WWDC/PlayerUI/Views/PUIAnnotationLayer.swift

//
//  PUIAnnotationLayer.swift
//  PlayerUI
//
//  Created by Guilherme Rambo on 01/05/17.
//  Copyright © 2017 Guilherme Rambo. All rights reserved.
//

import Cocoa

class PUIAnnotationLayer: PUIBoringLayer {

    private var attachmentSpacing: CGFloat = 0
    private var attachmentAttribute: NSLayoutAttribute = .notAnAttribute
    
    private(set) var attachedLayer: PUIBoringTextLayer = PUIBoringTextLayer()
    
    func attach(layer: PUIBoringTextLayer, attribute: NSLayoutAttribute, spacing: CGFloat) {
        guard attribute == .top else {
            fatalError("Only .top is implemented for now")
        }
        
        attachmentSpacing = spacing
        attachmentAttribute = attribute
        
        addSublayer(layer)
        
        attachedLayer = layer
        
        layoutAttached(layer: layer)
    }
    
    private func layoutAttached(layer: PUIBoringTextLayer) {
        layer.layoutIfNeeded()
        
        var f = layer.frame
        
        if let textLayerContents = layer.string as? NSAttributedString {
            let s = textLayerContents.size()
            f.size.width = ceil(s.width)
            f.size.height = ceil(s.height)
        }
        
        let y: CGFloat = -f.height - attachmentSpacing
        let x: CGFloat = -f.width / 2 + self.bounds.width / 2
        
        f.origin.x = x
        f.origin.y = y
        
        layer.frame = f
    }
    
    override func layoutSublayers() {
        super.layoutSublayers()
        
        layoutAttached(layer: attachedLayer)
    }
    
}