/**
 * ╔═══════════════════════════════════════════════════════════════════════════╗
 * ║                    AUDITORY PERCEPTION SERVICE                             ║
 * ║═══════════════════════════════════════════════════════════════════════════║
 * ║  The system's "ears" - listens to log streams, detects anomalies,         ║
 * ║  and interprets system "sounds" (events, errors, patterns)                ║
 * ╚═══════════════════════════════════════════════════════════════════════════╝
 */

import { EventEmitter } from 'events';
import { neo4jAdapter } from '../adapters/Neo4jAdapter.js';
import { v4 as uuidv4 } from 'uuid';

// ═══════════════════════════════════════════════════════════════════════════
// Types
// ═══════════════════════════════════════════════════════════════════════════

export interface AudioSignal {
    id: string;
    type: 'LOG' | 'ERROR' | 'WARNING' | 'ANOMALY' | 'HEARTBEAT' | 'VOICE';
    source: string;
    content: string;
    volume: 'WHISPER' | 'NORMAL' | 'LOUD' | 'ALARM';
    frequency: number; // occurrences per minute
    timestamp: string;
    metadata?: Record<string, unknown>;
}

export interface AnomalyPattern {
    id: string;
    pattern: string;
    description: string;
    severity: 'LOW' | 'MEDIUM' | 'HIGH' | 'CRITICAL';
    occurrences: number;
    firstSeen: string;
    lastSeen: string;
    isActive: boolean;
}

export interface ListeningSession {
    id: string;
    source: string;
    startedAt: string;
    signalsReceived: number;
    anomaliesDetected: number;
    isActive: boolean;
}

// ═══════════════════════════════════════════════════════════════════════════
// Auditory Service
// ═══════════════════════════════════════════════════════════════════════════

class AuditoryService extends EventEmitter {
    private static instance: AuditoryService;
    private sessions: Map<string, ListeningSession> = new Map();
    private signalBuffer: AudioSignal[] = [];
    private anomalyPatterns: Map<string, AnomalyPattern> = new Map();
    private frequencyTracker: Map<string, number[]> = new Map();

    // Anomaly detection thresholds
    private readonly ANOMALY_THRESHOLD = 10; // signals per minute
    private readonly BUFFER_MAX_SIZE = 1000;
    private readonly FREQUENCY_WINDOW_MS = 60000; // 1 minute

    // Known error patterns
    private readonly ERROR_PATTERNS = [
        { regex: /ECONNREFUSED/i, severity: 'HIGH' as const, description: 'Connection refused - service down' },
        { regex: /ETIMEDOUT/i, severity: 'MEDIUM' as const, description: 'Connection timeout' },
        { regex: /OutOfMemory|heap/i, severity: 'CRITICAL' as const, description: 'Memory exhaustion' },
        { regex: /ENOSPC/i, severity: 'CRITICAL' as const, description: 'Disk space exhausted' },
        { regex: /EACCES|EPERM/i, severity: 'HIGH' as const, description: 'Permission denied' },
        { regex: /deadlock/i, severity: 'CRITICAL' as const, description: 'Database deadlock detected' },
        { regex: /rate.?limit/i, severity: 'MEDIUM' as const, description: 'Rate limiting triggered' },
        { regex: /authentication.?fail/i, severity: 'HIGH' as const, description: 'Authentication failure' },
        { regex: /ssl|tls|certificate/i, severity: 'HIGH' as const, description: 'SSL/TLS issue' },
        { regex: /crash|fatal|panic/i, severity: 'CRITICAL' as const, description: 'Critical failure' },
    ];

    private constructor() {
        super();
        this.startBackgroundListening();
    }

    public static getInstance(): AuditoryService {
        if (!AuditoryService.instance) {
            AuditoryService.instance = new AuditoryService();
        }
        return AuditoryService.instance;
    }

    // ═══════════════════════════════════════════════════════════════════════
    // Core Listening Functions
    // ═══════════════════════════════════════════════════════════════════════

