1import { appendFile, mkdir } from "node:fs/promises";
2import path from "node:path";
3 
4export interface LogEntry {
5  ts: string;
6  level: "info" | "warn" | "error";
7  event: string;
8  [k: string]: unknown;
9}
10 
11export class JsonLogger {
12  constructor(private logFile: string | null, public verbose: boolean) {}
13 
14  async log(level: LogEntry["level"], event: string, extra: Record<string, unknown> = {}): Promise<void> {
15    const entry: LogEntry = { ts: new Date().toISOString(), level, event, ...extra };
16    const line = JSON.stringify(entry);
17    if (this.verbose) process.stderr.write(`[${level}] ${event} ${jsonExtras(extra)}\n`);
18    if (this.logFile) {
19      await mkdir(path.dirname(this.logFile), { recursive: true });
20      await appendFile(this.logFile, line + "\n", "utf-8");
21    }
22  }
23 
24  info(event: string, extra?: Record<string, unknown>) {
25    return this.log("info", event, extra);
26  }
27  warn(event: string, extra?: Record<string, unknown>) {
28    return this.log("warn", event, extra);
29  }
30  error(event: string, extra?: Record<string, unknown>) {
31    return this.log("error", event, extra);
32  }
33}
34 
35function jsonExtras(extra: Record<string, unknown>): string {
36  const entries = Object.entries(extra);
37  if (entries.length === 0) return "";
38  return entries.map(([k, v]) => `${k}=${typeof v === "string" ? v : JSON.stringify(v)}`).join(" ");
39}
40