import { useState } from 'react';
import { View, Text, ScrollView, TouchableOpacity, ActivityIndicator, Linking, Alert, TextInput, Modal } from 'react-native';
import { SafeAreaView } from 'react-native-safe-area-context';
import { useLocalSearchParams, router } from 'expo-router';
import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
import MapView, { Marker } from 'react-native-maps';
import { api } from '../../../services/api';

const TABS = ['Profile', 'Subscription', 'Invoices', 'Tickets'] as const;
type Tab = typeof TABS[number];

const STATUS_COLOR: Record<string, string> = { ACTIVE: '#166534', SUSPENDED: '#92400E', CANCELLED: '#991B1B', PENDING: '#475569' };
const STATUS_BG: Record<string, string>    = { ACTIVE: '#DCFCE7', SUSPENDED: '#FEF3C7', CANCELLED: '#FEE2E2', PENDING: '#F1F5F9' };
const TICKET_STATUS_COLOR: Record<string, string> = { OPEN: '#0891B2', IN_PROGRESS: '#D97706', RESOLVED: '#16A34A', CLOSED: '#6B7280' };
const TYPE_COLOR: Record<string, string>   = { INSTALLATION: '#0891B2', SUPPORT: '#7C3AED', BILLING: '#D97706' };

const INV_STATUS: Record<string, { label: string; color: string; bg: string }> = {
  PAID:    { label: 'Paid',    color: '#166534', bg: '#DCFCE7' },
  SENT:    { label: 'Unpaid',  color: '#92400E', bg: '#FEF3C7' },
  OVERDUE: { label: 'Overdue', color: '#991B1B', bg: '#FEE2E2' },
  PARTIAL: { label: 'Partial', color: '#0E7490', bg: '#CFFAFE' },
  DRAFT:   { label: 'Draft',   color: '#6B7280', bg: '#F1F5F9' },
  VOID:    { label: 'Void',    color: '#6B7280', bg: '#F1F5F9' },
};

function InfoRow({ label, value, isLast }: { label: string; value?: string | null; isLast?: boolean }) {
  return (
    <View style={{ paddingHorizontal: 20, paddingVertical: 16, borderBottomWidth: isLast ? 0 : 1, borderBottomColor: '#F1F5F9' }}>
      <Text style={{ fontSize: 12, fontWeight: '600', color: '#94A3B8', textTransform: 'uppercase', letterSpacing: 0.4, marginBottom: 4 }}>{label}</Text>
      <Text style={{ fontSize: 17, fontWeight: '500', color: value ? '#0F172A' : '#CBD5E1' }}>{value ?? '—'}</Text>
    </View>
  );
}

// ── Pay Invoice Modal ─────────────────────────────────────────────────────────
function PayInvoiceModal({ invoice, onClose, onSuccess }: { invoice: any; onClose: () => void; onSuccess: () => void }) {
  const [amount, setAmount]   = useState('');
  const [method, setMethod]   = useState('CASH');
  const [ref,    setRef]      = useState('');
  const [loading, setLoading] = useState(false);
  const METHODS = ['CASH', 'GCASH', 'MAYA', 'BANK'];

  const submit = async () => {
    const amt = Number(amount);
    if (!amt || amt <= 0) return Alert.alert('Required', 'Enter a valid amount.');
    if (amt > Number(invoice.balance)) {
      Alert.alert('Over Payment', `Amount exceeds balance of ₱${Number(invoice.balance).toLocaleString()}`);
      return;
    }
    setLoading(true);
    try {
      await api.post('/api/v1/payments', {
        clientId:        invoice.clientId,
        invoiceId:       invoice.id,
        amount:          amt,
        channel:         method,
        referenceNumber: ref.trim() || undefined,
        paymentDate:     new Date().toISOString(),
      });
      Alert.alert('Payment Recorded!', `₱${amt.toLocaleString()} applied to ${invoice.invoiceNumber}`);
      onSuccess();
    } catch (e: any) {
      const msg = e?.response?.data?.message;
      Alert.alert('Error', Array.isArray(msg) ? msg.join('\n') : msg ?? 'Payment failed.');
    } finally { setLoading(false); }
  };

  return (
    <Modal visible animationType="slide" transparent onRequestClose={onClose}>
      <TouchableOpacity style={{ flex: 1, backgroundColor: 'rgba(0,0,0,0.5)', justifyContent: 'flex-end' }} activeOpacity={1} onPress={onClose}>
        <TouchableOpacity activeOpacity={1} style={{ backgroundColor: '#FFF', borderTopLeftRadius: 28, borderTopRightRadius: 28, padding: 24 }}>
          <Text style={{ fontSize: 20, fontWeight: '800', color: '#0F172A', marginBottom: 4 }}>Record Payment</Text>
          <Text style={{ fontSize: 15, color: '#64748B', marginBottom: 20 }}>
            {invoice.invoiceNumber} · Balance: <Text style={{ fontWeight: '700', color: '#991B1B' }}>₱{Number(invoice.balance).toLocaleString()}</Text>
          </Text>

