//
//  TestCompositionLayer.swift
//  lottie-swift
//
//  Created by Brandon Withrow on 1/25/19.
//

import Foundation
import CoreGraphics
import QuartzCore
import CoreText

class DisabledTextLayer: CATextLayer {
  override func action(forKey event: String) -> CAAction? {
    return nil
  }
}

class TextCompositionLayer: CompositionLayer {
  
  let rootNode: TextAnimatorNode?
  let textDocument: KeyframeInterpolator<TextDocument>?
  
  let textLayer: DisabledTextLayer = DisabledTextLayer()
  
  init(textLayer: TextLayerModel) {
    var rootNode: TextAnimatorNode?
    for animator in textLayer.animators {
      rootNode = TextAnimatorNode(parentNode: rootNode, textAnimator: animator)
    }
    self.rootNode = rootNode
    self.textDocument = KeyframeInterpolator(keyframes: textLayer.text.keyframes)
    
    super.init(layer: textLayer, size: .zero)
    contentsLayer.addSublayer(self.textLayer)
    self.textLayer.masksToBounds = false
    
  }
  
  required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
  }
  
  override init(layer: Any) {
    /// Used for creating shadow model layers. Read More here: https://developer.apple.com/documentation/quartzcore/calayer/1410842-init
    guard let layer = layer as? TextCompositionLayer else {
      fatalError("init(layer:) Wrong Layer Class")
    }
    self.rootNode = nil
    self.textDocument = nil
    super.init(layer: layer)
  }
  
  override func displayContentsWithFrame(frame: CGFloat, forceUpdates: Bool) {
    guard let textDocument = textDocument else { return }
    let documentUpdate = textDocument.hasUpdate(frame: frame)
    let animatorUpdate = rootNode?.updateContents(frame, forceLocalUpdate: forceUpdates) ?? false
    guard documentUpdate == true || animatorUpdate == true else { return }
    
    let text = textDocument.value(frame: frame) as! TextDocument
    rootNode?.rebuildOutputs(frame: frame)
    
    let fillColor = rootNode?.textOutputNode.fillColor ?? text.fillColorData.cgColorValue
    let strokeColor = rootNode?.textOutputNode.strokeColor ?? text.strokeColorData?.cgColorValue
    let strokeWidth = rootNode?.textOutputNode.strokeWidth ?? CGFloat(text.strokeWidth ?? 0)
    let tracking = rootNode?.textOutputNode.tracking ?? CGFloat(text.tracking)
    // TODO LINE HEIGHT
    
    let matrix = rootNode?.textOutputNode.xform ?? CATransform3DIdentity
    let ctFont = CTFontCreateWithName(text.fontFamily as CFString, CGFloat(text.fontSize), nil)
    
    var attributes: [NSAttributedStringKey : Any] = [
      NSAttributedStringKey.font: ctFont,
      NSAttributedStringKey.foregroundColor: fillColor,
      NSAttributedStringKey.kern: tracking,
      ]
    
    if let strokeColor = strokeColor {
      attributes[NSAttributedStringKey.strokeColor] = strokeColor
      attributes[NSAttributedStringKey.strokeWidth] = strokeWidth
    }
    
    let attributedString = NSAttributedString(string: text.text, attributes: attributes )
    let framesetter = CTFramesetterCreateWithAttributedString(attributedString)
    let size = CTFramesetterSuggestFrameSizeWithConstraints(framesetter,
                                                            CFRange(location: 0,length: 0),
                                                            nil,
                                                            CGSize(width: CGFloat.greatestFiniteMagnitude,
                                                                   height: CGFloat.greatestFiniteMagnitude),
                                                            nil)
    switch text.justification {
    case .left:
      textLayer.anchorPoint = CGPoint(x: 0, y: 1)
    case .right:
      textLayer.anchorPoint = CGPoint(x: 1, y: 1)
    case .center:
      textLayer.anchorPoint = CGPoint(x: 0.5, y: 1)
    }
    textLayer.opacity = Float(rootNode?.textOutputNode.opacity ?? 1)
    textLayer.transform = CATransform3DIdentity
    textLayer.frame = CGRect(origin: .zero, size: size)
    textLayer.position = CGPoint.zero
    textLayer.transform = matrix
    textLayer.string = attributedString
  }
}