[README] Add readme functionality

README.md

@@ -1,24 +1,265 @@
 # LlmEvalRuby
 
-TODO: Delete this and the text below, and describe your gem
+A Ruby gem for LLM evaluation that provides prompt management and tracing functionality. This gem supports both local and [Langfuse](https://langfuse.com/) backends for managing prompts and traces.
 
-Welcome to your new gem! In this directory, you'll find the files you need to be able to package up your Ruby library into a gem. Put your Ruby code in the file `lib/llm_eval_ruby`. To experiment with that code, run `bin/console` for an interactive prompt.
+## Features
+
+- **Prompt Management**: Fetch and compile prompts from local files or Langfuse
+- **Tracing**: Track LLM calls with spans, generations, and traces
+- **Observable Pattern**: Automatically trace method calls with decorators
+- **Multiple Adapters**: Support for local file system and Langfuse backends
+- **Template Support**: Liquid templating for dynamic prompt compilation
 
 ## Installation
 
-TODO: Replace `UPDATE_WITH_YOUR_GEM_NAME_IMMEDIATELY_AFTER_RELEASE_TO_RUBYGEMS_ORG` with your gem name right after releasing it to RubyGems.org. Please do not do it earlier due to security reasons. Alternatively, replace this section with instructions to install your gem from git if you don't plan to release to RubyGems.org.
+Add this line to your application's Gemfile:
+
+```ruby
+gem 'llm_eval_ruby'
+```
+
+And then execute:
+
+    $ bundle install
+
+Or install it yourself as:
+
+    $ gem install llm_eval_ruby
+
+## Configuration
 
-Install the gem and add to the application's Gemfile by executing:
+Configure the gem in your application initializer:
 
-    $ bundle add UPDATE_WITH_YOUR_GEM_NAME_IMMEDIATELY_AFTER_RELEASE_TO_RUBYGEMS_ORG
+```ruby
+LlmEvalRuby.configure do |config|
+  # Choose your adapter: :local or :langfuse
+  config.adapter = :langfuse
 
-If bundler is not being used to manage dependencies, install the gem by executing:
+  # Langfuse configuration
+  config.langfuse_options = {
+    public_key: "your_public_key",
+    secret_key: "your_secret_key",
+    host: "https://your-langfuse-instance.com"
+  }
 
-    $ gem install UPDATE_WITH_YOUR_GEM_NAME_IMMEDIATELY_AFTER_RELEASE_TO_RUBYGEMS_ORG
+  # Local configuration (for Rails applications)
+  config.local_options = {
+    prompts_path: "app/prompts"
+  }
+end
+```
 