          <Text style={{ fontSize: 15, fontWeight: '700', color: '#0F172A', marginBottom: 8 }}>Amount (₱)</Text>
          <TextInput
            style={{ backgroundColor: '#F8FAFC', borderWidth: 1.5, borderColor: '#E2E8F0', borderRadius: 14, paddingHorizontal: 16, paddingVertical: 14, fontSize: 24, fontWeight: '800', color: '#0F172A', textAlign: 'center', marginBottom: 16 }}
            placeholder="0.00"
            placeholderTextColor="#CBD5E1"
            keyboardType="decimal-pad"
            value={amount}
            onChangeText={setAmount}
          />

          <Text style={{ fontSize: 15, fontWeight: '700', color: '#0F172A', marginBottom: 10 }}>Method</Text>
          <View style={{ flexDirection: 'row', marginBottom: 16 }}>
            {METHODS.map(m => (
              <TouchableOpacity key={m} onPress={() => setMethod(m)}
                style={{ flex: 1, borderRadius: 12, paddingVertical: 12, alignItems: 'center', marginHorizontal: 3, backgroundColor: method === m ? '#0891B2' : '#F1F5F9' }}
                activeOpacity={0.7}
              >
                <Text style={{ fontSize: 13, fontWeight: '700', color: method === m ? '#FFF' : '#64748B' }}>{m}</Text>
              </TouchableOpacity>
            ))}
          </View>

          <Text style={{ fontSize: 15, fontWeight: '700', color: '#0F172A', marginBottom: 8 }}>Reference # <Text style={{ fontWeight: '400', color: '#94A3B8' }}>(optional)</Text></Text>
          <TextInput
            style={{ backgroundColor: '#F8FAFC', borderWidth: 1.5, borderColor: '#E2E8F0', borderRadius: 14, paddingHorizontal: 16, paddingVertical: 12, fontSize: 16, color: '#0F172A', marginBottom: 20 }}
            placeholder="GCash ref, OR number..."
            placeholderTextColor="#94A3B8"
            value={ref}
            onChangeText={setRef}
          />

          <TouchableOpacity
            style={{ backgroundColor: amount && Number(amount) > 0 ? '#059669' : '#CBD5E1', borderRadius: 14, paddingVertical: 18, alignItems: 'center' }}
            onPress={submit}
            disabled={loading}
            activeOpacity={0.8}
          >
            {loading ? <ActivityIndicator color="#FFF" /> : <Text style={{ color: '#FFF', fontSize: 17, fontWeight: '700' }}>Confirm Payment</Text>}
          </TouchableOpacity>
        </TouchableOpacity>
      </TouchableOpacity>
    </Modal>
  );
}

// ── Main Screen ───────────────────────────────────────────────────────────────
export default function ClientDetailScreen() {
  const params = useLocalSearchParams<{ id: string; tab?: string }>();
  const id = params.id;
  const qc = useQueryClient();

  const initialTab = (params.tab === 'invoices' ? 'Invoices' : 'Profile') as Tab;
  const [activeTab, setActiveTab] = useState<Tab>(initialTab);
  const [payingInvoice, setPayingInvoice] = useState<any>(null);

  const { data: client, isLoading } = useQuery({
    queryKey: ['client', id],
    queryFn: () => api.get(`/api/v1/clients/${id}`).then(r => r.data),
  });

  const { data: invoices } = useQuery({
    queryKey: ['client-invoices', id],
    queryFn: async () => {
      const res = await api.get(`/api/v1/invoices?clientId=${id}&limit=50`);
      const items: any[] = res.data?.data ?? res.data ?? [];
      items.sort((a, b) => new Date(b.createdAt).getTime() - new Date(a.createdAt).getTime());
      return items;
    },
    enabled: activeTab === 'Invoices',
  });

  const { data: tickets } = useQuery({
    queryKey: ['client-tickets', id],
    queryFn: async () => {
      const res = await api.get(`/api/v1/tickets?clientId=${id}&limit=50`);
      return res.data?.data ?? res.data ?? [];
    },
    enabled: activeTab === 'Tickets',
  });

  const sub = client?.subscriptions?.[0];

