Firebase Configuration

Overview

NASAExplorer uses Firebase for user authentication and cloud storage of favorite images with personal notes. This guide covers the complete Firebase setup process.

Firebase Services Used

Firebase Authentication: Email/password authentication
Firebase Realtime Database: Store user favorites and comments
Firebase SDK: Version 33.5.1 (using BoM)

Prerequisites

Google account
Android Studio Koala or higher
Active internet connection
Completed NASA API setup

Firebase Console Setup

Create Firebase Project

Go to Firebase Console
Click Add project or Create a project
Enter project name (e.g., “NASAExplorer”)
Choose whether to enable Google Analytics (optional)
Click Create project and wait for setup to complete

Add Android App

In your Firebase project:

Click the Android icon to add an Android app
Enter your package name:

com.ccandeladev.nasaexplorer

(Optional) Add app nickname: “NASAExplorer”
(Optional) Add SHA-1 certificate (not required for email auth)
Click Register app

Download google-services.json

Download the google-services.json configuration file
Move it to your project’s app/ directory:

NASAExplorer/
├── app/
│   ├── google-services.json  ← Place here
│   ├── build.gradle.kts
│   └── src/
└── build.gradle.kts

The google-services.json file contains your Firebase project configuration. Never commit it to public repositories.

Enable Firebase Authentication

In Firebase Console, navigate to Authentication
Click Get started
Go to Sign-in method tab
Enable Email/Password provider
Save changes

Set Up Realtime Database

Navigate to Realtime Database in Firebase Console
Click Create Database
Choose a location (e.g., europe-west1)
Start in Test mode for development

Test mode allows all reads/writes. You’ll configure security rules later.

Project Configuration

Gradle Setup

The project is already configured with Firebase dependencies:

build.gradle.kts (Project level)

plugins {
    // ... other plugins
    id("com.google.gms.google-services") version "4.4.0" apply false
}

app/build.gradle.kts

plugins {
    alias(libs.plugins.android.application)
    alias(libs.plugins.jetbrains.kotlin.android)
    kotlin("kapt")
    alias(libs.plugins.hilt)
    
    // Firebase plugin
    id("com.google.gms.google-services")
}

dependencies {
    // Firebase BoM (Bill of Materials)
    implementation(platform("com.google.firebase:firebase-bom:33.5.1"))
    
    // Firebase products
    implementation("com.google.firebase:firebase-analytics")
    implementation("com.google.firebase:firebase-auth-ktx")
    implementation("com.google.firebase:firebase-database-ktx")
}

Using Firebase BoM ensures all Firebase dependencies use compatible versions. No need to specify individual version numbers.

Dependency Injection with Hilt

Firebase services are provided through Hilt modules:

Firebase Module

FirebaseModule.kt

package com.ccandeladev.nasaexplorer.data.di

import com.google.firebase.database.DatabaseReference
import com.google.firebase.database.FirebaseDatabase
import dagger.Module
import dagger.Provides
import dagger.hilt.InstallIn
import dagger.hilt.components.SingletonComponent
import javax.inject.Singleton

@Module
@InstallIn(SingletonComponent::class)
object FirebaseModule {

    @Provides
    @Singleton
    fun provideFirebaseDatabase(): FirebaseDatabase {
        return FirebaseDatabase.getInstance()
    }
}

Authentication Module

AuthNetworkModule.kt

@Module
@InstallIn(SingletonComponent::class)
object AuthNetworkModule {

    @Provides
    @Singleton
    fun provideFirebaseAuth(): FirebaseAuth {
        return FirebaseAuth.getInstance()
    }
}

Authentication Service

The AuthService handles user authentication operations:

AuthService.kt

package com.ccandeladev.nasaexplorer.data.auth

import com.google.firebase.auth.AuthResult
import com.google.firebase.auth.FirebaseAuth
import com.google.firebase.auth.FirebaseUser
import kotlinx.coroutines.tasks.await
import javax.inject.Inject

class AuthService @Inject constructor(
    private val firebaseAuth: FirebaseAuth
) {

    /**
     * User login with email and password
     */
    suspend fun login(email: String, password: String): FirebaseUser? {
        return firebaseAuth
            .signInWithEmailAndPassword(email, password)
            .await()
            .user
    }

    /**
     * User registration with email and password
     */
    suspend fun register(email: String, password: String): FirebaseUser? {
        return firebaseAuth
            .createUserWithEmailAndPassword(email, password)
            .await()
            .user
    }

