// server/http/static.js — the static file server (routes.js hands it every GET / HEAD that is not an API route):
// (i18n-ignore-file: the error pages are bilingual by design, 中文 · English — docs/I18N.md)
//
//     /        → public/      (index.html for directories)
//     /data/   → data/        (generated game data)
//     /shared/ → shared/      (ESM shared with the browser)
//     /sim/    → server/sim/  (the battle simulation, read-only, `.js` only — client-side
//                              combat, DESIGN §14; the Node-only loader nodeData.js is not served)
//     /data.js → a generated browser stand-in of server/data.js (the sim's content modules
//                import `../../../data.js`; in the browser it serves the data injected with
//                /sim/simdata.js setSimData). No other server file is ever served.
//     /media/bgm/act1 → public/assets/audio/bgm/act1.mp3 — the same audio files, addressed
//                **without** an extension so download managers (IDM / 迅雷 …) stop popping a
//                "下载文件信息" dialog for every BGM track (media.js, shared/media.js, public/js/media.js)
//     /packs/index.json → the content packs of this server (server/packs.js: the language packs of
//                public/i18n/ and the pack folders of packs/, re-read when they change; never cached)
//     /packs/<id>/<file> → a file of a pack folder — only one its manifest names (server/packs.js servable)
//     /assets/~<hash>/…, /fonts/~<hash>/…, /media/~<hash>/… → the same files: the content-hash segment
//                (shared/assetPaths.js) is stripped. A hash that names the file's current bytes (assetIndex.js
//                urlHashOk: its own hash, or its Spine model's) answers `immutable` for a year; any other hash —
//                an old page, a URL derived from another file's — the current file with `no-cache`
//     /data/assets.json, /data/local-assets.json → the served manifests (assetViews.js: every art URL with its
//                content-hash segment; no-cache, the ETag of the view) once the asset index is ready, the files as
//                they are before that or without an index
//
// Files under public/assets/ and public/fonts/ get their content hash as ETag when the index has it (a file whose
// size or mtime changed since asks for a rescan), others size + mtime. Traversal & dotfile protection, a directory
// without its trailing slash → 301, 404 page; an absent data/local-assets.json is answered with an empty manifest.
// Files go out through files.js serveFile.

import fsp from 'node:fs/promises';
import path from 'node:path';
import { MEDIA_PREFIX } from '../../shared/media.js';
import { splitHashedPath } from '../../shared/assetPaths.js';
import { ROOT, noopLog } from './config.js';
import { sendError, sendJson } from './common.js';
import { MIME, CompressCache, isNotModified, serveFile, serveBuffer } from './files.js';
import { ASSET_INDEX_ROOTS, hashedFileOpts } from './assetIndex.js';
import { serveMedia } from './media.js';
import { createPackRegistry } from '../packs.js';
import { PACKS_URL, PACK_INDEX_FILE } from '../../shared/packs.js';

/** Browser stand-in of server/data.js, served at /data.js (see the header). Served byte for byte: its first line names the entry, server/index.js. */
export const DATA_SHIM_JS = `// Generated by server/index.js — browser stand-in for server/data.js (DESIGN §14 client-side combat).
// The simulation's content modules (/sim/content/support/index.js) import getData() from here; it returns the game data
// the page injected with /sim/simdata.js setSimData(data).
import { getSimData } from './sim/simdata.js';
export function getData() { return getSimData() || {}; }
export function resetData() {}
`;
/** Files under server/sim that are never served (Node-only). */
const SIM_PRIVATE = new Set(['nodedata.js']); // lower-case (compared case-insensitively)

// ---------------------------------------------------------------------------------------------------
// Static file handler
// ---------------------------------------------------------------------------------------------------

/** Optional per-machine art manifest (tools/local-extract) and the empty stand-in served when it is absent. */
const LOCAL_ART_MANIFEST = 'local-assets.json';
const EMPTY_LOCAL_ART = Buffer.from(JSON.stringify({ version: 1, source: 'none', count: 0, groups: {} }));

