Handler.swift

public enum HandlerContainerBehaviour {
  case resetting
  case preceding
  case appending
}

public typealias Handler = Handler1

/// A wrapper for clusure-based interaction between objects
///
/// Provides a public API to set internal closure-based hanlder or delegate with a functional API
@propertyWrapper
public class Handler1<Input> {
  public struct Container {
    public typealias Behaviour = HandlerContainerBehaviour

    @usableFromInline
    internal var action: ((Input) -> Void)?

    internal init() {}

    public init(action: ((Input) -> Void)?) {
      self.action = action
    }

    @inlinable
    public mutating func callAsFunction(perform action: ((Input) -> Void)?) {
      self.action = action
    }

    @available(
      *,
      deprecated,
      message:
      """
      This API will be removed, \
      consider using redeclaration with `(Input) -> Output` signature function. \
      Feel free to discuss the API here \
      https://github.com/CaptureContext/swift-declarative-configuration/issues/1
      """
    )
    @inlinable
    public mutating func callAsFunction(_ behaviour: Behaviour, perform action: ((Input) -> Void)?)
    {
      switch behaviour {
      case .resetting:
        self.action = action
      case .preceding:
        let oldAction = self.action
        self.action = { input in
          action?(input)
          oldAction?(input)
        }
      case .appending:
        let oldAction = self.action
        self.action = { input in
          action?(input)
          oldAction?(input)
        }
      }
    }
  }

  public init() {}

  public init(wrappedValue: Container) {
    self.wrappedValue = wrappedValue
  }

  public var wrappedValue: Container = .init()

  public var projectedValue: ((Input) -> Void)? {
    get { wrappedValue.action }
    set { wrappedValue.action = newValue }
  }

  public func callAsFunction(_ input: Input) {
    projectedValue?(input)
  }

  public func callAsFunction() where Input == Void {
    projectedValue?(())
  }
}

// MARK: Typed handlers

/// A wrapper for clusure-based interaction between objects
///
/// Provides a public API to set internal closure-based hanlder or delegate with a functional API
@propertyWrapper
public class Handler2<T0, T1> {
  public struct Container {
    public typealias Behaviour = HandlerContainerBehaviour

    internal var action: ((T0, T1) -> Void)?

    internal init() {}

    public init(action: ((T0, T1) -> Void)?) {
      self.action = action
    }

    public mutating func callAsFunction(perform action: ((T0, T1) -> Void)?) {
      self.action = action
    }

    @available(
      *,
      deprecated,
      message:
      """
      This API will be removed, \
      consider using redeclaration with `(Input) -> Output` signature function. \
      Feel free to discuss the API here \
      https://github.com/MakeupStudio/swift-declarative-configuration/issues/1
      """
    )
    public mutating func callAsFunction(_ behaviour: Behaviour, perform action: ((T0, T1) -> Void)?)
    {
      switch behaviour {
      case .resetting:
        self.action = action
      case .preceding:
        let oldAction = self.action
        self.action = { t0, t1 in
          action?(t0, t1)
          oldAction?(t0, t1)
        }
      case .appending:
        let oldAction = self.action
        self.action = { t0, t1 in
          action?(t0, t1)
          oldAction?(t0, t1)
        }
      }
    }
  }

  public init() {}

  public init(wrappedValue: Container) {
    self.wrappedValue = wrappedValue
  }

  public var wrappedValue: Container = .init()

  public var projectedValue: ((T0, T1) -> Void)? {
    get { wrappedValue.action }
    set { wrappedValue.action = newValue }
  }

  public func callAsFunction(_ t0: T0, _ t1: T1) {
    projectedValue?(t0, t1)
  }
}

/// A wrapper for clusure-based interaction between objects
///
/// Provides a public API to set internal closure-based hanlder or delegate with a functional API
@propertyWrapper
public class Handler3<T0, T1, T2> {
  public struct Container {
    public typealias Behaviour = HandlerContainerBehaviour

    internal var action: ((T0, T1, T2) -> Void)?

    internal init() {}

    public init(action: ((T0, T1, T2) -> Void)?) {
      self.action = action
    }

    public mutating func callAsFunction(perform action: ((T0, T1, T2) -> Void)?) {
      self.action = action
    }

