/**
 * @file avatars.js
 * @description A server-mode account's own avatar (Settings → Account, shown
 * in the sidebar). One raster image per account, stored as
 * `<data dir>/avatars/u<id>.<png|jpg|gif|webp>` — a name made from the
 * account id and the type its magic bytes say, never from the request — and
 * `users.avatar_at` records when it was set, so the client can version the
 * URL. Raster only: an SVG served from the dashboard's origin runs script.
 * At most `MAX_AVATAR_BYTES`; the serving route adds `nosniff` and a
 * `sandbox` CSP like every other user-supplied file.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

const fs = require("node:fs");
const path = require("node:path");
const { getDataDir } = require("./claude-home");
const { sniffImage } = require("./pets");

const MAX_AVATAR_BYTES = 1024 * 1024;
const EXTS = ["png", "jpg", "gif", "webp"];
const TYPES = { png: "image/png", jpg: "image/jpeg", gif: "image/gif", webp: "image/webp" };

const fail = (code, message) => Object.assign(new Error(message), { code });

const avatarsDir = () => path.join(getDataDir(), "avatars");

function fileName(userId, ext) {
  const id = Number(userId);
  if (!Number.isSafeInteger(id) || id <= 0) throw fail("EBADFIELD", "bad account id");
  return path.join(avatarsDir(), `u${id}.${ext}`);
}

const db = () => require("../db").db;

/** Deletes every stored avatar file of the account and clears `avatar_at`. */
function removeAvatar(userId) {
  for (const ext of EXTS) fs.rmSync(fileName(userId, ext), { force: true });
  db().prepare("UPDATE users SET avatar_at = NULL WHERE id = ?").run(Number(userId));
}

/** Stores `buf` as the account's avatar (EBADIMAGE / ETOOBIG); returns `avatar_at`. */
function setAvatar(userId, buf) {
  if (!Buffer.isBuffer(buf) || buf.length === 0) throw fail("EBADIMAGE", "no image sent");
  if (buf.length > MAX_AVATAR_BYTES) throw fail("ETOOBIG", "the image is too large");
  const ext = sniffImage(buf);
  if (!ext) throw fail("EBADIMAGE", "only PNG, JPEG, GIF or WebP images");
  const target = fileName(userId, ext);
  fs.mkdirSync(avatarsDir(), { recursive: true, mode: 0o700 });
  // Written beside, then renamed: a reader never sees half an image.
  const tmp = `${target}.${process.pid}.tmp`;
  fs.writeFileSync(tmp, buf, { mode: 0o600 });
  fs.renameSync(tmp, target);
  for (const other of EXTS) {
    if (other !== ext) fs.rmSync(fileName(userId, other), { force: true });
  }
  const at = new Date().toISOString();
  db().prepare("UPDATE users SET avatar_at = ? WHERE id = ?").run(at, Number(userId));
  return at;
}

/** The account's avatar file and its type, or null when it has none. */
function avatarFile(userId) {
  for (const ext of EXTS) {
    const file = fileName(userId, ext);
    const st = fs.lstatSync(file, { throwIfNoEntry: false });
    if (st?.isFile()) return { path: file, type: TYPES[ext] };
  }
  return null;
}

module.exports = { MAX_AVATAR_BYTES, setAvatar, removeAvatar, avatarFile, avatarsDir };