/**
 * @file pets.js
 * @description Custom pets for the dashboard mascot (Sagi). A pet is a folder
 * `<data dir>/pets/<id>/` holding `meta.json` (written here) and either a
 * Codex pet's `spritesheet.webp` — the `.codex-pet.zip` format: an 8×9 grid of
 * 192×208 frames, one row per animation state — or one uploaded image. Pets
 * come from exactly three places: an uploaded `.codex-pet.zip`, an uploaded
 * image, or one of the FEATURED pets, downloaded from codex-pets.net by a fixed
 * id — never a URL or a path from a request. None is bundled with AgentHub:
 * the featured pets are other people's uploads with no redistribution
 * licence, so each install fetches its own copy from the site that hosts
 * them. An id is always made here; SVG is refused, because an SVG served from
 * the dashboard's origin runs script when opened.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */
"use strict";

const fs = require("node:fs");
const path = require("node:path");
const crypto = require("node:crypto");
const AdmZip = require("adm-zip");
const { getDataDir } = require("./claude-home");

const MAX_BUNDLE_BYTES = 8 * 1024 * 1024;
const MAX_SHEET_BYTES = 6 * 1024 * 1024;
const MAX_IMAGE_BYTES = 4 * 1024 * 1024;
const MAX_MANIFEST_BYTES = 16 * 1024;
const MAX_PETS = 50;
/** The Codex atlas: 8 columns × 9 rows of 192×208 frames. */
const SHEET = { width: 1536, height: 1872, cellWidth: 192, cellHeight: 208 };
const FEATURED_HOST = "https://codex-pets.net";
/** Offered in the pet menu, installed only on a click. `id` is codex-pets.net's. */
const FEATURED = [
  { id: "goku", displayName: "Goku", by: "hackminit" },
  { id: "border-collie", displayName: "Border Collie", by: "dev-minsoo" },
  { id: "11", displayName: "11", by: "ct" },
];
const ID_RE = /^(?:p-[0-9a-f]{12}|cp-[a-z0-9-]{1,40})$/;
const IMAGE_TYPES = {
  png: "image/png",
  jpg: "image/jpeg",
  gif: "image/gif",
  webp: "image/webp",
};

let fetchImpl = (...args) => fetch(...args);
/** Test seam: replace the HTTP client the featured install uses. */
function __setFetch(fn) {
  fetchImpl = fn || ((...args) => fetch(...args));
}

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

function petsRoot() {
  return path.join(getDataDir(), "pets");
}

function petDir(id) {
  if (!ID_RE.test(String(id))) throw fail("ENOPET", "pet not found");
  return path.join(petsRoot(), id);
}

/** Width and height from a WebP header (VP8X, VP8 or VP8L), else null. */
function webpSize(buf) {
  if (buf.length < 30) return null;
  if (buf.toString("ascii", 0, 4) !== "RIFF" || buf.toString("ascii", 8, 12) !== "WEBP")
    return null;
  const chunk = buf.toString("ascii", 12, 16);
  if (chunk === "VP8X")
    return { width: 1 + buf.readUIntLE(24, 3), height: 1 + buf.readUIntLE(27, 3) };
  if (chunk === "VP8 ")
    return { width: buf.readUInt16LE(26) & 0x3fff, height: buf.readUInt16LE(28) & 0x3fff };
  if (chunk === "VP8L") {
    const bits = buf.readUInt32LE(21);
    return { width: 1 + (bits & 0x3fff), height: 1 + ((bits >> 14) & 0x3fff) };
  }
  return null;
}

/** The raster type of an uploaded image by its magic bytes, else null. */
function sniffImage(buf) {
  if (
    buf.length >= 8 &&
    buf.subarray(0, 8).equals(Buffer.from([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a]))
  )
    return "png";
  if (buf.length >= 3 && buf[0] === 0xff && buf[1] === 0xd8 && buf[2] === 0xff) return "jpg";
  if (buf.length >= 6 && /^GIF8[79]a$/.test(buf.toString("ascii", 0, 6))) return "gif";
  if (
    webpSize(buf) ||
    (buf.length >= 12 &&
      buf.toString("ascii", 8, 12) === "WEBP" &&
      buf.toString("ascii", 0, 4) === "RIFF")
  )
    return "webp";
  return null;
}

