/**
 * THE HIVE DNA AI ENGINE
 * Advanced Neural Pattern Recognition & Adaptive Learning System
 *
 * This AI engine creates a "collective intelligence" that learns from all users,
 * adapts to individual playing styles, and provides real-time coaching.
 */

class HiveDNAAI {
    constructor() {
        this.version = '1.0.0';
        this.initialized = false;

        // Neural pattern recognition
        this.patternMemory = new Map();
        this.userDNA = {
            timingAccuracy: [],
            velocityControl: [],
            rhythmicPatterns: [],
            weaknesses: [],
            strengths: [],
            learningRate: 1.0,
            muscleMemory: new Map()
        };

        // Collective intelligence (The Hive)
        this.hiveKnowledge = {
            commonMistakes: [],
            successPatterns: [],
            learningPaths: [],
            communityInsights: []
        };

        // Real-time analysis
        this.realtimeBuffer = [];
        this.analysisWindow = 100; // Analyze last 100 hits

        // Adaptive coaching
        this.coachingEngine = {
            currentLevel: 1,
            nextGoal: null,
            personalizedExercises: [],
            motivationalState: 'neutral'
        };

        // Performance prediction
        this.predictionModel = {
            hitPrediction: [],
            performanceTrend: 'stable',
            nextLevelETA: null
        };

        console.log('🧬 Hive DNA AI Engine initialized');
    }

    /**
     * Initialize AI with user profile
     */
    async initialize(userProfile = {}) {
        this.userDNA = {
            ...this.userDNA,
            userId: userProfile.id || 'anonymous',
            skillLevel: userProfile.level || 1,
            practiceTime: userProfile.totalTime || 0,
            sessionCount: userProfile.sessions || 0
        };

        // Load community patterns
        await this.loadHiveKnowledge();

        // Initialize neural networks
        this.initializeNeuralPatterns();

        this.initialized = true;
        console.log('🧠 AI initialized for user:', this.userDNA.userId);
    }

    /**
     * Neural Pattern Recognition - The core of timing analysis
     */
    analyzeHit(hitData) {
        const { drum, timestamp, velocity, targetTime, isCorrect } = hitData;

        // Calculate timing accuracy
        const timingError = targetTime ? Math.abs(timestamp - targetTime) : 0;
        const timingAccuracy = targetTime ? Math.max(0, 100 - (timingError * 10)) : 0;

        // Analyze velocity control
        const velocityScore = this.analyzeVelocity(velocity, drum);

        // Pattern recognition
        this.recordPattern(drum, timestamp, velocity);

        // Update user DNA
        this.updateUserDNA({
            timingError,
            timingAccuracy,
            velocityScore,
            drum,
            timestamp
        });

        // Real-time prediction
        const prediction = this.predictNextHit(drum);

        // Add to realtime buffer
        this.realtimeBuffer.push({
            drum,
            timestamp,
            velocity,
            timingAccuracy,
            velocityScore,
            prediction
        });

        // Keep buffer size manageable
        if (this.realtimeBuffer.length > this.analysisWindow) {
            this.realtimeBuffer.shift();
        }

        return {
            timingAccuracy,
            velocityScore,
            overallScore: (timingAccuracy * 0.7) + (velocityScore * 0.3),
            prediction,
            feedback: this.generateSmartFeedback(timingAccuracy, velocityScore, drum)
        };
    }

    /**
     * Velocity Analysis - Detects ghost notes, accents, dynamics
     */
    analyzeVelocity(velocity, drum) {
        const ideal = this.getIdealVelocity(drum);
        const difference = Math.abs(velocity - ideal);

        // Score based on how close to ideal
        const score = Math.max(0, 100 - (difference * 50));

        // Detect playing characteristics
        if (velocity < 40) {
            this.userDNA.characteristics = this.userDNA.characteristics || [];
            this.userDNA.characteristics.push('ghost_notes');
        } else if (velocity > 100) {
            this.userDNA.characteristics = this.userDNA.characteristics || [];
            this.userDNA.characteristics.push('accent_heavy');
        }

        return score;
    }

    /**
     * Pattern Recording - Builds muscle memory map
     */
    recordPattern(drum, timestamp, velocity) {
        const patternKey = this.getPatternKey(drum);

        if (!this.patternMemory.has(patternKey)) {
            this.patternMemory.set(patternKey, []);
        }

        const pattern = this.patternMemory.get(patternKey);
        pattern.push({ timestamp, velocity });

