AutoEquatable.swift

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

import Foundation

protocol Compatible {
    func equal(rhs: Compatible) -> Bool
}

extension String: Compatible {
    func equal(rhs: Compatible) -> Bool {
        guard let rhs = rhs as? String else {
            return false
        }
        return self == rhs
    }
}
extension Float: Compatible {
    func equal(rhs: Compatible) -> Bool {
        guard let rhs = rhs as? Float else {
            return false
        }
        return self == rhs
    }
}
extension Int: Compatible {
    func equal(rhs: Compatible) -> Bool {
        guard let rhs = rhs as? Int else {
            return false
        }
        return self == rhs
    }
}
extension Bool: Compatible {
    func equal(rhs: Compatible) -> Bool {
        guard let rhs = rhs as? Bool else {
            return false
        }
        return self == rhs
    }
}
extension Double: Compatible {
    func equal(rhs: Compatible) -> Bool {
        guard let rhs = rhs as? Double else {
            return false
        }
        return self == rhs
    }
}

struct CustomType {
    var someNumber = 11
}

struct Person {
    var name = "John Nash"
    var age = 42
    var isOld = false
    var height = 5.11
    var floatability: Float = 0.12
    var customType = CustomType()
}

let person0 = Person()
var person1 = Person()

func areEqual<T>(lhs lhs: T, rhs: T) -> Bool {
    let leftKeyValues = Mirror(reflecting: lhs).children
    let rightKeyValues = Mirror(reflecting: rhs).children
    
    var leftKeys = [String]()
    leftKeyValues.forEach { (key, _) -> () in
        guard let key = key else { return }
        leftKeys.append(key)
    }
    
    var rightKeys = [String]()
    rightKeyValues.forEach { (key, _) -> () in
        guard let key = key else { return }
        rightKeys.append(key)
    }
    
    guard leftKeys == rightKeys else { return false }
    
    for (lKey, lValue) in leftKeyValues {
        for (rKey, rValue) in rightKeyValues {
            if lKey == rKey {
                
                if let lPrimitive = lValue as? Compatible,
                    rPrimitive = rValue as? Compatible {
                        if !lPrimitive.equal(rPrimitive) {
                            return false
                        }
                } else {
                    if !areEqual(lhs: lValue, rhs: rValue) {
                        return false
                    }
                }
                
            }
        }
    }
    
    return true
}

areEqual(lhs:person0, rhs:person1)