athena-framework

What this skill does

# Athena Framework Skill

Athena Framework is a modular web framework for Crystal, inspired by Symfony. It consists of independent, reusable components that can be used together or à la carte.

## When to Use This Skill

Use this skill when you are:
- **Building web applications** with the Athena Framework (ATH)
- **Creating REST APIs** using Athena's routing and controller system
- **Implementing dependency injection** with ADI (Athena DependencyInjection)
- **Adding HTTP routing** with ART (Athena Routing)
- **Serializing objects** with ASR (Athena Serializer)
- **Validating data** with AVD (Athena Validator)
- **Writing CLI commands** with ACON (Athena Console)
- **Implementing event-driven architecture** with AED (Athena EventDispatcher)
- **Working with individual Athena components** in any Crystal project
- **Debugging Athena applications**
- **Learning Crystal web development patterns**

## Key Concepts

### Component Overview

| Component | Alias | Purpose |
|-----------|-------|---------|
| Framework | `ATH` | Full-stack web framework with controllers, middleware, responses |
| DependencyInjection | `ADI` | IoC container for managing service dependencies |
| Routing | `ART` | HTTP routing with annotations, requirements, and matching |
| Serializer | `ASR` | Object (de)serialization to JSON, YAML, etc. |
| Validator | `AVD` | Declarative object validation with constraints |
| Console | `ACON` | CLI command framework with styled output |
| EventDispatcher | `AED` | Event-driven architecture with listeners/dispatchers |
| Negotiation | `ANEG` | Content negotiation for requests/responses |
| ImageSize | `AIS` | Get image dimensions without processing |
| Clock | `ACLK` | Time abstraction for testing |

## Quick Reference

### HTTP Routing (ART)

**Define a route with requirements:**

```crystal
class ExampleController < ATH::Controller
  @[ARTA::Get("/user/{id}")]
  def get_user(id : Int64) : Int64
    id
  end

  @[ARTA::Get("/article/{slug}")]
  def get_article(slug : String) : String
    slug
  end
end
```

**Built-in route requirements:**

```crystal
# Only matches digits
ART::Requirement::DIGITS        # /[0-9]+/

# Matches URL-safe slugs
ART::Requirement::ASCII_SLUG    # /[A-Za-z0-9]+(?:-[A-Za-z0-9]+)*/

# Date format YYYY-MM-DD
ART::Requirement::DATE_YMD      # /[0-9]{4}-(?:0[1-9]|1[012])-(?:0[1-9]|[12][0-9]|(?<!02-)3[01])/

# UUID formats
ART::Requirement::UID_BASE32    # /[0-9A-HJKMNP-TV-Z]{26}/
ART::Requirement::UID_BASE58    # /[1-9A-HJ-NP-Za-km-z]{22}/
ART::Requirement::UID_RFC4122   # /[0-9a-f]{8}(?:-[0-9a-f]{4}){3}-[0-9a-f]{12}/
```

**Route with optional parameters:**

```crystal
# /blog would match with default page=1
# /blog/10 would match with page=10
ART::Route.new "/blog/{page}", {"page" => 1}, {"page" => /\d+/}
```

**Route with custom conditions:**

```crystal
route = ART::Route.new "/contact"
route.condition do |context, request|
  request.headers["user-agent"].includes? "Firefox"
end
```

### Dependency Injection (ADI)

**Register and inject services:**

```crystal
# Register a service with constructor injection
@[ADI::Register(public: true)]
class DatabaseService
  def initialize(@connection_string : String); end
end

# Use ADI::Inject to specify which constructor to use
@[ADI::Register(_value: 2, public: true)]
class SomeService
  @active : Bool = false

  # Regular constructor
  def initialize(value : String, @active : Bool)
    @value = value.to_i
  end

  # DI-specific constructor
  @[ADI::Inject]
  def initialize(@value : Int32); end
end
```

### Event Dispatcher (AED)

**Create and dispatch events:**

```crystal
# Define a custom event
class MyEvent < AED::Event
  property data : String

  def initialize(@data)
  end
end

# Register a listener
dispatcher = AED::EventDispatcher.new
dispatcher.listener(MyEvent) do |event|
  puts "Event received: #{event.data}"
end

# Dispatch the event
dispatcher.dispatch(MyEvent.new("Hello World"))
```