 ## Usage
 
-TODO: Write usage instructions here
+### Prompt Management
+
+#### Text Prompts
+
+```ruby
+# Fetch a text prompt
+prompt = LlmEvalRuby::PromptRepositories::Text.fetch(name: "my_prompt")
+
+# Fetch and compile with variables
+compiled_prompt = LlmEvalRuby::PromptRepositories::Text.fetch_and_compile(
+  name: "my_prompt",
+  variables: { user_name: "John", task: "summarize" }
+)
+```
+
+#### Chat Prompts
+
+```ruby
+# Fetch chat prompts (returns array of messages)
+messages = LlmEvalRuby::PromptRepositories::Chat.fetch(name: "chat_prompt")
+
+# Fetch and compile chat prompts with variables
+compiled_messages = LlmEvalRuby::PromptRepositories::Chat.fetch_and_compile(
+  name: "chat_prompt",
+  variables: { context: "some context", question: "What is Ruby?" }
+)
+```
+
+#### Versioned Prompts
+
+```ruby
+# Fetch specific version
+prompt = LlmEvalRuby::PromptRepositories::Text.fetch(
+  name: "my_prompt",
+  version: "v1.2.0"
+)
+```
+
+### Tracing
+
+#### Basic Tracing
+
+```ruby
+# Create a trace
+# Langfuse does an upsert if id is given
+trace = LlmEvalRuby::Tracer.trace(
+  id: "trace_id",
+  name: "llm_call",
+  input: { prompt: "Hello, world!" }
+)
+
+# Create a span within a trace
+span = LlmEvalRuby::Tracer.span(
+  name: "preprocessing",
+  trace_id: trace.id,
+  input: { data: "raw input" }
+)
+
+# Create a generation (LLM call)
+generation = LlmEvalRuby::Tracer.generation(
+  name: "gpt_call",
+  trace_id: trace.id,
+  input: { messages: [{ role: "user", content: "Hello!" }] },
+  model: "gpt-4"
+)
+```
+
+#### Block-based Tracing
+
+```ruby
+# Trace with automatic timing
+result = LlmEvalRuby::Tracer.span(
+  name: "data_processing",
+  input: { data: input_data }
+) do |span|
+  # Your processing logic here
+  process_data(input_data)
+end
+
+# Generation with automatic result capture
+response = LlmEvalRuby::Tracer.generation(
+  name: "llm_call",
+  input: { prompt: "Translate this text" },
+  model: "gpt-4"
+) do |generation|
+  # Your LLM call here
+  client.completions(prompt: "Translate this text")
+end
+```
+
+### Observable Pattern
+
+Use the `Observable` module to automatically trace method calls:
+
+```ruby
+class MyLLMService
+  include LlmEvalRuby::Observable
+
+  # Trace as a span
+  observe :preprocess_data, type: :span
+  def preprocess_data(input)
+    # Method implementation
+  end
+
+  # Trace as a generation
+  observe :call_llm, type: :generation
+  def call_llm(messages)
+    # LLM call implementation
+  end
+
+  # Trace as a regular trace
+  observe :process_request
+  def process_request(request)
+    # Processing logic
+  end
+end
+
+# Usage
+service = MyLLMService.new
+service.instance_variable_set(:@trace_id, "some-trace-id")
+service.process_request(request_data)
+```
+
+### Local Prompt Management
+
+For local prompt management, organize your prompts in the configured directory:
+
+```
+app/prompts/
+├── my_chat_prompt/
+│   ├── system.txt
+│   └── user.txt
+└── my_text_prompt/
+    └── user.txt
+```
+
+Example prompt files with Liquid templating:
+
+**app/prompts/summarize/system.txt**
+```
+You are a helpful assistant that summarizes text.
+```
+
+**app/prompts/summarize/user.txt**
+```
+Please summarize the following text for {{ user_name }}:
+
+{{ text_to_summarize }}
+```
+
+### Advanced Usage
+
+#### Updating Generations
+
+```ruby
+# Update a generation with results
+LlmEvalRuby::Tracer.update_generation(
+  id: generation.id,
+  output: { response: "Generated text" },
+  usage: { prompt_tokens: 10, completion_tokens: 20 }
+)
+```
+
+#### Custom Trace Data
+
+```ruby
+trace = LlmEvalRuby::Tracer.trace(
+  name: "complex_workflow",
+  input: { query: "user query" },
+  metadata: { user_id: "123", session_id: "abc" },
+  tags: ["production", "important"]
+)
+```
+
+## Adapters
+
+### Langfuse Adapter
+
+The Langfuse adapter provides:
+- Cloud-based prompt management
+- Advanced tracing and analytics
+- Version control for prompts
+- Team collaboration features
+
+### Local Adapter
+
+The local adapter provides:
+- File-based prompt storage
+- Local development workflow
+- No external dependencies
+- Simple prompt organization
+
+## Error Handling
+
+The gem includes basic error handling:
+
+```ruby
+begin
+  prompt = LlmEvalRuby::PromptRepositories::Text.fetch(name: "nonexistent")
+rescue LlmEvalRuby::Error => e
+  puts "Error: #{e.message}"
+end
+```
+
+## Requirements
+
+- Ruby >= 3.3.0
+- HTTParty for API calls
+- Liquid for template rendering
 
 ## Development
 
@@ -28,12 +269,12 @@ To install this gem onto your local machine, run `bundle exec rake install`. To
 
 ## Contributing
 
-Bug reports and pull requests are welcome on GitHub at https://github.com/[USERNAME]/llm_eval_ruby. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the [code of conduct](https://github.com/[USERNAME]/llm_eval_ruby/blob/master/CODE_OF_CONDUCT.md).
+Bug reports and pull requests are welcome on GitHub at https://github.com/test-IO/llm_eval_ruby. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the [code of conduct](https://github.com/test-IO/llm_eval_ruby/blob/HEAD/CODE_OF_CONDUCT.md).
 
 ## License
 
 The gem is available as open source under the terms of the [MIT License](https://opensource.org/licenses/MIT).
 
 ## Code of Conduct
 
-Everyone interacting in the LlmEvalRuby project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the [code of conduct](https://github.com/[USERNAME]/llm_eval_ruby/blob/master/CODE_OF_CONDUCT.md).
+Everyone interacting in the LlmEvalRuby project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the [code of conduct](https://github.com/test-IO/llm_eval_ruby/blob/HEAD/CODE_OF_CONDUCT.md).