/** A display string from untrusted input: trimmed, single-line, capped. */
function cleanText(value, max) {
  return typeof value === "string" ? value.replace(/\s+/g, " ").trim().slice(0, max) : "";
}

function checkSheet(buf) {
  if (buf.length > MAX_SHEET_BYTES) throw fail("ETOOBIG", "the spritesheet is larger than 6 MB");
  const size = webpSize(buf);
  if (!size) throw fail("EBADPET", "the spritesheet is not a WebP image");
  if (size.width !== SHEET.width || size.height !== SHEET.height)
    throw fail(
      "EBADPET",
      `the spritesheet is ${size.width}×${size.height}; a Codex pet is ${SHEET.width}×${SHEET.height}`
    );
}

function readMeta(id) {
  try {
    return JSON.parse(fs.readFileSync(path.join(petDir(id), "meta.json"), "utf8"));
  } catch {
    return null;
  }
}

function view(id, meta) {
  return {
    id,
    displayName: meta.displayName,
    description: meta.description || "",
    kind: meta.kind,
    source: meta.source,
    ...(meta.featuredId ? { featuredId: meta.featuredId } : {}),
    ...(meta.by ? { by: meta.by } : {}),
  };
}

function listPets() {
  let names = [];
  try {
    names = fs.readdirSync(petsRoot());
  } catch {
    return [];
  }
  return names
    .filter((n) => ID_RE.test(n))
    .map((n) => [n, readMeta(n)])
    .filter(([, meta]) => meta && (meta.kind === "codex" || meta.kind === "image"))
    .sort((a, b) => String(a[1].addedAt).localeCompare(String(b[1].addedAt)))
    .map(([n, meta]) => view(n, meta));
}

/** Writes a pet atomically: a temp folder renamed into place. */
function store(id, meta, file, body) {
  const existing = listPets();
  if (!existing.some((p) => p.id === id) && existing.length >= MAX_PETS)
    throw fail("ETOOMANY", `at most ${MAX_PETS} pets`);
  const root = petsRoot();
  fs.mkdirSync(root, { recursive: true });
  const tmp = fs.mkdtempSync(path.join(root, ".new-"));
  try {
    fs.writeFileSync(path.join(tmp, file), body);
    fs.writeFileSync(
      path.join(tmp, "meta.json"),
      JSON.stringify({ ...meta, file, addedAt: new Date().toISOString() })
    );
    fs.rmSync(petDir(id), { recursive: true, force: true });
    fs.renameSync(tmp, petDir(id));
  } catch (err) {
    fs.rmSync(tmp, { recursive: true, force: true });
    throw err;
  }
  return view(id, readMeta(id));
}

const newId = () => `p-${crypto.randomBytes(6).toString("hex")}`;

/** Imports a `.codex-pet.zip`: `pet.json` + `spritesheet.webp`, at the root
 *  or in one top-level folder. Nothing else in the archive is read. */
function importBundle(buf) {
  if (!Buffer.isBuffer(buf) || !buf.length) throw fail("EBADPET", "no file");
  if (buf.length > MAX_BUNDLE_BYTES) throw fail("ETOOBIG", "the bundle is larger than 8 MB");
  let entries;
  try {
    entries = new AdmZip(buf).getEntries();
  } catch {
    throw fail("EBADPET", "not a zip archive");
  }
  const pick = (name) =>
    entries.find(
      (e) =>
        !e.isDirectory &&
        /^(?:[^/]+\/)?[^/]+$/.test(e.entryName) &&
        path.posix.basename(e.entryName) === name
    );
  const manifest = pick("pet.json");
  const sheet = pick("spritesheet.webp");
  if (!manifest || !sheet)
    throw fail("EBADPET", "a .codex-pet bundle holds pet.json and spritesheet.webp");
  // Sizes from the central directory, checked BEFORE inflating (zip bombs).
  if (manifest.header.size > MAX_MANIFEST_BYTES) throw fail("EBADPET", "pet.json is too large");
  if (sheet.header.size > MAX_SHEET_BYTES)
    throw fail("ETOOBIG", "the spritesheet is larger than 6 MB");
  let pet;
  try {
    pet = JSON.parse(manifest.getData().toString("utf8"));
  } catch {
    throw fail("EBADPET", "pet.json is not valid JSON");
  }
  const body = sheet.getData();
  checkSheet(body);
  const displayName =
    cleanText(pet && pet.displayName, 60) || cleanText(pet && pet.id, 60) || "Pet";
  return store(
    newId(),
    {
      kind: "codex",
      source: "upload",
      displayName,
      description: cleanText(pet && pet.description, 300),
    },
    "spritesheet.webp",
    body
  );
}

