filesystem

import * as fs from "node:fs/promises";
import * as path from "node:path";
import { BACKUP_DIR_NAME } from "./pathGuard";

const LOG_HEADER = `# Activity log

Append-only record of mutations performed by LM Studio plugins on this root.
One line per event:
\`<ISO timestamp> [<kind>] <subject> — <message>\`

`;

export function logPathForRoot(root: string): string {
  return path.join(root, BACKUP_DIR_NAME, "log.md");
}

export async function appendAudit(
  root: string,
  kind: string,
  subject: string,
  message: string,
): Promise<void> {
  const logPath = logPathForRoot(root);
  const ts = new Date().toISOString();
  const safeSubject = subject.replace(/\n/g, " ").trim();
  const safeMessage = message.replace(/\n/g, " ").trim();
  const line = `${ts} [${kind}] ${safeSubject} — ${safeMessage}\n`;

  await fs.mkdir(path.dirname(logPath), { recursive: true });
  try {
    await fs.access(logPath);
  } catch {
    await fs.writeFile(logPath, LOG_HEADER, "utf-8");
  }
  await fs.appendFile(logPath, line, "utf-8");
}

export async function readAuditTail(root: string, n: number): Promise<string[]> {
  const logPath = logPathForRoot(root);
  try {
    const content = await fs.readFile(logPath, "utf-8");
    const lines = content.split("\n").filter((l) => /^\d{4}-\d{2}-\d{2}T/.test(l));
    return lines.slice(-n);
  } catch {
    return [];
  }
}