    /**
     * Start listening to a specific source
     */
    public startListening(source: string): ListeningSession {
        const session: ListeningSession = {
            id: `listen-${uuidv4()}`,
            source,
            startedAt: new Date().toISOString(),
            signalsReceived: 0,
            anomaliesDetected: 0,
            isActive: true
        };

        this.sessions.set(session.id, session);
        console.error(`[Auditory] 👂 Started listening to: ${source}`);

        return session;
    }

    /**
     * Stop listening to a source
     */
    public stopListening(sessionId: string): void {
        const session = this.sessions.get(sessionId);
        if (session) {
            session.isActive = false;
            console.error(`[Auditory] 🔇 Stopped listening: ${session.source}`);
        }
    }

    /**
     * Process an incoming signal (log, event, etc.)
     */
    public processSignal(input: {
        source: string;
        content: string;
        type?: AudioSignal['type'];
        metadata?: Record<string, unknown>;
    }): AudioSignal {
        const signal: AudioSignal = {
            id: `sig-${uuidv4()}`,
            type: input.type || this.classifySignalType(input.content),
            source: input.source,
            content: input.content,
            volume: this.calculateVolume(input.content),
            frequency: this.calculateFrequency(input.source),
            timestamp: new Date().toISOString(),
            metadata: input.metadata
        };

        // Add to buffer
        this.signalBuffer.push(signal);
        if (this.signalBuffer.length > this.BUFFER_MAX_SIZE) {
            this.signalBuffer.shift();
        }

        // Track frequency
        this.trackFrequency(input.source);

        // Check for anomalies
        this.detectAnomalies(signal);

        // Update session stats
        for (const session of this.sessions.values()) {
            if (session.isActive && session.source === input.source) {
                session.signalsReceived++;
            }
        }

        // Emit event for real-time listeners
        this.emit('signal', signal);

        return signal;
    }

    /**
     * Classify signal type based on content
     */
    private classifySignalType(content: string): AudioSignal['type'] {
        const lower = content.toLowerCase();

        if (/error|exception|fail|crash/i.test(lower)) return 'ERROR';
        if (/warn|caution|attention/i.test(lower)) return 'WARNING';
        if (/heartbeat|ping|alive|health/i.test(lower)) return 'HEARTBEAT';

        return 'LOG';
    }

    /**
     * Calculate volume (severity/importance) of signal
     */
    private calculateVolume(content: string): AudioSignal['volume'] {
        const lower = content.toLowerCase();

        if (/critical|fatal|crash|emergency|panic/i.test(lower)) return 'ALARM';
        if (/error|fail|exception/i.test(lower)) return 'LOUD';
        if (/warn|caution/i.test(lower)) return 'NORMAL';

        return 'WHISPER';
    }

    /**
     * Calculate signal frequency (signals per minute from source)
     */
    private calculateFrequency(source: string): number {
        const timestamps = this.frequencyTracker.get(source) || [];
        const now = Date.now();
        const recentTimestamps = timestamps.filter(t => now - t < this.FREQUENCY_WINDOW_MS);
        return recentTimestamps.length;
    }

    /**
     * Track frequency for anomaly detection
     */
    private trackFrequency(source: string): void {
        const timestamps = this.frequencyTracker.get(source) || [];
        timestamps.push(Date.now());

        // Keep only recent timestamps
        const now = Date.now();
        const recentTimestamps = timestamps.filter(t => now - t < this.FREQUENCY_WINDOW_MS);
        this.frequencyTracker.set(source, recentTimestamps);
    }

    // ═══════════════════════════════════════════════════════════════════════
    // Anomaly Detection
    // ═══════════════════════════════════════════════════════════════════════

