export type Language = 'en' | 'da';

export const languageOptions: { id: Language; label: string }[] = [
  { id: 'en', label: 'English' },
  { id: 'da', label: 'Dansk' },
];

export interface Chrome {
  subtitle: string;
  title: string;
  documentTitle: string;
  metaDescription: string;
  home: string;
  collection: string;
  language: string;
  test: string;
  experiments: string;
  overview: string;
  overviewTitle: string;
  overviewText: string;
  score: string;
  subjects: string;
  lessons: string;
  reset: string;
  original: string;
  parameters: string;
  measurements: string;
  camera: string;
  pause: string;
  resume: string;
  hint: string;
  notice: string;
  connect: string;
  physics: string;
  learn: string;
  try: string;
  scales: string;
  build: string;
  reasoning: string;
  originalAnswers: string;
  predict: string;
  reveal: string;
  hide: string;
  navigation: string;
  previous: string;
  next: string;
  view: string;
  viewport: string;
  study: string;
  canvas: string;
  webglStart: string;
  webglLost: string;
  experimentKicker: (index: number, total: number) => string;
  questionKicker: (section: string, question: number, points: number) => string;
}

const pad = (value: number) => String(value).padStart(2, '0');

const chrome: Record<Language, Chrome> = {
  en: {
    subtitle: 'Explore the invisible. Understand the physical.',
    title: 'Electrotechnique & Electrophysics',
    documentTitle: 'Test 4 in 3D · Electrophysics Lab',
    metaDescription: 'Learn electric work, potential energy and dipole rotation through six interactive 3D lessons from Test 4.',
    home: 'Field Lab home',
    collection: 'Learning collection',
    language: 'Language',
    test: 'Test 4 in 3D',
    experiments: 'All experiments',
    overview: 'FROM EQUATIONS TO INTUITION',
    overviewTitle: 'Electric energy, made visible.',
    overviewText: 'Explore the six questions from Test 4. Change the scene, make a prediction, then follow the derivation.',
    score: '6 questions · 3D study guide',
    subjects: 'Electrophysics subjects',
    lessons: 'Lessons',
    reset: 'Reset experiment',
    original: 'Original test question',
    parameters: 'Experiment parameters',
    measurements: 'Live measurements',
    camera: 'Reset camera',
    pause: 'Pause animation',
    resume: 'Resume animation',
    hint: 'Drag to orbit · Scroll to zoom · Right-drag to pan · Arrow keys to pan when focused',
    notice: 'NOTICE WHAT CHANGES',
    connect: 'Connect the scene to the answer',
    physics: 'THE PHYSICS',
    learn: 'Learn the physics',
    try: 'TRY THIS',
    scales: 'Model & visual scales',
    build: 'BUILD YOUR ANSWER',
    reasoning: 'Follow the reasoning',
    originalAnswers: 'Original answers ↗',
    predict: 'PAUSE & PREDICT',
    reveal: 'Reveal explanation',
    hide: 'Hide explanation',
    navigation: 'Question navigation',
    previous: '← Previous question',
    next: 'Next question →',
    view: '3D VIEW',
