Aplikasi absensi mahasiswa modern berbasis Android yang mengimplementasikan arsitektur MVVM (Model-View-ViewModel) dengan pendekatan offline-first. Sistem ini memastikan validitas kehadiran mahasiswa melalui verifikasi lokasi GPS dan pengambilan foto selfie secara real-time saat melakukan absensi.

Fitur utama:

Validasi lokasi berbasis GPS dengan radius 500 meter dari titik kampus
Pengambilan foto selfie wajib saat absensi
Penyimpanan data lokal dengan sinkronisasi otomatis ke backend
Sistem login offline dengan enkripsi data
Riwayat absensi tersimpan secara lokal
Anti-spam: Satu foto untuk satu kali absensi

DEPENDENCY LENGKAP (build.gradle.kts)

Core Android

// AndroidX Core
implementation("androidx.core:core-ktx:1.17.0")
// Kotlin standard library dan extensions

Jetpack Compose

// Compose BOM (Bill of Materials) - Mengelola versi Compose
implementation(platform("androidx.compose:compose-bom:2024.09.00"))

// Compose UI
implementation("androidx.compose.ui:ui")
implementation("androidx.compose.ui:ui-graphics")
implementation("androidx.compose.ui:ui-tooling-preview")

// Material Design 3
implementation("androidx.compose.material3:material3")

// Material Icons Extended
implementation("androidx.compose.material:material-icons-extended:1.6.0")

Lifecycle & ViewModel

// Lifecycle Runtime
implementation("androidx.lifecycle:lifecycle-runtime-ktx:2.9.4")
implementation("androidx.lifecycle:lifecycle-runtime-compose:2.7.0")

// ViewModel untuk Compose
implementation("androidx.lifecycle:lifecycle-viewmodel-compose:2.7.0")

// Activity untuk Compose
implementation("androidx.activity:activity-compose:1.9.0")

Location Services

// Google Play Services Location
implementation("com.google.android.gms:play-services-location:21.0.1")

Database (Room)

// Room components
implementation("androidx.room:room-runtime:2.6.1")
implementation("androidx.room:room-ktx:2.6.1")
kapt("androidx.room:room-compiler:2.6.1")  // Annotation processor

Network

// Retrofit
implementation("com.squareup.retrofit2:retrofit:2.9.0")
implementation("com.squareup.retrofit2:converter-gson:2.9.0")

// OkHttp
implementation("com.squareup.okhttp3:logging-interceptor:4.11.0")

Security

// Encrypted SharedPreferences
implementation("androidx.security:security-crypto:1.1.0-alpha06")

Background Work

// WorkManager
implementation("androidx.work:work-runtime-ktx:2.9.0")

Coroutines

// Kotlin Coroutines
implementation("org.jetbrains.kotlinx:kotlinx-coroutines-android:1.7.3")

Image Loading

// Coil untuk Compose
implementation("io.coil-kt:coil-compose:2.6.0")

JSON Processing

// Gson
implementation("com.google.code.gson:gson:2.10.1")

Testing

// Unit Testing
testImplementation("junit:junit:4.13.2")

// Instrumented Testing
androidTestImplementation("androidx.test.ext:junit:1.3.0")
androidTestImplementation("androidx.test.espresso:espresso-core:3.7.0")
androidTestImplementation(platform("androidx.compose:compose-bom:2024.09.00"))
androidTestImplementation("androidx.compose.ui:ui-test-junit4")

// Debug
debugImplementation("androidx.compose.ui:ui-tooling")
debugImplementation("androidx.compose.ui:ui-test-manifest")

Gradle Plugins

plugins {
    alias(libs.plugins.android.application)       // AGP 8.13.2
    alias(libs.plugins.kotlin.android)             // Kotlin 2.0.21
    alias(libs.plugins.kotlin.compose)             // Compose Compiler
    id("org.jetbrains.kotlin.kapt")               // KAPT untuk Room
}

ALASAN PEMILIHAN TEKNOLOGI

Mengapa Jetpack Compose?

Modern & Declarative: Lebih intuitif dan less boilerplate dibanding XML
Type-safe: Compile-time error detection
Reactive: Automatic UI updates saat state berubah
Performance: Efficient rendering dengan recomposition
Official: Recommended oleh Google untuk new projects
Community: Strong community support dan active development

Mengapa Room Database?