  const navigateToClient = () => {
    const lat = client?.lat;
    const lng = client?.lng;
    if (!lat || !lng) {
      Alert.alert('No Location', 'This client has no recorded location yet. Location is recorded during installation confirmation.');
      return;
    }
    Alert.alert('Navigate to Client', `${client?.firstName} ${client?.lastName}`, [
      { text: 'Google Maps', onPress: () => Linking.openURL(`https://www.google.com/maps/dir/?api=1&destination=${lat},${lng}`) },
      { text: 'Waze', onPress: () => Linking.openURL(`waze://?ll=${lat},${lng}&navigate=yes`) },
      { text: 'Cancel', style: 'cancel' },
    ]);
  };

  if (isLoading) {
    return (
      <SafeAreaView style={{ flex: 1, backgroundColor: '#0891B2' }} edges={['top']}>
        <View style={{ flex: 1, backgroundColor: '#F8FAFC', alignItems: 'center', justifyContent: 'center' }}>
          <ActivityIndicator color="#0891B2" size="large" />
        </View>
      </SafeAreaView>
    );
  }

  const statusStyle = {
    color: STATUS_COLOR[client?.status] ?? '#475569',
    bg:    STATUS_BG[client?.status]    ?? '#F1F5F9',
  };

  return (
    <SafeAreaView style={{ flex: 1, backgroundColor: '#0891B2' }} edges={['top']}>
      <View style={{ flex: 1, backgroundColor: '#F8FAFC' }}>

        {/* Header */}
        <View style={{ backgroundColor: '#0891B2', paddingHorizontal: 16, paddingTop: 12, paddingBottom: 18 }}>
          <TouchableOpacity onPress={() => router.back()} style={{ marginBottom: 12 }} activeOpacity={0.7}>
            <Text style={{ color: '#A5F3FC', fontSize: 17, fontWeight: '600' }}>← Back</Text>
          </TouchableOpacity>
          <Text style={{ color: '#FFF', fontSize: 24, fontWeight: '800' }}>{client?.firstName} {client?.lastName}</Text>
          <View style={{ flexDirection: 'row', alignItems: 'center', marginTop: 8, gap: 8 }}>
            <Text style={{ color: '#A5F3FC', fontSize: 14 }}>{client?.accountNumber}</Text>
            <View style={{ borderRadius: 20, paddingHorizontal: 12, paddingVertical: 5, backgroundColor: statusStyle.bg }}>
              <Text style={{ fontSize: 13, fontWeight: '700', color: statusStyle.color }}>{client?.status}</Text>
            </View>
          </View>
        </View>

        {/* Tabs */}
        <ScrollView horizontal showsHorizontalScrollIndicator={false} style={{ backgroundColor: '#FFF', borderBottomWidth: 1, borderBottomColor: '#F1F5F9' }} contentContainerStyle={{ paddingHorizontal: 8 }}>
          {TABS.map(tab => (
            <TouchableOpacity key={tab} onPress={() => setActiveTab(tab)} style={{ paddingHorizontal: 16, paddingVertical: 16, borderBottomWidth: 2.5, borderBottomColor: activeTab === tab ? '#0891B2' : 'transparent' }} activeOpacity={0.7}>
              <Text style={{ fontSize: 15, fontWeight: '700', color: activeTab === tab ? '#0891B2' : '#94A3B8' }}>{tab}</Text>
            </TouchableOpacity>
          ))}
        </ScrollView>

        {/* ── PROFILE TAB ── */}
        {activeTab === 'Profile' && (
          <ScrollView style={{ flex: 1 }} contentContainerStyle={{ paddingBottom: 40 }}>
            <View style={{ backgroundColor: '#FFF', borderRadius: 20, margin: 16, borderWidth: 1, borderColor: '#F1F5F9', overflow: 'hidden' }}>
              <InfoRow label="Full Name"   value={`${client?.firstName} ${client?.lastName}`} />
              <InfoRow label="Account #"   value={client?.accountNumber} />
              <InfoRow label="Email"       value={client?.email} />
              <InfoRow label="Phone"       value={client?.phone} />
              <InfoRow label="Address"     value={client?.address} />
              <InfoRow label="Area"        value={client?.area?.name} />
              <InfoRow label="Zone"        value={client?.zone?.name} isLast />
            </View>