    viewport: '3D workbench',
    study: 'Test answers and prediction',
    canvas: '3D experiment: drag to orbit, scroll to zoom, right-drag to pan',
    webglStart: 'WebGL could not start. Enable browser hardware acceleration and reload to see the 3D scenes. Lessons, controls and measurements still work.',
    webglLost: 'WebGL context lost. Reload to restore the 3D view. Numeric experiments still work.',
    experimentKicker: (index, total) => `EXPERIMENT ${pad(index)} / ${pad(total)}`,
    questionKicker: (section, question, points) => `TEST ${section} · QUESTION ${question} · ${points} POINTS`,
  },
  da: {
    subtitle: 'Udforsk det usynlige. Forstå fysikken.',
    title: 'Elektroteknik og elektrofysik',
    documentTitle: 'Test 4 i 3D · Elektrofysiklaboratoriet',
    metaDescription: 'Lær elektrisk arbejde, potentiel energi og dipolrotation gennem seks interaktive 3D-lektioner fra Test 4.',
    home: 'Feltlaboratoriets forside',
    collection: 'Læringssamling',
    language: 'Sprog',
    test: 'Test 4 i 3D',
    experiments: 'Alle eksperimenter',
    overview: 'FRA LIGNINGER TIL INTUITION',
    overviewTitle: 'Elektrisk energi gjort synlig.',
    overviewText: 'Udforsk de seks spørgsmål fra Test 4. Ændr scenen, forudsig resultatet, og følg derefter udledningen.',
    score: '6 spørgsmål · 3D-studievejledning',
    subjects: 'Elektrofysikkens emner',
    lessons: 'Lektioner',
    reset: 'Nulstil eksperiment',
    original: 'Oprindeligt eksamensspørgsmål',
    parameters: 'Eksperimentparametre',
    measurements: 'Målinger i realtid',
    camera: 'Nulstil kamera',
    pause: 'Sæt animation på pause',
    resume: 'Genoptag animation',
    hint: 'Træk for at dreje · Rul for at zoome · Højreklik og træk for at panorere · Piletaster panorerer, når feltet er valgt',
    notice: 'BEMÆRK, HVAD DER ÆNDRER SIG',
    connect: 'Forbind scenen med svaret',
    physics: 'FYSIKKEN',
    learn: 'Lær fysikken',
    try: 'PRØV DETTE',
    scales: 'Model- og visuelle skalaer',
    build: 'BYG DIT SVAR',
    reasoning: 'Følg ræsonnementet',
    originalAnswers: 'Oprindelige svar ↗',
    predict: 'PAUSE OG FORUDSIG',
    reveal: 'Vis forklaring',
    hide: 'Skjul forklaring',
    navigation: 'Spørgsmålsnavigation',
    previous: '← Forrige spørgsmål',
    next: 'Næste spørgsmål →',
    view: '3D-VISNING',
    viewport: '3D-arbejdsbord',
    study: 'Prøvesvar og forudsigelse',
    canvas: '3D-eksperiment: træk for at dreje, rul for at zoome, højreklik og træk for at panorere',
    webglStart: 'WebGL kunne ikke starte. Slå browserens hardwareacceleration til, og genindlæs for at se 3D-scenerne. Lektioner, betjening og målinger virker stadig.',
    webglLost: 'WebGL-konteksten gik tabt. Genindlæs for at gendanne 3D-visningen. De numeriske eksperimenter virker stadig.',
    experimentKicker: (index, total) => `EKSPERIMENT ${pad(index)} / ${pad(total)}`,
    questionKicker: (section, question, points) => `TEST ${section} · SPØRGSMÅL ${question} · ${points} POINT`,
  },
};