Type-safe SQL: Compile-time SQL query verification
Coroutine Support: Native async/await dengan suspend functions
Reactive Queries: Flow untuk reactive updates
Migration Support: Easy database version management
Performance: Optimized SQLite wrapper
Official: Part of Android Jetpack

Mengapa WorkManager?

Guaranteed Execution: Task akan dijalankan meski app tertutup
Battery Efficient: System-managed scheduling
Constraints: Network, battery, storage constraints
Backward Compatible: Works dari API 14+
Retry Logic: Built-in retry dengan backoff
Official: Recommended untuk background work

Mengapa Retrofit + OkHttp?

Type-safe: Type-safe REST client
Coroutine Support: Native suspend functions
Converter: Auto JSON parsing dengan Gson
Interceptor: Logging, auth, retry logic
Industry Standard: Most popular Android HTTP client
Maintained: Active development dan support

Mengapa Encrypted SharedPreferences?

Security: AES256-GCM encryption
Hardware-backed: Android Keystore System
Transparent: No manual encryption code needed
Simple API: Same as regular SharedPreferences
Official: Part of Jetpack Security
Compliant: Meets security best practices

Mengapa Kotlin Coroutines?

Lightweight: Efficient thread management
Structured Concurrency: Prevents memory leaks
Sequential Code: Async code looks synchronous
Exception Handling: Structured exception propagation
Cancellation: Automatic cleanup
Official: First-class support in Android

Mengapa Coil untuk Image Loading?

Kotlin-first: Written in Kotlin untuk Kotlin
Compose-native: AsyncImage composable
Coroutine-based: Non-blocking operations
Modern: Uses OkHttp, supports latest formats
Lightweight: Smaller APK size vs Glide/Picasso
Fast: Memory & disk caching

PERBANDINGAN ALTERNATIF

UI Framework

Jetpack Compose vs XML Views
- Compose: Less code, reactive, modern
- XML: Mature, more resources, backward compatible
- Pilihan: Compose (future-proof, better DX)

Database

Room vs Realm vs SQLite
- Room: Type-safe, official, Jetpack integration
- Realm: Fast, cross-platform
- SQLite: Full control, verbose
- Pilihan: Room (best practices, official support)

Image Loading

Coil vs Glide vs Picasso
- Coil: Kotlin-first, Compose-native, modern
- Glide: Mature, feature-rich, large
- Picasso: Simple, lightweight, older
- Pilihan: Coil (best for Compose)

HTTP Client

Retrofit vs Ktor vs Volley
- Retrofit: Type-safe, widely used, mature
- Ktor: Kotlin-native, modern, less adoption
- Volley: Google-made, older, less features
- Pilihan: Retrofit (industry standard)

State Management

StateFlow vs LiveData vs RxJava
- StateFlow: Kotlin-native, Compose-friendly
- LiveData: Lifecycle-aware, older
- RxJava: Powerful, steep learning curve
- Pilihan: StateFlow (modern, simple, official)

ARSITEKTUR APLIKASI

Pattern & Struktur

MVVM (Model-View-ViewModel) dengan Offline-First Architecture

presentation/           UI Layer (Jetpack Compose)
├── auth/              Halaman Login & Registrasi
├── absensi/           Halaman Absensi Utama
└── history/           Halaman Riwayat Absensi

data/                   Data Layer
├── local/             Local Storage
│   ├── database/      Room Database
│   ├── dao/           Data Access Object
│   └── entity/        Database Entity
├── repository/        Repository Pattern
├── network/           Network Service (n8n)
├── worker/            Background Sync Worker
└── model/             Data Models

utils/                  Utility Classes
├── NetworkUtils       Network Connection Check
└── ImageUtils         Image Processing & Base64

TEKNOLOGI & LIBRARY

Platform & Bahasa

Platform: Android
Bahasa: Kotlin 2.0.21
Min SDK: 28 (Android 9.0 Pie)
- Alasan: Support untuk Security Crypto, modern permission system, dan coverage market share yang memadai
Target SDK: 36 (Android 14+)
Compile SDK: 36
JDK: Java 11 (source & target compatibility)

