/**
* Rotating File Transport
*
* Provides file logging with automatic rotation based on size and age.
*/
import { existsSync, mkdirSync, statSync, unlinkSync, readdirSync } from 'fs';
import { appendFileSync } from 'fs';
import { join, dirname } from 'path';
import { ILogTransport, ILogFormatter, LogEntry, LogLevel } from './index.js';
export interface RotatingFileOptions {
maxFileSize: number; // in bytes
maxFiles: number; // number of files to keep
maxAge: number; // in milliseconds
}
export class RotatingFileTransport implements ILogTransport {
private formatter: ILogFormatter;
private filePath: string;
private minLevel: LogLevel;
private options: RotatingFileOptions;
constructor(
filePath: string,
formatter: ILogFormatter,
options: RotatingFileOptions,
minLevel: LogLevel = 'info'
) {
this.filePath = filePath;
this.formatter = formatter;
this.minLevel = minLevel;
this.options = options;
// Ensure directory exists
const dir = dirname(filePath);
if (!existsSync(dir)) {
mkdirSync(dir, { recursive: true });
}
}
async log(entry: LogEntry): Promise<void> {
if (!this.shouldLog(entry.level)) {
return;
}
// Check if rotation is needed
this.rotateIfNeeded();
const formatted = this.formatter.format(entry) + '\n';
try {
appendFileSync(this.filePath, formatted);
} catch (error) {
// Use stderr for transport errors to avoid infinite loops
process.stderr.write(`[ROTATING-FILE-TRANSPORT-ERROR] Failed to write to ${this.filePath}: ${error}\n`);
}
}
async flush(): Promise<void> {
// File system handles flushing
}
async close(): Promise<void> {
// Cleanup old files on close
this.cleanupOldFiles();
}
private shouldLog(level: LogLevel): boolean {
const levels = ['debug', 'info', 'warn', 'error', 'fatal'];
return levels.indexOf(level) >= levels.indexOf(this.minLevel);
}
private rotateIfNeeded(): void {
if (!existsSync(this.filePath)) {
return;
}
const stats = statSync(this.filePath);
// Check size-based rotation
if (stats.size >= this.options.maxFileSize) {
this.rotateFile();
return;
}
// Check age-based rotation
const age = Date.now() - stats.mtime.getTime();
if (age >= this.options.maxAge) {
this.rotateFile();
}
}
private rotateFile(): void {
const timestamp = new Date().toISOString().replace(/[:.]/g, '-');
const rotatedPath = `${this.filePath}.${timestamp}`;
try {
// Rename current log file
require('fs').renameSync(this.filePath, rotatedPath);
// Cleanup old files
this.cleanupOldFiles();
} catch (error) {
process.stderr.write(`[ROTATING-FILE-TRANSPORT-ERROR] Failed to rotate log file: ${error}\n`);
}
}
private cleanupOldFiles(): void {
try {
const dir = dirname(this.filePath);
const baseName = require('path').basename(this.filePath);
// Get all rotated files
const files = readdirSync(dir)
.filter(file => file.startsWith(baseName + '.'))
.map(file => ({
name: file,
path: join(dir, file),
stats: statSync(join(dir, file))
}))
.sort((a, b) => b.stats.mtime.getTime() - a.stats.mtime.getTime());
// Remove excess files
if (files.length > this.options.maxFiles) {
const filesToDelete = files.slice(this.options.maxFiles);
filesToDelete.forEach(file => {
try {
unlinkSync(file.path);
} catch (error) {
process.stderr.write(`[ROTATING-FILE-TRANSPORT-ERROR] Failed to delete old log file ${file.path}: ${error}\n`);
}
});
}
} catch (error) {
process.stderr.write(`[ROTATING-FILE-TRANSPORT-ERROR] Failed to cleanup old log files: ${error}\n`);
}
}
}
