import fs from "node:fs/promises";
import path from "node:path";

export class AuditLog {
  constructor(filePath) {
    this.filePath = filePath ? path.resolve(filePath) : null;
    this.pending = Promise.resolve();
  }

  record(event) {
    const line = `${JSON.stringify({ timestamp: new Date().toISOString(), ...event })}\n`;
    if (!this.filePath) {
      process.stderr.write(`[mcp-audit] ${line}`);
      return;
    }
    this.pending = this.pending
      .then(() => fs.mkdir(path.dirname(this.filePath), { recursive: true }))
      .then(() => fs.appendFile(this.filePath, line, { encoding: "utf8", mode: 0o600 }))
      .catch(() => {
        // Auditing must not make a coding operation unavailable. Deployment should monitor this path.
      });
  }
}