import { useState, useCallback, useEffect } from 'react';
import toast from 'react-hot-toast';
import { useAuthenticatedFetch } from './useAuthenticatedFetch';
import type { UserPreferences } from '../types';
import { COLOR_SCHEMES } from '../types';

const LOCAL_API_KEYS_STORAGE = 'kaboot.apiKeys';

type LocalApiKeys = Pick<UserPreferences, 'geminiApiKey' | 'openRouterApiKey' | 'openAIApiKey'>;

const normalizeApiKey = (value: unknown): string | undefined => {
  if (typeof value !== 'string') return undefined;
  const trimmed = value.trim();
  return trimmed ? trimmed : undefined;
};

const readLocalApiKeys = (): LocalApiKeys => {
  if (typeof window === 'undefined') return {};
  try {
    const raw = window.localStorage.getItem(LOCAL_API_KEYS_STORAGE);
    if (!raw) return {};
    const parsed = JSON.parse(raw) as Record<string, unknown>;
    return {
      geminiApiKey: normalizeApiKey(parsed.geminiApiKey),
      openRouterApiKey: normalizeApiKey(parsed.openRouterApiKey),
      openAIApiKey: normalizeApiKey(parsed.openAIApiKey),
    };
  } catch {
    return {};
  }
};

const writeLocalApiKeys = (keys: LocalApiKeys) => {
  if (typeof window === 'undefined') return;
  const normalized = {
    geminiApiKey: normalizeApiKey(keys.geminiApiKey),
    openRouterApiKey: normalizeApiKey(keys.openRouterApiKey),
    openAIApiKey: normalizeApiKey(keys.openAIApiKey),
  };
  const hasAny = Boolean(
    normalized.geminiApiKey || normalized.openRouterApiKey || normalized.openAIApiKey
  );
  if (!hasAny) {
    window.localStorage.removeItem(LOCAL_API_KEYS_STORAGE);
    return;
  }
  window.localStorage.setItem(LOCAL_API_KEYS_STORAGE, JSON.stringify(normalized));
};

const mergePreferencesWithLocalKeys = (prefs: UserPreferences, localKeys: LocalApiKeys): UserPreferences => ({
  ...prefs,
  geminiApiKey: localKeys.geminiApiKey ?? prefs.geminiApiKey,
  openRouterApiKey: localKeys.openRouterApiKey ?? prefs.openRouterApiKey,
  openAIApiKey: localKeys.openAIApiKey ?? prefs.openAIApiKey,
});

const DEFAULT_PREFERENCES: UserPreferences = {
  colorScheme: 'blue',
  aiProvider: 'gemini',
};

export const applyColorScheme = (schemeId: string) => {
  const scheme = COLOR_SCHEMES.find(s => s.id === schemeId) || COLOR_SCHEMES[0];
  document.documentElement.style.setProperty('--theme-primary', scheme.primary);
  document.documentElement.style.setProperty('--theme-primary-dark', scheme.primaryDark);
  document.documentElement.style.setProperty('--theme-primary-darker', scheme.primaryDarker);
};

interface SubscriptionInfo {
  hasAccess: boolean;
  accessType: 'group' | 'subscription' | 'none';
  generationCount: number | null;
  generationLimit: number | null;
  generationsRemaining: number | null;
}

interface UseUserPreferencesReturn {
  preferences: UserPreferences;
  hasAIAccess: boolean;
  hasEarlyAccess: boolean;
  subscription: SubscriptionInfo | null;
  loading: boolean;
  saving: boolean;
  fetchPreferences: () => Promise<void>;
  savePreferences: (prefs: UserPreferences) => Promise<void>;
  applyColorScheme: (schemeId: string) => void;
}

export const useUserPreferences = (): UseUserPreferencesReturn => {
  const { authFetch, isAuthenticated } = useAuthenticatedFetch();
  const [preferences, setPreferences] = useState<UserPreferences>(DEFAULT_PREFERENCES);
  const [hasAIAccess, setHasAIAccess] = useState(false);
  const [hasEarlyAccess, setHasEarlyAccess] = useState(false);
  const [subscription, setSubscription] = useState<SubscriptionInfo | null>(null);
  const [loading, setLoading] = useState(false);
  const [saving, setSaving] = useState(false);

