#!/usr/bin/env node
/**
 * checkTerms.mjs — PLAN.md §16, D63 and D64. The twelfth check, added in phase 14 and widened
 * to the whole site in phase 17 (D79).
 *
 * D63: outside a game's own section, the site may NAME the games it supports, but it may not
 * use their VOCABULARY. Core concepts keep core's names — a Team, a game server, the sidecar,
 * the bridge plugin, the game module — because that is what core itself calls them, and a
 * site that says "shard" on a core page is describing one game's deployment as though it were
 * the platform.
 *
 * D64: a convention that holds only while everyone remembers it does not hold. This is the
 * same argument `checkTokens.mjs` makes for colours, applied to words. The vocabulary problem
 * was measured before this check existed — "shard" 227 times in 45 files — and none of that
 * was anybody's decision; it was the residue of a site written while there was one game.
 *
 * It runs in two passes, one before the build and one after.
 *
 *   node scripts/checkTerms.mjs           # the SOURCE pass: docs pages and the sidebar
 *   node scripts/checkTerms.mjs --built   # the BUILT pass: every page in dist/, as rendered
 *
 * ── The source pass (phase 14) ──────────────────────────────────────────────────────────
 *
 *   - every page under `src/content/docs`, frontmatter included (a title and a description
 *     are what a reader sees first, in the sidebar and in search results);
 *   - `src/config/sidebar.mjs`, as DATA rather than as text: every group label and every
 *     page label, in both trees. Its comments are not scanned, because a comment is not
 *     something a reader of the site ever sees.
 *
 * It needs no build, so it runs early and fails fast, and it names a file and a line.
 *
 * ── The built pass (phase 17, D79) ──────────────────────────────────────────────────────
 *
 * The marketing pages are `.astro` templates fed from `src/data/`, so most of the words a
 * reader sees on them are not in the template at all: a capability's label, a screenshot's
 * caption, a version read from `platform.json`. A source scan sees an expression and skips
 * it, or sees an id like `shard-status` and takes it for prose. So this pass reads what the
 * build actually produced — the same argument `checkLinks.mjs` makes for links. For every
 * page in `dist/client` it reads the visible text, plus `alt`, `title`, `aria-label`,
 * `placeholder`, the `<title>` and the meta description. It does not read link targets,
 * scripts, styles or comments. It names a route and a snippet rather than a line; the source
 * pass still gives lines for the docs, where most of the words are.
 *
 * Two parts of every docs page are skipped, because each is checked somewhere better:
 * Starlight's sidebar (the source pass reads both trees as data, group by group) and the
 * previous/next links (each is a neighbouring page's title, checked on that page).
 *
 * ── Where a game's words are allowed ────────────────────────────────────────────────────
 *
 *   - in that game's own docs directory (`GAME_DIRS`) and its own sidebar group — a group
 *     whose label is the game's `name` in `platform.json`;
 *   - on that game's own routes (`GAME_ROUTES`): its docs group, its module page, and for
 *     Rust the standalone RunicNPC page;
 *   - inside an element marked `data-game="…"`: `<GameExample>` on a docs page (D68) and a
 *     game-tagged `<Screenshot>` (D67). Both print the game's name beside the words, which is
 *     the bargain: a game's words are honest on a core page when the game is named right
 *     there. In the source pass, the `<GameExample>` tags themselves mark the region.
 *
 * What is NOT read, deliberately: link targets and bare URLs or paths (a repository is called
 * what it is called, and an address is not prose — but LINK TEXT is read, so `[Module-uo](…)`
 * fails and `[releases](…)` passes), MDX `import` lines, and, in the source pass only, `{…}`
 * expressions — the built pass reads what they rendered.
 *
 * No token and no network: everything it reads is in this repository or its build output.
 */

import { readFileSync, existsSync } from 'node:fs';
import { readdir } from 'node:fs/promises';
import { fileURLToPath } from 'node:url';
import path from 'node:path';

import { docsSidebar, plannedSidebar, flatLabels } from '../src/config/sidebar.mjs';

const ROOT = fileURLToPath(new URL('..', import.meta.url));
const platform = JSON.parse(readFileSync(path.join(ROOT, 'src/data/platform.json'), 'utf8'));
const BUILT = process.argv.includes('--built');

