Improve structure in `NuguClient`

[yHoonyK]

Overviews

Category

• [ ] New feature
• [x] Update feature
• [x] Update documentation
• [x] Idea
• [x] Architecture
• [x] Structure

Summary

NuguClient.Builder() is always make all of capability-agent. Some capability-agent may not be used. (like LocationAgent)

Reference

Discussion(Internal): https://github.com/orgs/nugu-developers/teams/nugu-sdk/discussions/7

[yHoonyK]

It contains updating protocol for capability-agent. It is that about internal mandatory property.

[yHoonyK]

Proposal

Improve access control by NuguInterface

Branch

https://github.com/yHoonyK/nugu-ios/tree/feature/improve-nugu-client

Detail

public protocol ExtensionAgentProtocol:
CapabilityAgentable,
ContextInfoDelegate,
HandleDirectiveDelegate {
    /// The object that acts as the delegate of extension-agent
    var delegate: ExtensionAgentDelegate? { get set }
}

public protocol ExtensionAgentConcretable {
    var messageSender: MessageSendable! { get set }
}

final public class ExtensionAgent: ExtensionAgentProtocol, ExtensionAgentConcretable {}

If we want to use it like that, the coordinating role must be involved by the NuguClient.Builder. like this,

public class NuguClient {
   public let extensionAgent: ExtensionAgentProtocol?

   init(extensionAgent: ExtensionAgentProtocol?,
      ...
    ) {
       self.extensionAgent = extensionAgent
       ...
   }
}

extension NuguClient {
    public class Builder {
       public lazy var extensionAgent: (ExtensionAgentProtocol & ExtensionAgentConcretable)? = ExtensionAgent()

       public func build() -> NuguClient {
             let client = NuguClient(...)

             // coordinate for extension-agent
             extensionAgent?.messageSender = client.networkManager
             client.directiveSequencer.add(handleDirectiveDelegate: extensionAgent)
              ...
             return client
       }
   }
}

[yHoonyK]

Swift official answer for access-control protected: https://developer.apple.com/swift/blog/?id=11

[yHoonyK]

discussion(internal): https://github.com/orgs/nugu-developers/teams/nugu-sdk-ios-team/discussions/3

[Minddol]

Suggestion - Use protocol initializer instead of property.

public protocol ExtensionAgentProtocol:
CapabilityAgentable,
ContextInfoDelegate,
HandleDirectiveDelegate {
    init(messageSender: MessageSendable)

    /// The object that acts as the delegate of extension-agent
    var delegate: ExtensionAgentDelegate? { get set }
}

final public class ExtensionAgent: ExtensionAgentProtocol {
    private let messageSender: MessageSendable

    public init(messageSender: MessageSendable) {
        self.messageSender = messageSender
    }
}

    let client: NuguClient = {
        let builder = NuguClient.Builder()
        return builder
            .with(extensionAgent: ExtensionAgent(messageSender: builder.networkManager))
            .build()
    }()

[yHoonyK]

I think @Minddol's suggestion is the best way.

[yHoonyK]

Proposal

Improve issue that NuguClient.Builder() is always make all of capability-agent.

Concept

extension NuguClient.Builder {
    enum DefaultType {
        case .nothing // no has default capability-agent instance (only has `SystemAgent`)
        case .basic // has basic capability-agent instances (`SystemAgent`, `ASRAgent`, `TTSAgent`, `TextAgent`..?)
        case .complete // has all capability-agent instances
    }
}

class NuguClient.Builder {
    init(defaultType: DefaultType) {}
}

let client = NuguClient.Builder(defaultType: .basic).build()

[yHoonyK]

Builder pattern with director. https://johngrib.github.io/wiki/builder-pattern/

[yHoonyK]

I consider to change architecture to 'abstract factory pattern' for capability-agent.

[yHoonyK]

Check-list

• [x] Implements
• [x] Documentation (readme, developers .. )

[yHoonyK]

Revert renaming capability-agents.

[yHoonyK]

Summary

Issue

1. NuguClient.Builder() is always make all of capability-agent.
   • Resolved: To inject capability-agent has be changed design-pattern to 'Abstract Factory Pattern'
2. capability-agent's access-control issue. (public properties in protocol)
   • Resolved: Remove properties to inject dependency using 'setter injection' in capability-agent protocol, concrete class has inject dependency using 'constructor injection'.

Result

• NuguClient conform to DI(Dependency injection) pattern and using 'constructor injection' type of DI.
• CapabilityAgentFactory and MediaPlayerFactory conform to 'Abstract Factory' pattern.

[yHoonyK]

Resolved by #147

[yHoonyK]

It wasn't be completed.

[yHoonyK]

Improve capability-agent protocol structure to PoP (Protocol Oriented Programming)

[yHoonyK]

Resolved by #170

After that, we consider that NuguClient change design-pattern to IoC container. It will makes another github issue.