import { useState, useEffect, useCallback, useRef } from 'react';
import { useLocalStorage } from '../useLocalStorage';
import * as bip39 from '@scure/bip39';
import { wordlist } from '@scure/bip39/wordlists/english';
import { initializeCoco, ConsoleLogger, getEncodedToken, type Repositories } from 'coco-cashu-core';
import { IndexedDbRepositories } from 'coco-cashu-indexeddb';
import type { Mint } from 'coco-cashu-core';

// Types from coco-cashu-core
type CocoManager = Awaited<ReturnType<typeof initializeCoco>>;

// Singleton pattern to prevent multiple initializations
let globalCocoInstance: CocoManager | null = null;
let globalRepositories: Repositories | null = null;
let globalInitializationPromise: Promise<{ coco: CocoManager; repositories: Repositories }> | null = null;

export interface UseCashuReturn {
  // The typed coco manager (direct library access)
  coco: CocoManager | null;
  
  // Repositories for direct access to proof data
  repositories: Repositories | null;
  
  // React state (for reactivity)
  balances: { [mintUrl: string]: number };
  mints: Array<{ url: string; name?: string; info?: unknown }>;
  totalBalance: number;
  
  // Status
  isInitialized: boolean;
  isLoading: boolean;
  error: Error | null;
  
  // Mnemonic management
  mnemonic: string | null;
  setMnemonic: (mnemonic: string) => void;
  generateMnemonic: () => string;
  
  // Utility functions
  clearError: () => void;
  getEncodedToken: typeof getEncodedToken;
  refreshMints: () => Promise<void>;
}

export function useCashu(): UseCashuReturn {
  const [isInitialized, setIsInitialized] = useState(false);
  const [isLoading, setIsLoading] = useState(false);
  const [error, setError] = useState<Error | null>(null);
  
  // Mnemonic management with localStorage
  const [mnemonic, setMnemonicState] = useLocalStorage<string | null>('cashu-mnemonic', null);
  
  // Manager instance ref
  const cocoRef = useRef<CocoManager | null>(null);
  const repositoriesRef = useRef<Repositories | null>(null);
  
  // React state for UI reactivity
  const [balances, setBalances] = useState<{ [mintUrl: string]: number }>({});
  const [mints, setMints] = useState<Array<{ url: string; name?: string; info?: unknown }>>([]);

  const clearError = useCallback(() => {
    setError(null);
  }, []);

  const generateMnemonic = useCallback(() => {
    return bip39.generateMnemonic(wordlist);
  }, []);

  const refreshMints = useCallback(async () => {
    const coco = cocoRef.current;
    if (!coco) return;
    
    try {
      // Only show trusted mints in the UI
      const mintList = await coco.mint.getAllTrustedMints();
      setMints(mintList.map((m: Mint) => ({ 
        url: m.mintUrl, 
        name: m.name,
        info: m.mintInfo
      })));
    } catch (err) {
      console.error('Failed to refresh mints:', err);
    }
  }, []);

  const setMnemonic = useCallback((newMnemonic: string) => {
    if (!bip39.validateMnemonic(newMnemonic, wordlist)) {
      throw new Error('Invalid mnemonic');
    }
    setMnemonicState(newMnemonic);
    // Reinitialize manager with new mnemonic
    setIsInitialized(false);
  }, [setMnemonicState]);

  // Initialize the coco manager
  const initializeCocoManager = useCallback(async () => {
    if (isInitialized || isLoading) return;
    
    setIsLoading(true);
    setError(null);
    
    try {
      // Use singleton pattern to prevent multiple initializations
      if (globalCocoInstance && globalRepositories) {
        cocoRef.current = globalCocoInstance;
        repositoriesRef.current = globalRepositories;
        setIsInitialized(true);
        setIsLoading(false);
        return;
      }
      
      // If there's already an initialization in progress, wait for it
      if (globalInitializationPromise) {
        console.log('[Cashu] Waiting for existing initialization...');
        const { coco, repositories } = await globalInitializationPromise;
        cocoRef.current = coco;
        repositoriesRef.current = repositories;
        setIsInitialized(true);
        setIsLoading(false);
        return;
      }
      
      // Generate or retrieve mnemonic
      let currentMnemonic = mnemonic;
      if (!currentMnemonic) {
        currentMnemonic = bip39.generateMnemonic(wordlist);
        setMnemonicState(currentMnemonic);
      }
      
