'use client';

import { useState, useEffect, useCallback, useMemo } from 'react';
import type {
  UseTranslationConfigReturn,
  Language,
  TranslationMode,
  Provider,
  TranslationConfig,
  AvailableProvider,
} from './types';
import { API_BASE } from '@/lib/config';
import { useTranslationStore } from '@/lib/store';

/** Fallback when API fails — Google is always available server-side */
const FALLBACK_PROVIDERS: AvailableProvider[] = [
  { id: 'google', label: 'Google Traduction', description: 'Traduction rapide, 130+ langues', mode: 'classic' },
];

const FALLBACK_LANGUAGES: Language[] = [
  // Top 5 — dominant on the internet
  { code: 'en', name: 'English' },
  { code: 'es', name: 'Spanish' },
  { code: 'de', name: 'German' },
  { code: 'fr', name: 'French' },
  { code: 'ja', name: 'Japanese' },
  // Top 6-15
  { code: 'pt', name: 'Portuguese' },
  { code: 'ru', name: 'Russian' },
  { code: 'it', name: 'Italian' },
  { code: 'zh-CN', name: 'Chinese (Simplified)' },
  { code: 'zh-TW', name: 'Chinese (Traditional)' },
  { code: 'pl', name: 'Polish' },
  { code: 'nl', name: 'Dutch' },
  { code: 'tr', name: 'Turkish' },
  { code: 'ko', name: 'Korean' },
  { code: 'ar', name: 'Arabic' },
  // Top 16-25
  { code: 'fa', name: 'Persian (Farsi)' },
  { code: 'vi', name: 'Vietnamese' },
  { code: 'id', name: 'Indonesian' },
  { code: 'uk', name: 'Ukrainian' },
  { code: 'sv', name: 'Swedish' },
  { code: 'cs', name: 'Czech' },
  { code: 'el', name: 'Greek' },
  { code: 'he', name: 'Hebrew' },
  { code: 'hi', name: 'Hindi' },
  { code: 'ro', name: 'Romanian' },
  // Others
  { code: 'da', name: 'Danish' },
  { code: 'fi', name: 'Finnish' },
  { code: 'no', name: 'Norwegian' },
  { code: 'hu', name: 'Hungarian' },
  { code: 'th', name: 'Thai' },
  { code: 'sk', name: 'Slovak' },
  { code: 'bg', name: 'Bulgarian' },
  { code: 'hr', name: 'Croatian' },
  { code: 'ca', name: 'Catalan' },
  { code: 'ms', name: 'Malay' },
];

export function useTranslationConfig(hasFile: boolean): UseTranslationConfigReturn {
  const { settings } = useTranslationStore();
  const [sourceLang, setSourceLang] = useState('auto');
  const [targetLang, setTargetLang] = useState(settings.defaultTargetLanguage || '');
  const [provider, setProvider] = useState<Provider | null>(null);
  const [glossaryId, setGlossaryId] = useState<string | null>(null);
  const [availableProviders, setAvailableProviders] = useState<AvailableProvider[]>([]);
  const [isLoadingProviders, setIsLoadingProviders] = useState(false);
  const [languages, setLanguages] = useState<Language[]>([]);
  const [isPro, setIsPro] = useState(false);
  const [isLoadingLanguages, setIsLoadingLanguages] = useState(false);
  const [languagesError, setLanguagesError] = useState<string | null>(null);

  // Sync with store default target language
  useEffect(() => {
    if (settings.defaultTargetLanguage && !targetLang) {
      setTargetLang(settings.defaultTargetLanguage);
    }
  }, [settings.defaultTargetLanguage]); // eslint-disable-line react-hooks/exhaustive-deps

  // Reset glossary selection when source language changes
  useEffect(() => {
    setGlossaryId(null);
  }, [sourceLang]); // eslint-disable-line react-hooks/exhaustive-deps

  // Fetch available (admin-configured) providers
  useEffect(() => {
    const controller = new AbortController();
    const timeoutId = setTimeout(() => controller.abort(), 8000);

    const fetchProviders = async () => {
      setIsLoadingProviders(true);
      try {
        const token = localStorage.getItem('token');
        const headers: Record<string, string> = {};
        if (token) headers['Authorization'] = `Bearer ${token}`;

        const response = await fetch(`${API_BASE}/api/v1/providers/available`, {
          headers,
          signal: controller.signal,
        });
        if (response.ok) {
          const data = await response.json();
          const list = data.providers || [];
          setAvailableProviders(list.length > 0 ? list : FALLBACK_PROVIDERS);
        } else {
          setAvailableProviders(FALLBACK_PROVIDERS);
        }
      } catch {
        // Backend down or timeout — use fallback so user can still try
        setAvailableProviders(FALLBACK_PROVIDERS);
      } finally {
        clearTimeout(timeoutId);
        setIsLoadingProviders(false);
      }
    };

    fetchProviders();
    return () => { controller.abort(); clearTimeout(timeoutId); };
  }, []);

