elasticsearch/ts/domain/logging/enrichers.ts

/**
 * Common log enrichers
 */

import type { LogEntry, LogEnricher } from './types.js';
import { hostname } from 'os';

/**
 * Add hostname to log entry
 */
export const addHostInfo: LogEnricher = (entry: LogEntry): LogEntry => {
  return {
    ...entry,
    host: hostname(),
  };
};

/**
 * Add environment from NODE_ENV
 */
export const addEnvironment: LogEnricher = (entry: LogEntry): LogEntry => {
  return {
    ...entry,
    environment: process.env.NODE_ENV || 'development',
  };
};

/**
 * Add service info from environment variables
 */
export const addServiceInfo: LogEnricher = (entry: LogEntry): LogEntry => {
  return {
    ...entry,
    service: entry.service || process.env.SERVICE_NAME,
    version: entry.version || process.env.SERVICE_VERSION,
  };
};

/**
 * Add process info (PID, memory, uptime)
 */
export const addProcessInfo: LogEnricher = (entry: LogEntry): LogEntry => {
  const memoryUsage = process.memoryUsage();

  return {
    ...entry,
    metadata: {
      ...entry.metadata,
      process: {
        pid: process.pid,
        uptime: process.uptime(),
        memory: {
          heapUsed: memoryUsage.heapUsed,
          heapTotal: memoryUsage.heapTotal,
          external: memoryUsage.external,
          rss: memoryUsage.rss,
        },
      },
    },
  };
};

/**
 * Add timestamp if not present
 */
export const addTimestamp: LogEnricher = (entry: LogEntry): LogEntry => {
  return {
    ...entry,
    timestamp: entry.timestamp || new Date().toISOString(),
  };
};

/**
 * Sanitize sensitive data from log entry
 */
export const sanitizeSensitiveData = (
  patterns: Array<{ path: string; replacement?: string }>
): LogEnricher => {
  return (entry: LogEntry): LogEntry => {
    const sanitized = { ...entry };

    for (const { path, replacement = '[REDACTED]' } of patterns) {
      const parts = path.split('.');
      let current: any = sanitized;

      for (let i = 0; i < parts.length - 1; i++) {
        if (current === null || current === undefined) break;
        current = current[parts[i] as string];
      }

      if (current && parts.length > 0) {
        const lastPart = parts[parts.length - 1];
        if (lastPart && current[lastPart] !== undefined) {
          current[lastPart] = replacement;
        }
      }
    }

    return sanitized;
  };
};

/**
 * Add custom tags based on log content
 */
export const addDynamicTags = (
  taggers: Array<{ condition: (entry: LogEntry) => boolean; tag: string }>
): LogEnricher => {
  return (entry: LogEntry): LogEntry => {
    const tags = new Set(entry.tags || []);

    for (const { condition, tag } of taggers) {
      if (condition(entry)) {
        tags.add(tag);
      }
    }

    return {
      ...entry,
      tags: Array.from(tags),
    };
  };
};

/**
 * Chain multiple enrichers
 */
export const chainEnrichers = (...enrichers: LogEnricher[]): LogEnricher => {
  return async (entry: LogEntry): Promise<LogEntry> => {
    let enriched = entry;
    for (const enricher of enrichers) {
      enriched = await enricher(enriched);
    }
    return enriched;
  };
};