      // Create seed from mnemonic
      const seed = bip39.mnemonicToSeedSync(currentMnemonic);
      
      // Initialize repositories with proper initialization
      const repo = new IndexedDbRepositories({ name: "cashu-wallet" });
      await repo.init();
      
      // Create initialization promise
      globalInitializationPromise = (async () => {
        const coco = await initializeCoco({
          repo,
          seedGetter: async () => seed,
          logger: new ConsoleLogger("coco", { level: "info" })
        });
        return { coco, repositories: repo };
      })();
      
      // Initialize coco manager
      const { coco, repositories } = await globalInitializationPromise;
      
      // Store as singleton
      console.log('[Cashu] Storing new coco instance as singleton');
      globalCocoInstance = coco;
      globalRepositories = repositories;
      globalInitializationPromise = null;
      cocoRef.current = coco;
      repositoriesRef.current = repositories;
      
      // Enable built-in services for automatic quote processing
      try {
        console.log('[Cashu] Enabling coco services...');
        await coco.enableMintQuoteWatcher({ watchExistingPendingOnStart: false });
        await coco.enableMintQuoteProcessor();
        await coco.enableProofStateWatcher();
        console.log('[Cashu] All coco services enabled successfully');
      } catch (err) {
        console.warn('[Cashu] Failed to enable some coco services:', err);
      }
      
      // Add default mint if no mints exist.
      // NOTE: the mint MUST send permissive CORS headers, otherwise the browser
      // blocks every request with a NetworkError ("Failed to fetch mint").
      // mint.minibits.cash does NOT set Access-Control-Allow-Origin, so it can't
      // be used directly from a browser — we default to a CORS-enabled mint.
      try {
        const DEFAULT_MINT_URL = 'https://mint.coinos.io';
        const existingMints = await coco.mint.getAllTrustedMints();
        const hasDefaultMint = existingMints.some((m: Mint) => 
          m.mintUrl.toLowerCase() === DEFAULT_MINT_URL.toLowerCase()
        );
        
        if (!hasDefaultMint && existingMints.length === 0) {
          console.log('[Cashu] Adding default mint:', DEFAULT_MINT_URL);
          await coco.mint.addMint(DEFAULT_MINT_URL, { trusted: true });
          console.log('[Cashu] Default mint added successfully');
        }
      } catch (err) {
        console.warn('[Cashu] Failed to add default mint:', err);
      }
      
      setIsInitialized(true);
    } catch (err) {
      const errorMessage = err instanceof Error ? err.message : 'Failed to initialize Cashu wallet';
      setError(new Error(errorMessage));
      globalInitializationPromise = null;
    } finally {
      setIsLoading(false);
    }
  }, [isInitialized, isLoading, mnemonic, setMnemonicState]);

  // Initialize on mount and when mnemonic changes
  useEffect(() => {
    initializeCocoManager();
  }, [initializeCocoManager]);

  // Auto-refresh balances and mints on manager events
  useEffect(() => {
    const coco = cocoRef.current;
    if (!coco) return;
    
    const refreshBalances = async () => {
      try {
        const newBalances = await coco.wallet.getBalances();
        setBalances(newBalances);
      } catch (err) {
        console.error('[Cashu] Failed to refresh balances:', err);
      }
    };
    
    // Initial load
    refreshBalances();
    refreshMints();
    
    // Listen to events
    const unsubs = [
      coco.on('proofs:saved', refreshBalances),
      coco.on('proofs:state-changed', refreshBalances),
      coco.on('send:created', refreshBalances),
      coco.on('receive:created', refreshBalances),
      coco.on('mint:added', refreshMints),
      coco.on('mint:updated', refreshMints),
    ];
    
    return () => unsubs.forEach(unsub => unsub());
  }, [isInitialized, refreshMints]);

  // Calculate total balance
  const totalBalance = Object.values(balances).reduce((sum, balance) => sum + balance, 0);

  return {
    coco: cocoRef.current,
    repositories: repositoriesRef.current,
    balances,
    mints,
    totalBalance,
    isInitialized,
    isLoading,
    error,
    mnemonic,
    setMnemonic,
    generateMnemonic,
    clearError,
    getEncodedToken,
    refreshMints,
  };
}