//
//  MyDoubleSlider.swift
//  Jour-7-CustomControls
//
//  Created by Ludivine Maret on 22/11/2017.
//  Copyright © 2017 student. All rights reserved.
//

import UIKit

class MyDoubleSlider: UIView {

    var valueMin : Float = 0
    var valueMax : Float = 1

    override init(frame: CGRect) {
        super.init(frame: frame)
        setupGestures()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        setupGestures()
    }

    var panRecognizer = UIPanGestureRecognizer()

    func setupGestures() {
        panRecognizer = UIPanGestureRecognizer(target: self, action: #selector(panEvent(_:)))
        self.addGestureRecognizer(panRecognizer)
    }

    enum InteractionStatus {
        case none
        case panMin
        case panMax
    }

    var interactionStatus = InteractionStatus.none

    @objc func panEvent(_ recognizer : UIPanGestureRecognizer) {

        let r = CGFloat(8) // 8px
        let w = bounds.width

        let gmin = CGFloat(0)
        let gmax = w - 2 * r

        switch recognizer.state {
            case .began:
                let panX = recognizer.location(in: self).x
                let minX = CGFloat(valueMin) * (gmax - gmin) + gmin + r
                let maxX = CGFloat(valueMax) * (gmax - gmin) + gmin + r

                let distToMin = abs(minX - panX)
                let distToMax = abs(maxX - panX)

                if distToMin < distToMax {
                    interactionStatus = .panMin
                } else {
                    interactionStatus = .panMax
                }

            case .changed:
                let panX = recognizer.location(in: self).x

                //update value
                var value = (panX - gmin - r) / (gmax-gmin)
                value = min(1.0, max(0.0, value))

                if interactionStatus == .panMin {
                    valueMin = Float(value)
                } else {
                    valueMax = Float(value)
                }

                setNeedsDisplay() // Ne jamais appeler draw(rect:)

            case .ended:
                interactionStatus = .none
            case .possible, .cancelled, .failed:
                interactionStatus = .none
                // do nothing
                break;
        }
        print(recognizer)
    }

    // Only override draw() if you perform custom drawing.
    // An empty implementation adversely affects performance during animation.
    override func draw(_ rect: CGRect) {
        // Drawing code

        let r = CGFloat(8) // 8px
        let w = bounds.width
        let h = bounds.height

        let gmin = CGFloat(0)
        let gmax = w - 2 * r

        let pmin = CGFloat(valueMin) * (gmax - gmin) + gmin
        let pmax = CGFloat(valueMax) * (gmax - gmin) + gmin

        // Trait de fond
        UIColor.blue.set()
        UIRectFill(CGRect(x: r, y: h/2, width: w - 2 * r, height: 2))

        // Puce 1
        UIColor.red.set()
        UIRectFill(CGRect(x: pmin, y: h/2-r, width: 2 * r, height: 2 * r))

        // Puce 2
        UIColor.green.set()
        UIRectFill(CGRect(x: pmax, y: h/2-r, width: 2 * r, height: 2 * r))
    }

}