    /**
     * Detect anomalies in incoming signals
     */
    private detectAnomalies(signal: AudioSignal): void {
        // Check against known error patterns
        for (const pattern of this.ERROR_PATTERNS) {
            if (pattern.regex.test(signal.content)) {
                this.registerAnomaly({
                    pattern: pattern.regex.source,
                    description: pattern.description,
                    severity: pattern.severity,
                    signal
                });
            }
        }

        // Check for frequency anomalies
        if (signal.frequency > this.ANOMALY_THRESHOLD) {
            this.registerAnomaly({
                pattern: `HIGH_FREQUENCY:${signal.source}`,
                description: `Abnormal signal frequency from ${signal.source}: ${signal.frequency}/min`,
                severity: 'MEDIUM',
                signal
            });
        }

        // Check for sudden volume increase
        if (signal.volume === 'ALARM') {
            this.registerAnomaly({
                pattern: `ALARM:${signal.type}`,
                description: `Alarm-level signal: ${signal.content.substring(0, 100)}`,
                severity: 'HIGH',
                signal
            });
        }
    }

    /**
     * Register a detected anomaly
     */
    private async registerAnomaly(params: {
        pattern: string;
        description: string;
        severity: AnomalyPattern['severity'];
        signal: AudioSignal;
    }): Promise<void> {
        const existing = this.anomalyPatterns.get(params.pattern);

        if (existing) {
            existing.occurrences++;
            existing.lastSeen = new Date().toISOString();
            existing.isActive = true;
        } else {
            const anomaly: AnomalyPattern = {
                id: `anomaly-${uuidv4()}`,
                pattern: params.pattern,
                description: params.description,
                severity: params.severity,
                occurrences: 1,
                firstSeen: new Date().toISOString(),
                lastSeen: new Date().toISOString(),
                isActive: true
            };
            this.anomalyPatterns.set(params.pattern, anomaly);

            // Persist to Neo4j
            await this.persistAnomaly(anomaly, params.signal);
        }

        // Update session stats
        for (const session of this.sessions.values()) {
            if (session.isActive && session.source === params.signal.source) {
                session.anomaliesDetected++;
            }
        }

        // Emit anomaly event
        this.emit('anomaly', { anomaly: this.anomalyPatterns.get(params.pattern), signal: params.signal });

        console.error(`[Auditory] 🚨 Anomaly detected: ${params.description}`);
    }

    /**
     * Persist anomaly to Neo4j
     */
    private async persistAnomaly(anomaly: AnomalyPattern, signal: AudioSignal): Promise<void> {
        try {
            await neo4jAdapter.executeQuery(`
                CREATE (a:Anomaly {
                    id: $id,
                    pattern: $pattern,
                    description: $description,
                    severity: $severity,
                    occurrences: $occurrences,
                    firstSeen: $firstSeen,
                    lastSeen: $lastSeen,
                    signalSource: $signalSource,
                    signalContent: $signalContent
                })
            `, {
                id: anomaly.id,
                pattern: anomaly.pattern,
                description: anomaly.description,
                severity: anomaly.severity,
                occurrences: anomaly.occurrences,
                firstSeen: anomaly.firstSeen,
                lastSeen: anomaly.lastSeen,
                signalSource: signal.source,
                signalContent: signal.content.substring(0, 500)
            });
        } catch (error) {
            console.warn('[Auditory] Failed to persist anomaly:', error);
        }
    }

    // ═══════════════════════════════════════════════════════════════════════
    // Query Functions
    // ═══════════════════════════════════════════════════════════════════════

    /**
     * Get recent signals
     */
    public getRecentSignals(params: {
        source?: string;
        type?: AudioSignal['type'];
        volume?: AudioSignal['volume'];
        limit?: number;
    } = {}): AudioSignal[] {
        let signals = [...this.signalBuffer];

        if (params.source) {
            signals = signals.filter(s => s.source === params.source);
        }
        if (params.type) {
            signals = signals.filter(s => s.type === params.type);
        }
        if (params.volume) {
            signals = signals.filter(s => s.volume === params.volume);
        }

        return signals.slice(-(params.limit || 50));
    }

    /**
     * Get active anomalies
     */
    public getActiveAnomalies(): AnomalyPattern[] {
        return Array.from(this.anomalyPatterns.values()).filter(a => a.isActive);
    }

