import { mkdir, readdir, stat, unlink } from "node:fs/promises";
import { randomBytes } from "node:crypto";
import { resolve } from "node:path";
import { db, dbPath } from "./db.mjs";

const projectRoot = resolve(import.meta.dirname, "..");
const backupRoot = resolve(projectRoot, "data", "backups");
const relativeBackupRoot = "data/backups";

function backupEntry(name, fileStat) {
  return {
    name,
    relativePath: `${relativeBackupRoot}/${name}`,
    bytes: Number(fileStat.size || 0),
    createdAt: fileStat.birthtime?.toISOString?.() || fileStat.mtime?.toISOString?.() || null,
    modifiedAt: fileStat.mtime?.toISOString?.() || null
  };
}

export async function listDatabaseBackups() {
  let names = [];
  try {
    names = await readdir(backupRoot);
  } catch (error) {
    if (error.code !== "ENOENT") throw error;
  }
  const entries = await Promise.all(names.filter((name) => /^platform-[A-Z0-9-]+\.sqlite$/i.test(name)).map(async (name) => {
    try {
      return backupEntry(name, await stat(resolve(backupRoot, name)));
    } catch (error) {
      if (error.code === "ENOENT") return null;
      throw error;
    }
  }));
  return entries.filter(Boolean).sort((left, right) => String(right.modifiedAt || "").localeCompare(String(left.modifiedAt || "")));
}

export async function backupSummary() {
  const backups = await listDatabaseBackups();
  return {
    root: relativeBackupRoot,
    source: dbPath,
    count: backups.length,
    latest: backups[0] || null,
    backups
  };
}

export async function createDatabaseBackup() {
  await mkdir(backupRoot, { recursive: true });
  const stamp = new Date().toISOString().replace(/[^0-9TZ]/g, "-");
  const name = `platform-${stamp}-${randomBytes(4).toString("hex")}.sqlite`;
  const target = resolve(backupRoot, name);
  const escapedTarget = target.replaceAll("'", "''");
  try {
    db.exec(`VACUUM INTO '${escapedTarget}'`);
    const entry = backupEntry(name, await stat(target));
    return { backup: entry, ...(await backupSummary()) };
  } catch (error) {
    await unlink(target).catch(() => {});
    throw error;
  }
}