docs: add comprehensive AAR integration troubleshooting guide

- Add AAR Duplicate Class Issues section to BUILDING.md with step-by-step solutions - Create dedicated docs/aar-integration-troubleshooting.md with complete troubleshooting guide - Document project reference approach (recommended) vs AAR-only approach - Add verification steps, prevention strategies, and best practices - Update README.md with links to new documentation - Resolve duplicate class issues through proper project reference configuration Fixes AAR integration issues that caused build failures due to plugin being included both as project reference and AAR file simultaneously.
1 day ago · ef37b10503
3 changed files with 446 additions and 0 deletions
--- a/BUILDING.md
+++ b/BUILDING.md
@ -537,6 +537,45 @@ adb install app/build/outputs/apk/debug/app-debug.apk
 - Interactive testing interface
 - Comprehensive logging and debugging

+**Plugin Integration Approach:**
+The Vue 3 test app uses a **project reference approach** for plugin integration:
+
+1. **Project Reference Configuration**:
+   ```gradle
+   // capacitor.settings.gradle
+   include ':timesafari-daily-notification-plugin'
+   project(':timesafari-daily-notification-plugin').projectDir = new File('../../../android/plugin')
+   
+   // capacitor.build.gradle
+   implementation project(':timesafari-daily-notification-plugin')
+   ```
+
+2. **Required Dependencies**:
+   ```gradle
+   // app/build.gradle
+   implementation 'androidx.work:work-runtime:2.9.0'
+   implementation 'androidx.lifecycle:lifecycle-service:2.7.0'
+   implementation 'com.google.code.gson:gson:2.10.1'
+   ```
+
+3. **Plugin Discovery**:
+   ```json
+   // assets/capacitor.plugins.json
+   [
+     {
+       "id": "DailyNotification",
+       "name": "DailyNotification", 
+       "class": "com.timesafari.dailynotification.DailyNotificationPlugin"
+     }
+   ]
+   ```
+
+**Troubleshooting Integration Issues:**
+- **Duplicate Classes**: Use project reference instead of AAR to avoid conflicts
+- **Gradle Cache**: Clear completely (`rm -rf ~/.gradle`) when switching approaches
+- **Path Issues**: Ensure correct project path (`../../../android/plugin`)
+- **Dependencies**: Include required WorkManager and Gson dependencies
+
 ### Integration Testing

 #### 1. Create External Test Capacitor App
@ -857,6 +896,39 @@ npm list @timesafari/daily-notification-plugin
 npx cap sync android
 ```

+#### AAR Duplicate Class Issues
+```bash
+# Problem: Duplicate class errors when integrating plugin AAR
+# Error: "Duplicate class com.timesafari.dailynotification.BootReceiver found in modules"
+# Root Cause: Plugin being included both as project reference and as AAR file
+
+# Solution 1: Use Project Reference Approach (Recommended)
+# 1. Clear Gradle cache completely
+./gradlew --stop
+rm -rf ~/.gradle
+rm -rf app/build
+rm -rf build
+
+# 2. Configure project reference in capacitor.settings.gradle
+include ':timesafari-daily-notification-plugin'
+project(':timesafari-daily-notification-plugin').projectDir = new File('../../../android/plugin')
+
+# 3. Add dependency in capacitor.build.gradle
+implementation project(':timesafari-daily-notification-plugin')
+
+# 4. Remove AAR dependency from app/build.gradle
+# Comment out: implementation(name: 'plugin-debug', ext: 'aar')
+
+# Solution 2: AAR-Only Approach (Alternative)
+# 1. Remove project references from capacitor.settings.gradle and capacitor.build.gradle
+# 2. Ensure only AAR dependency in app/build.gradle
+# 3. Remove any duplicate classes.jar files from libs/ directory
+# 4. Clear Gradle cache and rebuild
+
+# Verification: Check that plugin is included only once
+./gradlew :app:dependencies | grep timesafari
+```
+
 ### Debug Commands

 #### Android Debugging
--- a/README.md
+++ b/README.md
@ -735,6 +735,8 @@ MIT License - see [LICENSE](LICENSE) file for details.
