/**
 * Add New Contact — DChain explorer design style.
 * Sends CONTACT_REQUEST on-chain with correct amount/fee fields.
 */

import React, { useState } from 'react';
import {
  View, Text, ScrollView, Alert, TouchableOpacity, TextInput,
} from 'react-native';
import { router } from 'expo-router';
import { Ionicons } from '@expo/vector-icons';
import { useSafeAreaInsets } from 'react-native-safe-area-context';
import { useStore } from '@/lib/store';
import { getIdentity, buildContactRequestTx, submitTx } from '@/lib/api';
import { shortAddr } from '@/lib/crypto';
import { formatAmount } from '@/lib/utils';
import { Avatar } from '@/components/ui/Avatar';

const C = {
  bg:      '#0b1220',
  surface: '#111a2b',
  surface2:'#162035',
  line:    '#1c2840',
  text:    '#e6edf9',
  muted:   '#98a7c2',
  accent:  '#7db5ff',
  ok:      '#41c98a',
  warn:    '#f0b35a',
  err:     '#ff7a87',
} as const;

const MIN_CONTACT_FEE = 5000;

const FEE_OPTIONS = [
  { label: '5 000 µT',  value: 5_000,  note: 'минимум' },
  { label: '10 000 µT', value: 10_000, note: 'стандарт' },
  { label: '50 000 µT', value: 50_000, note: 'приоритет' },
];

interface Resolved {
  address:   string;
  nickname?: string;
  x25519?:   string;
}

export default function NewContactScreen() {
  const keyFile  = useStore(s => s.keyFile);
  const settings = useStore(s => s.settings);
  const balance  = useStore(s => s.balance);
  const insets   = useSafeAreaInsets();

  const [query,     setQuery]     = useState('');
  const [intro,     setIntro]     = useState('');
  const [fee,       setFee]       = useState(MIN_CONTACT_FEE);
  const [resolved,  setResolved]  = useState<Resolved | null>(null);
  const [searching, setSearching] = useState(false);
  const [sending,   setSending]   = useState(false);
  const [error,     setError]     = useState<string | null>(null);

  async function search() {
    const q = query.trim();
    if (!q) return;
    setSearching(true);
    setResolved(null);
    setError(null);
    try {
      let address = q;

      // @username lookup via registry contract
      if (q.startsWith('@') || (!q.match(/^[0-9a-f]{64}$/i) && !q.startsWith('DC'))) {
        const name = q.replace('@', '');
        const { resolveUsername } = await import('@/lib/api');
        const addr = await resolveUsername(settings.contractId, name);
        if (!addr) {
          setError(`@${name} не зарегистрирован в сети.`);
          return;
        }
        address = addr;
      }

      // Fetch identity to get nickname and x25519 key
      const identity = await getIdentity(address);
      setResolved({
        address:  identity?.pub_key ?? address,
        nickname: identity?.nickname || undefined,
        x25519:   identity?.x25519_pub || undefined,
      });
    } catch (e: any) {
      setError(e.message);
    } finally {
      setSearching(false);
    }
  }

  async function sendRequest() {
    if (!resolved || !keyFile) return;
    if (balance < fee + 1000) {
      Alert.alert('Недостаточно средств', `Нужно ${formatAmount(fee + 1000)} (fee + комиссия сети).`);
      return;
    }
    setSending(true);
    setError(null);
    try {
      const tx = buildContactRequestTx({
        from:       keyFile.pub_key,
        to:         resolved.address,
        contactFee: fee,
        intro:      intro.trim() || undefined,
        privKey:    keyFile.priv_key,
      });
      await submitTx(tx);
      Alert.alert(
        'Запрос отправлен',
        `Контакту ${resolved.nickname ? '@' + resolved.nickname : shortAddr(resolved.address)} отправлен запрос.`,
        [{ text: 'OK', onPress: () => router.back() }],
      );
    } catch (e: any) {
      setError(e.message);
    } finally {
      setSending(false);
    }
  }