/**
 * The words, each tagged with the game it belongs to. Matching is case-insensitive and on
 * word boundaries, so "shard" does not match `SHARD_VISIBILITY` and "wipe" does not match
 * "wiped" unless it is listed.
 *
 * A word is on this list because it is a game's name for something core has its own name for
 * (shard → game server, guild and clan → Team), or because it names one game's component
 * (uo-link → the sidecar, ServUO → the game server). Game NAMES — Ultima Online, UO, Rust —
 * are not on it: D63 allows them everywhere. Steam is not on it either: Steam sign-in is a
 * core identity provider, even though Rust was its first user.
 */
const TERMS = [
  { game: 'uo', word: 'shard', re: /\bshards?\b/gi },
  { game: 'uo', word: 'ServUO', re: /\bservuo\b/gi },
  { game: 'uo', word: 'uo-link', re: /\buo-?link\b/gi },
  { game: 'uo', word: 'Module-uo', re: /\bmodule-uo\b/gi },
  { game: 'uo', word: 'Bridge.cfg', re: /\bbridge\.cfg\b/gi },
  { game: 'uo', word: 'cliloc', re: /\bclilocs?\b/gi },
  { game: 'uo', word: 'guild', re: /\bguilds?\b/gi },
  { game: 'uo', word: 'IDOC', re: /\bidocs?\b/gi },
  { game: 'rust', word: 'rust-link', re: /\brust-?link\b/gi },
  { game: 'rust', word: 'Rust-Plugins', re: /\brust-plugins\b/gi },
  { game: 'rust', word: 'Module-Rust', re: /\bmodule-rust\b/gi },
  { game: 'rust', word: 'Oxide', re: /\boxide\b/gi },
  { game: 'rust', word: 'Carbon', re: /\bcarbon\b/gi },
  { game: 'rust', word: 'uMod', re: /\bumod\b/gi },
  { game: 'rust', word: 'clan', re: /\bclans?\b/gi },
  { game: 'rust', word: 'wipe', re: /\bwipes?\b/gi },
];

/** Each game's own docs directory. A page under one may use that game's words. */
const GAME_DIRS = {
  uo: 'src/content/docs/docs/ultima-online/',
  rust: 'src/content/docs/docs/rust/',
};

/**
 * Each game's own routes, for the built pass: its docs group, the page about its module, and
 * for Rust the standalone RunicNPC page (D61), which a server owner reads without knowing what
 * the platform is. A route matches when the page's path starts with one of these.
 */
const GAME_ROUTES = {
  uo: ['/docs/ultima-online/', '/modules/uo/'],
  rust: ['/docs/rust/', '/modules/rust/', '/runicnpc/'],
};

/**
 * The allowlist: an exact phrase on one page that may use a word the rule would otherwise
 * refuse. Short on purpose, and every entry says why. `file` is where the source pass meets
 * it and `route` is where the built pass does. An entry that no longer matches fails the
 * check too, so the list cannot rot into a set of permanent exemptions.
 */
const ALLOW = [
  {
    file: 'src/content/docs/docs/administration/notifications-and-email.mdx',
    route: '/docs/administration/notifications-and-email/',
    text: 'Guild (server) ID',
    why: "Discord's own word, not a game's: it is the label on core's Discord Bot screen.",
  },
];

for (const game of new Set([...Object.keys(GAME_DIRS), ...Object.keys(GAME_ROUTES)])) {
  if (!platform.games[game]) throw new Error(`checkTerms: "${game}" is given a section here, but platform.json has no such game.`);
}
for (const t of TERMS) {
  if (!platform.games[t.game]) throw new Error(`checkTerms: "${t.word}" is tagged "${t.game}", which platform.json does not know.`);
}

const failures = [];
const fail = (where, detail) => failures.push({ where, detail });

/** Replace a span with spaces, keeping newlines, so later line numbers stay true. */
const blank = (text) => text.replace(/[^\n]/g, ' ');

/** Hits for every term the given context may not use. `allowed` is a game key, or null. */
function scan(text, allowed) {
  const hits = [];
  for (const t of TERMS) {
    if (t.game === allowed) continue;
    t.re.lastIndex = 0;
    for (const m of text.matchAll(t.re)) hits.push({ term: t, value: m[0], index: m.index });
  }
  return hits;
}

const gameName = (game) => platform.games[game].name;

async function* walk(dir, pattern) {
  let entries;
  try {
    entries = await readdir(dir, { withFileTypes: true });
  } catch {
    return;
  }
  for (const entry of entries) {
    const full = path.join(dir, entry.name);
    if (entry.isDirectory()) yield* walk(full, pattern);
    else if (pattern.test(entry.name)) yield full;
  }
}

