//
//  DrawableView.swift
//  Drawing
//
//  Created by Taichi Tsuchida on 2017/03/22.
//  Copyright © 2017 Taichi Tsuchida. All rights reserved.
//

import UIKit

class DrawableView: UIView {

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

//    override func draw(_ rect: CGRect) {
//
//    }

    class Line {
        var points: [CGPoint]
        var color :CGColor
        var width: CGFloat

        init(color: CGColor, width: CGFloat){
            self.color = color
            self.width = width
            self.points = []
        }

        func drawOnContext(context: CGContext){
            UIGraphicsPushContext(context)

            context.setStrokeColor(self.color)
            context.setLineWidth(self.width)
            context.setLineCap(CGLineCap.round)

            // 2点以上ないと線描画する必要なし
            if self.points.count > 1 {
                for (index, point) in self.points.enumerated() {
                    if index == 0 {
                        context.move(to: CGPoint(x:point.x, y:point.y))
                    } else {
                        context.addLine(to: CGPoint(x:point.x, y:point.y))
                    }
                }
            }
            context.strokePath()

            UIGraphicsPopContext()
        }
    }

    var lines: [Line] = []
    var currentLine: Line? = nil

    // タッチされた
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        let point = touches.first!.location(in: self)
        currentLine = Line(color: UIColor.red.cgColor, width: 5)
        currentLine?.points.append(point)
    }

    // タッチが動いた
    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
        let point = touches.first!.location(in: self)
        currentLine?.points.append(point)
        self.setNeedsDisplay()
    }

    // タッチが終わった
    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
        // 2点以上のlineしか保存する必要なし
        if (currentLine?.points.count)! > 1 {
            lines.append(currentLine!)
        }

        currentLine = nil
        self.setNeedsDisplay()
    }

    func resetContext(context: CGContext) {
        context.clear(self.bounds)
        if let color = self.backgroundColor {
            color.setFill()
        } else {
            UIColor.white.setFill()
        }
        context.fill(self.bounds)
    }

    //描画設定
    override func draw(_ rect: CGRect) {

        let context = UIGraphicsGetCurrentContext()

        //画面を一旦初期化
        resetContext(context: context!)

        // 描き終わったline
        for line in lines {
            line.drawOnContext(context: context!)
        }

        // 描いてる途中のline
        if let line = currentLine {
            line.drawOnContext(context: context!)
        }
    }

}