9,
      rust: 0.6,
      lean: 0.7,
      signType: 0.9,
      reflective: 0.6,
      damaged: 0.8,
      species: 0.7,
      health: 0.6,
      diameter: 0.5,
      type: 0.8,
      condition: 0.7,
    };
    return weights[key] || 0.5;
  }

  areAttributesSimilar(key, val1, val2) {
    if (typeof val1 === 'number' && typeof val2 === 'number') {
      return Math.abs(val1 - val2) / Math.max(val1, val2) < 0.2;
    }
    return false;
  }

  createObject(observation) {
    const id = `obj_${crypto.randomBytes(6).toString('hex')}`;
    
    const object = {
      id,
      type: observation.objectType,
      location: { ...observation.location },
      gpsAccuracy: observation.gpsAccuracy || 3,
      attributes: { ...observation.attributes },
      firstSeen: observation.timestamp || new Date(),
      lastSeen: observation.timestamp || new Date(),
      evidence: [observation.id],
      confidence: 0.5,
    };
    
    this.objects.set(id, object);
    this.addToSpatialIndex(object);
    this.stats.created++;
    
    return {
      action: 'new_object',
      objectId: id,
      confidence: 0.5,
    };
  }

  mergeObservation(object, observation, confidence) {
    object.evidence.push(observation.id);
    object.lastSeen = observation.timestamp || new Date();
    object.confidence = Math.max(object.confidence, confidence);
    
    // Uppdatera attribut med viktat medelvärde
    if (observation.attributes) {
      for (const [key, value] of Object.entries(observation.attributes)) {
        if (typeof value === 'number' && typeof object.attributes[key] === 'number') {
          object.attributes[key] = (object.attributes[key] + value) / 2;
        } else if (!object.attributes[key]) {
          object.attributes[key] = value;
        }
      }
    }
    
    this.stats.merged++;
    
    return {
      action: 'merge',
      objectId: object.id,
      confidence,
    };
  }

  addToSpatialIndex(object) {
    const key = this.getGridKey(object.location);
    if (!this.spatialIndex.has(key)) {
      this.spatialIndex.set(key, new Set());
    }
    this.spatialIndex.get(key).add(object.id);
  }

  getStats() {
    return {
      ...this.stats,
      objectCount: this.objects.size,
    };
  }
}

module.exports = ObjectIdentityPipelineV2;