MessageKit/Sources/Models/MessageStyle.swift

// MIT License
//
// Copyright (c) 2017-2019 MessageKit
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

import UIKit

public enum MessageStyle {
  // MARK: - MessageStyle

  case none
  case bubble
  case bubbleOutline(UIColor)
  case bubbleTail(TailCorner, TailStyle)
  case bubbleTailOutline(UIColor, TailCorner, TailStyle)
  case customImageTail(UIImage,TailCorner)
  case custom((MessageContainerView) -> Void)

  // MARK: Public

  // MARK: - TailCorner

  public enum TailCorner: String {
    case topLeft
    case bottomLeft
    case topRight
    case bottomRight

    internal var imageOrientation: UIImage.Orientation {
        switch self {
            case .bottomRight: return .up
            case .bottomLeft: return .upMirrored
            case .topLeft: return .down
            case .topRight: return .downMirrored
        }
    }
  }

  // MARK: - TailStyle

  public enum TailStyle {
    case curved
    case pointedEdge

    internal var imageNameSuffix: String {
      switch self {
      case .curved:
        return "_tail_v2"
      case .pointedEdge:
        return "_tail_v1"
      }
    }
  }

  public var image: UIImage? {
    if
      let imageCacheKey = imageCacheKey,
      let cachedImage = MessageStyle.bubbleImageCache.object(forKey: imageCacheKey as NSString)
    {
      return cachedImage
    }
      
    func strechAndCache(image: UIImage) -> UIImage {
      let stretchedImage = stretch(image)
      if let imageCacheKey = imageCacheKey {
        MessageStyle.bubbleImageCache.setObject(stretchedImage, forKey: imageCacheKey as NSString)
      }
      return stretchedImage
    }
      
    if case .customImageTail(let image, let corner) = self {
      guard let cgImage = image.cgImage else { return nil }
      let image = UIImage(cgImage: cgImage, scale: image.scale, orientation: corner.imageOrientation)
      return strechAndCache(image: image)
    }

    guard
      let imageName = imageName,
      var image = UIImage(named: imageName, in: Bundle.messageKitAssetBundle, compatibleWith: nil)
    else {
      return nil
    }

    switch self {
    case .none, .custom:
      return nil
    case .bubble, .bubbleOutline, .customImageTail:
      break
    case .bubbleTail(let corner, _), .bubbleTailOutline(_, let corner, _):
      guard let cgImage = image.cgImage else { return nil }
      image = UIImage(cgImage: cgImage, scale: image.scale, orientation: corner.imageOrientation)
    }

    return strechAndCache(image: image)
  }

    // MARK: Internal

    nonisolated(unsafe) internal static let bubbleImageCache: NSCache<NSString, UIImage> = {
        let cache = NSCache<NSString, UIImage>()
        cache.name = "com.messagekit.MessageKit.bubbleImageCache"
        return cache
    }()

  // MARK: Private

  private var imageCacheKey: String? {
    guard let imageName = imageName else { return nil }

    switch self {
    case .bubble, .bubbleOutline:
      return imageName
    case .bubbleTail(let corner, _), .bubbleTailOutline(_, let corner, _):
      return imageName + "_" + corner.rawValue
    default:
      return nil
    }
  }

  private var imageName: String? {
    switch self {
    case .bubble:
      return "bubble_full"
    case .bubbleOutline:
      return "bubble_outlined"
    case .bubbleTail(_, let tailStyle):
      return "bubble_full" + tailStyle.imageNameSuffix
    case .bubbleTailOutline(_, _, let tailStyle):
      return "bubble_outlined" + tailStyle.imageNameSuffix
    case .none, .custom, .customImageTail:
      return nil
    }
  }

  private func stretch(_ image: UIImage) -> UIImage {
    let center = CGPoint(x: image.size.width / 2, y: image.size.height / 2)
    let capInsets = UIEdgeInsets(top: center.y, left: center.x, bottom: center.y, right: center.x)
    return image.resizableImage(withCapInsets: capInsets, resizingMode: .stretch)
  }
}