import { CameraView, useCameraPermissions } from "expo-camera";
import { useEffect, useRef, useState } from "react";
import {
  ActivityIndicator,
  Modal,
  Pressable,
  StyleSheet,
  Text,
  View,
} from "react-native";

interface ScanQRCodeProps {
  visible: boolean;
  onClose: () => void;
  onScanned: (data: string) => void;
}

export default function ScanQRCode({
  visible,
  onClose,
  onScanned,
}: ScanQRCodeProps) {
  const [permission, requestPermission] = useCameraPermissions();
  const [scanned, setScanned] = useState(false);
  const cameraRef = useRef(null);
  // Dùng ref để chặn quét nhiều lần trong cùng một frame/event loop
  const hasScannedRef = useRef(false);

  // Request camera permission when component mounts or when visible changes to true
  useEffect(() => {
    if (visible && !permission?.granted) {
      requestPermission();
    }
  }, [visible, permission, requestPermission]);

  // Reset scanned state when modal opens
  useEffect(() => {
    if (visible) {
      setScanned(false);
    }
  }, [visible]);

  // Mỗi khi reset scanned state thì reset luôn ref guard
  useEffect(() => {
    if (!scanned) {
      hasScannedRef.current = false;
    }
  }, [scanned]);

  const handleBarCodeScanned = ({
    type,
    data,
  }: {
    type: string;
    data: string;
  }) => {
    // Nếu đã scan rồi, bỏ qua
    if (hasScannedRef.current || scanned) return;
    hasScannedRef.current = true;
    setScanned(true);
    onScanned(data);
    onClose();
  };

  if (!permission) {
    return (
      <Modal visible={visible} transparent animationType="slide">
        <View style={styles.container}>
          <View style={styles.loadingContainer}>
            <ActivityIndicator size="large" color="#0000ff" />
            <Text style={styles.loadingText}>
              Requesting camera permission...
            </Text>
          </View>
        </View>
      </Modal>
    );
  }

  if (!permission.granted) {
    return (
      <Modal visible={visible} transparent animationType="slide">
        <View style={styles.container}>
          <View style={styles.permissionContainer}>
            <Text style={styles.permissionTitle}>
              Camera Permission Required
            </Text>
            <Text style={styles.permissionText}>
              This app needs camera access to scan QR codes. Please allow camera
              access in your settings.
            </Text>
            <Pressable
              style={styles.button}
              onPress={() => requestPermission()}
            >
              <Text style={styles.buttonText}>Request Permission</Text>
            </Pressable>
            <Pressable
              style={[styles.button, styles.cancelButton]}
              onPress={onClose}
            >
              <Text style={styles.buttonText}>Cancel</Text>
            </Pressable>
          </View>
        </View>
      </Modal>
    );
  }

  return (
    <Modal visible={visible} transparent animationType="slide">
      <CameraView
        ref={cameraRef}
        style={styles.camera}
        // Chỉ gắn handler khi chưa scan để ngắt lắng nghe ngay lập tức sau khi quét thành công
        onBarcodeScanned={scanned ? undefined : handleBarCodeScanned}
        barcodeScannerSettings={{
          barcodeTypes: ["qr"],
        }}
      >
        <View style={styles.overlay}>
          <View style={styles.unfocusedContainer} />
          <View style={styles.focusedRow}>
            <View style={styles.focusedContainer} />
          </View>
          <View style={styles.unfocusedContainer} />

          <View style={styles.bottomContainer}>
            <Text style={styles.scanningText}>
              {/* Align QR code within the frame */}
              Đặt mã QR vào khung hình
            </Text>
            <Pressable style={styles.closeButton} onPress={onClose}>
              <Text style={styles.closeButtonText}>✕ Đóng</Text>
            </Pressable>
          </View>
        </View>
      </CameraView>
    </Modal>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: "rgba(0, 0, 0, 0.8)",
    justifyContent: "center",
    alignItems: "center",
  },
  loadingContainer: {
    alignItems: "center",
    gap: 10,
  },
  loadingText: {
    color: "#fff",
    fontSize: 16,
  },
  permissionContainer: {
    backgroundColor: "#fff",
    marginHorizontal: 20,
    borderRadius: 12,
    padding: 20,
    alignItems: "center",
    gap: 15,
  },
  permissionTitle: {
    fontSize: 18,
    fontWeight: "600",
    color: "#333",
  },
  permissionText: {
    fontSize: 14,
    color: "#666",
    textAlign: "center",
    lineHeight: 20,
  },
  button: {
    backgroundColor: "#007AFF",
    paddingVertical: 12,
    paddingHorizontal: 30,
    borderRadius: 8,
    width: "100%",
    alignItems: "center",
  },
  cancelButton: {
    backgroundColor: "#666",
  },
  buttonText: {
    color: "#fff",
    fontSize: 16,
    fontWeight: "600",
  },
  camera: {
    flex: 1,
  },
  overlay: {
    flex: 1,
    backgroundColor: "rgba(0, 0, 0, 0.5)",
  },
  unfocusedContainer: {
    flex: 1,
  },
  focusedRow: {
    height: "80%",
    width: "100%",
    justifyContent: "center",
    alignItems: "center",
  },
  focusedContainer: {
    aspectRatio: 1,
    width: "70%",
    borderColor: "#00ff00",
    borderWidth: 3,
    borderRadius: 10,
  },
  bottomContainer: {
    flex: 1,
    justifyContent: "flex-end",
    alignItems: "center",
    paddingBottom: 40,
    gap: 20,
  },
  scanningText: {
    color: "#fff",
    fontSize: 16,
    fontWeight: "500",
  },
  closeButton: {
    backgroundColor: "rgba(0, 0, 0, 0.6)",
    paddingVertical: 10,
    paddingHorizontal: 20,
    borderRadius: 8,
  },
  closeButtonText: {
    color: "#fff",
    fontSize: 14,
    fontWeight: "600",
  },
});