Gson and Parcelize to kotlinx.serialization

[yet300]

Description

This PR migrates the entire Bitchat Android codebase from using Android's Parcelize and Google's Gson to Kotlin's native kotlinx.serialization library. This modernization brings significant benefits in terms of performance, type safety, and future-proofing.

🚀 Why This Migration?

Current Pain Points

• Reflection overhead: Gson uses heavy reflection at runtime, impacting performance
• Runtime errors: Type mismatches and serialization issues only discovered at runtime
• APK bloat: Gson adds significant binary size due to reflection metadata
• Maintenance burden: Two different serialization systems (Parcelize for Android, Gson for JSON)
• Limited multiplatform support: Gson is JVM-only, limiting future Kotlin Multiplatform adoption

Benefits of kotlinx.serialization

• Compile-time safety: All serialization code generated at compile time
• Better performance: No reflection overhead, faster serialization/deserialization
• Smaller APK: Reduced binary size without reflection metadata
• Unified approach: Single serialization system for all data formats
• Multiplatform ready: Native Kotlin solution works across all platforms
• Modern ecosystem: Official JetBrains library with active development

🔧 Technical Changes

Dependencies Updated

// Removed
implementation("com.google.code.gson:gson:2.13.1")
id("kotlin-parcelize")

// Added  
implementation("org.jetbrains.kotlinx:kotlinx-serialization-json:1.8.0")
id("org.jetbrains.kotlin.plugin.serialization")

Custom Serializers Created

• DateSerializer: Handles java.util.Date using milliseconds since epoch
• ByteArraySerializer: Handles ByteArray using Base64 encoding
• UByteSerializer & ULongSerializer: Handle unsigned integer types
• JsonUtil: Centralized JSON operations replacing Gson usage

Files Migrated

Model Classes (Parcelize → @serializable)

• BitchatMessage + DeliveryStatus enum
• IdentityAnnouncement
• NoisePayload, PrivateMessagePacket, ReadReceipt
• BitchatPacket with binary protocol support

Nostr Protocol Classes (Gson → kotlinx.serialization)

• NostrEvent with @SerialName field mapping
• NostrRequest with custom JSON array serialization
• NostrFilter with tag filter support
• NostrResponse with updated parsing logic

Service Classes

• SeenMessageStore: Message deduplication storage
• GeohashBookmarksStore: Location channel bookmarks
• LocationChannelManager: Channel data persistence
• FavoritesPersistenceService: Complex nested data structures
• DataManager: Application preferences
• NoiseChannelEncryption: Encrypted channel packets

📱 Impact Assessment

Positive Impacts

• Performance: Faster app startup and JSON operations
• Reliability: Compile-time error detection prevents runtime crashes
• Maintainability: Single, modern serialization approach
• Future-proofing: Ready for Kotlin Multiplatform expansion
• Developer experience: Better IDE support and debugging

Risk Mitigation

• Gradual rollout: Can be feature-flagged if needed
• Rollback plan: Previous Gson implementation preserved in git history
• Monitoring: Performance metrics tracked post-deployment
• Testing: Comprehensive test coverage ensures compatibility

🔍 Code Quality Improvements

• Type Safety: Eliminated Map<String, Any> usage with proper data classes
• Null Safety: Better null handling with kotlinx.serialization's optional fields
• Performance: Removed reflection-based serialization bottlenecks
• Consistency: Unified serialization approach across entire codebase

Checklist

• Remove Gson and Parcelize dependencies
• Add kotlinx.serialization dependencies
• Create custom serializers for Date, ByteArray, UByte, ULong
• Migrate all @Parcelize classes to @Serializable
• Replace all Gson usage with JsonUtil
• Update Nostr protocol JSON handling
• Migrate service layer persistence
• Update build configuration
• Verify all tests pass
• Performance testing completed

[callebtc]

Thank you, great addition. I will review this.