  // Auto-select first classic provider for non-Pro users
  useEffect(() => {
    if (isLoadingProviders) return;
    if (provider !== null) return;
    if (isPro) return;
    if (availableProviders.length === 0) return;
    const firstClassic = availableProviders.find((p) => p.mode === 'classic');
    if (firstClassic) setProvider(firstClassic.id);
  }, [availableProviders, isLoadingProviders, isPro, provider]);

  // Fetch supported languages
  useEffect(() => {
    const controller = new AbortController();
    const timeoutId = setTimeout(() => controller.abort(), 8000);

    const fetchLanguages = async () => {
      setIsLoadingLanguages(true);
      setLanguagesError(null);
      try {
        const token = localStorage.getItem('token');
        const headers: Record<string, string> = { 'Content-Type': 'application/json' };
        if (token) headers['Authorization'] = `Bearer ${token}`;

        const response = await fetch(`${API_BASE}/api/v1/languages`, {
          headers,
          signal: controller.signal,
        });
        if (!response.ok) throw new Error(`HTTP error! status: ${response.status}`);
        const data = await response.json();
        const langList: Language[] = Object.entries(data.supported_languages || {}).map(
          ([code, name]) => ({ code, name: name as string })
        );
        setLanguages(langList.length > 0 ? langList : FALLBACK_LANGUAGES);
      } catch (error) {
        if (error instanceof DOMException && error.name === 'AbortError') {
          console.warn('Language fetch timed out, using fallback list');
        } else {
          setLanguagesError(error instanceof Error ? error.message : 'Failed to load languages');
        }
        setLanguages(FALLBACK_LANGUAGES);
      } finally {
        clearTimeout(timeoutId);
        setIsLoadingLanguages(false);
      }
    };

    fetchLanguages();
    return () => { controller.abort(); clearTimeout(timeoutId); };
  }, []);

  // Check user tier
  useEffect(() => {
    const checkTier = async () => {
      const isProTier = (u: any) => ['pro', 'business', 'enterprise'].includes(u?.plan ?? u?.tier ?? '');
      const userStr = localStorage.getItem('user');
      if (userStr) {
        try {
          const user = JSON.parse(userStr);
          if (user?.plan || user?.tier) { setIsPro(isProTier(user)); }
        } catch { /* continue */ }
      }
      try {
        const token = localStorage.getItem('token');
        if (!token) { setIsPro(false); return; }
        const response = await fetch(`${API_BASE}/api/v1/auth/me`, {
          headers: { 'Authorization': `Bearer ${token}` },
        });
        if (response.ok) {
          const result = await response.json();
          const user = result.data;
          setIsPro(isProTier(user));
          localStorage.setItem('user', JSON.stringify(user));
        } else {
          setIsPro(false);
        }
      } catch { setIsPro(false); }
    };
    checkTier();
  }, []);

  // Mode is derived from the selected provider, never set manually.
  const mode = useMemo<TranslationMode>(() => {
    if (!provider) return 'classic';
    const p = availableProviders.find((ap) => ap.id === provider);
    return p?.mode === 'llm' ? 'llm' : 'classic';
  }, [provider, availableProviders]);

  const isConfigValid = useMemo(() => {
    if (!hasFile || !targetLang) return false;
    if (!provider) return false;
    return true;
  }, [hasFile, targetLang, provider]);

  const getConfig = useCallback((): TranslationConfig => ({
    sourceLang,
    targetLang,
    mode,
    provider: provider ?? undefined,
    glossaryId,
  }), [sourceLang, targetLang, mode, provider, glossaryId]);

  return {
    sourceLang,
    targetLang,
    mode,
    provider,
    availableProviders,
    isLoadingProviders,
    languages,
    isPro,
    isConfigValid,
    isLoadingLanguages,
    languagesError,
    setSourceLang,
    setTargetLang,
    setProvider,
    glossaryId,
    setGlossaryId,
    getConfig,
  };
}