Factory.swift

//
//  Created by Apostolos Giokas on 10.03.21.
//

import Foundation

private protocol ICreator {
    var identifier: ObjectIdentifier { get }
    func create(for: Any) -> Any?
}

protocol IFactory {
    associatedtype Return
    func create(for object: Any) -> Return?
    func register<T>(for type: T.Type, factory: @escaping (T) -> Return)
}

open class Factory<Return>: IFactory {
    private var items = [ObjectIdentifier: ICreator]()

    public init() {}

    public func register<T>(for type: T.Type, factory: @escaping (T) -> Return) {
        items[ObjectIdentifier(type)] = Creator<T>(for: type, factory: factory)
    }

    public func create(for object: Any) -> Return? {
        let resolver = items[ObjectIdentifier(type(of: object))]
        return resolver?.create(for: object) as? Return
    }

    private class Creator<Input>: ICreator {
        let factory: (Input) -> Return
        let identifier: ObjectIdentifier
        let type: Input.Type

        init(for type: Input.Type, factory: @escaping (Input) -> Return) {
            self.factory = factory
            self.type = type
            identifier = ObjectIdentifier(type)
        }

        func create(for object: Any) -> Any? {
            guard let someVM = object as? Input else { return nil }
            return factory(someVM)
        }
    }
}