/**
 * Account Created confirmation screen.
 * Shows address, pubkeys, and export options.
 */

import React, { useState } from 'react';
import { View, Text, ScrollView, Alert, Share } from 'react-native';
import { router } from 'expo-router';
import * as Clipboard from 'expo-clipboard';
import * as FileSystem from 'expo-file-system';
import * as Sharing from 'expo-sharing';
import { useStore } from '@/lib/store';
import { shortAddr } from '@/lib/crypto';
import { Button } from '@/components/ui/Button';
import { Card } from '@/components/ui/Card';
import { Separator } from '@/components/ui/Separator';

export default function AccountCreatedScreen() {
  const keyFile = useStore(s => s.keyFile);
  const [copied, setCopied] = useState<string | null>(null);

  if (!keyFile) {
    router.replace('/');
    return null;
  }

  async function copy(value: string, label: string) {
    await Clipboard.setStringAsync(value);
    setCopied(label);
    setTimeout(() => setCopied(null), 2000);
  }

  async function exportKey() {
    try {
      const json = JSON.stringify(keyFile, null, 2);
      const path = FileSystem.cacheDirectory + 'dchain_key.json';
      await FileSystem.writeAsStringAsync(path, json);
      if (await Sharing.isAvailableAsync()) {
        await Sharing.shareAsync(path, {
          mimeType: 'application/json',
          dialogTitle: 'Save your DChain key file',
        });
      } else {
        Alert.alert('Export', 'Sharing not available on this device.');
      }
    } catch (e: any) {
      Alert.alert('Export failed', e.message);
    }
  }

  return (
    <ScrollView
      className="flex-1 bg-background"
      contentContainerClassName="px-6 pt-16 pb-10"
    >
      {/* Success header */}
      <View className="items-center mb-8">
        <View className="w-20 h-20 rounded-full bg-success/20 items-center justify-center mb-4">
          <Text className="text-4xl">✓</Text>
        </View>
        <Text className="text-white text-2xl font-bold">Account Created!</Text>
        <Text className="text-muted text-sm mt-2 text-center">
          Your keys have been generated and stored securely.
        </Text>
      </View>

      {/* Address card */}
      <Card className="mb-4">
        <Text className="text-muted text-xs uppercase tracking-widest mb-3 font-semibold">
          Your Address (Ed25519)
        </Text>
        <Text className="text-white font-mono text-xs leading-5 mb-3">
          {keyFile.pub_key}
        </Text>
        <Button
          variant="secondary"
          size="sm"
          onPress={() => copy(keyFile.pub_key, 'address')}
        >
          {copied === 'address' ? '✓ Copied' : 'Copy Address'}
        </Button>
      </Card>

      {/* X25519 key */}
      <Card className="mb-4">
        <Text className="text-muted text-xs uppercase tracking-widest mb-3 font-semibold">
          Encryption Key (X25519)
        </Text>
        <Text className="text-white font-mono text-xs leading-5 mb-3">
          {keyFile.x25519_pub}
        </Text>
        <Button
          variant="secondary"
          size="sm"
          onPress={() => copy(keyFile.x25519_pub, 'x25519')}
        >
          {copied === 'x25519' ? '✓ Copied' : 'Copy Encryption Key'}
        </Button>
      </Card>

      {/* Export warning */}
      <Card className="mb-8 border-yellow-500/30 bg-yellow-500/10">
        <Text className="text-yellow-400 text-sm font-semibold mb-2">🔐 Backup your key file</Text>
        <Text className="text-muted text-xs leading-5 mb-3">
          Export <Text className="text-white font-mono">dchain_key.json</Text> and store it safely.
          This file contains your private keys — keep it secret.
        </Text>
        <Button variant="outline" onPress={exportKey}>
          Export key.json
        </Button>
      </Card>

      <Button size="lg" onPress={() => router.replace('/(app)/chats')}>
        Open Messenger
      </Button>
    </ScrollView>
  );
}