import { useMemo, useState } from 'react';
import { Redirect, router } from 'expo-router';
import { ActivityIndicator, Pressable, ScrollView, StyleSheet, Text, TextInput, View } from 'react-native';

import { useAuth, useTokenStorageInfo } from '@/src/providers/auth-provider';

const PRIMARY = '#69c350';

export default function TenantSelectScreen() {
  const { token, tenants, activeTenantId, requiresTenantSelection, switchTenant, user, logout } = useAuth();
  const storageInfo = useTokenStorageInfo();

  const [switchingTenantId, setSwitchingTenantId] = useState<number | null>(null);
  const [search, setSearch] = useState('');
  const [error, setError] = useState<string | null>(null);

  const filteredTenants = useMemo(() => {
    const terms = search.trim().toLowerCase().split(/\s+/).filter(Boolean);
    if (terms.length === 0) return tenants;

    return tenants.filter((tenant) => {
      const haystack = `${String(tenant.name || '').toLowerCase()} ${String(tenant.id || '').toLowerCase()} ${
        String(tenant.short || '').toLowerCase()
      }`;
      return terms.every((term) => haystack.includes(term));
    });
  }, [search, tenants]);

  if (!token) {
    return <Redirect href="/login" />;
  }

  if (!requiresTenantSelection && activeTenantId) {
    return <Redirect href="/(tabs)" />;
  }

  async function onSelectTenant(tenantId: number) {
    setSwitchingTenantId(tenantId);
    setError(null);

    try {
      await switchTenant(tenantId);
      router.replace('/(tabs)');
    } catch (err) {
      setError(err instanceof Error ? err.message : 'Tenant konnte nicht gewechselt werden.');
    } finally {
      setSwitchingTenantId(null);
    }
  }

  async function onLogout() {
    setSwitchingTenantId(null);
    await logout();
    router.replace('/login');
  }

  return (
    <ScrollView contentContainerStyle={styles.container}>
      <View style={styles.headerCard}>
        <Text style={styles.title}>Tenant auswählen</Text>
        <Text style={styles.subtitle}>Wähle den Mandanten für diese Session.</Text>
        <Text style={styles.meta}>User: {String(user?.email || user?.id || 'unbekannt')}</Text>
        <Text style={styles.meta}>Storage: {storageInfo.mode}</Text>
      </View>

      {error ? <Text style={styles.error}>{error}</Text> : null}

      <TextInput
        value={search}
        onChangeText={setSearch}
        placeholder="Tenant suchen"
        placeholderTextColor="#9ca3af"
        style={styles.searchInput}
      />

      {filteredTenants.length === 0 ? <Text style={styles.empty}>Keine passenden Tenants gefunden.</Text> : null}

      {filteredTenants.map((tenant) => {
        const tenantId = Number(tenant.id);
        const isBusy = switchingTenantId === tenantId;

        return (
          <Pressable
            key={String(tenant.id)}
            style={[styles.tenantButton, isBusy ? styles.tenantButtonDisabled : null]}
            onPress={() => onSelectTenant(tenantId)}
            disabled={switchingTenantId !== null}>
            <View style={styles.tenantInfo}>
              <Text style={styles.tenantName} numberOfLines={1}>
                {tenant.name}
              </Text>
              <Text style={styles.tenantMeta}>ID: {tenantId}</Text>
            </View>
            {isBusy ? <ActivityIndicator color={PRIMARY} /> : <Text style={styles.tenantAction}>Auswählen</Text>}
          </Pressable>
        );
      })}

      <Pressable style={styles.logoutButton} onPress={onLogout} disabled={switchingTenantId !== null}>
        <Text style={styles.logoutText}>Anderen Nutzer anmelden</Text>
      </Pressable>
    </ScrollView>
  );
}

const styles = StyleSheet.create({
  container: {
    flexGrow: 1,
    padding: 16,
    gap: 12,
    backgroundColor: '#f9fafb',
  },
  headerCard: {
    borderRadius: 12,
    borderWidth: 1,
    borderColor: '#e5e7eb',
    backgroundColor: '#ffffff',
    padding: 14,
    gap: 4,
  },
  title: {
    fontSize: 22,
    fontWeight: '700',
    color: '#111827',
  },
  subtitle: {
    color: '#6b7280',
    marginBottom: 2,
  },
  meta: {
    color: '#6b7280',
    fontSize: 12,
  },
  error: {
    color: '#dc2626',
    fontSize: 13,
  },
  searchInput: {
    borderWidth: 1,
    borderColor: '#d1d5db',
    borderRadius: 10,
    paddingHorizontal: 12,
    paddingVertical: 10,
    fontSize: 15,
    color: '#111827',
    backgroundColor: '#ffffff',
  },
  tenantButton: {
    borderRadius: 12,
    padding: 14,
    borderWidth: 1,
    borderColor: '#d1d5db',
    backgroundColor: '#ffffff',
    flexDirection: 'row',
    justifyContent: 'space-between',
    alignItems: 'center',
  },
  tenantButtonDisabled: {
    opacity: 0.6,
  },
  tenantInfo: {
    flex: 1,
    minWidth: 0,
    paddingRight: 10,
  },
  tenantName: {
    fontSize: 16,
    fontWeight: '600',
    color: '#111827',
  },
  tenantMeta: {
    color: '#6b7280',
    marginTop: 4,
  },
  tenantAction: {
    color: PRIMARY,
    fontWeight: '600',
  },
  empty: {
    color: '#6b7280',
    fontSize: 13,
    textAlign: 'center',
    paddingVertical: 8,
  },
  logoutButton: {
    marginTop: 4,
    minHeight: 42,
    borderRadius: 10,
    borderWidth: 1,
    borderColor: '#d1d5db',
    backgroundColor: '#ffffff',
    alignItems: 'center',
    justifyContent: 'center',
  },
  logoutText: {
    color: '#374151',
    fontWeight: '600',
  },
});