 - **API Reference**: Complete TypeScript definitions
 - **Migration Guide**: [doc/migration-guide.md](doc/migration-guide.md)
 - **Integration Guide**: [INTEGRATION_GUIDE.md](INTEGRATION_GUIDE.md) - Complete integration instructions
+- **Building Guide**: [BUILDING.md](BUILDING.md) - Comprehensive build instructions and troubleshooting
+- **AAR Integration Troubleshooting**: [docs/aar-integration-troubleshooting.md](docs/aar-integration-troubleshooting.md) - Resolving duplicate class issues
 - **Implementation Guide**: [doc/STARRED_PROJECTS_POLLING_IMPLEMENTATION.md](doc/STARRED_PROJECTS_POLLING_IMPLEMENTATION.md) - Generic polling interface
 - **UI Requirements**: [doc/UI_REQUIREMENTS.md](doc/UI_REQUIREMENTS.md) - Complete UI component requirements
 - **Host App Examples**: [examples/hello-poll.ts](examples/hello-poll.ts) - Generic polling integration
--- a/docs/aar-integration-troubleshooting.md
+++ b/docs/aar-integration-troubleshooting.md
@ -0,0 +1,372 @@
+# AAR Integration Troubleshooting Guide
+
+**Author**: Matthew Raymer  
+**Last Updated**: 2025-01-27  
+**Version**: 1.0.0
+
+## Overview
+
+This document provides comprehensive troubleshooting guidance for integrating the DailyNotification plugin AAR into Android applications, specifically addressing the common duplicate class issues that occur during plugin integration.
+
+## Table of Contents
+
+- [Common Issues](#common-issues)
+- [Root Cause Analysis](#root-cause-analysis)
+- [Solution Approaches](#solution-approaches)
+- [Step-by-Step Resolution](#step-by-step-resolution)
+- [Verification Steps](#verification-steps)
+- [Prevention Strategies](#prevention-strategies)
+- [Best Practices](#best-practices)
+
+## Common Issues
+
+### Duplicate Class Errors
+
+**Error Message:**
+```
+Duplicate class com.timesafari.dailynotification.BootReceiver found in modules:
+- plugin-debug.aar -> plugin-debug-runtime (:plugin-debug:)
+- plugin-debug.aar -> plugin-debug-runtime (plugin-debug.aar)
+```
+
+**Symptoms:**
+- Build fails with duplicate class errors
+- Plugin classes appear twice in dependency tree
+- Gradle build process hangs or fails
+- AAR integration appears broken
+
+### Gradle Cache Corruption
+
+**Error Message:**
+```
+Could not read workspace metadata from /home/user/.gradle/caches/8.13/transforms/.../metadata.bin
+No matching variant of project :timesafari-daily-notification-plugin was found
+```
+
+**Symptoms:**
+- Gradle sync failures
+- Project reference resolution issues
+- Inconsistent build behavior
+- Cache-related build errors
+
+## Root Cause Analysis
+
+### Primary Cause: Dual Inclusion
+
+The duplicate class issue occurs when the plugin is included **twice** in the build process:
+
+1. **As Project Reference**: Capacitor's automatic plugin discovery includes the plugin as a project reference
+2. **As AAR File**: The AAR file is also included directly in the build dependencies
+
+### Contributing Factors
+
+1. **Capacitor Auto-Discovery**: Capacitor automatically discovers plugins via `capacitor.plugins.json`
+2. **Symlinked Dependencies**: Node modules may create symlinks that confuse Gradle
+3. **Gradle Cache Issues**: Corrupted cache can cause inconsistent behavior
+4. **Path Resolution**: Incorrect project paths can cause module resolution failures
+
+### Technical Details
+
+**Project Reference Path:**
+```gradle
+project(':timesafari-daily-notification-plugin').projectDir = new File('../../../android/plugin')
+```
+
+**AAR File Path:**
+```gradle
+implementation(name: 'plugin-debug', ext: 'aar')
+```
+
+**Capacitor Discovery:**
+```json
+{
+  "id": "DailyNotification",