            {/* Map + Navigate */}
            <View style={{ marginHorizontal: 16, marginBottom: 16 }}>
              <Text style={{ fontSize: 16, fontWeight: '700', color: '#0F172A', marginBottom: 10 }}>Location</Text>
              {client?.lat && client?.lng ? (
                <>
                  <View style={{ borderRadius: 16, overflow: 'hidden', height: 200, marginBottom: 10 }}>
                    <MapView
                      style={{ flex: 1 }}
                      initialRegion={{ latitude: client.lat, longitude: client.lng, latitudeDelta: 0.005, longitudeDelta: 0.005 }}
                      scrollEnabled={false}
                      zoomEnabled={false}
                    >
                      <Marker coordinate={{ latitude: client.lat, longitude: client.lng }} title={`${client.firstName} ${client.lastName}`} description={client.address ?? ''} />
                    </MapView>
                  </View>
                  <TouchableOpacity
                    style={{ backgroundColor: '#0891B2', borderRadius: 14, paddingVertical: 16, alignItems: 'center' }}
                    onPress={navigateToClient}
                    activeOpacity={0.8}
                  >
                    <Text style={{ color: '#FFF', fontSize: 16, fontWeight: '700' }}>📍 Navigate to Client</Text>
                  </TouchableOpacity>
                </>
              ) : (
                <View style={{ backgroundColor: '#F1F5F9', borderRadius: 16, padding: 24, alignItems: 'center' }}>
                  <Text style={{ fontSize: 15, color: '#94A3B8', marginBottom: 6 }}>No location recorded</Text>
                  <Text style={{ fontSize: 13, color: '#CBD5E1', textAlign: 'center' }}>Location is recorded when a technician confirms an installation</Text>
                </View>
              )}
            </View>
          </ScrollView>
        )}

        {/* ── SUBSCRIPTION TAB ── */}
        {activeTab === 'Subscription' && (
          <ScrollView style={{ flex: 1 }} contentContainerStyle={{ padding: 16, paddingBottom: 40 }}>
            {!sub ? (
              <View style={{ alignItems: 'center', paddingVertical: 48 }}>
                <Text style={{ fontSize: 15, color: '#94A3B8' }}>No active subscription</Text>
              </View>
            ) : (
              <View style={{ backgroundColor: '#FFF', borderRadius: 20, borderWidth: 1, borderColor: '#F1F5F9', overflow: 'hidden' }}>
                <InfoRow label="Plan"        value={sub.plan?.name} />
                <InfoRow label="Speed"       value={sub.plan?.speed ? `${sub.plan.speed} Mbps` : null} />
                <InfoRow label="Monthly"     value={sub.plan?.price ? `₱${Number(sub.plan.price).toLocaleString()}` : null} />
                <InfoRow label="Status"      value={sub.status} />
                <InfoRow label="Start Date"  value={sub.startDate ? new Date(sub.startDate).toLocaleDateString('en-PH', { year: 'numeric', month: 'long', day: 'numeric' }) : null} />
                <InfoRow label="Billing Day" value={sub.billingDay ? `Day ${sub.billingDay}` : null} isLast />
              </View>
            )}
          </ScrollView>
        )}

        {/* ── INVOICES TAB ── */}
        {activeTab === 'Invoices' && (
          <ScrollView style={{ flex: 1 }} contentContainerStyle={{ padding: 16, paddingBottom: 40 }}>
            {!invoices ? (
              <ActivityIndicator color="#0891B2" style={{ marginTop: 40 }} />
            ) : invoices.length === 0 ? (
              <View style={{ alignItems: 'center', paddingVertical: 48 }}>
                <Text style={{ fontSize: 15, color: '#94A3B8' }}>No invoices found</Text>
              </View>
            ) : (
              invoices.map((inv: any) => {
                const st = INV_STATUS[inv.status] ?? { label: inv.status, color: '#6B7280', bg: '#F1F5F9' };
                const isUnpaid = ['SENT', 'PARTIAL', 'OVERDUE'].includes(inv.status) && Number(inv.balance) > 0;
                const issued = inv.createdAt ? new Date(inv.createdAt).toLocaleDateString('en-PH', { month: 'short', day: 'numeric', year: 'numeric' }) : '—';
                return (
                  <View key={inv.id} style={{ backgroundColor: '#FFF', borderRadius: 16, padding: 16, marginBottom: 12, borderWidth: 1, borderColor: '#F1F5F9' }}>
                    <View style={{ flexDirection: 'row', justifyContent: 'space-between', alignItems: 'flex-start', marginBottom: 10 }}>
                      <View>
                        <Text style={{ fontSize: 15, fontWeight: '700', color: '#0F172A' }}>{inv.invoiceNumber}</Text>
                        <Text style={{ fontSize: 13, color: '#64748B', marginTop: 2 }}>Issued: {issued}</Text>
                        {inv.dueDate && (
                          <Text style={{ fontSize: 13, color: '#64748B' }}>Due: {new Date(inv.dueDate).toLocaleDateString('en-PH', { month: 'short', day: 'numeric', year: 'numeric' })}</Text>
                        )}
                      </View>
                      <View style={{ alignItems: 'flex-end' }}>
                        <View style={{ borderRadius: 20, paddingHorizontal: 12, paddingVertical: 5, backgroundColor: st.bg }}>
                          <Text style={{ fontSize: 13, fontWeight: '700', color: st.color }}>{st.label}</Text>
                        </View>
                        <Text style={{ fontSize: 16, fontWeight: '800', color: '#0F172A', marginTop: 6 }}>₱{Number(inv.total).toLocaleString()}</Text>
                        {isUnpaid && (
                          <Text style={{ fontSize: 13, color: '#991B1B', fontWeight: '600' }}>Balance: ₱{Number(inv.balance).toLocaleString()}</Text>
                        )}
                      </View>
                    </View>
                    {isUnpaid && (
                      <TouchableOpacity
                        style={{ backgroundColor: '#059669', borderRadius: 12, paddingVertical: 13, alignItems: 'center' }}
                        onPress={() => setPayingInvoice(inv)}
                        activeOpacity={0.8}
                      >
                        <Text style={{ color: '#FFF', fontSize: 15, fontWeight: '700' }}>+ Record Payment</Text>
                      </TouchableOpacity>
                    )}
                  </View>
                );
              })
            )}
          </ScrollView>
        )}