        // Keep only recent patterns
        if (pattern.length > 1000) {
            pattern.shift();
        }

        // Analyze for rhythmic DNA
        if (pattern.length >= 16) {
            this.analyzeRhythmicDNA(pattern, drum);
        }
    }

    /**
     * Rhythmic DNA Analysis - Discovers user's natural rhythm patterns
     */
    analyzeRhythmicDNA(pattern, drum) {
        const intervals = [];
        for (let i = 1; i < pattern.length; i++) {
            intervals.push(pattern[i].timestamp - pattern[i-1].timestamp);
        }

        // Find common intervals (user's natural rhythms)
        const intervalMap = new Map();
        intervals.forEach(interval => {
            const rounded = Math.round(interval / 50) * 50; // Round to nearest 50ms
            intervalMap.set(rounded, (intervalMap.get(rounded) || 0) + 1);
        });

        // Extract top 3 natural rhythms
        const naturalRhythms = Array.from(intervalMap.entries())
            .sort((a, b) => b[1] - a[1])
            .slice(0, 3)
            .map(([interval, count]) => ({ interval, frequency: count }));

        this.userDNA.rhythmicPatterns = naturalRhythms;

        return naturalRhythms;
    }

    /**
     * Hit Prediction using neural patterns
     */
    predictNextHit(currentDrum) {
        const patterns = this.patternMemory.get(this.getPatternKey(currentDrum));
        if (!patterns || patterns.length < 4) {
            return { confidence: 0, predictedTime: null };
        }

        // Analyze last 4 hits to predict next
        const recent = patterns.slice(-4);
        const intervals = [];
        for (let i = 1; i < recent.length; i++) {
            intervals.push(recent[i].timestamp - recent[i-1].timestamp);
        }

        // Average interval
        const avgInterval = intervals.reduce((a, b) => a + b, 0) / intervals.length;
        const lastHit = recent[recent.length - 1].timestamp;
        const predictedTime = lastHit + avgInterval;

        // Calculate confidence based on interval consistency
        const variance = this.calculateVariance(intervals);
        const confidence = Math.max(0, 100 - variance);

        return {
            confidence,
            predictedTime,
            expectedVelocity: recent[recent.length - 1].velocity,
            drumType: currentDrum
        };
    }

    /**
     * Update User DNA - Continuous learning about the user
     */
    updateUserDNA(hitAnalysis) {
        const { timingError, timingAccuracy, velocityScore, drum } = hitAnalysis;

        // Track timing accuracy over time
        this.userDNA.timingAccuracy.push(timingAccuracy);
        if (this.userDNA.timingAccuracy.length > 100) {
            this.userDNA.timingAccuracy.shift();
        }

        // Track velocity control
        this.userDNA.velocityControl.push(velocityScore);
        if (this.userDNA.velocityControl.length > 100) {
            this.userDNA.velocityControl.shift();
        }

        // Identify weaknesses and strengths
        if (timingAccuracy < 50) {
            this.userDNA.weaknesses.push({ drum, issue: 'timing', severity: 100 - timingAccuracy });
        }
        if (timingAccuracy > 90) {
            this.userDNA.strengths.push({ drum, skill: 'timing', level: timingAccuracy });
        }

        // Update learning rate based on improvement
        this.updateLearningRate();

        // Update muscle memory map
        this.updateMuscleMemory(drum, timingAccuracy);
    }

    /**
     * Adaptive Learning Rate - Adjusts difficulty based on performance
     */
    updateLearningRate() {
        const recentAccuracy = this.userDNA.timingAccuracy.slice(-20);
        if (recentAccuracy.length < 20) return;

        const avgRecent = recentAccuracy.reduce((a, b) => a + b, 0) / recentAccuracy.length;
        const previousAccuracy = this.userDNA.timingAccuracy.slice(-40, -20);
        const avgPrevious = previousAccuracy.reduce((a, b) => a + b, 0) / previousAccuracy.length;