    /**
     * Sign out current user
     */
    fun userLogout() {
        firebaseAuth.signOut()
    }

    /**
     * Check if user is logged in
     */
    fun isUserLogged(): Boolean {
        return getCurrentUser() != null
    }

    private fun getCurrentUser() = firebaseAuth.currentUser
}

Database Structure

The Realtime Database uses the following structure:

{
  "favorites": {
    "<user_id>": {
      "<image_id>": {
        "id": "<firebase_generated_id>",
        "title": "Image Title",
        "url": "https://..."
      }
    }
  },
  "comments": {
    "<user_id>": {
      "<image_id>": "User's personal comment"
    }
  }
}

Example Data

{
  "favorites": {
    "abc123userId": {
      "-NxR5tPqK_abc123": {
        "id": "-NxR5tPqK_abc123",
        "title": "Eagle Nebula",
        "url": "https://apod.nasa.gov/apod/image/..."
      }
    }
  },
  "comments": {
    "abc123userId": {
      "-NxR5tPqK_abc123": "My favorite nebula! The pillars of creation are stunning."
    }
  }
}

Database Operations

Saving Favorites

DailyImageViewModel.kt

fun saveToFavorites(nasaModel: NasaModel) {
    val userId = firebaseAuth.currentUser?.uid
    if (userId != null) {
        viewModelScope.launch {
            try {
                // Create new reference with auto-generated ID
                val favoriteRef = firebaseDatabase.reference
                    .child("favorites")
                    .child(userId)
                    .push()
                
                // Prepare data
                val favoriteImage = mapOf(
                    "id" to (favoriteRef.key ?: ""),
                    "title" to nasaModel.title,
                    "url" to nasaModel.url
                )
                
                // Save to Firebase
                favoriteRef.setValue(favoriteImage).await()
                _isFavorite.value = true
            } catch (e: Exception) {
                _errorMessage.value = "Error al guardar favorito ${e.message}"
            }
        }
    }
}

Loading Favorites

FavoritesViewModel.kt

fun loadFavoriteImages() {
    val userId = firebaseAuth.currentUser?.uid
    if (userId != null) {
        viewModelScope.launch {
            _isLoading.value = true
            try {
                val favoriteRef = firebaseDatabase.reference
                    .child("favorites")
                    .child(userId)
                val snapshot = favoriteRef.get().await()

                val favoriteList = snapshot.children.mapNotNull { child ->
                    val firebaseImageId = child.key ?: return@mapNotNull null
                    val title = child.child("title").getValue(String::class.java)
                    val url = child.child("url").getValue(String::class.java)

                    if (title != null && url != null) {
                        FavoriteNasaModel(
                            firebaseImageId = firebaseImageId,
                            title = title,
                            url = url
                        )
                    } else null
                }
                
                _favoriteImages.value = favoriteList
            } catch (e: Exception) {
                _errorMessage.value = "Error al mostrar la lista de favoritos"
            } finally {
                _isLoading.value = false
            }
        }
    }
}

Adding Comments

FavoritesViewModel.kt

fun addComment(firebaseImageId: String, comment: String) {
    val userId = firebaseAuth.currentUser?.uid
    if (userId != null) {
        viewModelScope.launch {
            try {
                val commentsRef = firebaseDatabase.reference
                    .child("comments")
                    .child(userId)
                
                commentsRef.child(firebaseImageId).setValue(comment).await()

                // Update local state
                val currentComment = _comments.value.toMutableMap()
                currentComment[firebaseImageId] = comment
                _comments.value = currentComment
            } catch (e: Exception) {
                _errorMessage.value = "Error al guardar el comentario: ${e.message}"
            }
        }
    }
}

Removing Favorites

FavoritesViewModel.kt

fun removeFromFavorites(
    favoriteNasaModel: FavoriteNasaModel,
    onRemoved: () -> Unit
) {
    val userId = firebaseAuth.currentUser?.uid
    if (userId != null) {
        viewModelScope.launch {
            try {
                val favoriteRef = firebaseDatabase.reference
                    .child("favorites")
                    .child(userId)
                
                // Find and remove the favorite
                val snapshot = favoriteRef
                    .orderByChild("id")
                    .equalTo(favoriteNasaModel.firebaseImageId)
                    .get()
                    .await()

                for (child in snapshot.children) {
                    child.ref.removeValue().await()
                }

