feat: add barcode scanner for medicine lookup

frontend-mobile/app/(tabs)/index.tsx

@@ -1,15 +1,18 @@
 import React, { useState, useEffect } from 'react';
-import { View, FlatList, StyleSheet, Text } from 'react-native';
+import { View, FlatList, StyleSheet, Text, TouchableOpacity } from 'react-native';
+import { Ionicons } from '@expo/vector-icons';
+import { useRouter } from 'expo-router';
 import { SearchBar } from '../../components/SearchBar';
 import { MedicineCard } from '../../components/MedicineCard';
 import { LoadingSpinner } from '../../components/LoadingSpinner';
 import { useDebounce } from '../../hooks/useDebounce';
 import { searchMedicines } from '../../services/medicines';
-import { colors, spacing } from '../../constants/theme';
+import { colors, spacing, borderRadius } from '../../constants/theme';
 import { Medicine } from '../../types';
 import { config } from '../../constants/config';
 
 export default function HomeScreen() {
+  const router = useRouter();
   const [query, setQuery] = useState('');
   const [results, setResults] = useState<Medicine[]>([]);
   const [isLoading, setIsLoading] = useState(false);
@@ -46,11 +49,19 @@ export default function HomeScreen() {
 
   return (
     <View style={styles.container}>
-      <SearchBar
+      <View style={styles.searchContainer}>
-        onSearch={handleSearch}
+        <SearchBar
-        value={query}
+          onSearch={handleSearch}
-        onChangeText={setQuery}
+          value={query}
-      />
+          onChangeText={setQuery}
+        />
+        <TouchableOpacity 
+          style={styles.scannerButton}
+          onPress={() => router.push('/scanner')}
+        >
+          <Ionicons name="scan" size={24} color={colors.primary} />
+        </TouchableOpacity>
+      </View>
       
       {isLoading && <LoadingSpinner message="Buscando medicamentos..." />}
       
@@ -82,6 +93,16 @@ const styles = StyleSheet.create({
     flex: 1,
     backgroundColor: colors.background,
   },
+  searchContainer: {
+    flexDirection: 'row',
+    alignItems: 'center',
+  },
+  scannerButton: {
+    marginRight: spacing.md,
+    padding: spacing.sm,
+    backgroundColor: colors.card,
+    borderRadius: borderRadius.md,
+  },
   list: {
     paddingBottom: spacing.xl,
   },

frontend-mobile/app/scanner.tsx

@@ -0,0 +1,46 @@
+import React, { useState } from 'react';
+import { View, StyleSheet } from 'react-native';
+import { useRouter } from 'expo-router';
+import { BarcodeScanner } from '../components/BarcodeScanner';
+import { searchMedicines } from '../services/medicines';
+
+export default function ScannerScreen() {
+  const router = useRouter();
+  const [isSearching, setIsSearching] = useState(false);
+
+  const handleBarcodeScanned = async (barcode: string) => {
+    setIsSearching(true);
+    try {
+      const results = await searchMedicines(barcode);
+      if (results.length > 0) {
+        router.push(`/medicine/${results[0].nregistro}`);
+      } else {
+        router.push(`/medicine/${barcode}`);
+      }
+    } catch (error) {
+      console.error('Error searching medicine:', error);
+      router.push(`/medicine/${barcode}`);
+    } finally {
+      setIsSearching(false);
+    }
+  };
+
+  const handleClose = () => {
+    router.back();
+  };
+
+  return (
+    <View style={styles.container}>
+      <BarcodeScanner
+        onBarcodeScanned={handleBarcodeScanned}
+        onClose={handleClose}
+      />
+    </View>
+  );
+}
+
+const styles = StyleSheet.create({
+  container: {
+    flex: 1,
+  },
+});