        // If improving rapidly, increase learning rate
        if (avgRecent > avgPrevious + 10) {
            this.userDNA.learningRate = Math.min(2.0, this.userDNA.learningRate + 0.1);
        }
        // If struggling, decrease learning rate
        else if (avgRecent < avgPrevious - 10) {
            this.userDNA.learningRate = Math.max(0.5, this.userDNA.learningRate - 0.1);
        }
    }

    /**
     * Muscle Memory Tracking
     */
    updateMuscleMemory(drum, accuracy) {
        if (!this.userDNA.muscleMemory.has(drum)) {
            this.userDNA.muscleMemory.set(drum, { hits: 0, avgAccuracy: 0, mastery: 0 });
        }

        const memory = this.userDNA.muscleMemory.get(drum);
        memory.hits++;
        memory.avgAccuracy = ((memory.avgAccuracy * (memory.hits - 1)) + accuracy) / memory.hits;
        memory.mastery = Math.min(100, (memory.hits / 1000) * memory.avgAccuracy);
    }

    /**
     * Smart Feedback Generation
     */
    generateSmartFeedback(timingAccuracy, velocityScore, drum) {
        let feedback = { type: 'neutral', message: '', tips: [] };

        if (timingAccuracy >= 95 && velocityScore >= 95) {
            feedback = {
                type: 'perfect',
                message: 'PERFECT! 🔥 That was flawless!',
                tips: ['Incredible timing!', 'Perfect dynamics', 'Keep this groove!']
            };
        } else if (timingAccuracy >= 85) {
            feedback = {
                type: 'great',
                message: 'Excellent! You\'re in the pocket!',
                tips: [velocityScore < 70 ? 'Focus on consistent velocity' : 'Great control!']
            };
        } else if (timingAccuracy >= 70) {
            feedback = {
                type: 'good',
                message: 'Good work! Getting closer!',
                tips: this.getPersonalizedTips(timingAccuracy, velocityScore, drum)
            };
        } else if (timingAccuracy >= 50) {
            feedback = {
                type: 'okay',
                message: 'Keep practicing, you\'re improving!',
                tips: this.getPersonalizedTips(timingAccuracy, velocityScore, drum)
            };
        } else {
            feedback = {
                type: 'miss',
                message: 'Don\'t worry, slow it down!',
                tips: [
                    'Try practicing at 70% tempo',
                    `Focus on the ${drum} sound`,
                    'Use a metronome to build timing'
                ]
            };
        }

        return feedback;
    }

    /**
     * Personalized Tips based on User DNA
     */
    getPersonalizedTips(timingAccuracy, velocityScore, drum) {
        const tips = [];

        // Analyze user's specific issues
        const muscleMemory = this.userDNA.muscleMemory.get(drum);
        const drumMastery = muscleMemory ? muscleMemory.mastery : 0;

        if (timingAccuracy < 70) {
            tips.push(`Your timing on ${drum} needs work. Practice with a metronome.`);
        }

        if (velocityScore < 70) {
            tips.push('Work on consistent stick control and velocity.');
        }

        if (drumMastery < 30) {
            tips.push(`You've only practiced ${drum} ${muscleMemory?.hits || 0} times. More reps needed!`);
        }

        // Check for rushing or dragging
        const recentErrors = this.realtimeBuffer.slice(-10)
            .filter(h => h.drum === drum)
            .map(h => h.timingAccuracy);

        if (recentErrors.length >= 3) {
            const avgError = recentErrors.reduce((a, b) => a + b, 0) / recentErrors.length;
            if (avgError < 0) {
                tips.push('You tend to rush. Relax and feel the groove.');
            } else if (avgError > 0) {
                tips.push('You tend to drag. Pick up the energy slightly.');
            }
        }

        return tips;
    }

    /**
     * Adaptive Difficulty Adjustment
     */
    adjustDifficulty(currentBPM, currentAccuracy) {
        const avgAccuracy = this.userDNA.timingAccuracy.slice(-50)
            .reduce((a, b) => a + b, 0) / Math.min(50, this.userDNA.timingAccuracy.length);

        let recommendation = {
            newBPM: currentBPM,
            shouldIncrease: false,
            shouldDecrease: false,
            reason: ''
        };

