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

import UIKit
import PlaygroundSupport

class ViewController: UIViewController {
    
    var aField = UITextField()
    var bField = UITextField()
    var cField = UITextField()
    var solsLabel = UILabel()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        
        makeFrames()
        solveEqn()
    }
    
    func makeFrames() {
        let eqnLabel = UILabel(frame: CGRect(x:  20, y: 20, width: 320, height: 25))
        eqnLabel.text = "          x^2 +           x +           = 0"
        aField = UITextField(frame: CGRect(x:  20, y: 20, width: 45, height: 30))
        aField.addTarget(self, action: #selector(self.solveEqn), for: .editingChanged)
        aField.borderStyle = .roundedRect
        bField = UITextField(frame: CGRect(x: 110, y: 20, width: 45, height: 30))
        bField.addTarget(self, action: #selector(self.solveEqn), for: .editingChanged)
        bField.borderStyle = .roundedRect
        cField = UITextField(frame: CGRect(x: 180, y: 20, width: 45, height: 30))
        cField.addTarget(self, action: #selector(self.solveEqn), for: .editingChanged)
        cField.borderStyle = .roundedRect
        
        self.view.addSubview(eqnLabel)
        self.view.addSubview(aField)
        self.view.addSubview(bField)
        self.view.addSubview(cField)
    }
    
    @objc func solveEqn() {
        let a = (aField.text! as NSString).integerValue
        let b = (bField.text! as NSString).integerValue
        let c = (cField.text! as NSString).integerValue
        
        let A = 2*a
        let B = -b
        let C = outFromSqrt(d: b*b-4*a*c)
        let D = leaveInSqrt(d: b*b-4*a*c)
        
        let G = findGCD(A: A, B: B, C: C)
        
        solsLabel.removeFromSuperview()
        dispSolution(A: A/G, B: B/G, C: C/G, D: D)
    }
    
    func outFromSqrt(d: Int) -> Int {
        var i = d
        while i > 1 {
            if d%(i*i) == 0 { return i }
            i = i-1
        }
        if i == 0 { return 0 } else { return 1 }
    }
    
    func leaveInSqrt(d: Int) -> Int {
        var i = d
        while i > 1 {
            if d%(i*i) == 0 { return d/(i*i) }
            i = i-1
        }
        return d
    }
    
    func findGCD(A: Int, B: Int, C: Int) -> Int {
        var i = max(abs(A), abs(B), abs(C))
        while i > 1 {
            if A%i == 0 && B%i == 0 && C%i == 0 { return i }
            i = i-1
        }
        return 1
    }
    
    func dispSolution(A: Int, B: Int, C: Int, D: Int) {
        solsLabel = UILabel(frame: CGRect(x:  20, y: 50, width: 320, height: 50))
        
        if D == 0 {
            solsLabel.text = "x = " + String(B) + " / " + String(A)
        } else if C == 1 {
            solsLabel.text = "x = {" + String(B) + " ± √(" + String(D) + ")} / " + String(A)
        } else {
            solsLabel.text = "x = {" + String(B) + " ± " + String(C) + "√(" + String(D) + ")} / " + String(A)
        }
        self.view.addSubview(solsLabel)
    }
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
    
}

let viewController = ViewController()
viewController.view.backgroundColor = UIColor.white

PlaygroundPage.current.liveView = viewController
PlaygroundPage.current.needsIndefiniteExecution = true