/**
 * Create the static request handler.
 * @param {{ publicDir: string, dataDir: string, sharedDir: string, simDir?: string, packsDir?: string,
 *   packs?: ReturnType<typeof createPackRegistry>, log?: object,
 *   assetIndex?: ReturnType<typeof import('./assetIndex.js').createAssetIndex> | null,
 *   views?: ReturnType<typeof import('./assetViews.js').createManifestViews> | null }} dirs
 *   packs: the server's pack registry (default: one over publicDir, dataDir and packsDir — ROOT/packs);
 *   assetIndex / views: the content hashes and the served manifests (none: plain URLs, size-mtime ETags)
 * @returns {(req: import('node:http').IncomingMessage, res: import('node:http').ServerResponse, rawPath: string, query: string) => Promise<void>}
 */
export function createStaticHandler({ publicDir, dataDir, sharedDir, simDir = path.join(ROOT, 'server', 'sim'), packsDir = path.join(ROOT, 'packs'), packs = null, log = noopLog,
  assetIndex = null, views = null }) {
  const registry = packs || createPackRegistry({ publicDir, dataDir, packsDir }, { log: /** @type {any} */ (log) });
  const mounts = [
    { prefix: '/data/', name: 'data', dir: path.resolve(dataDir) },
    { prefix: '/shared/', name: 'shared', dir: path.resolve(sharedDir) },
    // the simulation: ES modules only (no directory listings, no other file types, no Node-only loader)
    { prefix: '/sim/', name: 'sim', dir: path.resolve(simDir), only: new Set(['.js']), deny: SIM_PRIVATE },
    { prefix: '/', name: 'public', dir: path.resolve(publicDir) },
  ];
  const shimBody = Buffer.from(DATA_SHIM_JS);
  const shimTag = `"shim-${shimBody.length.toString(16)}"`;
  const gzipCache = new CompressCache(); // brotli and gzip bodies (files.js)

  return async function serveStatic(req, res, rawPath, query) {
    let decoded;
    try { decoded = decodeURIComponent(rawPath); } catch { sendError(req, res, 400, '请求地址无效 · Bad request'); return; }
    if (!decoded.startsWith('/') || decoded.includes('\0') || decoded.includes('\\')) {
      sendError(req, res, 400, '请求地址无效 · Bad request');
      return;
    }
    // /assets/~<hash>/x → /assets/x (the hash decides the cache policy below)
    const hashed = splitHashedPath(decoded);
    const urlHash = hashed.hash;
    decoded = hashed.path;
    if (decoded === '/data.js') {
      const headers = { 'Content-Type': MIME['.js'], 'Cache-Control': 'no-cache', ETag: shimTag, 'Content-Length': shimBody.length };
      if (isNotModified(req, shimTag, new Date(0))) { delete headers['Content-Length']; res.writeHead(304, headers); res.end(); return; }
      res.writeHead(200, headers);
      res.end(req.method === 'HEAD' ? undefined : shimBody);
      return;
    }
    // Content packs (server/packs.js): the live index, and only the files a pack's manifest names
    if (decoded.startsWith(PACKS_URL)) {
      const parts = decoded.slice(PACKS_URL.length).split('/');
      if (parts.length === 1 && parts[0] === PACK_INDEX_FILE) { sendJson(req, res, 200, registry.index()); return; }
      const abs = parts.length >= 2 && !parts.some((s) => s === '' || s === '.' || s === '..') ? registry.servable(parts[0], parts.slice(1).join('/')) : null;
      const st = abs ? await fsp.stat(abs).catch(() => null) : null;
      if (!st || !st.isFile()) { sendError(req, res, 404, '页面不存在 · Not found', decoded.length <= 200 ? decoded : ''); return; }
      await serveFile(req, res, abs, st, 'packs', parts, query, gzipCache, log);
      return;
    }
    // Extension-less audio (download-manager avoidance): /media/bgm/act1 → /assets/audio/bgm/act1.mp3
    if (decoded.startsWith(MEDIA_PREFIX)) {
      await serveMedia(req, res, decoded.slice(MEDIA_PREFIX.length), query, publicDir, gzipCache, log, { urlHash, assetIndex });
      return;
    }
    // The served manifests: every art URL with its content hash (assetViews.js), once the index is ready
    if (views && (decoded === '/data/assets.json' || decoded === '/data/local-assets.json')) {
      const view = await views.get(decoded.slice('/data/'.length));
      if (view) {
        await serveBuffer(req, res, { body: view.body, hash: view.hash, type: MIME['.json'], cacheControl: 'no-cache', key: `view:${decoded}`, cache: gzipCache });
        return;
      }
    }
    // Bare mount paths (e.g. "/data") → treat as the mount directory.
    const mount = mounts.find((m) => decoded.startsWith(m.prefix) || decoded === m.prefix.slice(0, -1)) || mounts[mounts.length - 1];
    const rest = decoded.length > mount.prefix.length ? decoded.slice(mount.prefix.length) : '';
    const segments = rest.split('/').filter((s) => s.length > 0);
    if (segments.some((s) => s === '..' || s === '.')) { sendError(req, res, 403, '禁止访问 · Forbidden'); return; }
    if (segments.some((s) => s.startsWith('.'))) { sendError(req, res, 404, '页面不存在 · Not found'); return; }
    if (mount.only && (!segments.length || !mount.only.has(path.extname(segments[segments.length - 1]).toLowerCase())
      // (case-insensitive: the host may be Windows / macOS, where NODEDATA.JS opens nodeData.js)
      || (mount.deny && mount.deny.has(segments[segments.length - 1].toLowerCase())))) {
      sendError(req, res, 404, '页面不存在 · Not found');
      return;
    }
    let absPath = path.join(mount.dir, ...segments);
    if (absPath !== mount.dir && !absPath.startsWith(mount.dir + path.sep)) { sendError(req, res, 403, '禁止访问 · Forbidden'); return; }

