/**
 * AmberCallbackHandler
 * 
 * This component handles Amber (NIP-55) callbacks at the app level.
 * It processes results from Amber after signing operations and login.
 * 
 * For web apps, Amber communication works via URL redirects:
 * 1. App opens nostrsigner: URL to request signing
 * 2. Amber opens and user approves/rejects
 * 3. Amber redirects back to callbackUrl with result in query params
 * 4. This component processes the result
 * 
 * PWA NOTE: PWAs can lose localStorage when redirecting to external apps.
 * This handler uses multiple fallback strategies:
 * 1. Check localStorage, sessionStorage, and IndexedDB for pending operation
 * 2. If all storage is lost but result looks like a pubkey, assume it's a login
 */

import { useEffect, useRef, useState } from 'react';
import { useLoginActions } from '@/hooks/useLoginActions';
import { useToast } from '@/hooks/useToast';
import {
  isAmberCallback,
  getAmberCallbackResult,
  getAmberPendingOperationAsync,
  clearAmberPendingOperation,
  cleanAmberCallbackUrl,
} from '@/lib/amber';

export function AmberCallbackHandler() {
  const login = useLoginActions();
  const { toast } = useToast();
  const hasProcessed = useRef(false);
  const [debugInfo, setDebugInfo] = useState<string | null>(null);

  useEffect(() => {
    // Log on mount for debugging
    console.log('[AmberCallback] Component mounted');
    console.log('[AmberCallback] URL:', window.location.href);
    console.log('[AmberCallback] Search:', window.location.search);
    console.log('[AmberCallback] Pre-captured event:', sessionStorage.getItem('amber_callback_event'));
    
    // Check if this is an Amber callback
    const isCallback = isAmberCallback();
    console.log('[AmberCallback] isAmberCallback():', isCallback);
    
    if (!isCallback) {
      return;
    }
    
    // Only process once per page load
    if (hasProcessed.current) {
      console.log('[AmberCallback] Already processed, skipping');
      return;
    }
    hasProcessed.current = true;

    console.log('[AmberCallback] Processing Amber callback...');
    
    // Show debug info temporarily
    setDebugInfo('Processing Amber login...');

    // Process async to allow IndexedDB lookup
    processAmberCallback();

    async function processAmberCallback() {
      const result = getAmberCallbackResult();
      
      console.log('[AmberCallback] Result:', result);
      setDebugInfo(`Got result: ${result ? result.substring(0, 16) + '...' : 'null'}`);

      // Clean up URL immediately to prevent re-processing on refresh
      cleanAmberCallbackUrl();

      if (!result) {
        // User cancelled or Amber failed
        clearAmberPendingOperation();
        setDebugInfo('No result from Amber');
        toast({
          title: 'Amber',
          description: 'No result received from Amber. Operation may have been cancelled.',
          variant: 'destructive',
        });
        return;
      }

      // Try to get pending operation from any storage
      const pendingOp = await getAmberPendingOperationAsync();
      console.log('[AmberCallback] Pending operation:', pendingOp);

      // FALLBACK: If no pending operation found, but result looks like a valid pubkey,
      // assume this is a login callback (PWA storage was cleared during redirect)
      const pubkeyRegex = /^[0-9a-fA-F]{64}$/;
      
      if (!pendingOp) {
        console.warn('[AmberCallback] No pending operation found - storage may have been cleared');
        
        // Check if result looks like a pubkey (login callback)
        if (pubkeyRegex.test(result)) {
          console.log('[AmberCallback] Result looks like pubkey, treating as login callback');
          setDebugInfo('Valid pubkey! Logging in...');
          try {
            login.amber(result.toLowerCase());
            setDebugInfo('Login successful!');
            toast({
              title: 'Logged in',
              description: 'Successfully logged in with Amber!',
            });
            // Clear debug after success
            setTimeout(() => setDebugInfo(null), 2000);
            return;
          } catch (error) {
            console.error('[AmberCallback] Amber login failed:', error);
            setDebugInfo(`Login error: ${error}`);
            toast({
              title: 'Login failed',
              description: 'Failed to complete Amber login. Please try again.',
              variant: 'destructive',
            });
            return;
          }
        }
        
        // Not a pubkey - can't determine what operation this was for
        setDebugInfo(`Invalid result format: ${result.substring(0, 20)}...`);
        toast({
          title: 'Amber',
          description: 'Session data was lost. Please try again.',
          variant: 'destructive',
        });
        return;
      }

      // Process based on operation type
      switch (pendingOp.type) {
        case 'get_public_key': {
          console.log('[AmberCallback] Processing get_public_key...');
          
          if (pubkeyRegex.test(result)) {
            try {
              login.amber(result.toLowerCase());
              clearAmberPendingOperation();
              console.log('[AmberCallback] Login successful!');
              toast({
                title: 'Logged in',
                description: 'Successfully logged in with Amber!',
              });
            } catch (error) {
              console.error('[AmberCallback] Amber login failed:', error);
              clearAmberPendingOperation();
              toast({
                title: 'Login failed',
                description: 'Failed to complete Amber login. Please try again.',
                variant: 'destructive',
              });
            }
          } else {
            console.warn('[AmberCallback] Invalid pubkey format:', result);
            clearAmberPendingOperation();
            toast({
              title: 'Login failed',
              description: 'Invalid pubkey received from Amber.',
              variant: 'destructive',
            });
          }
          break;
        }

        case 'sign_event': {
          // Store the signed event result for the caller to retrieve
          // This is tricky because the original caller's promise can't be resolved
          // after a page redirect. For now, we'll store it and show a toast.
          try {
            const signedEvent = JSON.parse(result);
            // Store in sessionStorage for potential retrieval
            sessionStorage.setItem('amber_signed_event', JSON.stringify(signedEvent));
            clearAmberPendingOperation();
            toast({
              title: 'Event signed',
              description: 'Your event has been signed by Amber.',
            });
            // Reload the page to re-submit the event
            // This is a workaround since we can't resolve the original promise
            window.location.reload();
          } catch (e) {
            console.error('Failed to parse signed event:', e);
            clearAmberPendingOperation();
            toast({
              title: 'Signing failed',
              description: 'Failed to process signed event from Amber.',
              variant: 'destructive',
            });
          }
          break;
        }

        case 'nip04_encrypt':
        case 'nip44_encrypt':
        case 'nip04_decrypt':
        case 'nip44_decrypt': {
          // Store encryption/decryption results
          sessionStorage.setItem('amber_crypto_result', result);
          clearAmberPendingOperation();
          toast({
            title: 'Operation complete',
            description: `${pendingOp.type.replace('_', ' ')} completed.`,
          });
          break;
        }

        default: {
          console.warn('Unknown Amber operation type:', pendingOp.type);
          clearAmberPendingOperation();
        }
      }
    }
  }, [login, toast]);

  // Show debug overlay when processing Amber callback
  if (debugInfo) {
    return (
      <div className="fixed top-0 left-0 right-0 z-[9999] bg-yellow-500 text-black px-4 py-2 text-center text-sm font-mono">
        🔐 Amber: {debugInfo}
      </div>
    );
  }

  return null;
}