UI Framework & Design System

Jetpack Compose - Modern Declarative UI Framework

Compose BOM: 2024.09.00
androidx.compose.ui: Core Compose UI
androidx.compose.ui.graphics: Graphics primitives
androidx.compose.ui.tooling: Preview & debugging tools
Keunggulan:
- Less code dibanding XML
- Reactive & declarative
- Type-safe
- Hot reload support
- Interoperability dengan View system

Material Design 3

androidx.compose.material3: Material Design 3 components
Components yang digunakan:
- Scaffold (app structure)
- TopAppBar (navigation bar)
- Card (content containers)
- Button & OutlinedButton (actions)
- OutlinedTextField (form inputs)
- Text (typography)
- CircularProgressIndicator (loading states)
- AlertDialog (confirmations)
Fitur: Dynamic color, adaptive layouts, modern color system

Material Icons Extended

Version: 1.6.0
Library: androidx.compose.material:material-icons-extended
Icons: Person, Lock, Visibility, VisibilityOff, CameraAlt, MyLocation, History, Logout, Check, Close
Total Icons: 2000+ icons tersedia

Database & Storage Layer

Room Database - SQLite ORM (Object-Relational Mapping)

Version: 2.6.1
Components:
- room-runtime: Core library
- room-ktx: Kotlin extensions & coroutine support
- room-compiler: Annotation processor (KAPT)
Fitur yang digunakan:
- @Entity (table definition)
- @Dao (data access object)
- @Query (SQL queries)
- @Insert, @Update, @Delete
- Flow untuk reactive queries
- Suspend functions untuk coroutines
- Migration support
Table: attendance_history
Keunggulan: Compile-time verification, type-safe queries, reactive streams

Encrypted SharedPreferences - Secure Key-Value Storage

Library: androidx.security:security-crypto:1.1.0-alpha06
Encryption: AES256-GCM (Galois/Counter Mode)
Key Management: MasterKey dengan Android Keystore System
Key Scheme: AES256_GCM
Value Encryption: AES256_GCM
Key Encryption: AES256_SIV (Synthetic IV)
Fitur: Transparent encryption/decryption, hardware-backed keys
Data yang disimpan: Username, Password, isRegistered, isLogin (semua terenkripsi)

Location Services

Google Play Services Location

Version: 21.0.1
Library: com.google.android.gms:play-services-location
API: Fused Location Provider API
Fitur yang digunakan:
- FusedLocationProviderClient (high-level API)
- LocationRequest (accuracy & interval settings)
- LocationCallback (location updates)
- Priority: PRIORITY_HIGH_ACCURACY
Validasi:
- 12 campus points dengan koordinat GPS
- Haversine Formula untuk kalkulasi jarak
- Location.distanceBetween() (Android built-in)
- Max radius: 500 meter
Keunggulan: Battery-efficient, most accurate location

Network & Backend Integration

Retrofit - Type-safe HTTP Client

Version: 2.9.0
Library: com.squareup.retrofit2:retrofit
Fitur: REST API calls, coroutine support, request/response converters
Usage: POST data absensi ke n8n webhook

Gson - JSON Serialization/Deserialization

Gson Version: 2.10.1
Retrofit Converter: com.squareup.retrofit2:converter-gson:2.9.0
Fitur: Automatic JSON parsing, custom type adapters
Usage: Convert data objects ke JSON payload

OkHttp - HTTP Client & Interceptor

Version: 4.11.0
Library: com.squareup.okhttp3:logging-interceptor
Fitur: HTTP logging, connection pooling, interceptors
Usage: Debug network requests/responses, timeout configuration
Timeout Settings: 30 detik connection & read timeout

n8n Webhook Integration

Backend: n8n Self-hosted Workflow Automation
Host: n8n.lab.ubharajaya.ac.id
Method: HTTP POST
Content-Type: application/json
Endpoint Production: /webhook/23c6993d-1792-48fb-ad1c-ffc78a3e6254
Endpoint Testing: /webhook-test/23c6993d-1792-48fb-ad1c-ffc78a3e6254
Payload: JSON dengan foto Base64, koordinat, timestamp, mata kuliah

Background Processing

WorkManager - Background Task Scheduler

Version: 2.9.0
Library: androidx.work:work-runtime-ktx
Fitur:
- Guaranteed execution (even after app restart)
- Constraints (network, battery, storage)
- Retry logic dengan exponential backoff
- Work chaining
- CoroutineWorker integration
Usage: AttendanceSyncWorker untuk sync data PENDING ke backend
Trigger: Network available constraint
Strategy: Periodic check & automatic retry

