Oier Bravo Urtasun
378fcbe5f4
New $lib/utils/accept-language.ts parses Accept-Language strings
(server-style "es;q=0.9,en;q=0.8") and navigator.languages arrays,
returns 'en' or 'es'. Rule (plan §10.8.1): the highest-q-scored 'es'
entry wins if q >= 0.5; otherwise fall back to 'en'. Unknown
languages (e.g. fr) → 'en'. Pure function, 12 unit tests covering
bare tags, regional variants, q-score ordering, malformed input,
navigator.languages arrays, and the borderline q=0.5 case.
The root +layout.svelte calls maybeBootstrapLanguage() after each
SIGNED_IN: it only fires for genuinely new users (public.users row
created within the last 60s) whose language is still the default
('en'); it reads navigator.languages, runs the parser, and
UPDATEs public.users.language if the result is 'es'. setLanguageTag()
flips the live Paraglide runtime so the user lands on the next
page already in Spanish — no reload needed.
Established users keep their explicit choice (plan §10.8.5 / Riesgo
5). Server-side Accept-Language sniffing was rejected: the OIDC
dance lives outside SvelteKit (Keycloak ↔ GoTrue), so a hooks.server.ts
would never see those requests. navigator.languages is the
client-side equivalent and survives Paraglide's compile-time
tree-shaking.
LANG-01/02 (vitest integration): UPDATE public.users RLS contract
the bootstrap relies on — own row OK, other user's row rejected.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
89 lines
2.5 KiB
TypeScript
89 lines
2.5 KiB
TypeScript
/**
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* Detect the user's preferred app language from an Accept-Language header
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* (or navigator.languages array) — Fase 10.8.
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*
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* Supported app languages (in sync with messages/{en,es}.json + Paraglide
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* languageTags): `en`, `es`. Anything else falls back to `en`.
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*
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* Rules (per plan §10.8.1):
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* * Inputs we accept:
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* - bare tag: `'es'`, `'en'`, `'es-ES'`, `'en-US'`
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* - RFC 7231 list: `'es;q=0.9,en;q=0.8'`
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* - `navigator.languages` array: `['es-ES', 'en-GB']`
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* - null / undefined / empty → `'en'`
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* * If the highest q-scored entry whose primary subtag is `es` has
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* q ≥ 0.5, the result is `'es'`. Otherwise (including unknown
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* languages, malformed input, or no clear preference) → `'en'`.
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*/
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export type AppLanguage = 'en' | 'es';
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interface ParsedTag {
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tag: string;
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primary: string;
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q: number;
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}
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function parseTags(raw: string): ParsedTag[] {
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return raw
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.split(',')
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.map((part) => {
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const segments = part.trim().split(';').map((s) => s.trim());
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if (!segments[0]) return null;
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const tag = segments[0].toLowerCase();
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let q = 1.0;
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for (const seg of segments.slice(1)) {
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const match = seg.match(/^q\s*=\s*([0-9.]+)$/);
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if (match) {
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const parsed = parseFloat(match[1]);
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if (!Number.isNaN(parsed)) q = parsed;
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}
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}
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const primary = tag.split('-')[0];
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// Filter junk: primary must be alpha-only and 1+ chars.
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if (!/^[a-z]+$/.test(primary)) return null;
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return { tag, primary, q };
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})
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.filter((p): p is ParsedTag => p !== null);
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}
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export function detectLanguage(
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input: string | string[] | null | undefined
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): AppLanguage {
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if (input == null) return 'en';
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let parsed: ParsedTag[];
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if (Array.isArray(input)) {
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// navigator.languages: ordered by user preference, no q-scores.
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parsed = input
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.map((tag, index) => {
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const t = tag.toLowerCase().trim();
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if (!t) return null;
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const primary = t.split('-')[0];
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if (!/^[a-z]+$/.test(primary)) return null;
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// Synthesize a decreasing q-score so first-listed wins.
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return { tag: t, primary, q: 1 - index * 0.01 };
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})
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.filter((p): p is ParsedTag => p !== null);
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} else {
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const s = input.trim();
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if (!s) return 'en';
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parsed = parseTags(s);
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}
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if (parsed.length === 0) return 'en';
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// Sort by q-score descending.
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parsed.sort((a, b) => b.q - a.q);
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// First app-known primary wins; if it's es with q ≥ 0.5 → es.
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for (const p of parsed) {
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if (p.primary === 'es') {
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return p.q >= 0.5 ? 'es' : 'en';
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}
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if (p.primary === 'en') return 'en';
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}
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return 'en';
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}
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