# Aplikasi Absensi Akademik Berbasis Koordinat dan Foto

Sistem Absensi Mahasiswa Universitas Bhayangkara Jakarta Raya
Berbasis Android dengan validasi lokasi GPS dan foto real-time

---

## INFORMASI PROYEK

Nama        : Rakha Adi Saputro
NPM         : 202310715083
Mata Kuliah : Pemrograman Mobile
Universitas : Universitas Bhayangkara Jakarta Raya
Tahun       : 2025-2026

---

## DESKRIPSI SISTEM

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

### Jetpack Compose
```kotlin
// 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
```kotlin
// 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 & Navigation
```kotlin
// Activity untuk Compose
implementation("androidx.activity:activity-compose:1.9.0")
```

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

### Database (Room)
```kotlin
// 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
```kotlin
// 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
```kotlin
// Encrypted SharedPreferences
implementation("androidx.security:security-crypto:1.1.0-alpha06")
```

### Background Work
```kotlin
// WorkManager
implementation("androidx.work:work-runtime-ktx:2.9.0")
```

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

### Image Loading
```kotlin
// Coil untuk Compose
implementation("io.coil-kt:coil-compose:2.6.0")
```

### JSON Processing
```kotlin
// Gson
implementation("com.google.code.gson:gson:2.10.1")
```

### Testing
```kotlin
// 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
```kotlin
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?
1. **Modern & Declarative**: Lebih intuitif dan less boilerplate dibanding XML
2. **Type-safe**: Compile-time error detection
3. **Reactive**: Automatic UI updates saat state berubah
4. **Performance**: Efficient rendering dengan recomposition
5. **Official**: Recommended oleh Google untuk new projects
6. **Community**: Strong community support dan active development

### Mengapa Room Database?
1. **Type-safe SQL**: Compile-time SQL query verification
2. **Coroutine Support**: Native async/await dengan suspend functions
3. **Reactive Queries**: Flow<T> untuk reactive updates
4. **Migration Support**: Easy database version management
5. **Performance**: Optimized SQLite wrapper
6. **Official**: Part of Android Jetpack

### Mengapa WorkManager?
1. **Guaranteed Execution**: Task akan dijalankan meski app tertutup
2. **Battery Efficient**: System-managed scheduling
3. **Constraints**: Network, battery, storage constraints
4. **Backward Compatible**: Works dari API 14+
5. **Retry Logic**: Built-in retry dengan backoff
6. **Official**: Recommended untuk background work

### Mengapa Retrofit + OkHttp?
1. **Type-safe**: Type-safe REST client
2. **Coroutine Support**: Native suspend functions
3. **Converter**: Auto JSON parsing dengan Gson
4. **Interceptor**: Logging, auth, retry logic
5. **Industry Standard**: Most popular Android HTTP client
6. **Maintained**: Active development dan support

### Mengapa Encrypted SharedPreferences?
1. **Security**: AES256-GCM encryption
2. **Hardware-backed**: Android Keystore System
3. **Transparent**: No manual encryption code needed
4. **Simple API**: Same as regular SharedPreferences
5. **Official**: Part of Jetpack Security
6. **Compliant**: Meets security best practices

### Mengapa Kotlin Coroutines?
1. **Lightweight**: Efficient thread management
2. **Structured Concurrency**: Prevents memory leaks
3. **Sequential Code**: Async code looks synchronous
4. **Exception Handling**: Structured exception propagation
5. **Cancellation**: Automatic cleanup
6. **Official**: First-class support in Android

### Mengapa Coil untuk Image Loading?
1. **Kotlin-first**: Written in Kotlin untuk Kotlin
2. **Compose-native**: AsyncImage composable
3. **Coroutine-based**: Non-blocking operations
4. **Modern**: Uses OkHttp, supports latest formats
5. **Lightweight**: Smaller APK size vs Glide/Picasso
6. **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<T> 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

### 1. SISTEM LOGIN OFFLINE
- 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:
```json
{
  "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:

```xml
<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:
```xml
<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
1. Google Sheets
   - URL: https://docs.google.com/spreadsheets/d/1jH15MfnNgpPGuGeid0hYfY7fFUHCEFbCmg8afTyyLZs
   - Columns: NPM, Nama, Mata Kuliah, Latitude, Longitude, Timestamp, Foto
   
2. 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:
1. Webhook Trigger (receive POST data)
2. Data Validation
3. Write to Google Sheets
4. Send notification via ntfy
5. 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:

1. PERSIAPAN
   - User buka aplikasi
   - Jika belum login: tampilkan AuthScreen
   - Jika sudah login: tampilkan AbsensiScreen

2. HALAMAN ABSENSI
   - Tampilkan NPM dan Nama (hardcoded)
   - Input mata kuliah
   - Tombol ambil foto
   - Request permissions (Camera & Location)

3. 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

4. VALIDASI
   - Cek jarak < 500 meter?
     - Ya: Lanjut proses
     - Tidak: Tampilkan error & batalkan
   - Cek foto valid?
     - Ya: Lanjut proses
     - Tidak: Minta foto ulang

5. PENYIMPANAN
   - Generate UUID untuk attendance ID
   - Simpan foto ke internal storage
   - Simpan data ke Room Database
   - Set syncStatus = PENDING

6. 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

7. BACKGROUND SYNC
   - WorkManager cek setiap internet tersedia
   - Ambil semua data PENDING
   - Kirim satu per satu ke n8n
   - Update status yang berhasil
   - Retry yang gagal

8. 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

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

### Target SDK 36 (Android 14+) - Latest Features
**Benefits:**
1. Google Play requirement compliance
2. Latest security patches
3. Performance optimizations
4. New API features
5. Better battery management
6. Enhanced privacy controls

### Compile SDK 36
- Access to latest Android APIs
- Build tools compatibility
- Preview features
- Development libraries

### Java Compatibility
```kotlin
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
```kotlin
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
```kotlin
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
```kotlin
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:
```bash
.\gradlew assembleDebug
```

Release Build:
```bash
.\gradlew assembleRelease
```

Clean Build:
```bash
.\gradlew clean assembleDebug
```

Install ke Device:
```bash
.\gradlew installDebug
```

Run Tests:
```bash
.\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