JSONSerializable

//: Playground - noun: a place where people can play

import Foundation

protocol JSONSerializable {
	func toJSON() throws -> Any?
}

enum CouldNotSerializeError: Error {
	case noImplementation(source: Any, type: String)
}

extension JSONSerializable {

	func toJSON() throws -> Any? {
		let mirror = Mirror(reflecting: self)

		guard !mirror.children.isEmpty else { return self }

		var result: [String: Any] = [:]

		for child in mirror.children {
			if let value = child.value as? JSONSerializable {
				result[child.label!] = try value.toJSON()
			} else {
				throw CouldNotSerializeError.noImplementation(source: self, type: String(describing: type(of: child.value)))
			}
		}
		return result
	}
}

struct Order {
	let uid = UUID()
	let itemsCount = 1
	let isDeleted = false
	let name = "A cup"
	let subtitle: String? = nil
	let category = Category(name: "Cups")
}

struct Category {
	let name: String
}

extension String: JSONSerializable {}
extension Int: JSONSerializable {}
extension Bool: JSONSerializable {}

extension Optional: JSONSerializable {
	func toJSON() throws -> Any? {
		if let x = self {
			if let value = x as? JSONSerializable {
				return try value.toJSON()
			}
			throw CouldNotSerializeError.noImplementation(source: x, type: String(describing: type(of: x)))
		}
		return nil
	}
}

extension UUID: JSONSerializable {
	func toJSON() throws -> Any? {
		return try uuidString.toJSON()
	}
}

extension Order: JSONSerializable {}
extension Category: JSONSerializable {}

do {
	try Order().toJSON()
} catch {
	print(error)
}