mastodon-ios/MastodonSDK/Sources/MastodonUI/View/Decoration/SawToothView.swift

//
//  SawToothView.swift
//  Mastodon
//
//  Created by sxiaojian on 2021/3/17.
//

import Foundation
import UIKit
import Combine
import MastodonCore

public final class SawToothView: UIView {
    static let widthUint = 8

    var disposeBag = Set<AnyCancellable>()

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

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

    func _init() {
        setupBackgroundColor(theme: ThemeService.shared.currentTheme.value)
        ThemeService.shared.currentTheme
            .receive(on: RunLoop.main)
            .sink { [weak self] theme in
                guard let self = self else { return }
                self.setupBackgroundColor(theme: theme)
            }
            .store(in: &disposeBag)
    }

    private func setupBackgroundColor(theme: Theme) {
        backgroundColor = theme.secondarySystemBackgroundColor
        setNeedsDisplay()
    }

    public override func draw(_ rect: CGRect) {
        let bezierPath = UIBezierPath()
        let bottomY = rect.height
        let topY = 0
        let count = Int(ceil(rect.width / CGFloat(SawToothView.widthUint)))
        bezierPath.move(to: CGPoint(x: 0, y: bottomY))
        for n in 0 ..< count {
            bezierPath.addLine(to: CGPoint(x: CGFloat((Double(n) + 0.5) * Double(SawToothView.widthUint)), y: CGFloat(topY)))
            bezierPath.addLine(to: CGPoint(x: CGFloat((Double(n) + 1) * Double(SawToothView.widthUint)), y: CGFloat(bottomY)))
        }
        bezierPath.addLine(to: CGPoint(x: 0, y: bottomY))
        bezierPath.close()
        ThemeService.shared.currentTheme.value.tableViewCellBackgroundColor.setFill()
        bezierPath.fill()
        bezierPath.lineWidth = 0
        bezierPath.stroke()
    }
    
}