  const displayName = resolved
    ? (resolved.nickname ? `@${resolved.nickname}` : shortAddr(resolved.address))
    : null;

  return (
    <ScrollView
      style={{ flex: 1, backgroundColor: C.bg }}
      contentContainerStyle={{
        paddingHorizontal: 16,
        paddingTop: insets.top + 8,
        paddingBottom: Math.max(insets.bottom, 32),
      }}
      keyboardShouldPersistTaps="handled"
    >
      {/* Header */}
      <View style={{ flexDirection: 'row', alignItems: 'center', gap: 6, marginBottom: 24, marginLeft: -8 }}>
        <TouchableOpacity
          onPress={() => router.back()}
          activeOpacity={0.6}
          style={{ padding: 8 }}
          hitSlop={{ top: 10, bottom: 10, left: 10, right: 10 }}
        >
          <Ionicons name="chevron-back" size={24} color={C.accent} />
        </TouchableOpacity>
        <Text style={{ color: C.text, fontSize: 20, fontWeight: '700' }}>Добавить контакт</Text>
      </View>

      {/* Search */}
      <Text style={{ color: C.muted, fontSize: 11, letterSpacing: 1, textTransform: 'uppercase', marginBottom: 8 }}>
        Адрес или @username
      </Text>
      <View style={{ flexDirection: 'row', gap: 8, marginBottom: 16 }}>
        <View style={{
          flex: 1, backgroundColor: C.surface, borderRadius: 10,
          paddingHorizontal: 12, paddingVertical: 2,
        }}>
          <TextInput
            value={query}
            onChangeText={t => { setQuery(t); setError(null); }}
            onSubmitEditing={search}
            placeholder="@username или 64-символьный hex"
            placeholderTextColor={C.muted}
            autoCapitalize="none"
            autoCorrect={false}
            style={{ color: C.text, fontSize: 14, height: 44 }}
          />
        </View>
        <TouchableOpacity
          onPress={search}
          disabled={searching || !query.trim()}
          style={{
            paddingHorizontal: 16, borderRadius: 10,
            backgroundColor: searching || !query.trim() ? C.surface2 : C.accent,
            alignItems: 'center', justifyContent: 'center',
          }}
        >
          <Text style={{ color: searching || !query.trim() ? C.muted : '#0b1220', fontWeight: '700', fontSize: 14 }}>
            {searching ? '…' : 'Найти'}
          </Text>
        </TouchableOpacity>
      </View>

      {/* Error */}
      {error && (
        <View style={{
          backgroundColor: 'rgba(255,122,135,0.08)', borderRadius: 10,
          paddingHorizontal: 12, paddingVertical: 10, marginBottom: 16,
        }}>
          <Text style={{ color: C.err, fontSize: 13 }}>⚠ {error}</Text>
        </View>
      )}

      {/* Resolved contact card */}
      {resolved && (
        <View style={{
          backgroundColor: C.surface, borderRadius: 12,
          padding: 14, marginBottom: 20,
          flexDirection: 'row', alignItems: 'center', gap: 12,
        }}>
          <Avatar name={displayName ?? resolved.address} size="md" />
          <View style={{ flex: 1, minWidth: 0 }}>
            {resolved.nickname && (
              <Text style={{ color: C.text, fontWeight: '600', fontSize: 15 }}>
                @{resolved.nickname}
              </Text>
            )}
            <Text style={{ color: C.muted, fontFamily: 'monospace', fontSize: 11 }} numberOfLines={1}>
              {resolved.address}
            </Text>
            {resolved.x25519 && (
              <Text style={{ color: C.ok, fontSize: 11, marginTop: 2 }}>
                ✓ Зашифрованные сообщения поддерживаются
              </Text>
            )}
          </View>
          <View style={{
            paddingHorizontal: 8, paddingVertical: 3,
            backgroundColor: 'rgba(65,201,138,0.12)', borderRadius: 999,
          }}>
            <Text style={{ color: C.ok, fontSize: 11, fontWeight: '600' }}>Найден</Text>
          </View>
        </View>
      )}

