Dependency yang dibutuhkan

1. geolocator : dibutuhkan untuk mendapatkan lokasi pengguana saat ini. https://pub.dev/packages/geolocator
2. flutter_image_compress : dibutuhkan untuk megkonpresi gambar yang akan diupload
3. image_picker : dibutuhkan untuk memilih gambar yang ingin diupload

Install ketiga dependensi di atas menggunakan perintah flutter pub add namadependensi.

Notes :

Aplikasi ini hanya bisa dijalankan pada platform android. Ikuti tutorial mengakses lokasi pada perangkat android dari https://pub.dev/packages/geolocator

Implementasi AddPostScreen

1. Buat screen dengan nama add_post_screen.dart di dalam folder screen
2. Lengkapi dengan script berikut

import 'dart:convert';
import 'dart:io';
import 'package:flutter/material.dart';
import 'package:image_picker/image_picker.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:geolocator/geolocator.dart';
import 'package:flutter_image_compress/flutter_image_compress.dart';
import 'package:firebase_auth/firebase_auth.dart';

class AddPostScreen extends StatefulWidget {
  const AddPostScreen({super.key});
  @override
  State<AddPostScreen> createState() => _AddPostScreenState();
}

class _AddPostScreenState extends State<AddPostScreen> {
  File? _image;
  String? _base64Image;
  final TextEditingController _descriptionController = TextEditingController();
  final ImagePicker _picker = ImagePicker();
  bool _isUploading = false;
  double? _latitude;
  double? _longitude;
  Future<void> _pickImage(ImageSource source) async {
    final pickedFile = await _picker.pickImage(source: source);
    if (pickedFile != null) {
      setState(() {
        _image = File(pickedFile.path);
      });
      await _compressAndEncodeImage();
    }
  }

  Future<void> _compressAndEncodeImage() async {
    if (_image == null) return;
    final compressedImage = await FlutterImageCompress.compressWithFile(
      _image!.path,
      quality: 50,
    );
    if (compressedImage == null) return;
    setState(() {
      _base64Image = base64Encode(compressedImage);
    });
  }

  Future<void> _getLocation() async {
    bool serviceEnabled;
    LocationPermission permission;
    serviceEnabled = await Geolocator.isLocationServiceEnabled();
    if (!serviceEnabled) {
      throw Exception('Location services are disabled.');
    }
    permission = await Geolocator.checkPermission();
    if (permission == LocationPermission.denied) {
      permission = await Geolocator.requestPermission();
      if (permission == LocationPermission.deniedForever ||
          permission == LocationPermission.denied) {
        throw Exception('Location permissions are denied.');
      }
    }
    try {
      final position = await Geolocator.getCurrentPosition(
        locationSettings: LocationSettings(accuracy: LocationAccuracy.high),
      ).timeout(const Duration(seconds: 10));
      setState(() {
        _latitude = position.latitude;
        _longitude = position.longitude;
      });
    } catch (e) {
      debugPrint('Failed to retrieve location: $e');
      setState(() {
        _latitude = null;
        _longitude = null;
      });
    }
  }

  Future<void> _submitPost() async {
    if (_base64Image == null || _descriptionController.text.isEmpty) return;
    setState(() => _isUploading = true);
    final now = DateTime.now().toIso8601String();
    final uid = FirebaseAuth.instance.currentUser?.uid;
    if (uid == null) {
      setState(() => _isUploading = false);
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('User not found.')),
      );
      return;
    }
    try {
      await _getLocation();
      // Ambil nama lengkap dari koleksi users
      final userDoc =
          await FirebaseFirestore.instance.collection('users').doc(uid).get();
      final fullName = userDoc.data()?['fullName'] ?? 'Anonymous';
      await FirebaseFirestore.instance.collection('posts').add({
        'image': _base64Image,
        'description': _descriptionController.text,
        'createdAt': now,
        'latitude': _latitude,
        'longitude': _longitude,
        'fullName': fullName,
        'userId': uid, // optional: jika ingin simpan UID juga
      });
      if (!mounted) return;
      Navigator.pop(context);
    } catch (e) {
      debugPrint('Upload failed: $e');
      if (!mounted) return;
      setState(() => _isUploading = false);
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('Failed to upload the post.')),
      );
    }
  }

  void _showImageSourceDialog() {
    showDialog(
      context: context,
      builder: (context) => AlertDialog(
        title: Text("Choose Image Source"),
        actions: [
          TextButton(
            onPressed: () {
              Navigator.pop(context);
              _pickImage(ImageSource.camera);
            },
            child: Text("Camera"),
          ),
          TextButton(
            onPressed: () {
              Navigator.pop(context);
              _pickImage(ImageSource.gallery);
            },
            child: Text("Gallery"),
          ),
        ],
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Add Post')),
      body: SingleChildScrollView(
        padding: EdgeInsets.all(16),
        child: Column(
          children: [
            _image != null
                ? Image.file(
                    _image!,
                    height: 200,
                    width: double.infinity,
                    fit: BoxFit.cover,
                  )
                : GestureDetector(
                    onTap: _showImageSourceDialog,
                    child: Container(
                      height: 200,
                      color: Colors.grey[300],
                      child: Center(
                        child: Icon(Icons.add_a_photo, size: 50),
                      ),
                    ),
                  ),
            SizedBox(height: 16),
            TextField(
              controller: _descriptionController,
              textCapitalization: TextCapitalization.sentences,
              maxLines: 3,
              decoration: InputDecoration(
                hintText: 'Add a brief description...',
                border: OutlineInputBorder(),
              ),
            ),
            SizedBox(height: 16),
            _isUploading
                ? CircularProgressIndicator()
                : ElevatedButton.icon(
                    onPressed: _submitPost,
                    icon: Icon(Icons.upload),
                    label: Text('Post'),
                  ),
          ],
        ),
      ),
    );
  }
}

Implementasi Floating Action Button pada Home Screen

1. Lengkapi property onPressed: pada widget Floating Action Button di HomeScreen dengan kode berikut

...
  onPressed: () {
    Navigator.of(context).push(
      MaterialPageRoute(builder: (context) => AddPostScreen()),
    );
  },
...