/**
 * Utility functions for logging operations
 */

import type { PerformanceTimer, LogMetadata } from './types';

/**
 * Create a performance timer to measure operation duration
 */
export function createTimer(operation: string): PerformanceTimer {
  const startTime = Date.now();
  
  return {
    operation,
    startTime,
    end() {
      const endTime = Date.now();
      return {
        operation,
        duration: endTime - startTime,
        startTime,
        endTime
      };
    }
  };
}

/**
 * Format error for logging
 */
export function formatError(error: Error | any): LogMetadata['error'] {
  if (error instanceof Error) {
    return {
      name: error.name,
      message: error.message,
      stack: error.stack
    };
  }
  
  if (typeof error === 'object' && error !== null) {
    return {
      name: error.constructor?.name || 'UnknownError',
      message: error.message || error.toString(),
      ...error
    };
  }
  
  return {
    name: 'UnknownError',
    message: String(error)
  };
}

/**
 * Sanitize sensitive data from log metadata
 */
export function sanitizeMetadata(metadata: LogMetadata): LogMetadata {
  const sensitiveKeys = [
    'password', 'token', 'secret', 'key', 'apiKey', 'api_key',
    'authorization', 'auth', 'credential', 'credentials'
  ];
  
  function sanitizeValue(value: any): any {
    if (typeof value === 'string') {
      return '[REDACTED]';
    }
    if (Array.isArray(value)) {
      return value.map(sanitizeValue);
    }
    if (typeof value === 'object' && value !== null) {
      const sanitized: any = {};
      for (const [key, val] of Object.entries(value)) {
        const lowerKey = key.toLowerCase();
        if (sensitiveKeys.some(sensitive => lowerKey.includes(sensitive))) {
          sanitized[key] = '[REDACTED]';
        } else {
          sanitized[key] = sanitizeValue(val);
        }
      }
      return sanitized;
    }
    return value;
  }
  
  const sanitized: LogMetadata = {};
  for (const [key, value] of Object.entries(metadata)) {
    const lowerKey = key.toLowerCase();
    if (sensitiveKeys.some(sensitive => lowerKey.includes(sensitive))) {
      sanitized[key] = '[REDACTED]';
    } else {
      sanitized[key] = sanitizeValue(value);
    }
  }
  
  return sanitized;
}

/**
 * Generate a correlation ID for request tracking
 */
export function generateCorrelationId(): string {
  return `${Date.now()}-${Math.random().toString(36).substr(2, 9)}`;
}

/**
 * Extract relevant HTTP request information for logging
 */
export function extractHttpMetadata(req: any): LogMetadata['request'] {
  if (!req) return undefined;
  
  return {
    method: req.method,
    url: req.url || req.originalUrl,
    userAgent: req.get?.('User-Agent') || req.headers?.['user-agent'],
    ip: req.ip || req.connection?.remoteAddress || req.headers?.['x-forwarded-for']
  };
}

/**
 * Create standardized business event metadata
 */
export function createBusinessEvent(
  type: string,
  action: string,
  options?: {
    entity?: string;
    result?: 'success' | 'failure' | 'partial';
    amount?: number;
    symbol?: string;
    [key: string]: any;
  }
): LogMetadata {
  return {
    business: {
      type,
      action,
      ...options
    },
    type: 'business_event'
  };
}

/**
 * Create standardized security event metadata
 */
export function createSecurityEvent(
  type: 'authentication' | 'authorization' | 'access' | 'vulnerability',
  options?: {
    user?: string;
    resource?: string;
    action?: string;
    result?: 'success' | 'failure';
    ip?: string;
    severity?: 'low' | 'medium' | 'high' | 'critical';
    [key: string]: any;
  }
): LogMetadata {
  return {
    security: {
      type,
      ...options
    },
    type: 'security_event'
  };
}

/**
 * Mask sensitive data in strings
 */
export function maskSensitiveData(str: string): string {
  // Credit card numbers
  str = str.replace(/\b\d{4}[\s-]?\d{4}[\s-]?\d{4}[\s-]?\d{4}\b/g, '****-****-****-****');
  
  // Email addresses
  str = str.replace(/\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,}\b/g, '***@***.***');
  
  // API keys (common patterns)
  str = str.replace(/\b[A-Za-z0-9]{32,}\b/g, '[API_KEY]');
  
  // JWT tokens
  str = str.replace(/eyJ[A-Za-z0-9_-]*\.[A-Za-z0-9_-]*\.[A-Za-z0-9_-]*/g, '[JWT_TOKEN]');
  
  return str;
}

/**
 * Calculate log entry size for batching
 */
export function calculateLogSize(entry: any): number {
  return JSON.stringify(entry).length;
}

/**
 * Throttle logging to prevent spam
 */
export class LogThrottle {
  private counters = new Map<string, { count: number; lastReset: number }>();
  private readonly maxLogs: number;
  private readonly windowMs: number;

  constructor(maxLogs = 100, windowMs = 60000) {
    this.maxLogs = maxLogs;
    this.windowMs = windowMs;
  }

  shouldLog(key: string): boolean {
    const now = Date.now();
    const counter = this.counters.get(key);
    
    if (!counter || now - counter.lastReset > this.windowMs) {
      this.counters.set(key, { count: 1, lastReset: now });
      return true;
    }
    
    if (counter.count >= this.maxLogs) {
      return false;
    }
    
    counter.count++;
    return true;
  }

  reset(key?: string): void {
    if (key) {
      this.counters.delete(key);
    } else {
      this.counters.clear();
    }
  }
}