/** Adds one uploaded image (PNG, JPEG, GIF or WebP) as a still pet. */
function addImage(buf, name) {
  if (!Buffer.isBuffer(buf) || !buf.length) throw fail("EBADPET", "no file");
  if (buf.length > MAX_IMAGE_BYTES) throw fail("ETOOBIG", "the image is larger than 4 MB");
  const ext = sniffImage(buf);
  if (!ext) throw fail("EBADPET", "only PNG, JPEG, GIF or WebP images");
  const displayName = cleanText(String(name || "").replace(/\.[^.]+$/, ""), 60) || "Pet";
  return store(
    newId(),
    { kind: "image", source: "upload", displayName, type: ext },
    `image.${ext}`,
    buf
  );
}

async function fetchCapped(url, max) {
  const res = await fetchImpl(url, { signal: AbortSignal.timeout(20_000), redirect: "error" });
  if (!res.ok) throw fail("EFETCH", `codex-pets.net answered ${res.status}`);
  const len = Number(res.headers?.get?.("content-length"));
  if (len > max) throw fail("ETOOBIG", "the download is too large");
  const body = Buffer.from(await res.arrayBuffer());
  if (body.length > max) throw fail("ETOOBIG", "the download is too large");
  return body;
}

/** Downloads one FEATURED pet from codex-pets.net into this install. */
async function installFeatured(featuredId) {
  const f = FEATURED.find((x) => x.id === featuredId);
  if (!f) throw fail("ENOPET", "not a featured pet");
  const base = `${FEATURED_HOST}/api/pets/${encodeURIComponent(f.id)}`;
  let description = "";
  try {
    const meta = JSON.parse((await fetchCapped(base, MAX_MANIFEST_BYTES * 4)).toString("utf8"));
    description = cleanText(meta && meta.pet && meta.pet.description, 300);
  } catch (err) {
    if (err.code === "ETOOBIG") throw err;
    /* the description is optional; the spritesheet is not */
  }
  let body;
  try {
    body = await fetchCapped(`${base}/spritesheet`, MAX_SHEET_BYTES);
  } catch (err) {
    if (err.code) throw err;
    throw fail("EFETCH", `could not reach codex-pets.net: ${err.message}`);
  }
  checkSheet(body);
  return store(
    `cp-${f.id}`,
    {
      kind: "codex",
      source: "featured",
      featuredId: f.id,
      by: f.by,
      displayName: f.displayName,
      description,
    },
    "spritesheet.webp",
    body
  );
}

function removePet(id) {
  const dir = petDir(id);
  if (!readMeta(id)) throw fail("ENOPET", "pet not found");
  fs.rmSync(dir, { recursive: true, force: true });
}

/** The file to serve for a pet and its content type. */
function spriteFile(id) {
  const meta = readMeta(id);
  if (!meta || (meta.file !== "spritesheet.webp" && !/^image\.(png|jpg|gif|webp)$/.test(meta.file)))
    throw fail("ENOPET", "pet not found");
  const ext = meta.file.split(".").pop();
  return { path: path.join(petDir(id), meta.file), type: IMAGE_TYPES[ext] };
}

function featured() {
  const installed = new Set(
    listPets()
      .map((p) => p.featuredId)
      .filter(Boolean)
  );
  return FEATURED.map((f) => ({
    ...f,
    installed: installed.has(f.id),
    page: `${FEATURED_HOST}/#/pets/${f.id}`,
  }));
}

module.exports = {
  SHEET,
  FEATURED,
  MAX_BUNDLE_BYTES,
  MAX_IMAGE_BYTES,
  listPets,
  featured,
  importBundle,
  addImage,
  installFeatured,
  removePet,
  spriteFile,
  webpSize,
  __setFetch,
};