frontend-mobile/components/BarcodeScanner.tsx

@@ -0,0 +1,207 @@
+import React, { useState } from 'react';
+import { View, Text, StyleSheet, TouchableOpacity } from 'react-native';
+import { CameraView, useCameraPermissions } from 'expo-camera';
+import { Ionicons } from '@expo/vector-icons';
+import { colors, spacing, borderRadius } from '../constants/theme';
+
+interface BarcodeScannerProps {
+  onBarcodeScanned: (barcode: string) => void;
+  onClose: () => void;
+}
+
+export function BarcodeScanner({ onBarcodeScanned, onClose }: BarcodeScannerProps) {
+  const [permission, requestPermission] = useCameraPermissions();
+  const [scanned, setScanned] = useState(false);
+
+  if (!permission) {
+    return <View style={styles.container} />;
+  }
+
+  if (!permission.granted) {
+    return (
+      <View style={styles.permissionContainer}>
+        <Ionicons name="camera" size={64} color={colors.textSecondary} />
+        <Text style={styles.permissionTitle}>Permiso de cámara requerido</Text>
+        <Text style={styles.permissionText}>
+          Necesitamos acceso a la cámara para escanear códigos de barras
+        </Text>
+        <TouchableOpacity style={styles.permissionButton} onPress={requestPermission}>
+          <Text style={styles.permissionButtonText}>Conceder permiso</Text>
+        </TouchableOpacity>
+        <TouchableOpacity style={styles.cancelButton} onPress={onClose}>
+          <Text style={styles.cancelButtonText}>Cancelar</Text>
+        </TouchableOpacity>
+      </View>
+    );
+  }
+
+  const handleBarCodeScanned = ({ type, data }: { type: string; data: string }) => {
+    if (scanned) return;
+    setScanned(true);
+    onBarcodeScanned(data);
+  };
+
+  return (
+    <View style={styles.container}>
+      <CameraView
+        style={StyleSheet.absoluteFillObject}
+        facing="back"
+        barcodeScannerSettings={{
+          barcodeTypes: ['ean13', 'ean8', 'upc_a', 'upc_e'],
+        }}
+        onBarcodeScanned={scanned ? undefined : handleBarCodeScanned}
+      />
+      
+      <View style={styles.overlay}>
+        <View style={styles.scannerFrame}>
+          <View style={[styles.corner, styles.topLeft]} />
+          <View style={[styles.corner, styles.topRight]} />
+          <View style={[styles.corner, styles.bottomLeft]} />
+          <View style={[styles.corner, styles.bottomRight]} />
+        </View>
+        
+        <Text style={styles.instruction}>
+          Apunta la cámara al código de barras del medicamento
+        </Text>
+        
+        <TouchableOpacity style={styles.closeButton} onPress={onClose}>
+          <Ionicons name="close" size={24} color={colors.textInverse} />
+        </TouchableOpacity>
+      </View>
+      
+      {scanned && (
+        <View style={styles.scannedOverlay}>
+          <TouchableOpacity 
+            style={styles.scanAgainButton}
+            onPress={() => setScanned(false)}
+          >
+            <Text style={styles.scanAgainText}>Escanear de nuevo</Text>
+          </TouchableOpacity>
+        </View>
+      )}
+    </View>
+  );
+}
+
+const styles = StyleSheet.create({
+  container: {
+    flex: 1,
+    backgroundColor: '#000',
+  },
+  permissionContainer: {
+    flex: 1,
+    justifyContent: 'center',
+    alignItems: 'center',
+    backgroundColor: colors.background,
+    padding: spacing.xl,
+  },
+  permissionTitle: {
+    fontSize: 20,
+    fontWeight: 'bold',
+    color: colors.text,
+    marginTop: spacing.lg,
+  },
+  permissionText: {
+    fontSize: 16,
+    color: colors.textSecondary,
+    textAlign: 'center',
+    marginTop: spacing.sm,
+    marginBottom: spacing.xl,
+  },
+  permissionButton: {
+    backgroundColor: colors.primary,
+    borderRadius: borderRadius.md,
+    paddingVertical: spacing.md,
+    paddingHorizontal: spacing.xl,
+  },
+  permissionButtonText: {
+    color: colors.textInverse,
+    fontSize: 16,
+    fontWeight: '600',
+  },
+  cancelButton: {
+    marginTop: spacing.md,
+  },
+  cancelButtonText: {
+    color: colors.textSecondary,
+    fontSize: 14,
+  },
+  overlay: {
+    flex: 1,
+    backgroundColor: 'transparent',
+    justifyContent: 'center',
+    alignItems: 'center',
+  },
+  scannerFrame: {
+    width: 250,
+    height: 250,
+    borderWidth: 2,
+    borderColor: 'transparent',
+    position: 'relative',
+  },
+  corner: {
+    position: 'absolute',
+    width: 30,
+    height: 30,
+    borderColor: colors.primary,
+  },
+  topLeft: {
+    top: 0,
+    left: 0,
+    borderTopWidth: 3,
+    borderLeftWidth: 3,
+  },
+  topRight: {
+    top: 0,
+    right: 0,
+    borderTopWidth: 3,
+    borderRightWidth: 3,
+  },
+  bottomLeft: {
+    bottom: 0,
+    left: 0,
+    borderBottomWidth: 3,
+    borderLeftWidth: 3,
+  },
+  bottomRight: {
+    bottom: 0,
+    right: 0,
+    borderBottomWidth: 3,
+    borderRightWidth: 3,
+  },
+  instruction: {
+    color: colors.textInverse,
+    fontSize: 14,
+    textAlign: 'center',
+    marginTop: spacing.xl,
+    backgroundColor: 'rgba(0,0,0,0.6)',
+    paddingHorizontal: spacing.md,
+    paddingVertical: spacing.sm,
+    borderRadius: borderRadius.sm,
+  },
+  closeButton: {
+    position: 'absolute',
+    top: spacing.xl,
+    right: spacing.xl,
+    backgroundColor: 'rgba(0,0,0,0.6)',
+    borderRadius: 20,
+    padding: spacing.sm,
+  },
+  scannedOverlay: {
+    position: 'absolute',
+    bottom: spacing.xxl,
+    left: spacing.xl,
+    right: spacing.xl,
+  },
+  scanAgainButton: {
+    backgroundColor: colors.primary,
+    borderRadius: borderRadius.md,
+    padding: spacing.md,
+    alignItems: 'center',
+  },
+  scanAgainText: {
+    color: colors.textInverse,
+    fontSize: 16,
+    fontWeight: '600',
+  },
+});