Kotlin Coroutines - Asynchronous Programming

Version: 1.7.3
Library: org.jetbrains.kotlinx:kotlinx-coroutines-android
Dispatchers:
- Dispatchers.Main: UI operations & state updates
- Dispatchers.IO: Network requests & database operations
- Dispatchers.Default: CPU-intensive computations
Features: suspend functions, async/await, structured concurrency
Usage: Semua async operations (database, network, location)

Flow & StateFlow - Reactive Streams

Flow: Cold stream untuk one-time operations
StateFlow: Hot stream untuk UI state management
MutableStateFlow: Mutable state holder
collectAsState(): Compose integration untuk observe state
Usage: ViewModel state management, database queries, UI updates

Image Processing

Coil - Image Loading Library untuk Compose

Version: 2.6.0
Library: io.coil-kt:coil-compose
Fitur:
- AsyncImage composable
- Memory & disk caching
- Image transformations
- Compose-first design
- Coroutine-based
Usage: Load & display foto absensi di riwayat

Custom Image Utils

Base64 Encoding: Convert Bitmap ke Base64 string
Bitmap Compression: JPEG compression dengan quality 80%
File I/O: Save/load foto dari internal storage
Camera Integration: ActivityResultContracts.TakePicture()
Usage: Prepare foto untuk kirim ke backend

Architecture Components

Lifecycle - Lifecycle-Aware Components

lifecycle-runtime-ktx: 2.9.4
lifecycle-runtime-compose: 2.7.0
lifecycle-viewmodel-compose: 2.7.0
Fitur: LifecycleOwner, ViewModelScope, collectAsStateWithLifecycle
Usage: Manage UI lifecycle, survive configuration changes

ViewModel - UI State Holder

Library: androidx.lifecycle:lifecycle-viewmodel-compose
Features: Survive configuration changes, ViewModelScope
ViewModels: AuthViewModel, AbsensiViewModel, AttendanceHistoryViewModel
State Management: StateFlow untuk expose state ke UI

Activity Compose

Version: 1.9.0
Library: androidx.activity:activity-compose
Features: setContent {} untuk Compose, ComponentActivity, permission handling
Usage: MainActivity sebagai entry point

Build Tools & Gradle

Gradle

Version: 8.13.2
Type: Kotlin DSL (build.gradle.kts)
Plugin: Android Gradle Plugin (AGP)
Features: Dependency management, build variants, ProGuard/R8

Kotlin Compiler

Kotlin Version: 2.0.21
Compose Compiler Plugin: org.jetbrains.kotlin.plugin.compose
KAPT: Kotlin Annotation Processing Tool (untuk Room compiler)
Target: JVM 11

Version Catalog

File: gradle/libs.versions.toml
Fitur: Centralized dependency management, type-safe accessors
Benefits: Single source of truth, easy updates, IDE support

Testing Framework

Unit Testing

JUnit: 4.13.2 (unit test framework)
Location: src/test/java/

Instrumented Testing

AndroidX Test JUnit: 1.3.0
Espresso Core: 3.7.0
Compose UI Test: androidx.compose.ui:ui-test-junit4
Location: src/androidTest/java/

Debug Tools

Compose UI Tooling: Preview & inspection
Compose UI Test Manifest: Test configuration

Utilities & Helpers

NetworkUtils.kt

Purpose: Network connectivity checking
API: ConnectivityManager
Usage: Cek internet sebelum sync ke backend

ImageUtils.kt

Purpose: Image processing & conversion
Functions: bitmapToBase64, compression, file operations
Usage: Prepare foto untuk upload

Security & Permissions

Android Permissions

ACCESS_FINE_LOCATION (GPS)
ACCESS_COARSE_LOCATION (Network location)
CAMERA (Take photos)
INTERNET (Network communication)

Security Features

Encrypted local storage
HTTPS communication
Hardware-backed key storage (Keystore)
No hardcoded credentials
Certificate transparency

