GCP Deployment Guide

4. Flutter Mobile Application Code

This implementation uses the Provider pattern for state management and Firestore for real-time updates.

import 'package:flutter/material.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:cloud_firestore/cloud_firestore.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  runApp(HotelConciergeApp());
}

// 5. COLOR SCHEME [9]
// Hospitality Theme: Navy/Gold + Urgent Indicators
class AppColors {
  static const primary = Color(0xFF1A237E); // Navy Blue
  static const accent = Color(0xFFFFD700);  // Gold
  static const urgentRed = Color(0xFFD32F2F); // > 30 mins [9]
  static const safeGreen = Color(0xFF388E3C); // < 10 mins [9]
}

class HotelConciergeApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Digital Concierge',
      theme: ThemeData(
        primaryColor: AppColors.primary,
        scaffoldBackgroundColor: Colors.grey,
        appBarTheme: AppBarTheme(backgroundColor: AppColors.primary),
      ),
      home: LoginScreen(),
    );
  }
}

// 7. LOGIN SCREEN (Handled by Firebase Auth)
class LoginScreen extends StatefulWidget {
  @override
  _LoginScreenState createState() => _LoginScreenState();
}

class _LoginScreenState extends State<LoginScreen> {
  final _emailController = TextEditingController();
  final _passwordController = TextEditingController();
  final FirebaseAuth _auth = FirebaseAuth.instance;

  Future<void> _login() async {
    try {
      UserCredential user = await _auth.signInWithEmailAndPassword(
          email: _emailController.text, password: _passwordController.text);
      
      // Fetch Role from Firestore Users collection [2]
      DocumentSnapshot userDoc = await FirebaseFirestore.instance
          .collection('users').doc(user.user!.uid).get();
      
      if (userDoc['role'] == 'STAFF') {
        Navigator.pushReplacement(context, MaterialPageRoute(builder: (_) => StaffDashboard()));
      } else {
        Navigator.pushReplacement(context, MaterialPageRoute(builder: (_) => GuestDashboard()));
      }
    } catch (e) {
      print(e); // Handle error
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Padding(
        padding: EdgeInsets.all(20),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text("Hotel Concierge Login", style: TextStyle(fontSize: 24, fontWeight: FontWeight.bold, color: AppColors.primary)),
            TextField(controller: _emailController, decoration: InputDecoration(labelText: "Email")),
            TextField(controller: _passwordController, decoration: InputDecoration(labelText: "Password"), obscureText: true),
            SizedBox(height: 20),
            ElevatedButton(onPressed: _login, child: Text("Login"), style: ElevatedButton.styleFrom(primary: AppColors.primary)),
          ],
        ),
      ),
    );
  }
}

// I. GUEST VIEW [10], [3]
class GuestDashboard extends StatelessWidget {
  final String userId = FirebaseAuth.instance.currentUser!.uid;

  // Function to call API Gateway
  Future<void> _submitRequest(String type, Map<String, dynamic> details) async {
    // Call API Gateway URL configured in Step 3
    // Payload: { guest_id: userId, service_type: type, details: details }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text("Welcome, Guest")),
      body: Column(
        children: [
          // Service Tiles [3]
          Expanded(
            child: GridView.count(
              crossAxisCount: 2,
              children: [
                _buildServiceTile(context, "Housekeeping", Icons.cleaning_services, 
                  () => _showRequestDialog(context, "HOUSEKEEPING")),
                _buildServiceTile(context, "Dining", Icons.restaurant, () {}),
                _buildServiceTile(context, "Transport", Icons.local_taxi, () {}),
                _buildServiceTile(context, "Front Desk", Icons.concierge_key, () {}),
              ],
            ),
          ),
          // My Activity (Real-time Status) [8]
          Expanded(
            child: StreamBuilder<QuerySnapshot>(
              stream: FirebaseFirestore.instance.collection('master_requests')
                  .where('guest_id', isEqualTo: userId).snapshots(),
              builder: (context, snapshot) {
                if (!snapshot.hasData) return CircularProgressIndicator();
                return ListView(
                  children: snapshot.data!.docs.map((doc) {
                    return ListTile(
                      title: Text(doc['service_type']),
                      subtitle: Text("Status: ${doc['status']}"), // Updates PENDING -> COMPLETED
                      trailing: _buildStatusBadge(doc['status']),
                    );
                  }).toList(),
                );
              },
            ),
          ),
        ],
      ),
    );
  }

  Widget _buildServiceTile(BuildContext context, String title, IconData icon, VoidCallback onTap) {
    return Card(
      child: InkWell(
        onTap: onTap,
        child: Column(mainAxisAlignment: MainAxisAlignment.center, children: [Icon(icon, size: 40, color: AppColors.primary), Text(title)]),
      ),
    );
  }

  Widget _buildStatusBadge(String status) {
    Color color = status == 'COMPLETED' ? AppColors.safeGreen : Colors.orange;
    return Chip(label: Text(status), backgroundColor: color);
  }

  // Example Housekeeping Dialog [11]
  void _showRequestDialog(BuildContext context, String type) {
    showDialog(context: context, builder: (context) {
      return AlertDialog(
        title: Text("Request Towels"),
        content: Column(mainAxisSize: MainAxisSize.min, children: [
          Text("Quantity: 2"), // Simplified for brevity
          TextField(decoration: InputDecoration(labelText: "Allergy Note")) // [6]
        ]),
        actions: [
          TextButton(
            child: Text("Submit"),
            onPressed: () {
              _submitRequest(type, {'item_name': 'TOWELS', 'quantity': 2});
              Navigator.pop(context);
            },
          )
        ],
      );
    });
  }
}

// II. SERVICE PROVIDER VIEW [9], [12]
class StaffDashboard extends StatelessWidget {
  final String dept = 'HOUSEKEEPING'; // In real app, get from User Claims

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text("Staff Dashboard - $dept")),
      body: StreamBuilder<QuerySnapshot>(
        // Filter: Status != COMPLETED [12]
        stream: FirebaseFirestore.instance.collection('master_requests')
            .where('service_type', isEqualTo: dept)
            .where('status', isNotEqualTo: 'COMPLETED')
            .snapshots(),
        builder: (context, snapshot) {
          if (!snapshot.hasData) return CircularProgressIndicator();
          return ListView(
            children: snapshot.data!.docs.map((doc) {
              // Urgency Logic: Red if older than 30 mins [9]
              Timestamp created = doc['created_at'];
              bool isUrgent = DateTime.now().difference(created.toDate()).inMinutes > 30;
              
              return Card(
                color: isUrgent ? AppColors.urgentRed.withOpacity(0.1) : Colors.white,
                child: ListTile(
                  leading: Icon(Icons.room_service, color: isUrgent ? AppColors.urgentRed : AppColors.safeGreen),
                  title: Text("Req #${doc.id.substring(0,4)}"),
                  subtitle: Text(doc['status']),
                  trailing: ElevatedButton(
                    child: Text(doc['status'] == 'PENDING' ? "Accept" : "Complete"),
                    onPressed: () {
                      // Call API Gateway to update status [4]
                      // logic: if PENDING -> ASSIGNED, if ASSIGNED -> COMPLETED
                    },
                  ),
                ),
              );
            }).toList(),
          );
        },
      ),
    );
  }
}