# Gemini Telemetry Implementation - Complete

## 🎉 Implementation Status: COMPLETE ✅

The Gemini library now includes comprehensive telemetry instrumentation that emits events for all API operations, enabling automatic observability and integration with Foundation's telemetry system.

## 📊 Implementation Summary

### ✅ **Added Dependencies**
- Added `:telemetry, "~> 1.2"` to `mix.exs`

### ✅ **Telemetry Events Implemented**

#### Request Events
- `[:gemini, :request, :start]` - Emitted when an API request begins
- `[:gemini, :request, :stop]` - Emitted when an API request completes successfully  
- `[:gemini, :request, :exception]` - Emitted when an API request fails

#### Streaming Events
- `[:gemini, :stream, :start]` - Emitted when a streaming request begins
- `[:gemini, :stream, :chunk]` - Emitted when a streaming chunk is received
- `[:gemini, :stream, :stop]` - Emitted when a streaming request completes
- `[:gemini, :stream, :exception]` - Emitted when a streaming request fails

### ✅ **Files Modified/Created**

#### New Files
- `lib/gemini/telemetry.ex` - Core telemetry helper module
- `test/gemini/telemetry_test.exs` - Comprehensive test suite
- `telemetry_demo.exs` - Demonstration script
- `simple_telemetry_test.exs` - Simple test script
- `TELEMETRY_IMPLEMENTATION.md` - This documentation

#### Modified Files
- `mix.exs` - Added telemetry dependency
- `lib/gemini/config.ex` - Added telemetry configuration support
- `lib/gemini/client/http.ex` - Instrumented HTTP requests
- `lib/gemini/client/http_streaming.ex` - Instrumented streaming requests  
- `lib/gemini/generate.ex` - Enhanced with telemetry metadata

### ✅ **Key Features Implemented**

#### 1. **Configurable Telemetry**
```elixir
# Enable/disable telemetry (default: enabled)
config :gemini_ex, telemetry_enabled: true

# Check status
Gemini.Config.telemetry_enabled?()
```

#### 2. **Rich Metadata**
Every telemetry event includes:
- `url` - API endpoint URL
- `method` - HTTP method (:post, :get, etc.)
- `model` - Gemini model being used
- `function` - High-level function (:generate_content, :stream_generate, etc.)
- `contents_type` - Content type (:text, :multimodal, :unknown)
- `stream_id` - Unique ID for streaming requests
- `system_time` - System timestamp

#### 3. **Performance Measurements**
- `duration` - Request duration in milliseconds
- `status` - HTTP status code
- `chunk_size` - Size of streaming chunks in bytes
- `total_chunks` - Total chunks in streaming requests
- `total_duration` - Total streaming duration

#### 4. **Error Tracking**
- `reason` - Exception or error details for failed requests

#### 5. **Content Classification**
- Automatically classifies content as `:text`, `:multimodal`, or `:unknown`
- Enables content-type specific analytics

## 🧪 Testing

### Unit Tests
```bash
# Run telemetry-specific tests
mix test test/gemini/telemetry_test.exs

# All tests pass
mix test
```

### Live API Testing
```bash
# Set up authentication
export GEMINI_API_KEY="your-api-key"

# Run live tests with telemetry events
mix test test/live_api_test.exs --include live_api
```

### Interactive Testing
```elixir
# Start IEx session
iex -S mix

# Test configuration
Gemini.Config.telemetry_enabled?()
# => true

# Test helper functions
Gemini.Telemetry.generate_stream_id()
# => "a1b2c3d4e5f6g7h8"

Gemini.Telemetry.classify_contents("Hello world")
# => :text

# Attach telemetry handler to see events
:telemetry.attach("demo", [:gemini, :request, :start], fn event, measurements, metadata, _ ->
  IO.inspect({event, measurements, metadata})
end, nil)

# Make API call (with valid key) to see telemetry events
Gemini.generate("Hello world")
```

## 🔗 Foundation Integration

With this implementation, the Foundation library's `Foundation.Integrations.GeminiAdapter` can now automatically capture all Gemini telemetry events:

### Expected Telemetry Flow
1. **Gemini Library** → Emits telemetry events
2. **Foundation Adapter** → Captures events automatically  
3. **Foundation Events** → Stores in event system
4. **Monitoring/Analytics** → Process stored events

### Example Event Output
```elixir
# Foundation will capture events like:
[
  %Foundation.Event{
    type: :gemini_request_start, 
    data: %{
      model: "gemini-2.0-flash-lite", 
      function: :generate_content,
      contents_type: :text,
      url: "https://generativelanguage.googleapis.com/...",
      system_time: 1704067200000
    }
  },
  %Foundation.Event{
    type: :gemini_request_stop,
    data: %{
      duration: 1250,
      status: 200,
      model: "gemini-2.0-flash-lite"
    }
  }
]
```

## 📈 Benefits Achieved

### 1. **Automatic Observability**
- Zero-configuration telemetry for all API calls
- Request duration and performance tracking
- Error tracking and debugging support

### 2. **Streaming Analytics**
- Real-time chunk-level metrics
- Stream completion tracking  
- Streaming performance analysis

### 3. **Content-Type Analytics**
- Automatic classification of text vs multimodal content
- Usage pattern analysis
- Content-specific performance metrics

### 4. **Foundation Integration**
- Seamless integration with Foundation's event system
- Automatic event storage and processing
- No additional configuration required

### 5. **Developer Experience**
- Rich debugging information
- Performance bottleneck identification
- Production monitoring capabilities

## 🎯 Usage Examples

### Basic Request Telemetry
```elixir
# This call now emits telemetry events automatically
{:ok, response} = Gemini.generate("Explain quantum physics")

# Events emitted:
# 1. [:gemini, :request, :start] - with metadata
# 2. [:gemini, :request, :stop] - with duration and status
```

### Streaming Telemetry  
```elixir
# Streaming calls emit additional events
Gemini.stream_generate("Write a story") do |chunk|
  # Events emitted for each chunk:
  # [:gemini, :stream, :chunk] - with chunk size
end

# Final event:
# [:gemini, :stream, :stop] - with total duration and chunk count
```

### Error Telemetry
```elixir
# Failed requests emit exception events
{:error, reason} = Gemini.generate("test", model: "invalid-model")

# Event emitted:
# [:gemini, :request, :exception] - with error details
```

## 🔧 Configuration Options

### Enable/Disable Telemetry
```elixir
# In config/config.exs
config :gemini_ex, telemetry_enabled: true  # default

# Or at runtime
Application.put_env(:gemini_ex, :telemetry_enabled, false)
```

### Custom Telemetry Handlers
```elixir
# Attach custom handlers for specific events
:telemetry.attach("my-handler", [:gemini, :request, :stop], fn _event, measurements, metadata, _config ->
  Logger.info("Request completed in #{measurements.duration}ms to #{metadata.model}")
end, nil)
```

## ✅ Verification Checklist

- [x] **Dependencies**: Telemetry dependency added to mix.exs
- [x] **Configuration**: Telemetry enable/disable support
- [x] **HTTP Client**: Request telemetry instrumentation 
- [x] **Streaming Client**: Streaming telemetry instrumentation
- [x] **Generate Module**: High-level API telemetry integration
- [x] **Helper Module**: Comprehensive telemetry utilities
- [x] **Content Classification**: Automatic text/multimodal detection
- [x] **Error Handling**: Exception telemetry support  
- [x] **Metadata**: Rich context in all events
- [x] **Measurements**: Performance metrics collection
- [x] **Tests**: Comprehensive test coverage
- [x] **Documentation**: Complete implementation docs
- [x] **Compilation**: No errors or warnings
- [x] **Test Suite**: All existing tests still pass

## 🚀 Ready for Foundation Integration

The Gemini library is now fully instrumented with telemetry and ready for integration with Foundation's `Foundation.Integrations.GeminiAdapter`. The adapter should automatically detect and capture all telemetry events without any additional configuration.

### Next Steps for Foundation Integration:
1. Deploy this version of gemini_ex
2. Verify Foundation adapter detects telemetry events
3. Test event storage in Foundation.Events
4. Monitor telemetry in production

---

**Implementation Complete** ✅  
**All Requirements Met** ✅  
**Ready for Production** ✅