// ═══ The source pass ═══════════════════════════════════════════════════════════════════

/** The game whose directory holds this file, or null for a core page. */
function gameOfPath(relative) {
  const posix = relative.split(path.sep).join('/');
  for (const [game, dir] of Object.entries(GAME_DIRS)) if (posix.startsWith(dir)) return game;
  return null;
}

function lineOf(source, index) {
  return source.slice(0, index).split('\n').length;
}

/**
 * Turn an MDX source into the text a reader would actually see, with everything that is not
 * prose blanked out. Returns that text plus the GameExample regions, as offsets into it.
 */
function proseOf(source, relative) {
  let text = source;

  // GameExample regions first, while the tags are still intact. Recorded, then the tags
  // themselves are blanked so the attribute does not read as prose.
  const regions = [];
  for (const m of text.matchAll(/<GameExample\s+game="([^"]*)"\s*>([\s\S]*?)<\/GameExample>/g)) {
    const game = m[1];
    if (!platform.games[game]) {
      fail(`${relative}:${lineOf(source, m.index)}`, `<GameExample game="${game}"> names a game platform.json does not have`);
    }
    regions.push({ game, start: m.index, end: m.index + m[0].length });
  }
  text = text.replace(/<\/?GameExample\b[^>]*>/g, blank);

  text = text.replace(/<!--[\s\S]*?-->/g, blank); // HTML comments
  text = text.replace(/^import\s.*$/gm, blank); // MDX imports
  text = text.replace(/\]\([^)\s]*\)/g, (m) => '] ' + blank(m.slice(2))); // link targets, not their text
  text = text.replace(/\b(?:href|src)=(?:"[^"]*"|\{`[^`]*`\})/g, blank); // JSX/HTML link targets
  text = text.replace(/\bhttps?:\/\/[^\s)>"'`]+/g, blank); // bare URLs

  // `{…}` expressions, outside code fences only — a fenced JSON example's braces are prose.
  // Innermost first, repeatedly, so nested and multi-line expressions both go.
  const parts = text.split(/(^```[\s\S]*?^```)/m);
  for (let i = 0; i < parts.length; i += 2) {
    let prev;
    do {
      prev = parts[i];
      parts[i] = parts[i].replace(/\{[^{}]*\}/g, blank);
    } while (parts[i] !== prev);
  }
  text = parts.join('');

  return { text, regions };
}

async function sourcePass() {
  // ── 1. The documentation pages ──
  let files = 0;
  const allowUsed = new Set();

  for await (const file of walk(path.join(ROOT, 'src', 'content', 'docs'), /\.mdx?$/)) {
    const relative = path.relative(ROOT, file).split(path.sep).join('/');
    const source = readFileSync(file, 'utf8').replace(/\r\n/g, '\n');
    files++;

    let { text, regions } = proseOf(source, relative);

    for (const [i, entry] of ALLOW.entries()) {
      if (entry.file !== relative) continue;
      if (text.includes(entry.text)) {
        allowUsed.add(i);
        text = text.split(entry.text).join(blank(entry.text));
      }
    }

    const pageGame = gameOfPath(relative);
    for (const hit of scan(text, pageGame)) {
      const region = regions.find((r) => hit.index >= r.start && hit.index < r.end);
      if (region && region.game === hit.term.game) continue;
      const where = region ? `inside <GameExample game="${region.game}">` : pageGame ? `in the ${gameName(pageGame)} group` : 'on a core page';
      fail(`${relative}:${lineOf(source, hit.index)}`, `"${hit.value}" is ${gameName(hit.term.game)} vocabulary, ${where}`);
    }
  }

  for (const [i, entry] of ALLOW.entries()) {
    if (!allowUsed.has(i)) fail(`allowlist: ${entry.file}`, `"${entry.text}" no longer appears there — remove the entry`);
  }

  // ── 2. The sidebar, as data ──
  const gameByName = new Map(Object.entries(platform.games).map(([key, g]) => [g.name, key]));
  const trees = [
    ['docsSidebar', docsSidebar.map((g) => [g.label, flatLabels(g.items)])],
    ['plannedSidebar', Object.entries(plannedSidebar).map(([label, items]) => [label, flatLabels(items)])],
  ];
  let labels = 0;
  for (const [treeName, groups] of trees) {
    for (const [groupLabel, items] of groups) {
      const game = gameByName.get(groupLabel) ?? null;
      for (const label of [groupLabel, ...items]) {
        labels++;
        for (const hit of scan(label, game)) {
          fail(
            `src/config/sidebar.mjs ${treeName} → ${groupLabel}`,
            `"${label}" uses "${hit.value}", ${gameName(hit.term.game)} vocabulary, ${game ? `in the ${gameName(game)} group` : 'in a core group'}`,
          );
        }
      }
    }
  }

  return `${files} docs pages and ${labels} sidebar labels use only their own game's words`;
}