    let stat;
    let viaDirectory = false;
    try {
      stat = await fsp.stat(absPath);
      if (stat.isDirectory()) {
        if (!decoded.endsWith('/')) {
          // Built from normalized segments (never from the raw path) so "//host" can't become an open redirect.
          const loc = (mount.prefix + segments.map(encodeURIComponent).join('/') + '/').replace(/\/{2,}/g, '/');
          res.writeHead(301, { Location: loc + (query ? `?${query}` : ''), 'Cache-Control': 'no-cache', 'Content-Length': 0 });
          res.end();
          return;
        }
        absPath = path.join(absPath, 'index.html');
        segments.push('index.html');
        viaDirectory = true;
        stat = await fsp.stat(absPath);
      }
      // Not a regular file, or a file addressed like a directory ("/app.js/") → 404.
      if (!stat.isFile() || (decoded.endsWith('/') && !viaDirectory)) {
        throw Object.assign(new Error('not a file'), { code: 'ENOENT' });
      }
      if (mount.deny) {
        // the on-disk name decides (case-insensitive file systems, Windows 8.3 short names like NODEDA~1.JS)
        const real = await fsp.realpath(absPath);
        if (mount.deny.has(path.basename(real).toLowerCase())) throw Object.assign(new Error('private'), { code: 'ENOENT' });
      }
    } catch (e) {
      if (e && e.code === 'ENOENT' && mount.name === 'data' && segments.length === 1 && segments[0] === LOCAL_ART_MANIFEST) {
        // Optional local-client art (DESIGN §13): an install without it gets an empty manifest instead of a 404,
        // so browsers don't log an error on every page load. Clients treat empty groups as "no local art".
        res.writeHead(200, { 'Content-Type': MIME['.json'], 'Cache-Control': 'no-cache', 'Content-Length': EMPTY_LOCAL_ART.length });
        res.end(req.method === 'HEAD' ? undefined : EMPTY_LOCAL_ART);
      } else if (e && (e.code === 'ENOENT' || e.code === 'ENOTDIR' || e.code === 'EISDIR' || e.code === 'ENAMETOOLONG')) {
        sendError(req, res, 404, '页面不存在 · Not found', decoded.length <= 200 ? decoded : '');
      } else if (e && (e.code === 'EACCES' || e.code === 'EPERM')) {
        sendError(req, res, 403, '禁止访问 · Forbidden');
      } else {
        log.error('[http] stat failed', e);
        sendError(req, res, 500, '服务器内部错误 · Internal error');
      }
      return;
    }
    const indexed = mount.name === 'public' && segments.length > 1 && ASSET_INDEX_ROOTS.includes(segments[0]);
    const opts = indexed ? hashedFileOpts(assetIndex, segments.join('/'), stat, urlHash) : (urlHash ? { cacheControl: 'no-cache' } : {});
    await serveFile(req, res, absPath, stat, mount.name, segments, query, gzipCache, log, opts);
  };
}