**Using generic events:**

```crystal
# Generic event with type safety
dispatcher.listener AED::GenericEvent(User, Int32) do |e|
  e["counter"] += 1
end

dispatcher.dispatch AED::GenericEvent.new user, data = {"counter" => 0}
```

**Callable listeners with priority:**

```crystal
callable = MyEvent.callable(priority: 10) do |event, dispatcher|
  # Handle event
end

dispatcher.listener callable
```

### Serializer (ASR)

**Serialize/deserialize objects:**

```crystal
require "athena-serializer"

record Example, id : Int32, name : String do
  include ASR::Serializable
end

# Deserialize from JSON
obj = ASR.serializer.deserialize Example, %({"id":1,"name":"George"}), :json

# Serialize to YAML
ASR.serializer.serialize obj, :yaml
# =>
# ---
# id: 1
# name: George
```

### Console (ACON)

**Create a CLI command:**

```crystal
class GreetCommand < ACON::Command
  def configure : Nil
    self
      .name("greet")
      .description("Greets someone")
      .argument("name", ACON::Input::Argument::Mode::REQUIRED, "Who to greet")
      .option("yell", mode: ACON::Input::Option::Mode::NONE, description: "Yell in uppercase")
  end

  def execute(input : ACON::Input::Interface, output : ACON::Output::Interface) : ACON::Command::Status
    name = input.argument("name", String)
    message = "Hello #{name}"

    if input.option("yell", Bool)
      message = message.upcase
    end

    output.puts message
    ACON::Command::Status::SUCCESS
  end
end
```

### Framework Controller (ATH)

**Basic controller with responses:**

```crystal
class ApiController < ATH::Controller
  # Returns JSON response
  @[ATHA::Get("/api/users")]
  @[ATHA::View("user_list.json.ecr")]
  def list_users : Iterable(User)
    UserRepository.all
  end

  # Returns plain text
  @[ATHA::Get("/health")]
  def health_check : String
    "OK"
  end

  # Custom response with headers
  @[ATHA::Post("/data")]
  def create_data(body : DataRequest) : ATH::Response
    ATH::Response.new(
      "Created",
      status: :created,
      headers: HTTP::Headers{"X-Custom" => "value"}
    )
  end
end
```

**HTTP testing expectations:**

```crystal
# In your specs
include ATH::Spec::Expectations::HTTP

client = ATH::Spec::APIClient.new(APP)

# Test response status
client.get("/health").assert_response_is_successful

# Test response headers
client.get("/api/data").assert_response_has_header("content-type")

# Test response body
client.get("/api/users").assert_json_contains({"users" => [...]})
```

### Testing Utilities (ASPEC)

**Compile-time and runtime assertions:**

```crystal
# Assert code fails to compile with specific message
ASPEC::Methods.assert_compile_time_error "can't instantiate abstract class Foo", <<-CR
  abstract class Foo; end
  Foo.new
CR

# Assert code compiles successfully
ASPEC::Methods.assert_compiles <<-CR
  puts 2 + 2
CR

# Assert code executes without error
ASPEC::Methods.assert_executes <<-CR
  puts "Running fine"
CR

# Assert code raises specific runtime error
ASPEC::Methods.assert_runtime_error "Oh noes!", <<-CR
  raise "Oh noes!"
CR
```

### CORS Configuration

The framework includes built-in CORS support:

```crystal
# Configure CORS in your application
ATH::Listeners::CORS is enabled by default
# Uses SAFELISTED_HEADERS and SAFELISTED_METHODS for standard browser requests
```

## Reference Files

This skill includes comprehensive documentation in `references/`:

| File | Description | Pages | Source |
|------|-------------|-------|--------|
| **framework.md** | Core framework API documentation | 332 | Official |
| **getting_started.md** | Getting started guides and routing | 44 | Official |
| **index.md** | Documentation index | - | Official |

Use `view` to read specific reference files when detailed information is needed.

## Working with This Skill

### For Beginners

1. Start with **getting_started.md** for foundational routing concepts
2. Review the Quick Reference examples above for common patterns
3. Use the official [Athena Framework documentation](https://athenaframework.org) for tutorials

### For Interm