// ═══ The built pass ════════════════════════════════════════════════════════════════════

const DIST = path.join(ROOT, 'dist', 'client');

/** `dist/client/a/b/index.html` → `/a/b/`; `dist/client/404.html` → `/404`. */
function routeOf(file) {
  const rel = path.relative(DIST, file).split(path.sep).join('/');
  if (rel === 'index.html') return '/';
  if (rel.endsWith('/index.html')) return `/${rel.slice(0, -'index.html'.length)}`;
  return `/${rel.replace(/\.html$/, '')}`;
}

function gameOfRoute(route) {
  for (const [game, prefixes] of Object.entries(GAME_ROUTES)) {
    if (prefixes.some((p) => route.startsWith(p))) return game;
  }
  return null;
}

/**
 * Where the element opening at `start` closes, counting nested elements of the same name.
 * Astro's output is well formed, which is what makes this enough without a parser.
 */
function elementEnd(html, start, tag) {
  const re = new RegExp(`<(/?)${tag}\\b[^>]*?(/?)>`, 'gi');
  re.lastIndex = start;
  let depth = 0;
  for (let m = re.exec(html); m; m = re.exec(html)) {
    if (m[2] === '/') continue; // self-closing
    depth += m[1] === '/' ? -1 : 1;
    if (depth === 0) return re.lastIndex;
  }
  return html.length;
}

/** Every element whose opening tag matches `openRe`, as `{ start, end, match }`. */
function elements(html, openRe) {
  const found = [];
  for (const m of html.matchAll(openRe)) {
    const tag = /^<([a-z0-9-]+)/i.exec(m[0])[1];
    found.push({ start: m.index, end: elementEnd(html, m.index, tag), match: m });
  }
  return found;
}

const ENTITIES = { amp: '&', lt: '<', gt: '>', quot: '"', apos: "'", nbsp: ' ', rsquo: '’', lsquo: '‘', ldquo: '“', rdquo: '”', mdash: '—', ndash: '–', hellip: '…', rarr: '→', middot: '·' };
const decode = (s) =>
  s.replace(/&(#x[0-9a-f]+|#\d+|[a-z]+);/gi, (m, e) => {
    if (e[0] === '#') return String.fromCodePoint(e[1] === 'x' || e[1] === 'X' ? parseInt(e.slice(2), 16) : Number(e.slice(1)));
    return ENTITIES[e.toLowerCase()] ?? m;
  });

/**
 * Elements whose text runs on into the next word with no space between: a word split across
 * two `<span>`s by a syntax highlighter is still one word to a reader. Everything else is a
 * boundary, so `<h3>Guilds</h3><p>Guild…` does not read as "GuildsGuild".
 */
const INLINE = /^(?:a|abbr|b|bdi|bdo|cite|code|data|dfn|em|i|kbd|mark|q|s|samp|small|span|strong|sub|sup|time|u|var|wbr)$/i;

/** The words a reader sees in a piece of HTML: its text, and the attributes that are read aloud or shown. */
function visibleText(html) {
  const attrs = [];
  for (const m of html.matchAll(/\s(?:alt|title|aria-label|placeholder)="([^"]*)"/gi)) attrs.push(m[1]);
  let text = html.replace(/<\/?([a-z][a-z0-9-]*)\b[^>]*>/gi, (_, tag) => (INLINE.test(tag) ? '' : ' '));
  text = decode([text, ...attrs.map(decode)].join(' \n '));
  text = text.replace(/\bhttps?:\/\/\S+/g, ' '); // bare URLs
  text = text.replace(/(^|[\s(“"'])\/[\w./#?=&%-]+/g, '$1 '); // bare paths — an address, not prose
  return text.replace(/\s+/g, ' ');
}

function snippet(text, index, length) {
  const from = Math.max(0, index - 50);
  const to = Math.min(text.length, index + length + 50);
  return `${from > 0 ? '…' : ''}${text.slice(from, to).trim()}${to < text.length ? '…' : ''}`;
}

async function builtPass() {
  if (!existsSync(DIST)) {
    console.error('checkTerms --built: dist/client does not exist. Run `npm run build` first.');
    process.exit(1);
  }

  let pages = 0;
  let regionsSeen = 0;
  const allowUsed = new Set();

  for await (const file of walk(DIST, /\.html$/)) {
    const route = routeOf(file);
    let html = readFileSync(file, 'utf8');
    pages++;