        if (avgAccuracy > 85) {
            recommendation.newBPM = Math.min(220, currentBPM + 5);
            recommendation.shouldIncrease = true;
            recommendation.reason = 'You\'re crushing it! Let\'s speed up!';
        } else if (avgAccuracy < 50) {
            recommendation.newBPM = Math.max(40, currentBPM - 10);
            recommendation.shouldDecrease = true;
            recommendation.reason = 'Let\'s slow down and build solid fundamentals';
        }

        return recommendation;
    }

    /**
     * Performance Analytics
     */
    getPerformanceAnalytics() {
        const timingAvg = this.average(this.userDNA.timingAccuracy);
        const velocityAvg = this.average(this.userDNA.velocityControl);

        // Calculate trends
        const recentTiming = this.average(this.userDNA.timingAccuracy.slice(-20));
        const previousTiming = this.average(this.userDNA.timingAccuracy.slice(-40, -20));
        const trend = recentTiming > previousTiming ? 'improving' :
                     recentTiming < previousTiming ? 'declining' : 'stable';

        // Mastery levels by drum
        const masteryByDrum = {};
        this.userDNA.muscleMemory.forEach((value, drum) => {
            masteryByDrum[drum] = value.mastery;
        });

        // Overall skill level
        const overallSkill = (timingAvg * 0.6) + (velocityAvg * 0.4);
        const level = this.calculateLevel(overallSkill);

        return {
            overall: {
                score: Math.round(overallSkill),
                level,
                trend
            },
            timing: {
                average: Math.round(timingAvg),
                consistency: this.calculateConsistency(this.userDNA.timingAccuracy)
            },
            velocity: {
                average: Math.round(velocityAvg),
                consistency: this.calculateConsistency(this.userDNA.velocityControl)
            },
            mastery: masteryByDrum,
            weaknesses: this.identifyTopWeaknesses(),
            strengths: this.identifyTopStrengths(),
            learningRate: this.userDNA.learningRate,
            predictions: {
                nextLevelETA: this.predictNextLevel(overallSkill, trend),
                recommendedPractice: this.recommendPractice()
            }
        };
    }

    /**
     * Hive Knowledge - Learn from community patterns
     */
    async loadHiveKnowledge() {
        // In production, this would fetch from your backend
        // For now, we'll use simulated collective intelligence

        this.hiveKnowledge = {
            commonMistakes: [
                { pattern: 'rushing_fills', frequency: 67, solution: 'Practice fills at 50% tempo' },
                { pattern: 'weak_snare', frequency: 54, solution: 'Focus on snare velocity control' },
                { pattern: 'inconsistent_hihat', frequency: 48, solution: 'Metronome practice with hi-hat only' }
            ],
            successPatterns: [
                { pattern: 'steady_kick', mastery: 85, practice: 'Isolate kick drum first' },
                { pattern: 'ghost_notes', mastery: 73, practice: 'Start very slow, build speed gradually' }
            ],
            learningPaths: [
                { from: 'beginner', to: 'intermediate', avgTime: '30 hours', keySkills: ['timing', 'basic_fills'] },
                { from: 'intermediate', to: 'advanced', avgTime: '100 hours', keySkills: ['dynamics', 'polyrhythms'] }
            ]
        };
    }

    /**
     * AI Coaching Recommendations
     */
    recommendPractice() {
        const weaknesses = this.identifyTopWeaknesses();
        const recommendations = [];

        weaknesses.forEach(weakness => {
            const hiveWisdom = this.hiveKnowledge.commonMistakes.find(m =>
                m.pattern.includes(weakness.drum) || m.pattern.includes(weakness.issue)
            );

            if (hiveWisdom) {
                recommendations.push({
                    focus: weakness.drum,
                    exercise: hiveWisdom.solution,
                    duration: '10 minutes',
                    priority: 'high'
                });
            }
        });

        return recommendations;
    }

    // ========== HELPER FUNCTIONS ==========

    getIdealVelocity(drum) {
        const ideals = {
            'Kick': 100,
            'Snare': 90,
            'Hi-Hat': 70,
            'Tom 1': 85,
            'Tom 2': 85,
            'Tom 3': 85,
            'Crash': 95,
            'Ride': 75
        };
        return ideals[drum] || 80;
    }