+  "name": "DailyNotification",
+  "class": "com.timesafari.dailynotification.DailyNotificationPlugin"
+}
+```
+
+## Solution Approaches
+
+### Approach 1: Project Reference (Recommended)
+
+**Advantages:**
+- ✅ No duplicate class issues
+- ✅ Better development experience
+- ✅ Automatic dependency resolution
+- ✅ Easier debugging and testing
+
+**Disadvantages:**
+- ❌ Requires correct project structure
+- ❌ More complex initial setup
+- ❌ Path-dependent configuration
+
+### Approach 2: AAR-Only
+
+**Advantages:**
+- ✅ Simpler dependency management
+- ✅ Self-contained distribution
+- ✅ No project structure dependencies
+
+**Disadvantages:**
+- ❌ Prone to duplicate class issues
+- ❌ Requires manual dependency management
+- ❌ Harder to debug and test
+
+## Step-by-Step Resolution
+
+### Method 1: Project Reference Resolution
+
+#### Step 1: Clear Gradle Cache
+```bash
+# Stop Gradle daemon
+./gradlew --stop
+
+# Clear all Gradle caches
+rm -rf ~/.gradle
+
+# Clear project build directories
+rm -rf app/build
+rm -rf build
+```
+
+#### Step 2: Configure Project Reference
+```gradle
+# capacitor.settings.gradle
+include ':timesafari-daily-notification-plugin'
+project(':timesafari-daily-notification-plugin').projectDir = new File('../../../android/plugin')
+```
+
+#### Step 3: Add Project Dependency
+```gradle
+# capacitor.build.gradle
+dependencies {
+    implementation project(':timesafari-daily-notification-plugin')
+}
+```
+
+#### Step 4: Remove AAR Dependency
+```gradle
+# app/build.gradle
+dependencies {
+    // Comment out or remove AAR dependency
+    // implementation(name: 'plugin-debug', ext: 'aar')
+    
+    // Keep required dependencies
+    implementation 'androidx.work:work-runtime:2.9.0'
+    implementation 'androidx.lifecycle:lifecycle-service:2.7.0'
+    implementation 'com.google.code.gson:gson:2.10.1'
+}
+```
+
+#### Step 5: Verify Plugin Discovery
+```json
+// assets/capacitor.plugins.json
+[
+  {
+    "id": "DailyNotification",
+    "name": "DailyNotification",
+    "class": "com.timesafari.dailynotification.DailyNotificationPlugin"
+  }
+]
+```
+
+### Method 2: AAR-Only Resolution
+
+#### Step 1: Remove Project References
+```gradle
+# capacitor.settings.gradle - Comment out project reference
+// include ':timesafari-daily-notification-plugin'
+// project(':timesafari-daily-notification-plugin').projectDir = new File('../../../android/plugin')
+
+# capacitor.build.gradle - Comment out project dependency
+// implementation project(':timesafari-daily-notification-plugin')
+```
+
+#### Step 2: Ensure AAR-Only Dependency
+```gradle
+# app/build.gradle
+dependencies {
+    implementation(name: 'plugin-debug', ext: 'aar')
+    implementation 'androidx.work:work-runtime:2.9.0'
+    implementation 'androidx.lifecycle:lifecycle-service:2.7.0'
+    implementation 'com.google.code.gson:gson:2.10.1'
+}
+```
+
+#### Step 3: Remove Duplicate Files
+```bash
+# Remove any duplicate classes.jar files
+rm -f libs/classes.jar
+rm -f libs/*.jar
+
+# Clean and rebuild
+./gradlew clean build
+```
+
+## Verification Steps
+
+### 1. Check Dependency Tree
+```bash
+# Verify plugin is included only once
+./gradlew :app:dependencies | grep timesafari
+```
+
+**Expected Output:**
+```
+--- project :timesafari-daily-notification-plugin
+```
+
+**Problematic Output:**
+```
+--- project :timesafari-daily-notification-plugin
+--- plugin-debug.aar
+```
+
+### 2. Build Verification
+```bash
+# Clean build should succeed
+./gradlew clean assembleDebug
+```
+
+**Success Indicators:**
+- ✅ Build completes without errors
+- ✅ No duplicate class warnings
+- ✅ APK generated successfully
+