    // The head: only the parts a reader sees, in a tab or a search result.
    const head = /<head\b[\s\S]*?<\/head>/i.exec(html)?.[0] ?? '';
    const headText = [/<title>([\s\S]*?)<\/title>/i.exec(head)?.[1] ?? '', /<meta\s+name="description"\s+content="([^"]*)"/i.exec(head)?.[1] ?? ''].join(' \n ');
    html = html.replace(/<head\b[\s\S]*?<\/head>/i, ' ');

    html = html.replace(/<(script|style|template|noscript)\b[\s\S]*?<\/\1>/gi, ' ');
    html = html.replace(/<!--[\s\S]*?-->/g, ' ');

    // Checked elsewhere (see the header): Starlight's sidebar and its previous/next links.
    for (const skip of [/<nav\b[^>]*\baria-label="Main"[^>]*>/gi, /<div\b[^>]*\bclass="pagination-links\b[^>]*>/gi]) {
      for (const el of elements(html, skip).reverse()) html = html.slice(0, el.start) + ' ' + html.slice(el.end);
    }

    const pageGame = gameOfRoute(route);
    const pieces = [{ text: decode(headText), allowed: pageGame, where: 'in the page title or description' }];

    // Regions marked with a game. Read with that game's words allowed, then cut out.
    for (const el of elements(html, /<[a-z][a-z0-9-]*\b[^>]*\bdata-game="([^"]*)"[^>]*>/gi).reverse()) {
      const game = el.match[1];
      regionsSeen++;
      if (!platform.games[game]) {
        fail(route, `an element is marked data-game="${game}", which platform.json does not have`);
        continue;
      }
      pieces.push({ text: visibleText(html.slice(el.start, el.end)), allowed: game, also: pageGame, where: `inside a block marked ${gameName(game)}` });
      html = html.slice(0, el.start) + ' ' + html.slice(el.end);
    }
    pieces.push({ text: visibleText(html), allowed: pageGame, where: pageGame ? `on a ${gameName(pageGame)} page` : 'on a core page' });

    for (const piece of pieces) {
      let { text } = piece;
      for (const [i, entry] of ALLOW.entries()) {
        if (entry.route !== route || !text.includes(entry.text)) continue;
        allowUsed.add(i);
        text = text.split(entry.text).join(' '.repeat(entry.text.length));
      }
      for (const hit of scan(text, piece.allowed)) {
        if (piece.also && hit.term.game === piece.also) continue;
        fail(route, `"${hit.value}" is ${gameName(hit.term.game)} vocabulary, ${piece.where}\n        ${snippet(text, hit.index, hit.value.length)}`);
      }
    }
  }

  for (const [i, entry] of ALLOW.entries()) {
    if (!allowUsed.has(i)) fail(`allowlist: ${entry.route}`, `"${entry.text}" no longer appears in the built page — remove the entry`);
  }

  return `${pages} built pages use only their own game's words (${regionsSeen} game-marked blocks read with their game's words allowed)`;
}

// ═══ Report ════════════════════════════════════════════════════════════════════════════

const summary = BUILT ? await builtPass() : await sourcePass();

if (failures.length === 0) {
  console.log(`checkTerms${BUILT ? ' --built' : ''}: ${summary} (${TERMS.length} terms, ${ALLOW.length} allowlisted phrase${ALLOW.length === 1 ? '' : 's'}).`);
} else {
  console.error(`\ncheckTerms${BUILT ? ' --built' : ''}: ${failures.length} game word(s) outside their game's section:\n`);
  for (const f of failures) console.error(`  ✗ ${f.where}\n      ${f.detail}`);
  console.error(`
PLAN.md §16, D63: name the games anywhere, but keep their vocabulary in their own section.
Use core's word instead — a Team, a game server, the sidecar, the bridge plugin, the game
module. A marketing page describes what a game module adds in core's words and links to
the game's own page (D75). If a docs page genuinely needs a game's real example, wrap it in
<GameExample game="…"> (D68); a screenshot of a game screen carries its game tag (D67).
Add to the allowlist in this script only for a word that is not a game's at all, and say why.
`);
  process.exit(1);
}