import React, { useState } from 'react';
import {
  KeyboardAvoidingView,
  Platform,
  Pressable,
  ScrollView,
  StyleSheet,
  Text,
  View,
} from 'react-native';
import { useSafeAreaInsets } from 'react-native-safe-area-context';
import { Ionicons } from '@expo/vector-icons';
import { Button, Field, TextField } from '@/components/ui';
import { useRouter } from 'expo-router';
import { useAuth } from '@/auth/AuthContext';
import { USE_MOCK } from '@/api';
import { useT } from '@/i18n';
import { colors, fontSize, radii, spacing } from '@/theme';

export default function LoginScreen() {
  const insets = useSafeAreaInsets();
  const { signIn } = useAuth();
  const router = useRouter();
  const t = useT();

  const [email, setEmail] = useState(USE_MOCK ? 'j.smith@casadoc.app' : '');
  const [password, setPassword] = useState(USE_MOCK ? 'demo' : '');
  const [showPass, setShowPass] = useState(false);
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState<string | null>(null);

  async function onSignIn() {
    if (!email.trim() || !password) {
      setError(t('login.missingFields'));
      return;
    }
    setError(null);
    setLoading(true);
    try {
      await signIn(email.trim(), password);
    } catch (e: any) {
      // Unverified is not a wrong password: send them to the code screen.
      if (e?.code === 'email_not_verified') {
        router.push(`/verify?email=${encodeURIComponent(email.trim())}`);
        return;
      }
      // The backend's message is English-only; ours says the same, localized.
      setError(e?.status === 401 || e?.status === 422 ? t('login.failed') : (e?.message ?? t('login.failed')));
    } finally {
      setLoading(false);
    }
  }

  return (
    <KeyboardAvoidingView
      style={{ flex: 1, backgroundColor: colors.surface }}
      behavior={Platform.OS === 'ios' ? 'padding' : undefined}
    >
      <ScrollView
        contentContainerStyle={[
          styles.container,
          { paddingTop: insets.top + spacing[8], paddingBottom: insets.bottom + spacing[6] },
        ]}
        keyboardShouldPersistTaps="handled"
      >
        <View style={styles.brandWrap}>
          <View style={styles.brandMark}>
            <Ionicons name="home" size={30} color={colors.onDark} />
          </View>
          <Text style={styles.brand}>
            Casa<Text style={{ color: colors.teal500 }}>Doc</Text>
          </Text>
          <Text style={styles.tagline}>
            {t('login.tagline')}
          </Text>
        </View>

        <View style={{ marginTop: spacing[9] }}>
          <Field label={t('login.email')}>
            <TextField
              icon="mail-outline"
              value={email}
              onChangeText={setEmail}
              placeholder={t('login.emailPlaceholder')}
              autoCapitalize="none"
              keyboardType="email-address"
              autoComplete="email"
            />
          </Field>

          <Field label={t('login.password')}>
            <TextField
              icon="lock-closed-outline"
              value={password}
              onChangeText={setPassword}
              placeholder={t('login.passwordPlaceholder')}
              secureTextEntry={!showPass}
              autoCapitalize="none"
            />
            <Pressable onPress={() => setShowPass((s) => !s)} style={styles.showPass} hitSlop={8}>
              <Text style={styles.showPassText}>{showPass ? t('login.hide') : t('login.show')}</Text>
            </Pressable>
          </Field>

          {error ? (
            <View style={styles.errorBox}>
              <Ionicons name="alert-circle-outline" size={18} color={colors.dangerText} />
              <Text style={styles.errorText}>{error}</Text>
            </View>
          ) : null}

          <Button
            title={t('login.signIn')}
            iconRight="arrow-forward"
            size="lg"
            block
            loading={loading}
            onPress={onSignIn}
            style={{ marginTop: spacing[3] }}
          />

          <Pressable onPress={() => router.push('/forgot')} style={styles.forgot}>
            <Text style={styles.linkText}>{t('login.forgot')}</Text>
          </Pressable>

          <Pressable onPress={() => router.push('/register')} style={styles.registerRow}>
            <Text style={styles.muted}>
              {t('login.noAccount')} <Text style={styles.linkText}>{t('register.submit')}</Text>
            </Text>
          </Pressable>

          {USE_MOCK ? (
            <Text style={styles.demoHint}>{t('login.demoHint')}</Text>
          ) : null}
        </View>

        <View style={styles.trust}>
          <Ionicons name="shield-checkmark-outline" size={16} color={colors.slate500} />
          <Text style={styles.trustText}>{t('login.trust')}</Text>
        </View>
      </ScrollView>
    </KeyboardAvoidingView>
  );
}

const styles = StyleSheet.create({
  container: { paddingHorizontal: spacing[5], flexGrow: 1 },
  brandWrap: { alignItems: 'center' },
  brandMark: {
    width: 68,
    height: 68,
    borderRadius: 20,
    backgroundColor: colors.ink900,
    alignItems: 'center',
    justifyContent: 'center',
  },
  brand: { fontSize: fontSize['3xl'], fontWeight: '700', color: colors.ink, marginTop: spacing[4] },
  tagline: {
    fontSize: fontSize.sm,
    color: colors.textMuted,
    textAlign: 'center',
    marginTop: 8,
    maxWidth: 260,
  },
  showPass: { position: 'absolute', right: 14, top: 40 },
  showPassText: { color: colors.teal700, fontWeight: '600', fontSize: fontSize.sm },
  errorBox: {
    flexDirection: 'row',
    alignItems: 'center',
    gap: 8,
    backgroundColor: colors.dangerBg,
    borderRadius: radii.md,
    padding: spacing[3],
    marginBottom: spacing[3],
  },
  errorText: { color: colors.dangerText, fontSize: fontSize.sm, flex: 1 },
  forgot: { alignSelf: 'center', marginTop: spacing[4] },
  registerRow: { alignItems: 'center', marginTop: spacing[5] },
  linkText: { color: colors.teal700, fontWeight: '600', fontSize: fontSize.sm },
  muted: { fontSize: fontSize.sm, color: colors.textMuted },
  demoHint: { textAlign: 'center', color: colors.textMuted2, fontSize: fontSize.xs, marginTop: spacing[4] },
  trust: {
    flexDirection: 'row',
    alignItems: 'center',
    justifyContent: 'center',
    gap: 7,
    marginTop: 'auto',
    paddingTop: spacing[7],
  },
  trustText: { fontSize: fontSize.sm, color: colors.slate500 },
});