export type ThemeMode = 'dark' | 'light';
export type InterfaceLanguage = 'english' | 'spanish' | 'french' | 'german';
export type FontSizePreference = 'small' | 'medium' | 'large';

export type DeliveryAddress = {
  fullName: string;
  phone: string;
  street: string;
  city: string;
  state: string;
  pincode: string;
  country: string;
};

export type UserPreferences = {
  themeMode: ThemeMode;
  language: InterfaceLanguage;
  fontSize: FontSizePreference;
  emailNotifications: boolean;
  pushNotifications: boolean;
  soundEnabled: boolean;
  autoSave: boolean;
  twoFactorEnabled: boolean;
  twoFactorCode: string;
  dataAnalytics: boolean;
  address: DeliveryAddress;
  updatedAt: string;
};

type ImportedPreferencesPayload = Partial<UserPreferences> & {
  version?: number;
  exportedAt?: string;
};

export type AnalyticsEvent = {
  type: string;
  createdAt: string;
  payload?: Record<string, string | number | boolean | null>;
};

const PREFERENCES_STORAGE_PREFIX = 'ryp_preferences';
const ANALYTICS_STORAGE_PREFIX = 'ryp_analytics';
const LEGACY_ADDRESS_KEY = 'cq_delivery_address';
const LEGACY_KEYS = {
  emailNotifications: 'emailNotifications',
  pushNotifications: 'pushNotifications',
  soundEnabled: 'soundEnabled',
  autoSave: 'autoSave',
  twoFactorEnabled: 'twoFactorEnabled',
  dataAnalytics: 'dataAnalytics',
  language: 'language',
  fontSize: 'fontSize',
  themeMode: 'theme_mode',
} as const;

export const SETTINGS_EXPORT_VERSION = 1;
export const EMPTY_ADDRESS: DeliveryAddress = {
  fullName: '',
  phone: '',
  street: '',
  city: '',
  state: '',
  pincode: '',
  country: 'India',
};

export function createDefaultPreferences(themeMode: ThemeMode = 'dark'): UserPreferences {
  return {
    themeMode,
    language: 'english',
    fontSize: 'medium',
    emailNotifications: true,
    pushNotifications: true,
    soundEnabled: true,
    autoSave: true,
    twoFactorEnabled: false,
    twoFactorCode: '',
    dataAnalytics: true,
    address: { ...EMPTY_ADDRESS },
    updatedAt: new Date().toISOString(),
  };
}

function preferencesStorageKey(userId: string) {
  return `${PREFERENCES_STORAGE_PREFIX}_${userId}`;
}

function analyticsStorageKey(userId: string) {
  return `${ANALYTICS_STORAGE_PREFIX}_${userId}`;
}

export function userScopedStorageKey(scope: string, userId: string) {
  return `ryp_${scope}_${userId}`;
}

function isPlainObject(value: unknown): value is Record<string, unknown> {
  return Boolean(value) && typeof value === 'object' && !Array.isArray(value);
}

function normalizeBoolean(value: unknown, fallback: boolean) {
  return typeof value === 'boolean' ? value : fallback;
}

function normalizeThemeMode(value: unknown, fallback: ThemeMode): ThemeMode {
  return value === 'light' || value === 'dark' ? value : fallback;
}

function normalizeLanguage(value: unknown, fallback: InterfaceLanguage): InterfaceLanguage {
  return value === 'english' || value === 'spanish' || value === 'french' || value === 'german'
    ? value
    : fallback;
}

function normalizeFontSize(value: unknown, fallback: FontSizePreference): FontSizePreference {
  return value === 'small' || value === 'medium' || value === 'large' ? value : fallback;
}

export function normalizeAddress(value: unknown): DeliveryAddress {
  if (!isPlainObject(value)) {
    return { ...EMPTY_ADDRESS };
  }

  return {
    fullName: typeof value.fullName === 'string' ? value.fullName : '',
    phone: typeof value.phone === 'string' ? value.phone : '',
    street: typeof value.street === 'string' ? value.street : '',
    city: typeof value.city === 'string' ? value.city : '',
    state: typeof value.state === 'string' ? value.state : '',
    pincode: typeof value.pincode === 'string' ? value.pincode : '',
    country: typeof value.country === 'string' && value.country.trim() ? value.country : EMPTY_ADDRESS.country,
  };
}

export function normalizePreferences(
  value: unknown,
  fallbackThemeMode: ThemeMode = 'dark',
): UserPreferences {
  const defaults = createDefaultPreferences(fallbackThemeMode);
  if (!isPlainObject(value)) {
    return defaults;
  }