FITUR APLIKASI

Konsep: First-time setup dengan one-time registration
Metode: Offline (tidak menggunakan server)
Penyimpanan: Encrypted SharedPreferences
Enkripsi: AES256-GCM dengan MasterKey
Data tersimpan:
- Username (terenkripsi)
- Password (terenkripsi)
- isRegistered flag
- isLogin flag
Flow:
- Pertama kali: Buat username & password
- Selanjutnya: Login dengan kredensial tersimpan
- Validasi: Dilakukan secara lokal

2. ABSENSI BERBASIS LOKASI

Validasi radius: Maksimal 500 meter dari titik kampus
Jumlah titik kampus: 12 lokasi strategis
Titik kampus meliputi:
- Kampus Ubhara Jaya (Pusat)
- Fakultas Ilmu Komputer
- Fakultas Ekonomi dan Bisnis
- Fakultas Psikologi
- Perpustakaan Tanoto
- Grha Tanoto
- Masjid Ulul Albab
- Work Caffe Bekasi
- Lapangan Ubhara
- Sekretariat Kapal Baja
- Ruang Sedang Semu
- ATM BRI Ubhara Jaya
Algoritma: Haversine Formula untuk hitung jarak
Response: Menampilkan nama lokasi terdekat & jarak

3. PENGAMBILAN FOTO ABSENSI

Mode: Kamera depan (selfie)
Trigger: Langsung saat proses absensi
Batasan: Satu foto untuk satu kali absensi (anti-spam)
Penyimpanan: Internal storage aplikasi
Format: JPEG dengan kompresi
Pengiriman: Konversi ke Base64 untuk dikirim ke backend

4. PENYIMPANAN DATA LOKAL

Database: Room (SQLite) Table: attendance_history

Schema:

id: String (UUID, Primary Key)
studentId: String (NPM mahasiswa)
studentName: String (Nama mahasiswa)
courseName: String (Nama mata kuliah)
photoPath: String (Path foto di storage)
dateTime: Long (Timestamp Unix)
latitude: Double (Koordinat lintang)
longitude: Double (Koordinat bujur)
locationName: String (Nama lokasi terdekat)
distanceMeter: Int (Jarak dari titik kampus)
attendanceStatus: String (SUCCESS/FAILED)
syncStatus: String (PENDING/SYNCED)
createdAt: Long (Timestamp pembuatan)

5. SINKRONISASI BACKEND

Service: n8n Webhook Automation
Method: POST HTTP Request
Format: JSON dengan foto Base64
Strategy: Offline-first dengan background sync
Worker: AttendanceSyncWorker (WorkManager)
Retry: Otomatis saat koneksi internet tersedia
Flow:
1. Simpan data ke local database
2. Cek koneksi internet
3. Jika online: Kirim langsung ke n8n
4. Jika offline: Tandai PENDING
5. Background worker cek pending data
6. Kirim ulang saat internet tersedia
7. Update status menjadi SYNCED

Payload ke n8n:

{
  "npm": "202310715083",
  "nama": "Rakha Adi Saputro",
  "mata_kuliah": "Nama Mata Kuliah",
  "latitude": -6.224158,
  "longitude": 107.009268,
  "timestamp": "2025-01-14T10:30:00Z",
  "foto_base64": "base64_encoded_image_string"
}

6. RIWAYAT ABSENSI

Screen: AttendanceHistoryScreen
Data source: Room Database (local)
Layout: LazyColumn (efficient scrolling)
Card components:
- Thumbnail foto absensi
- Nama mata kuliah
- Waktu absensi (formatted)
- Koordinat lokasi
- Jarak dari kampus
- Status sinkronisasi (PENDING/SYNCED)
Filter: Semua data dari lokal
Offline support: Full offline browsing

7. DATA MAHASISWA

Data mahasiswa yang digunakan fixed (hardcoded):

NPM: 202310715083
Nama: Rakha Adi Saputro

Catatan: Data ini tidak diambil dari login, tetapi langsung diset di aplikasi

PERMISSIONS ANDROID

Aplikasi memerlukan izin berikut:

<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
<uses-permission android:name="android.permission.CAMERA"/>

Hardware features:

<uses-feature android:name="android.hardware.camera" android:required="false"/>

BACKEND INTEGRATION

n8n Workflow Automation

Platform: n8n (Self-hosted)
Host: n8n.lab.ubharajaya.ac.id
Endpoint Production: /webhook/23c6993d-1792-48fb-ad1c-ffc78a3e6254
Endpoint Testing: /webhook-test/23c6993d-1792-48fb-ad1c-ffc78a3e6254

