ComputedLayout+QuickLook.swift

//
//  ComputedLayout+QuickLook.swift
//  CoreLayout
//
//  Created by Jake Marsh on 10/2/16.
//  Copyright © 2016 Jake Marsh. All rights reserved.
//

import Foundation

#if os(iOS)
  public typealias DebugImageType = UIImage
#elseif os(macOS)
  public typealias DebugImageType = NSImage
#endif

extension ComputedLayout {
//  @objc
  public func debugQuickLookObject() -> UIImage {
    return generateQuickLookImage()!
  }
  
  public static let debugIdentifierFont = UIFont.monospacedDigitSystemFont(ofSize: 14.0, weight: UIFontWeightSemibold)

  public func generateQuickLookImage() -> DebugImageType? {
    let drawRect = frame.insetBy(dx: -8, dy: -8)
    
    #if os(iOS)
      UIGraphicsBeginImageContextWithOptions(drawRect.size, true, 2.0)
      let c = UIGraphicsGetCurrentContext()

      let strokeColor = UIColor(red: 0.10, green: 0.41, blue: 1.0, alpha: 1.0)
      let fillColor = strokeColor.withAlphaComponent(0.15)

      UIColor.white.setFill()
      UIRectFill(CGRect(x: 0, y: 0, width: drawRect.size.width, height: drawRect.size.height))

      func draw(layout: ComputedLayout, offset: CGPoint) {
        let layoutFrame = layout.frame.integral.offsetBy(dx: offset.x, dy: offset.y)
        let childOffset = layoutFrame.origin

        fillColor.setFill()
        UIBezierPath(roundedRect: layoutFrame, cornerRadius: 2).fill()

        strokeColor.setStroke()
        UIBezierPath(roundedRect: layoutFrame, cornerRadius: 2).stroke()

        if let identifier = layout.identifier {
          let font = ComputedLayout.debugIdentifierFont

          var textRect = layoutFrame
          textRect.origin.y = textRect.origin.y + ((textRect.size.height - font.pointSize) / 2)
//          textRect.origin.y = 0

          let style = NSMutableParagraphStyle()
          style.alignment = .center

          (identifier as NSString).draw(in: textRect, withAttributes: [
            NSParagraphStyleAttributeName : style,
            NSFontAttributeName : font,
            NSForegroundColorAttributeName : strokeColor
          ])
        }

        for child in layout.children {
          draw(layout: child, offset: childOffset)
        }
      }

      draw(layout: self, offset: CGPoint(x: 8, y: 8))

      let image = UIGraphicsGetImageFromCurrentImageContext()

      UIGraphicsEndImageContext()
    #elseif os(macOS)
      // TODO
    #endif
    
    return image
  }
}

extension ComputedLayout : CustomPlaygroundQuickLookable {
  public var customPlaygroundQuickLook: PlaygroundQuickLook { return .image(generateQuickLookImage()!) }
}