const scenePhrases = {
  en: {
    origin: 'Origin',
    onRightCharge: 'on right charge',
    gaussian: 'Gaussian surface',
    probe: 'Probe',
    isolated: 'isolated',
    connected: 'supply connected',
    noCurrent: 'No net current',
    conventional: 'Conventional current',
    drift: String.raw`Electron drift · displayed $\times600$`,
    conduction: 'Conduction band',
    valence: 'Valence band',
    midgap: 'midgap',
    gap: 'gap',
    energyConstant: 'Energy changes form · total stays constant',
  },
  da: {
    origin: 'Origo',
    onRightCharge: 'på højre ladning',
    gaussian: 'Gaussisk flade',
    probe: 'Sonde',
    isolated: 'isoleret',
    connected: 'forsyning tilsluttet',
    noCurrent: 'Ingen nettostrøm',
    conventional: 'Konventionel strøm',
    drift: String.raw`Elektrondrift · vist $\times600$`,
    conduction: 'Ledningsbånd',
    valence: 'Valensbånd',
    midgap: 'båndmidte',
    gap: 'gab',
    energyConstant: 'Energien skifter form · summen er konstant',
  },
} as const;

export type SceneKey = keyof typeof scenePhrases.en;

const words: Record<Language, Record<string, string>> = {
  en: {},
  da: {
    Repulsive: 'Frastødende',
    Attractive: 'Tiltrækkende',
    'On surface': 'På overfladen',
    Inside: 'Inden for',
    Outside: 'Uden for',
    Undefined: 'Udefineret',
    pairs: 'par',
  },
};

const measurementLabels: Record<Language, Record<string, string>> = {
  en: {},
  da: {
    '|E| at origin': '|E| i origo',
    '|Force on right charge|': '|Kraft på højre ladning|',
    Interaction: 'Vekselvirkning',
    'Net electric flux': 'Netto elektrisk flux',
    'Enclosed charge': 'Indesluttet ladning',
    'Source location': 'Kildens placering',
    'Interaction energy': 'Vekselvirkningsenergi',
    'Work by field, from 6 m': 'Feltets arbejde fra 6 m',
    '|Force on moving charge|': '|Kraft på den bevægelige ladning|',
    'Potential at probe': 'Potential ved sonden',
    'Ex at probe': 'Ex ved sonden',
    '|E| at probe': '|E| ved sonden',
    Capacitance: 'Kapacitans',
    'Stored free charge |Q|': 'Lagret fri ladning |Q|',
    'Electric field': 'Elektrisk felt',
    'Stored energy': 'Lagret energi',
    'Plate voltage': 'Pladespænding',
    'Free charge |Q|': 'Fri ladning |Q|',
    'Net field': 'Nettofelt',
    'Polarization |P|': 'Polarisering |P|',
    Resistance: 'Resistans',
    'Conventional current': 'Konventionel strøm',
    'Electron drift, x': 'Elektrondrift, x',
    'Dissipated power': 'Afgivet effekt',
    'Electron density n': 'Elektrontæthed n',
    'Hole density p': 'Hulletæthed p',
    'Conductivity σ': 'Ledningsevne σ',
    'Fermi shift EF − Ei': 'Forskydning af Fermi EF − Ei',
    'Field work a → b': 'Feltets arbejde a → b',
    'Work to current position': 'Arbejde til nuværende position',
    'Potential energy Uᵦ': 'Potentiel energi Uᵦ',
    'Potential energy U': 'Potentiel energi U',
    'Kinetic energy K': 'Kinetisk energi K',
    'Total K + U': 'Samlet K + U',
    'Particle speed': 'Partikelhastighed',
    'Potential energy Uₐ': 'Potentiel energi Uₐ',
    'Energy of current assembly': 'Energi af den aktuelle samling',
    'Three-charge energy U₁₂₃': 'Tre ladningers energi U₁₂₃',
    'Additional energy ΔU₀': 'Ekstra energi ΔU₀',
    'Pairs currently assembled': 'Par samlet nu',
    'Projection Δx': 'Projektion Δx',
    'Current angle θ': 'Aktuel vinkel θ',
    'Torque τz': 'Kraftmoment τz',
    'Work to current angle': 'Arbejde til aktuel vinkel',
  },
};

function storedLanguage(): Language {
  try {
    const stored = globalThis.localStorage?.getItem('language');
    if (stored === 'da' || stored === 'en') return stored;
  } catch {
    // Storage can be unavailable in private or non-browser contexts.
  }
  return 'en';
}

let language: Language = storedLanguage();
const listeners = new Set<() => void>();

export function getLanguage(): Language {
  return language;
}

export function setLanguage(next: Language) {
  language = next;
  try {
    localStorage.setItem('language', next);
  } catch {
    // Ignore storage failures; the in-memory choice still applies.
  }
  if (typeof document !== 'undefined') document.documentElement.lang = next;
  for (const listener of listeners) listener();
}

export function onLanguageChange(listener: () => void) {
  listeners.add(listener);
  return () => listeners.delete(listener);
}

export function t<K extends keyof Chrome>(key: K): Chrome[K] {
  return chrome[language][key];
}

export function scene(key: SceneKey): string {
  return scenePhrases[language][key];
}

export function word(english: string): string {
  return words[language][english] ?? english;
}

export function measurementLabel(english: string): string {
  return measurementLabels[language][english] ?? english;
}

export const daMeasurementLabels = measurementLabels.da;
export const daWords = words.da;