Data Destination

Google Sheets
- URL: https://docs.google.com/spreadsheets/d/1jH15MfnNgpPGuGeid0hYfY7fFUHCEFbCmg8afTyyLZs
- Columns: NPM, Nama, Mata Kuliah, Latitude, Longitude, Timestamp, Foto
ntfy Notification Service
- URL: https://ntfy.ubharajaya.ac.id/EAS
- Purpose: Real-time notification untuk dosen/admin

Workflow n8n

File: n8n-workflow-EAS.json Flow:

Webhook Trigger (receive POST data)
Data Validation
Write to Google Sheets
Send notification via ntfy
Return response to mobile app

STRUKTUR DATA FLOW

User Action (Absensi)
    |
    v
Validasi Lokasi GPS
    |
    v
Ambil Foto Selfie
    |
    v
Simpan ke Room Database (Local)
    |
    v
Update UI (Riwayat bertambah)
    |
    v
Cek Koneksi Internet
    |
    +---> [Online]  ---> Kirim ke n8n Webhook
    |                         |
    |                         v
    |                    Update syncStatus = SYNCED
    |
    +---> [Offline] ---> Set syncStatus = PENDING
                              |
                              v
                         WorkManager scheduled
                              |
                              v
                    [Internet tersedia]
                              |
                              v
                    Retry kirim data PENDING
                              |
                              v
                    Update syncStatus = SYNCED

CARA KERJA SISTEM

Flow Lengkap Absensi:

PERSIAPAN
- User buka aplikasi
- Jika belum login: tampilkan AuthScreen
- Jika sudah login: tampilkan AbsensiScreen
HALAMAN ABSENSI
- Tampilkan NPM dan Nama (hardcoded)
- Input mata kuliah
- Tombol ambil foto
- Request permissions (Camera & Location)
PROSES ABSENSI
- User klik tombol absensi
- Sistem cek permission camera
- Buka camera untuk selfie
- User ambil foto
- Foto ditampilkan sebagai preview
- Sistem ambil koordinat GPS otomatis
- Validasi jarak dari titik kampus
VALIDASI
- Cek jarak < 500 meter?
  - Ya: Lanjut proses
  - Tidak: Tampilkan error & batalkan
- Cek foto valid?
  - Ya: Lanjut proses
  - Tidak: Minta foto ulang
PENYIMPANAN
- Generate UUID untuk attendance ID
- Simpan foto ke internal storage
- Simpan data ke Room Database
- Set syncStatus = PENDING
SINKRONISASI
- Cek koneksi internet
- Jika online:
  - Encode foto ke Base64
  - Kirim POST ke n8n webhook
  - Jika sukses: Update syncStatus = SYNCED
  - Jika gagal: Tetap PENDING
- Jika offline:
  - Skip sync
  - Data tetap PENDING
  - WorkManager akan retry nanti
BACKGROUND SYNC
- WorkManager cek setiap internet tersedia
- Ambil semua data PENDING
- Kirim satu per satu ke n8n
- Update status yang berhasil
- Retry yang gagal
RIWAYAT
- User bisa lihat semua absensi di HistoryScreen
- Data diambil dari Room Database
- Menampilkan status PENDING/SYNCED
- Full offline support

KEAMANAN

1. Enkripsi Data

Encrypted SharedPreferences dengan AES256-GCM
MasterKey untuk enkripsi kredensial login
Password tidak disimpan plain text

2. Validasi Lokasi

Multi-point validation (12 titik kampus)
Radius enforcement (500 meter maksimal)
Real-time distance calculation

3. Anti-Fraud

Satu foto untuk satu absensi
Foto harus diambil real-time (tidak bisa dari gallery)
Timestamp server-side di n8n
Validasi koordinat di backend (opsional)

4. Offline Security

Data lokal terenkripsi
No sensitive data in plain text
Secure file storage

KONFIGURASI ENDPOINT

File: ApiConfig.kt Location: data/network/ApiConfig.kt

object ApiConfig {
    const val N8N_WEBHOOK_URL = 
        "https://n8n.lab.ubharajaya.ac.id/webhook/23c6993d-1792-48fb-ad1c-ffc78a3e6254"
    