    @available(
      *,
      deprecated,
      message:
      """
      This API will be removed, \
      consider using redeclaration with `(Input) -> Output` signature function. \
      Feel free to discuss the API here \
      https://github.com/MakeupStudio/swift-declarative-configuration/issues/1
      """
    )
    public mutating func callAsFunction(
      _ behaviour: Behaviour,
      perform action: ((T0, T1, T2) -> Void)?
    ) {
      switch behaviour {
      case .resetting:
        self.action = action
      case .preceding:
        let oldAction = self.action
        self.action = { t0, t1, t2 in
          action?(t0, t1, t2)
          oldAction?(t0, t1, t2)
        }
      case .appending:
        let oldAction = self.action
        self.action = { t0, t1, t2 in
          action?(t0, t1, t2)
          oldAction?(t0, t1, t2)
        }
      }
    }
  }

  public init() {}

  public init(wrappedValue: Container) {
    self.wrappedValue = wrappedValue
  }

  public var wrappedValue: Container = .init()

  public var projectedValue: ((T0, T1, T2) -> Void)? {
    get { wrappedValue.action }
    set { wrappedValue.action = newValue }
  }

  public func callAsFunction(_ t0: T0, _ t1: T1, _ t2: T2) {
    projectedValue?(t0, t1, t2)
  }
}

/// A wrapper for clusure-based interaction between objects
///
/// Provides a public API to set internal closure-based hanlder or delegate with a functional API
@propertyWrapper
public class Handler4<T0, T1, T2, T3> {
  public struct Container {
    public typealias Behaviour = HandlerContainerBehaviour

    internal var action: ((T0, T1, T2, T3) -> Void)?

    internal init() {}

    public init(action: ((T0, T1, T2, T3) -> Void)?) {
      self.action = action
    }

    public mutating func callAsFunction(perform action: ((T0, T1, T2, T3) -> Void)?) {
      self.action = action
    }

    @available(
      *,
      deprecated,
      message:
      """
      This API will be removed, \
      consider using redeclaration with `(Input) -> Output` signature function. \
      Feel free to discuss the API here \
      https://github.com/MakeupStudio/swift-declarative-configuration/issues/1
      """
    )
    public mutating func callAsFunction(
      _ behaviour: Behaviour,
      perform action: ((T0, T1, T2, T3) -> Void)?
    ) {
      switch behaviour {
      case .resetting:
        self.action = action
      case .preceding:
        let oldAction = self.action
        self.action = { t0, t1, t2, t3 in
          action?(t0, t1, t2, t3)
          oldAction?(t0, t1, t2, t3)
        }
      case .appending:
        let oldAction = self.action
        self.action = { t0, t1, t2, t3 in
          action?(t0, t1, t2, t3)
          oldAction?(t0, t1, t2, t3)
        }
      }
    }
  }

  public init() {}

  public init(wrappedValue: Container) {
    self.wrappedValue = wrappedValue
  }

  public var wrappedValue: Container = .init()

  public var projectedValue: ((T0, T1, T2, T3) -> Void)? {
    get { wrappedValue.action }
    set { wrappedValue.action = newValue }
  }

  public func callAsFunction(_ t0: T0, _ t1: T1, _ t2: T2, _ t3: T3) {
    projectedValue?(t0, t1, t2, t3)
  }
}

/// A wrapper for clusure-based interaction between objects
///
/// Provides a public API to set internal closure-based hanlder or delegate with a functional API
@propertyWrapper
public class Handler5<T0, T1, T2, T3, T4> {
  public struct Container {
    public typealias Behaviour = HandlerContainerBehaviour

    internal var action: ((T0, T1, T2, T3, T4) -> Void)?

    internal init() {}

    public init(action: ((T0, T1, T2, T3, T4) -> Void)?) {
      self.action = action
    }

    public mutating func callAsFunction(perform action: ((T0, T1, T2, T3, T4) -> Void)?) {
      self.action = action
    }

    @available(
      *,
      deprecated,
      message:
      """
      This API will be removed, \
      consider using redeclaration with `(Input) -> Output` signature function. \
      Feel free to discuss the API here \
      https://github.com/MakeupStudio/swift-declarative-configuration/issues/1
      """
    )
    public mutating func callAsFunction(
      _ behaviour: Behaviour,
      perform action: ((T0, T1, T2, T3, T4) -> Void)?
    ) {
      switch behaviour {
      case .resetting:
        self.action = action
      case .preceding:
        let oldAction = self.action
        self.action = { t0, t1, t2, t3, t4 in
          action?(t0, t1, t2, t3, t4)
          oldAction?(t0, t1, t2, t3, t4)
        }
      case .appending:
        let oldAction = self.action
        self.action = { t0, t1, t2, t3, t4 in
          action?(t0, t1, t2, t3, t4)
          oldAction?(t0, t1, t2, t3, t4)
        }
      }
    }
  }

  public init() {}

  public init(wrappedValue: Container) {
    self.wrappedValue = wrappedValue
  }

  public var wrappedValue: Container = .init()

  public var projectedValue: ((T0, T1, T2, T3, T4) -> Void)? {
    get { wrappedValue.action }
    set { wrappedValue.action = newValue }
  }

  public func callAsFunction(_ t0: T0, _ t1: T1, _ t2: T2, _ t3: T3, _ t4: T4) {
    projectedValue?(t0, t1, t2, t3, t4)
  }
}