      {/* Intro + fee (shown after search succeeds) */}
      {resolved && (
        <>
          {/* Intro */}
          <Text style={{ color: C.muted, fontSize: 11, letterSpacing: 1, textTransform: 'uppercase', marginBottom: 8 }}>
            Сообщение (необязательно)
          </Text>
          <View style={{
            backgroundColor: C.surface, borderRadius: 10,
            paddingHorizontal: 12, paddingVertical: 8, marginBottom: 20,
          }}>
            <TextInput
              value={intro}
              onChangeText={setIntro}
              placeholder="Привет, хочу добавить тебя в контакты…"
              placeholderTextColor={C.muted}
              multiline
              numberOfLines={3}
              maxLength={280}
              style={{
                color: C.text, fontSize: 14, lineHeight: 20,
                minHeight: 72, textAlignVertical: 'top',
              }}
            />
            <Text style={{ color: C.muted, fontSize: 11, textAlign: 'right', marginTop: 4 }}>
              {intro.length}/280
            </Text>
          </View>

          {/* Fee selector */}
          <Text style={{ color: C.muted, fontSize: 11, letterSpacing: 1, textTransform: 'uppercase', marginBottom: 8 }}>
            Антиспам-сбор (отправляется контакту)
          </Text>
          <View style={{ flexDirection: 'row', gap: 8, marginBottom: 8 }}>
            {FEE_OPTIONS.map(opt => (
              <TouchableOpacity
                key={opt.value}
                onPress={() => setFee(opt.value)}
                style={{
                  flex: 1, borderRadius: 10, paddingVertical: 10, alignItems: 'center',
                  backgroundColor: fee === opt.value
                    ? 'rgba(125,181,255,0.15)' : C.surface,
                  borderWidth: fee === opt.value ? 1 : 0,
                  borderColor: fee === opt.value ? C.accent : 'transparent',
                }}
              >
                <Text style={{
                  color: fee === opt.value ? C.accent : C.text,
                  fontWeight: '600', fontSize: 13,
                }}>
                  {opt.label}
                </Text>
                <Text style={{ color: C.muted, fontSize: 11, marginTop: 2 }}>{opt.note}</Text>
              </TouchableOpacity>
            ))}
          </View>

          {/* Balance info */}
          <View style={{
            flexDirection: 'row', alignItems: 'center', gap: 8,
            backgroundColor: C.surface, borderRadius: 8,
            paddingHorizontal: 12, paddingVertical: 9, marginBottom: 20,
          }}>
            <Text style={{ color: C.muted, fontSize: 13 }}>Ваш баланс:</Text>
            <Text style={{ color: balance >= fee + 1000 ? C.text : C.err, fontSize: 13, fontWeight: '600' }}>
              {formatAmount(balance)}
            </Text>
            <Text style={{ color: C.muted, fontSize: 13, marginLeft: 'auto' as any }}>
              Итого: {formatAmount(fee + 1000)}
            </Text>
          </View>

          {/* Send button */}
          <TouchableOpacity
            onPress={sendRequest}
            disabled={sending || balance < fee + 1000}
            style={{
              paddingVertical: 15, borderRadius: 10, alignItems: 'center',
              backgroundColor: (sending || balance < fee + 1000) ? C.surface2 : C.accent,
            }}
          >
            <Text style={{
              color: (sending || balance < fee + 1000) ? C.muted : '#0b1220',
              fontWeight: '700', fontSize: 15,
            }}>
              {sending ? 'Отправка…' : 'Отправить запрос'}
            </Text>
          </TouchableOpacity>
        </>
      )}

      {/* Hint when no search yet */}
      {!resolved && !error && (
        <View style={{
          backgroundColor: C.surface, borderRadius: 12,
          padding: 16, marginTop: 8, alignItems: 'center',
        }}>
          <Text style={{ color: C.muted, fontSize: 14, textAlign: 'center', lineHeight: 21 }}>
            Введите @username или вставьте 64-символьный hex-адрес пользователя DChain.
          </Text>
        </View>
      )}
    </ScrollView>
  );
}