    // Untuk testing:
    // const val N8N_WEBHOOK_URL = 
    //     "https://n8n.lab.ubharajaya.ac.id/webhook-test/23c6993d-1792-48fb-ad1c-ffc78a3e6254"
    
    const val CONNECTION_TIMEOUT = 30000 // 30 detik
    const val READ_TIMEOUT = 30000 // 30 detik
}

Keuntungan centralized config:

Mudah switch antara production & testing
Tidak perlu ubah banyak file
Maintenance lebih simple
Deploy lebih aman

ANDROID SDK CONFIGURATION

SDK Versions

android {
    compileSdk = 36
    
    defaultConfig {
        applicationId = "id.ac.ubharajaya.sistemakademik"
        minSdk = 28
        targetSdk = 36
        versionCode = 1
        versionName = "1.0"
    }
}

Min SDK 28 (Android 9.0 Pie) - Coverage & Features

Alasan pemilihan Min SDK 28:

Market Coverage: ~80% devices (2024-2025 data)
Security Features:
- Mandatory HTTPS
- BiometricPrompt API
- Security Crypto support
Modern APIs:
- ImageDecoder API
- DisplayCutout support
- Indoor positioning (WiFi RTT)
Location Features:
- Foreground location access
- Better battery optimization
Camera Features:
- Multi-camera API
- Session parameters
Performance:
- ART improvements
- Background restrictions

Target SDK 36 (Android 14+) - Latest Features

Benefits:

Google Play requirement compliance
Latest security patches
Performance optimizations
New API features
Better battery management
Enhanced privacy controls

Compile SDK 36

Access to latest Android APIs
Build tools compatibility
Preview features
Development libraries

Java Compatibility

compileOptions {
    sourceCompatibility = JavaVersion.VERSION_11
    targetCompatibility = JavaVersion.VERSION_11
}

kotlinOptions {
    jvmTarget = "11"
}

Java 11 Features:

Lambda expressions
Method references
Stream API
Optional class
Try-with-resources
Type inference (var)

BUILD CONFIGURATION

Build Types

Debug Build

buildTypes {
    debug {
        isMinifyEnabled = false
        isDebuggable = true
        applicationIdSuffix = ".debug"
        versionNameSuffix = "-DEBUG"
    }
}

Features:

No code obfuscation
Full logging enabled
Faster build time
Debug symbols included
Network profiler enabled

Release Build

buildTypes {
    release {
        isMinifyEnabled = false  // Set true for production
        proguardFiles(
            getDefaultProguardFile("proguard-android-optimize.txt"),
            "proguard-rules.pro"
        )
        signingConfig = signingConfigs.getByName("release")
    }
}

Features:

Code shrinking (ProGuard/R8)
Obfuscation
Optimization
Signing required
Smaller APK size

Build Features

buildFeatures {
    compose = true
}

Enables Jetpack Compose
Compose compiler integration
Preview support

ProGuard/R8 Configuration

File: proguard-rules.pro

Purpose:

Code shrinking (remove unused code)
Obfuscation (rename classes/methods)
Optimization (inline, etc.)
APK size reduction

Keep Rules for:

Room entities (@Entity)
Retrofit interfaces
Gson models
Parcelable classes

APK Outputs

Debug APK:

Path: app/build/outputs/apk/debug/app-debug.apk
Size: ~15-20 MB (with debug symbols)
Command: .\gradlew assembleDebug

Release APK:

Path: app/build/outputs/apk/release/app-release.apk
Size: ~8-12 MB (minified)
Command: .\gradlew assembleRelease

GRADLE BUILD SYSTEM

Requirements

Android Studio Ladybug atau lebih baru
JDK 11 atau lebih tinggi
Android SDK 28-36
Gradle 8.13.2
Koneksi internet (untuk dependency download)

Build Commands

Development Build:

.\gradlew assembleDebug

Release Build:

.\gradlew assembleRelease

Clean Build:

.\gradlew clean assembleDebug

Install ke Device:

.\gradlew installDebug

Run Tests:

.\gradlew test

Output Location

APK Debug: app/build/outputs/apk/debug/app-debug.apk APK Release: app/build/outputs/apk/release/app-release.apk