  const fetchPreferences = useCallback(async () => {
    if (!isAuthenticated) return;

    setLoading(true);
    try {
      const response = await authFetch('/api/users/me/preferences');
      if (response.ok) {
        const data = await response.json();
        const serverPrefs: UserPreferences = {
          colorScheme: data.colorScheme || 'blue',
          aiProvider: data.aiProvider || 'gemini',
          geminiApiKey: data.geminiApiKey || undefined,
          geminiModel: data.geminiModel || undefined,
          openRouterApiKey: data.openRouterApiKey || undefined,
          openRouterModel: data.openRouterModel || undefined,
          openAIApiKey: data.openAIApiKey || undefined,
          openAIModel: data.openAIModel || undefined,
        };
        const localKeys = readLocalApiKeys();
        const mergedPrefs = mergePreferencesWithLocalKeys(serverPrefs, localKeys);
        const mergedLocalKeys: LocalApiKeys = {
          geminiApiKey: localKeys.geminiApiKey ?? serverPrefs.geminiApiKey,
          openRouterApiKey: localKeys.openRouterApiKey ?? serverPrefs.openRouterApiKey,
          openAIApiKey: localKeys.openAIApiKey ?? serverPrefs.openAIApiKey,
        };
        writeLocalApiKeys(mergedLocalKeys);
        setPreferences(mergedPrefs);
        setHasAIAccess(data.hasAIAccess || false);
        setHasEarlyAccess(data.hasEarlyAccess || false);
        applyColorScheme(mergedPrefs.colorScheme);
        
        const backendUrl = import.meta.env.VITE_BACKEND_URL || 'http://localhost:3001';
        try {
          const subResponse = await authFetch(`${backendUrl}/api/payments/status`);
          if (subResponse.ok) {
            const subData = await subResponse.json();
            setSubscription({
              hasAccess: subData.hasAccess,
              accessType: subData.accessType,
              generationCount: subData.generationCount,
              generationLimit: subData.generationLimit,
              generationsRemaining: subData.generationsRemaining,
            });
          }
        } catch {
          // Payments not configured, ignore
        }
      }
    } catch {
    } finally {
      setLoading(false);
    }
  }, [authFetch, isAuthenticated]);

  const savePreferences = useCallback(async (prefs: UserPreferences) => {
    setSaving(true);
    try {
      const nextPrefs: UserPreferences = { ...preferences, ...prefs };
      const localKeys: LocalApiKeys = {
        geminiApiKey: nextPrefs.geminiApiKey,
        openRouterApiKey: nextPrefs.openRouterApiKey,
        openAIApiKey: nextPrefs.openAIApiKey,
      };
      writeLocalApiKeys(localKeys);

      const serverPrefs = {
        ...nextPrefs,
        geminiApiKey: undefined,
        openRouterApiKey: undefined,
        openAIApiKey: undefined,
      };

      const response = await authFetch('/api/users/me/preferences', {
        method: 'PUT',
        body: JSON.stringify(serverPrefs),
      });

      if (!response.ok) {
        throw new Error('Failed to save preferences');
      }

      const normalizedLocalKeys = readLocalApiKeys();
      const mergedPrefs = mergePreferencesWithLocalKeys(nextPrefs, normalizedLocalKeys);
      setPreferences(mergedPrefs);
      applyColorScheme(mergedPrefs.colorScheme);
      toast.success('Preferences saved!');
    } catch (err) {
      const message = err instanceof Error ? err.message : 'Failed to save preferences';
      toast.error(message);
      throw err;
    } finally {
      setSaving(false);
    }
  }, [authFetch, preferences]);

  useEffect(() => {
    fetchPreferences();
  }, [fetchPreferences]);

  return {
    preferences,
    hasAIAccess,
    hasEarlyAccess,
    subscription,
    loading,
    saving,
    fetchPreferences,
    savePreferences,
    applyColorScheme,
  };
};