import { type BarcodeScanningResult, Camera, CameraView } from 'expo-camera';
import { useCallback, useEffect, useState } from 'react';
import { Pressable, StyleSheet, Text, View } from 'react-native';

import {
  cancelQrCodeScan,
  completeQrCodeScan,
  failQrCodeScan,
  subscribeQrScannerState,
} from '../host-bridge/scanner';

function logQrScannerPermissionFailure(_error: unknown) {
  console.warn('mobile QR scanner permission request failed');
}

export function QrScannerOverlay() {
  const [isActive, setIsActive] = useState(false);
  const [requestKey, setRequestKey] = useState(0);
  const [hasPermission, setHasPermission] = useState(false);
  const [scanCompleted, setScanCompleted] = useState(false);

  useEffect(
    () =>
      subscribeQrScannerState((state) => {
        setIsActive(state.active);
        setRequestKey(state.requestKey);
      }),
    [],
  );

  useEffect(() => {
    if (!isActive) {
      setHasPermission(false);
      setScanCompleted(false);
      return;
    }

    let disposed = false;
    setHasPermission(false);
    setScanCompleted(false);
    void Camera.requestCameraPermissionsAsync()
      .then((permission) => {
        if (disposed) {
          return;
        }
        if (!permission.granted) {
          failQrCodeScan();
          return;
        }
        setHasPermission(true);
      })
      .catch((error: unknown) => {
        if (!disposed) {
          logQrScannerPermissionFailure(error);
          failQrCodeScan();
        }
      });

    return () => {
      disposed = true;
    };
  }, [isActive, requestKey]);

  const handleBarcodeScanned = useCallback(
    (result: BarcodeScanningResult) => {
      if (scanCompleted || result.type !== 'qr') {
        return;
      }

      if (completeQrCodeScan(result.data)) {
        setScanCompleted(true);
      }
    },
    [scanCompleted],
  );

  if (!isActive) {
    return null;
  }

  return (
    <View style={styles.root}>
      {hasPermission ? (
        <CameraView
          style={styles.camera}
          facing="back"
          onBarcodeScanned={scanCompleted ? undefined : handleBarcodeScanned}
          barcodeScannerSettings={{
            barcodeTypes: ['qr'],
          }}
        />
      ) : null}
      <View pointerEvents="none" style={styles.frame} />
      <Pressable
        accessibilityRole="button"
        accessibilityLabel="关闭扫码"
        onPress={cancelQrCodeScan}
        style={styles.closeButton}
      >
        <Text style={styles.closeButtonText}>关闭</Text>
      </Pressable>
    </View>
  );
}

const styles = StyleSheet.create({
  root: {
    position: 'absolute',
    top: 0,
    right: 0,
    bottom: 0,
    left: 0,
    backgroundColor: '#0c0a09',
  },
  camera: {
    flex: 1,
  },
  frame: {
    position: 'absolute',
    top: '22%',
    right: 42,
    bottom: '22%',
    left: 42,
    borderWidth: 2,
    borderColor: '#fffdf9',
    borderRadius: 8,
  },
  closeButton: {
    position: 'absolute',
    top: 20,
    right: 20,
    minWidth: 76,
    minHeight: 40,
    alignItems: 'center',
    justifyContent: 'center',
    borderRadius: 8,
    backgroundColor: '#fffdf9',
    paddingHorizontal: 16,
  },
  closeButtonText: {
    color: '#211a16',
    fontSize: 15,
    fontWeight: '700',
    lineHeight: 20,
  },
});