    /**
     * Get all anomaly patterns
     */
    public getAllAnomalies(): AnomalyPattern[] {
        return Array.from(this.anomalyPatterns.values());
    }

    /**
     * Get listening sessions
     */
    public getListeningSessions(): ListeningSession[] {
        return Array.from(this.sessions.values());
    }

    /**
     * Get auditory system status
     */
    public getStatus(): {
        activeSessions: number;
        totalSignals: number;
        activeAnomalies: number;
        signalBuffer: number;
        frequencySources: number;
    } {
        return {
            activeSessions: Array.from(this.sessions.values()).filter(s => s.isActive).length,
            totalSignals: this.signalBuffer.length,
            activeAnomalies: this.getActiveAnomalies().length,
            signalBuffer: this.signalBuffer.length,
            frequencySources: this.frequencyTracker.size
        };
    }

    /**
     * Acknowledge/dismiss an anomaly
     */
    public acknowledgeAnomaly(pattern: string): boolean {
        const anomaly = this.anomalyPatterns.get(pattern);
        if (anomaly) {
            anomaly.isActive = false;
            return true;
        }
        return false;
    }

    // ═══════════════════════════════════════════════════════════════════════
    // Background Listening
    // ═══════════════════════════════════════════════════════════════════════

    /**
     * Start background listening for system events
     */
    private startBackgroundListening(): void {
        // Intercept console.error for system-wide listening
        const originalError = console.error;
        console.error = (...args: unknown[]) => {
            originalError.apply(console, args);

            // Don't process our own logs
            const content = args.map(a => String(a)).join(' ');
            if (!content.includes('[Auditory]')) {
                this.processSignal({
                    source: 'console.error',
                    content,
                    type: 'ERROR'
                });
            }
        };

        // Periodic cleanup of old frequency data
        setInterval(() => {
            const now = Date.now();
            for (const [source, timestamps] of this.frequencyTracker.entries()) {
                const recent = timestamps.filter(t => now - t < this.FREQUENCY_WINDOW_MS);
                if (recent.length === 0) {
                    this.frequencyTracker.delete(source);
                } else {
                    this.frequencyTracker.set(source, recent);
                }
            }
        }, 30000); // Every 30 seconds

        console.error('[Auditory] 👂 Background listening started');
    }

    /**
     * Analyze log content for insights
     */
    public analyzeLogContent(logs: string[]): {
        summary: string;
        errorCount: number;
        warningCount: number;
        patterns: string[];
        recommendations: string[];
    } {
        let errorCount = 0;
        let warningCount = 0;
        const patterns: Set<string> = new Set();
        const recommendations: string[] = [];

        for (const log of logs) {
            if (/error|exception|fail/i.test(log)) errorCount++;
            if (/warn|caution/i.test(log)) warningCount++;

            // Detect patterns
            for (const pattern of this.ERROR_PATTERNS) {
                if (pattern.regex.test(log)) {
                    patterns.add(pattern.description);
                }
            }
        }

        // Generate recommendations
        if (errorCount > 10) {
            recommendations.push('High error rate detected - consider investigating root cause');
        }
        if (patterns.has('Memory exhaustion')) {
            recommendations.push('Memory issues detected - consider increasing heap size or optimizing memory usage');
        }
        if (patterns.has('Connection refused - service down')) {
            recommendations.push('Service connectivity issues - check if dependent services are running');
        }

        return {
            summary: `Analyzed ${logs.length} logs: ${errorCount} errors, ${warningCount} warnings`,
            errorCount,
            warningCount,
            patterns: Array.from(patterns),
            recommendations
        };
    }
}

export const auditoryService = AuditoryService.getInstance();