  const twoFactorEnabled = normalizeBoolean(value.twoFactorEnabled, defaults.twoFactorEnabled);
  const twoFactorCode = typeof value.twoFactorCode === 'string' ? value.twoFactorCode.trim() : '';

  return {
    themeMode: normalizeThemeMode(value.themeMode, defaults.themeMode),
    language: normalizeLanguage(value.language, defaults.language),
    fontSize: normalizeFontSize(value.fontSize, defaults.fontSize),
    emailNotifications: normalizeBoolean(value.emailNotifications, defaults.emailNotifications),
    pushNotifications: normalizeBoolean(value.pushNotifications, defaults.pushNotifications),
    soundEnabled: normalizeBoolean(value.soundEnabled, defaults.soundEnabled),
    autoSave: normalizeBoolean(value.autoSave, defaults.autoSave),
    twoFactorEnabled: twoFactorEnabled && twoFactorCode.length >= 6,
    twoFactorCode,
    dataAnalytics: normalizeBoolean(value.dataAnalytics, defaults.dataAnalytics),
    address: normalizeAddress(value.address),
    updatedAt: typeof value.updatedAt === 'string' && value.updatedAt.trim()
      ? value.updatedAt
      : defaults.updatedAt,
  };
}

function readJson<T>(key: string): T | null {
  if (typeof window === 'undefined') {
    return null;
  }

  const raw = window.localStorage.getItem(key);
  if (!raw) {
    return null;
  }

  try {
    return JSON.parse(raw) as T;
  } catch {
    return null;
  }
}

function writeJson(key: string, value: unknown) {
  if (typeof window === 'undefined') {
    return;
  }

  window.localStorage.setItem(key, JSON.stringify(value));
}

function removeValue(key: string) {
  if (typeof window === 'undefined') {
    return;
  }

  window.localStorage.removeItem(key);
}

function readLegacyPreferences(themeMode: ThemeMode): UserPreferences {
  if (typeof window === 'undefined') {
    return createDefaultPreferences(themeMode);
  }

  const defaults = createDefaultPreferences(themeMode);
  const legacyAddress = normalizeAddress(readJson<DeliveryAddress>(LEGACY_ADDRESS_KEY));

  return {
    ...defaults,
    themeMode: normalizeThemeMode(window.localStorage.getItem(LEGACY_KEYS.themeMode), defaults.themeMode),
    language: normalizeLanguage(window.localStorage.getItem(LEGACY_KEYS.language), defaults.language),
    fontSize: normalizeFontSize(window.localStorage.getItem(LEGACY_KEYS.fontSize), defaults.fontSize),
    emailNotifications: window.localStorage.getItem(LEGACY_KEYS.emailNotifications) !== 'false',
    pushNotifications: window.localStorage.getItem(LEGACY_KEYS.pushNotifications) !== 'false',
    soundEnabled: window.localStorage.getItem(LEGACY_KEYS.soundEnabled) !== 'false',
    autoSave: window.localStorage.getItem(LEGACY_KEYS.autoSave) !== 'false',
    twoFactorEnabled: window.localStorage.getItem(LEGACY_KEYS.twoFactorEnabled) === 'true',
    dataAnalytics: window.localStorage.getItem(LEGACY_KEYS.dataAnalytics) !== 'false',
    address: legacyAddress,
  };
}

function clearLegacySettings() {
  if (typeof window === 'undefined') {
    return;
  }

  Object.values(LEGACY_KEYS).forEach((key) => {
    window.localStorage.removeItem(key);
  });
  window.localStorage.removeItem(LEGACY_ADDRESS_KEY);
}

export function loadUserPreferences(userId: string, fallbackThemeMode: ThemeMode = 'dark') {
  const stored = readJson<ImportedPreferencesPayload>(preferencesStorageKey(userId));
  if (stored) {
    return normalizePreferences(stored, fallbackThemeMode);
  }

  const migrated = readLegacyPreferences(fallbackThemeMode);
  saveUserPreferences(userId, migrated);
  clearLegacySettings();
  return migrated;
}

export function saveUserPreferences(userId: string, preferences: UserPreferences) {
  const normalized = normalizePreferences(preferences, preferences.themeMode);
  normalized.updatedAt = new Date().toISOString();
  writeJson(preferencesStorageKey(userId), normalized);
  return normalized;
}

