CDCodabarView.swift

//
//  CDCodabarView.swift
//  CDCodabarViewSample
//
//  Created by Cole Dunsby on 2015-12-21.
//  Copyright © 2017 Cole Dunsby. All rights reserved.
//

import UIKit

@IBDesignable
public final class CDCodabarView: UIView {

    @IBInspectable public var barColor: UIColor = #colorLiteral(red: 0, green: 0, blue: 0, alpha: 1) { didSet { setNeedsDisplay() }}
    @IBInspectable public var textColor: UIColor = #colorLiteral(red: 0, green: 0, blue: 0, alpha: 1) { didSet { setNeedsDisplay() }}
    @IBInspectable public var padding: CGFloat = 2.0 { didSet { setNeedsDisplay() }}
    @IBInspectable public var hideCode: Bool = false { didSet { setNeedsDisplay() }}
    
    @IBInspectable public var code: String = "A123456789B" {
        didSet {
            encoder = try? CDCodabarEncoder(code: code)
            setNeedsDisplay()
        }
    }
    
    public var font = UIFont.systemFont(ofSize: 15.0) { didSet { setNeedsDisplay() }}
    
    private var encoder: CDCodabarEncoder?
    
    override init(frame: CGRect) {
        super.init(frame: frame)
    }

    required public init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }
    
    override public func draw(_ rect: CGRect) {
        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.alignment = .center
        
        let attributes: [String: Any] = [
            NSFontAttributeName: font,
            NSForegroundColorAttributeName: textColor,
            NSParagraphStyleAttributeName: paragraphStyle,
        ]
        
        guard let encoder = encoder else {
            let text = "Invalid Code"
            
            let textSize = text.boundingRect(
                with: CGSize(width: bounds.size.width, height: CGFloat.greatestFiniteMagnitude),
                options: [.truncatesLastVisibleLine, .usesLineFragmentOrigin],
                attributes: [NSFontAttributeName: font],
                context: nil
            )
            
            text.draw(
                at: CGPoint(x: bounds.size.width / 2 - textSize.width / 2, y: bounds.size.height / 2 - textSize.height / 2),
                withAttributes: attributes
            )
            
            return
        }

        barColor.setFill()
        
        let multiplier = CGFloat(1.25)
        let labelHeight = ceil(code.boundingRect(
            with: CGSize(width: bounds.size.width, height: CGFloat.greatestFiniteMagnitude),
            options: [.truncatesLastVisibleLine, .usesLineFragmentOrigin],
            attributes: [NSFontAttributeName: font],
            context: nil).height)
        let barHeight = bounds.size.height - (hideCode ? 0 : labelHeight + padding)
        let sequence = encoder.sequence()
        
        var narrow = 0
        var wide = 0
        
        (0 ..< sequence.count).forEach {
            if sequence[$0] == 0 {
                narrow += 1
            } else {
                if $0 < sequence.count - 1 {
                    if sequence[$0 + 1] == 1 {
                        wide += 1
                    } else {
                        narrow += 1
                    }
                } else {
                    narrow += 1
                }
            }
        }
        
        let barWidth = CGFloat(bounds.size.width / (CGFloat(narrow) + multiplier * CGFloat(wide)))
        var x = CGFloat(0)
        
        (0 ..< sequence.count).forEach {
            if sequence[$0] == 0 {
                x += barWidth
            } else {
                var customBarWidth = barWidth
                
                if $0 < sequence.count - 1 {
                    if sequence[$0 + 1] == 1 {
                        customBarWidth *= multiplier
                    }
                }
                
                UIRectFill(CGRect(x: x, y: 0, width: customBarWidth, height: barHeight))
                
                x += customBarWidth
            }
        }
        
        if !hideCode {
            code.draw(
                in: CGRect(x: 0, y: barHeight + padding, width: x, height: labelHeight),
                withAttributes: attributes
            )
        }
    }
}