    getPatternKey(drum) {
        return `pattern_${drum.toLowerCase().replace(/\s/g, '_')}`;
    }

    average(arr) {
        if (!arr || arr.length === 0) return 0;
        return arr.reduce((a, b) => a + b, 0) / arr.length;
    }

    calculateVariance(arr) {
        const avg = this.average(arr);
        const squareDiffs = arr.map(value => Math.pow(value - avg, 2));
        return Math.sqrt(this.average(squareDiffs));
    }

    calculateConsistency(values) {
        if (values.length < 2) return 0;
        const variance = this.calculateVariance(values);
        return Math.max(0, 100 - variance);
    }

    calculateLevel(overallScore) {
        if (overallScore < 30) return 'Beginner';
        if (overallScore < 50) return 'Novice';
        if (overallScore < 70) return 'Intermediate';
        if (overallScore < 85) return 'Advanced';
        return 'Expert';
    }

    identifyTopWeaknesses() {
        const weaknessMap = new Map();

        this.userDNA.weaknesses.forEach(w => {
            const key = `${w.drum}_${w.issue}`;
            if (!weaknessMap.has(key)) {
                weaknessMap.set(key, { ...w, count: 0 });
            }
            const weakness = weaknessMap.get(key);
            weakness.count++;
            weakness.severity = (weakness.severity + w.severity) / 2;
        });

        return Array.from(weaknessMap.values())
            .sort((a, b) => b.count * b.severity - a.count * a.severity)
            .slice(0, 3);
    }

    identifyTopStrengths() {
        const strengthMap = new Map();

        this.userDNA.strengths.forEach(s => {
            const key = `${s.drum}_${s.skill}`;
            if (!strengthMap.has(key)) {
                strengthMap.set(key, { ...s, count: 0 });
            }
            const strength = strengthMap.get(key);
            strength.count++;
            strength.level = (strength.level + s.level) / 2;
        });

        return Array.from(strengthMap.values())
            .sort((a, b) => b.level - a.level)
            .slice(0, 3);
    }

    predictNextLevel(currentScore, trend) {
        if (trend === 'improving') {
            const pointsNeeded = this.getPointsToNextLevel(currentScore);
            const improvementRate = this.calculateImprovementRate();
            const hoursNeeded = pointsNeeded / improvementRate;
            return `${Math.round(hoursNeeded)} hours`;
        }
        return 'Keep practicing consistently!';
    }

    getPointsToNextLevel(score) {
        const thresholds = [30, 50, 70, 85, 100];
        for (let threshold of thresholds) {
            if (score < threshold) {
                return threshold - score;
            }
        }
        return 0;
    }

    calculateImprovementRate() {
        if (this.userDNA.timingAccuracy.length < 40) return 1;

        const recent = this.average(this.userDNA.timingAccuracy.slice(-20));
        const previous = this.average(this.userDNA.timingAccuracy.slice(-40, -20));

        return Math.max(0.1, recent - previous);
    }

    initializeNeuralPatterns() {
        // Initialize pattern recognition for each drum
        const drums = ['Kick', 'Snare', 'Hi-Hat', 'Tom 1', 'Tom 2', 'Tom 3', 'Crash', 'Ride'];
        drums.forEach(drum => {
            this.patternMemory.set(this.getPatternKey(drum), []);
        });
    }

    /**
     * Export user's DNA profile for sharing/analysis
     */
    exportUserDNA() {
        return {
            ...this.userDNA,
            analytics: this.getPerformanceAnalytics(),
            timestamp: Date.now(),
            version: this.version
        };
    }

    /**
     * Reset AI learning (for practice mode or new user)
     */
    reset() {
        this.realtimeBuffer = [];
        this.userDNA.timingAccuracy = [];
        this.userDNA.velocityControl = [];
        this.userDNA.weaknesses = [];
        this.userDNA.strengths = [];
        this.initializeNeuralPatterns();
        console.log('🔄 AI Engine reset');
    }
}

// Export for use in other modules
if (typeof module !== 'undefined' && module.exports) {
    module.exports = HiveDNAAI;
}