        {/* ── TICKETS TAB ── */}
        {activeTab === 'Tickets' && (
          <ScrollView style={{ flex: 1 }} contentContainerStyle={{ padding: 16, paddingBottom: 40 }}>
            <TouchableOpacity
              style={{ backgroundColor: '#0891B2', borderRadius: 14, paddingVertical: 14, alignItems: 'center', marginBottom: 16 }}
              onPress={() => router.push({ pathname: '/(app)/tasks/new', params: { prefillClientId: id, prefillName: `${client?.firstName} ${client?.lastName}` } })}
              activeOpacity={0.8}
            >
              <Text style={{ color: '#FFF', fontSize: 16, fontWeight: '700' }}>+ New Ticket</Text>
            </TouchableOpacity>

            {!tickets ? (
              <ActivityIndicator color="#0891B2" style={{ marginTop: 40 }} />
            ) : tickets.length === 0 ? (
              <View style={{ alignItems: 'center', paddingVertical: 48 }}>
                <Text style={{ fontSize: 15, color: '#94A3B8' }}>No tickets for this client</Text>
              </View>
            ) : (
              tickets.map((t: any) => {
                const typeColor   = TYPE_COLOR[t.type]   ?? '#6B7280';
                const statusColor = TICKET_STATUS_COLOR[t.status] ?? '#6B7280';
                return (
                  <TouchableOpacity
                    key={t.id}
                    onPress={() => router.push(`/(app)/tasks/${t.id}`)}
                    activeOpacity={0.8}
                    style={{ backgroundColor: '#FFF', borderRadius: 14, padding: 16, marginBottom: 10, borderWidth: 1, borderColor: '#F1F5F9', borderLeftWidth: 4, borderLeftColor: typeColor }}
                  >
                    <View style={{ flexDirection: 'row', justifyContent: 'space-between', marginBottom: 6 }}>
                      <View style={{ borderRadius: 20, paddingHorizontal: 8, paddingVertical: 3, backgroundColor: `${typeColor}20` }}>
                        <Text style={{ fontSize: 12, fontWeight: '700', color: typeColor }}>{t.type}</Text>
                      </View>
                      <Text style={{ fontSize: 13, fontWeight: '600', color: statusColor }}>{t.status?.replace('_', ' ')}</Text>
                    </View>
                    <Text style={{ fontSize: 15, fontWeight: '700', color: '#0F172A' }} numberOfLines={1}>{t.subject}</Text>
                    <Text style={{ fontSize: 13, color: '#64748B', marginTop: 3 }}>
                      {t.assignedTo ? `Assigned: ${t.assignedTo.firstName} ${t.assignedTo.lastName}` : 'Unassigned'}
                    </Text>
                  </TouchableOpacity>
                );
              })
            )}
          </ScrollView>
        )}
      </View>

      {/* Pay Invoice Modal */}
      {payingInvoice && (
        <PayInvoiceModal
          invoice={payingInvoice}
          onClose={() => setPayingInvoice(null)}
          onSuccess={() => {
            setPayingInvoice(null);
            qc.invalidateQueries({ queryKey: ['client-invoices', id] });
            qc.invalidateQueries({ queryKey: ['unpaid-invoices'] });
          }}
        />
      )}
    </SafeAreaView>
  );
}