TESTING

Akun Testing

Saat pertama kali buka aplikasi:

Buat username dan password bebas
Data tersimpan secara offline
Login selanjutnya gunakan kredensial tersebut

Testing Lokasi

Opsi 1: Test di lokasi kampus (ideal) Opsi 2: Mock location untuk development:

Enable Developer Options
Select mock location app
Gunakan koordinat salah satu dari 12 titik kampus

Testing n8n Webhook

Gunakan endpoint testing:

https://n8n.lab.ubharajaya.ac.id/webhook-test/23c6993d-1792-48fb-ad1c-ffc78a3e6254

Ganti di ApiConfig.kt untuk testing

Monitoring

Google Sheets: Cek data masuk
ntfy: Cek notifikasi real-time
Logcat: Monitor logs di Android Studio

TROUBLESHOOTING

Issue: Foto tidak terkirim ke backend

Solusi:

Cek koneksi internet
Cek endpoint n8n aktif
Lihat syncStatus di riwayat (PENDING berarti belum terkirim)
Background worker akan retry otomatis

Issue: Lokasi tidak valid padahal di kampus

Solusi:

Pastikan GPS aktif
Tunggu GPS lock (butuh waktu)
Cek permission lokasi granted
Pastikan tidak menggunakan VPN yang mengubah lokasi

Issue: Kamera tidak bisa dibuka

Solusi:

Cek permission camera granted
Restart aplikasi
Pastikan camera tidak digunakan app lain
Cek hardware camera berfungsi

Issue: Data tidak tersimpan di database

Solusi:

Cek storage permission
Cek disk space mencukupi
Lihat logcat untuk error Room
Clear app data dan coba lagi

Issue: WorkManager tidak sync

Solusi:

Pastikan internet stabil
Cek battery optimization (disable untuk app ini)
Force sync dengan buka riwayat
Restart device

Author

NAMA : RAKHA ADI SAPUTRO
NPM : 202310715083

README.md

Aplikasi Absensi Akademik Berbasis Koordinat dan Foto

INFORMASI PROYEK

DESKRIPSI SISTEM

DEPENDENCY LENGKAP (build.gradle.kts)

Core Android

Jetpack Compose

Lifecycle & ViewModel

Activity & Navigation

Location Services

Database (Room)

Network

Security

Background Work

Coroutines

Image Loading

JSON Processing

Testing

Gradle Plugins

ALASAN PEMILIHAN TEKNOLOGI

Mengapa Jetpack Compose?

Mengapa Room Database?

Mengapa WorkManager?

Mengapa Retrofit + OkHttp?

Mengapa Encrypted SharedPreferences?

Mengapa Kotlin Coroutines?

Mengapa Coil untuk Image Loading?

PERBANDINGAN ALTERNATIF

UI Framework

Database

Image Loading

HTTP Client

State Management

ARSITEKTUR APLIKASI

Pattern & Struktur

TEKNOLOGI & LIBRARY

Platform & Bahasa

UI Framework & Design System

Database & Storage Layer

Location Services

Network & Backend Integration

Background Processing

Image Processing

Architecture Components

Build Tools & Gradle

Testing Framework

Utilities & Helpers

Security & Permissions

FITUR APLIKASI

1. SISTEM LOGIN OFFLINE

2. ABSENSI BERBASIS LOKASI

3. PENGAMBILAN FOTO ABSENSI

4. PENYIMPANAN DATA LOKAL

5. SINKRONISASI BACKEND

6. RIWAYAT ABSENSI

7. DATA MAHASISWA

PERMISSIONS ANDROID

BACKEND INTEGRATION

n8n Workflow Automation

Data Destination

Workflow n8n

STRUKTUR DATA FLOW

CARA KERJA SISTEM

Flow Lengkap Absensi:

KEAMANAN

1. Enkripsi Data

2. Validasi Lokasi

3. Anti-Fraud

4. Offline Security

KONFIGURASI ENDPOINT

ANDROID SDK CONFIGURATION

SDK Versions

Min SDK 28 (Android 9.0 Pie) - Coverage & Features

Target SDK 36 (Android 14+) - Latest Features

Compile SDK 36

Java Compatibility

BUILD CONFIGURATION

Build Types

Debug Build

Release Build