export function resetUserPreferences(userId: string, themeMode: ThemeMode = 'dark') {
  const defaults = createDefaultPreferences(themeMode);
  writeJson(preferencesStorageKey(userId), defaults);
  return defaults;
}

export function exportUserPreferences(preferences: UserPreferences) {
  return {
    version: SETTINGS_EXPORT_VERSION,
    exportedAt: new Date().toISOString(),
    ...preferences,
  };
}

export function parseImportedPreferences(
  rawText: string,
  fallbackThemeMode: ThemeMode = 'dark',
) {
  const parsed = JSON.parse(rawText) as ImportedPreferencesPayload;
  return normalizePreferences(parsed, fallbackThemeMode);
}

export function createTwoFactorCode() {
  return String(Math.floor(100000 + Math.random() * 900000));
}

export function fontSizeToRootRem(fontSize: FontSizePreference) {
  if (fontSize === 'small') {
    return '14px';
  }
  if (fontSize === 'large') {
    return '18px';
  }
  return '16px';
}

export function getCodeEditorFontSize(fontSize: FontSizePreference) {
  if (fontSize === 'small') {
    return 13;
  }
  if (fontSize === 'large') {
    return 17;
  }
  return 15;
}

export function trackAnalyticsEvent(
  userId: string,
  enabled: boolean,
  type: string,
  payload?: Record<string, string | number | boolean | null>,
) {
  if (!enabled || typeof window === 'undefined') {
    return;
  }

  const current = readJson<AnalyticsEvent[]>(analyticsStorageKey(userId)) ?? [];
  const next = [
    {
      type,
      payload,
      createdAt: new Date().toISOString(),
    },
    ...current,
  ].slice(0, 50);

  writeJson(analyticsStorageKey(userId), next);
}

export function loadAnalyticsEvents(userId: string) {
  return readJson<AnalyticsEvent[]>(analyticsStorageKey(userId)) ?? [];
}

export function clearAnalyticsEvents(userId: string) {
  removeValue(analyticsStorageKey(userId));
}

export function saveUserScopedJson(scope: string, userId: string, value: unknown) {
  writeJson(userScopedStorageKey(scope, userId), value);
}

export function loadUserScopedJson<T>(scope: string, userId: string) {
  return readJson<T>(userScopedStorageKey(scope, userId));
}

export function removeUserScopedJson(scope: string, userId: string) {
  removeValue(userScopedStorageKey(scope, userId));
}

export async function requestBrowserNotificationPermission() {
  if (typeof window === 'undefined' || !('Notification' in window)) {
    return 'unsupported' as const;
  }

  if (Notification.permission === 'granted') {
    return 'granted' as const;
  }

  if (Notification.permission === 'denied') {
    return 'denied' as const;
  }

  return Notification.requestPermission();
}

export function sendBrowserNotification(
  enabled: boolean,
  title: string,
  options?: NotificationOptions,
) {
  if (
    !enabled ||
    typeof window === 'undefined' ||
    !('Notification' in window) ||
    Notification.permission !== 'granted'
  ) {
    return;
  }

  try {
    const notification = new Notification(title, options);
    window.setTimeout(() => notification.close(), 5000);
  } catch {
    // Ignore browser notification failures.
  }
}

export function playUiSound(enabled: boolean, variant: 'success' | 'error' | 'soft' = 'soft') {
  if (!enabled || typeof window === 'undefined') {
    return;
  }

  const AudioCtor = window.AudioContext || (window as typeof window & { webkitAudioContext?: typeof AudioContext }).webkitAudioContext;
  if (!AudioCtor) {
    return;
  }

  const context = new AudioCtor();
  const oscillator = context.createOscillator();
  const gain = context.createGain();
  const now = context.currentTime;

  oscillator.type = variant === 'error' ? 'sawtooth' : 'sine';
  oscillator.frequency.setValueAtTime(variant === 'error' ? 220 : variant === 'success' ? 660 : 440, now);
  gain.gain.setValueAtTime(0.0001, now);
  gain.gain.exponentialRampToValueAtTime(0.05, now + 0.02);
  gain.gain.exponentialRampToValueAtTime(0.0001, now + (variant === 'soft' ? 0.12 : 0.18));

  oscillator.connect(gain);
  gain.connect(context.destination);
  oscillator.start(now);
  oscillator.stop(now + (variant === 'soft' ? 0.12 : 0.18));
  window.setTimeout(() => {
    void context.close().catch(() => undefined);
  }, variant === 'soft' ? 180 : 260);
}