// components/sync/QRScanner.tsx
import React, { useState, useEffect, useRef } from 'react';
import {
  View,
  Text,
  StyleSheet,
  TouchableOpacity,
  Alert,
} from 'react-native';
import { CameraView, Camera, BarcodeScanningResult } from 'expo-camera';
import { X } from 'lucide-react-native';

interface QRScannerProps {
  onScanned: (shareId: string) => void;
  onCancel: () => void;
}

export default function QRScanner({ onScanned, onCancel }: QRScannerProps) {
  const [hasPermission, setHasPermission] = useState<boolean | null>(null);
  const [scanned, setScanned] = useState(false);
  const lastScannedRef = useRef<string | null>(null);

  useEffect(() => {
    requestPermission();
  }, []);

  const requestPermission = async () => {
    const { status } = await Camera.requestCameraPermissionsAsync();
    setHasPermission(status === 'granted');
  };

  const handleBarCodeScanned = (result: BarcodeScanningResult) => {
    if (scanned) return;
    const { data } = result;

    // Prevent duplicate scans of the same code
    if (lastScannedRef.current === data) return;
    lastScannedRef.current = data;

    // Extract Share ID — expected format: "TL-XXXXXXXX" (8 alphanumeric chars)
    const match = data.match(/TL-[A-Z0-9]{8}/i);
    if (match) {
      setScanned(true);
      onScanned(match[0].toUpperCase());
    } else {
      Alert.alert(
        'Invalid QR Code',
        'This QR code does not contain a valid TerritoryLog Share ID.',
        [
          {
            text: 'Try Again',
            onPress: () => {
              lastScannedRef.current = null;
            },
          },
          { text: 'Cancel', onPress: onCancel },
        ]
      );
    }
  };

  if (hasPermission === null) {
    return (
      <View style={styles.centered}>
        <Text style={styles.message}>Requesting camera permission…</Text>
      </View>
    );
  }

  if (hasPermission === false) {
    return (
      <View style={styles.centered}>
        <Text style={styles.message}>Camera access denied.</Text>
        <Text style={styles.submessage}>
          Enable camera access in your device settings to scan QR codes.
        </Text>
        <TouchableOpacity style={styles.cancelBtn} onPress={onCancel}>
          <Text style={styles.cancelText}>Go Back</Text>
        </TouchableOpacity>
      </View>
    );
  }

  return (
    <View style={styles.container}>
      <CameraView
        style={StyleSheet.absoluteFillObject}
        barcodeScannerSettings={{
          barcodeTypes: ['qr'],
        }}
        onBarcodeScanned={scanned ? undefined : handleBarCodeScanned}
      />

      {/* Overlay */}
      <View style={styles.overlay}>
        {/* Top */}
        <View style={styles.overlayTop}>
          <TouchableOpacity style={styles.closeBtn} onPress={onCancel}>
            <X size={24} color="#fff" />
          </TouchableOpacity>
          <Text style={styles.overlayTitle}>Scan Partner QR Code</Text>
          <Text style={styles.overlaySubtitle}>
            Point your camera at your partner's TerritoryLog QR code
          </Text>
        </View>

        {/* Scan frame row */}
        <View style={styles.frameRow}>
          <View style={styles.frameShade} />
          <View style={styles.frame}>
            {/* Corner markers */}
            <View style={[styles.corner, styles.cornerTL]} />
            <View style={[styles.corner, styles.cornerTR]} />
            <View style={[styles.corner, styles.cornerBL]} />
            <View style={[styles.corner, styles.cornerBR]} />
          </View>
          <View style={styles.frameShade} />
        </View>

        {/* Bottom */}
        <View style={styles.overlayBottom}>
          <Text style={styles.overlayHint}>Share ID format: TL-XXXXXXXX</Text>
        </View>
      </View>
    </View>
  );
}

const FRAME_SIZE = 240;

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: '#000',
  },
  centered: {
    flex: 1,
    backgroundColor: '#111827',
    justifyContent: 'center',
    alignItems: 'center',
    padding: 24,
    gap: 12,
  },
  message: {
    color: '#F9FAFB',
    fontSize: 16,
    textAlign: 'center',
  },
  submessage: {
    color: '#9CA3AF',
    fontSize: 14,
    textAlign: 'center',
  },
  cancelBtn: {
    marginTop: 16,
    paddingVertical: 12,
    paddingHorizontal: 24,
    backgroundColor: '#1A6B72',
    borderRadius: 12,
  },
  cancelText: {
    color: '#fff',
    fontSize: 15,
    fontWeight: '600',
  },
  overlay: {
    flex: 1,
    flexDirection: 'column',
  },
  overlayTop: {
    flex: 1,
    backgroundColor: 'rgba(0,0,0,0.6)',
    alignItems: 'center',
    paddingTop: 60,
    paddingHorizontal: 24,
    gap: 8,
  },
  closeBtn: {
    position: 'absolute',
    top: 52,
    right: 24,
    width: 40,
    height: 40,
    borderRadius: 20,
    backgroundColor: 'rgba(255,255,255,0.2)',
    justifyContent: 'center',
    alignItems: 'center',
  },
  overlayTitle: {
    color: '#fff',
    fontSize: 20,
    fontWeight: '700',
    marginTop: 8,
  },
  overlaySubtitle: {
    color: '#D1D5DB',
    fontSize: 13,
    textAlign: 'center',
  },
  frameRow: {
    flexDirection: 'row',
    height: FRAME_SIZE,
  },
  frameShade: {
    flex: 1,
    backgroundColor: 'rgba(0,0,0,0.6)',
  },
  frame: {
    width: FRAME_SIZE,
    height: FRAME_SIZE,
    backgroundColor: 'transparent',
  },
  corner: {
    position: 'absolute',
    width: 28,
    height: 28,
    borderColor: '#1A6B72',
    borderWidth: 3,
  },
  cornerTL: { top: 0, left: 0, borderBottomWidth: 0, borderRightWidth: 0 },
  cornerTR: { top: 0, right: 0, borderBottomWidth: 0, borderLeftWidth: 0 },
  cornerBL: { bottom: 0, left: 0, borderTopWidth: 0, borderRightWidth: 0 },
  cornerBR: { bottom: 0, right: 0, borderTopWidth: 0, borderLeftWidth: 0 },
  overlayBottom: {
    flex: 1,
    backgroundColor: 'rgba(0,0,0,0.6)',
    alignItems: 'center',
    paddingTop: 24,
  },
  overlayHint: {
    color: '#9CA3AF',
    fontSize: 13,
  },
});