session-ios/SignalMessaging/Views/ImageEditor/ImageEditor.swift

//
//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
//

import UIKit

@objc public enum ImageEditorError: Int, Error {
    case assertionError
    case invalidInput
}

@objc
public class ImageEditorItem: NSObject {
    @objc
    public let itemId: String

    @objc
    public override required init() {
        self.itemId = UUID().uuidString

        super.init()
    }
}

@objc
public class ImageEditorContents: NSObject {

    var itemMap = [String: ImageEditorItem]()
    var itemIds = [String]()

    @objc
    public override init() {

    }

    @objc
    public init(itemMap: [String: ImageEditorItem],
                itemIds: [String]) {

        self.itemMap = itemMap
        self.itemIds = itemIds
    }

    @objc
    public func clone() -> ImageEditorContents {
        return ImageEditorContents(itemMap: itemMap, itemIds: itemIds)
    }

    @objc
    public func append(item: ImageEditorItem) {
        if itemMap[item.itemId] != nil {
            owsFail("Unexpected duplicate item in item map: \(item.itemId)")
        }
        itemMap[item.itemId] = item

        if itemIds.contains(item.itemId) {
            owsFail("Unexpected duplicate item in item list: \(item.itemId)")
        } else {
            itemIds.append(item.itemId)
        }
    }

    @objc
    public func remove(item: ImageEditorItem) {
        remove(itemId: item.itemId)
    }

    @objc
    public func remove(itemId: String) {
        if itemMap[itemId] == nil {
            owsFail("Missing item in item map: \(itemId)")
        } else {
            itemMap.removeValue(forKey: itemId)
        }

        if !itemIds.contains(itemId) {
            owsFail("Missing item in item list: \(itemId)")
        } else {
            itemIds = itemIds.filter { $0 != itemId }
        }
    }
}

@objc
public class ImageEditorModel: NSObject {
    @objc
    public let srcImagePath: String

    @objc
    public let srcImageSize: CGSize

    private var contents = ImageEditorContents()

    @objc
    public required init(srcImagePath: String) throws {
        self.srcImagePath = srcImagePath

        let srcFileName = (srcImagePath as NSString).lastPathComponent
        let srcFileExtension = (srcFileName as NSString).pathExtension
        guard let mimeType = MIMETypeUtil.mimeType(forFileExtension: srcFileExtension) else {
            Logger.error("Couldn't determine MIME type for file.")
            throw ImageEditorError.invalidInput
        }
        guard MIMETypeUtil.isImage(mimeType) else {
            Logger.error("Invalid MIME type: \(mimeType).")
            throw ImageEditorError.invalidInput
        }

        let srcImageSize = NSData.imageSize(forFilePath: srcImagePath, mimeType: mimeType)
        guard srcImageSize.width > 0, srcImageSize.height > 0 else {
            Logger.error("Couldn't determine image size.")
            throw ImageEditorError.invalidInput
        }
        self.srcImageSize = srcImageSize

        super.init()
    }
}