+### 3. Runtime Verification
+```bash
+# Install and test
+adb install app/build/outputs/apk/debug/app-debug.apk
+adb logcat | grep DailyNotification
+```
+
+**Success Indicators:**
+- ✅ App launches without crashes
+- ✅ Plugin detected in logs
+- ✅ Plugin methods accessible
+
+## Prevention Strategies
+
+### 1. Consistent Approach Selection
+
+**Choose One Approach:**
+- **Development**: Use project reference for better debugging
+- **Production**: Use AAR for simpler distribution
+- **Never Mix**: Don't use both approaches simultaneously
+
+### 2. Gradle Cache Management
+
+**Regular Maintenance:**
+```bash
+# Weekly cache cleanup
+./gradlew --stop
+rm -rf ~/.gradle/caches
+```
+
+**Before Major Changes:**
+```bash
+# Clear cache before switching approaches
+rm -rf ~/.gradle
+```
+
+### 3. Project Structure Validation
+
+**Verify Paths:**
+```bash
+# Check project structure
+ls -la ../../../android/plugin/
+ls -la libs/
+```
+
+**Validate Configuration:**
+```bash
+# Check Gradle configuration
+./gradlew :app:dependencies --configuration debugRuntimeClasspath
+```
+
+## Best Practices
+
+### 1. Development Workflow
+
+**Initial Setup:**
+1. Choose integration approach (project reference recommended)
+2. Configure all necessary files
+3. Clear Gradle cache
+4. Build and test
+
+**Ongoing Development:**
+1. Avoid switching approaches mid-development
+2. Clear cache when making structural changes
+3. Test integration after major updates
+
+### 2. Configuration Management
+
+**File Organization:**
+- Keep `capacitor.settings.gradle` minimal
+- Use `capacitor.build.gradle` for dependencies
+- Maintain `capacitor.plugins.json` for discovery
+
+**Version Consistency:**
+- Use consistent Android Gradle Plugin versions
+- Align Gradle wrapper versions
+- Match dependency versions across modules
+
+### 3. Testing Strategy
+
+**Build Testing:**
+- Test both debug and release builds
+- Verify on multiple Android versions
+- Check dependency resolution
+
+**Runtime Testing:**
+- Test plugin functionality
+- Verify permission handling
+- Check background task execution
+
+## Troubleshooting Checklist
+
+### Before Starting
+- [ ] Clear Gradle cache (`rm -rf ~/.gradle`)
+- [ ] Stop Gradle daemon (`./gradlew --stop`)
+- [ ] Verify project structure
+- [ ] Check file permissions
+
+### During Integration
+- [ ] Use only one integration approach
+- [ ] Verify all configuration files
+- [ ] Check dependency tree
+- [ ] Test build process
+
+### After Integration
+- [ ] Verify app launches
+- [ ] Test plugin functionality
+- [ ] Check logs for errors
+- [ ] Validate permissions
+
+### Common Mistakes
+- [ ] Mixing project reference and AAR approaches
+- [ ] Incorrect project paths
+- [ ] Forgetting to clear Gradle cache
+- [ ] Missing required dependencies
+- [ ] Incorrect plugin discovery configuration
+
+## Support and Resources
+
+### Documentation
+- [BUILDING.md](../BUILDING.md) - Main build documentation
+- [INTEGRATION_GUIDE.md](../INTEGRATION_GUIDE.md) - Integration guide
+- [API.md](../API.md) - Plugin API documentation
+
+### Community
+- [GitHub Issues](https://github.com/timesafari/daily-notification-plugin/issues)
+- [Capacitor Community](https://github.com/ionic-team/capacitor/discussions)
+
+### Tools
+- `./gradlew :app:dependencies` - Dependency analysis
+- `adb logcat | grep DailyNotification` - Runtime debugging
+- `./gradlew clean build` - Clean build verification
+
+---
+
+**Remember**: The key to successful AAR integration is consistency. Choose one approach, configure it properly, and maintain it throughout development. When in doubt, clear the Gradle cache and start fresh.