                // Remove associated comment
                val commentRef = firebaseDatabase.reference
                    .child("comments")
                    .child(userId)
                commentRef.child(favoriteNasaModel.firebaseImageId)
                    .removeValue()
                    .await()

                onRemoved()
            } catch (e: Exception) {
                _errorMessage.value = "Error al eliminar favoritos ${e.message}"
            }
        }
    }
}

google-services.json Structure

Your google-services.json file contains:

google-services.json (example)

{
  "project_info": {
    "project_number": "712153274569",
    "firebase_url": "https://nasaexplorer-f002d-default-rtdb.europe-west1.firebasedatabase.app",
    "project_id": "nasaexplorer-f002d",
    "storage_bucket": "nasaexplorer-f002d.firebasestorage.app"
  },
  "client": [
    {
      "client_info": {
        "mobilesdk_app_id": "1:712153274569:android:3f05db2b139e424b669518",
        "android_client_info": {
          "package_name": "com.ccandeladev.nasaexplorer"
        }
      },
      "api_key": [
        {
          "current_key": "AIzaSyBZHCsycE5UynnESeXZ9gDnO_3TsM1xCY0"
        }
      ]
    }
  ]
}

This file contains sensitive configuration. The project .gitignore excludes it from version control.

Troubleshooting

google-services.json Not Found

If you see a build error about missing configuration:

Verify google-services.json is in the app/ directory
Ensure the file name is exact (lowercase, no spaces)
Sync Gradle files in Android Studio
Clean and rebuild the project

Package Name Mismatch

Error: No matching client found for package name Solution:

Verify the package name in google-services.json matches your applicationId in build.gradle.kts:
```
applicationId = "com.ccandeladev.nasaexplorer"
```

Authentication Failures

If login/registration fails:

Check Firebase Console that Email/Password auth is enabled
Verify internet connectivity
Check Firebase Authentication logs in console
Ensure proper error handling in your code

Database Permission Denied

If you get permission errors:

Check your database rules (see Security Configuration)
Verify user is authenticated before database operations
Ensure proper userId is being used

Testing Firebase Integration

Run the App

Build and run NASAExplorer on an emulator or physical device.

Test Registration

Navigate to the registration screen
Create a new account with email/password
Check Firebase Console > Authentication to see the new user

Test Database Operations

Log in with your test account
Add an image to favorites
Check Firebase Console > Realtime Database to see the data
Add a comment to the favorite
Verify both favorites and comments appear in the database

Next Steps

Now that Firebase is configured:

Set up security rules for production
Learn about MVVM architecture
Review Testing guide

Remember to configure proper security rules before deploying to production. See the Security Configuration guide for details.

Get Started

Core Features

Architecture

Configuration

Overview

Firebase Services Used

Prerequisites

Firebase Console Setup

Project Configuration

Gradle Setup

Dependency Injection with Hilt

Firebase Module

Authentication Module

Authentication Service

Database Structure

Example Data

Database Operations

Saving Favorites

Loading Favorites

Adding Comments

Removing Favorites

google-services.json Structure

Troubleshooting

google-services.json Not Found

Package Name Mismatch

Authentication Failures

Database Permission Denied

Testing Firebase Integration

Next Steps

Build docs developers (and LLMs) love

Get Started

Core Features

Architecture

Configuration

​Overview

​Firebase Services Used

​Prerequisites

​Firebase Console Setup

​Project Configuration

​Gradle Setup

​Dependency Injection with Hilt

​Firebase Module

​Authentication Module

​Authentication Service

​Database Structure

​Example Data

​Database Operations

​Saving Favorites

​Loading Favorites

​Adding Comments

​Removing Favorites

​google-services.json Structure

​Troubleshooting

​google-services.json Not Found

​Package Name Mismatch

​Authentication Failures

​Database Permission Denied

​Testing Firebase Integration

​Next Steps

Build docs developers (and LLMs) love

Overview

Firebase Services Used

Prerequisites

Firebase Console Setup

Project Configuration

Gradle Setup

Dependency Injection with Hilt

Firebase Module

Authentication Module

Authentication Service

Database Structure

Example Data

Database Operations

Saving Favorites

Loading Favorites

Adding Comments

Removing Favorites

google-services.json Structure

Troubleshooting

google-services.json Not Found

Package Name Mismatch

Authentication Failures

Database Permission Denied

Testing Firebase Integration

Next Steps