/*

    Copyright (C) 2016 Apple Inc. All Rights Reserved.

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    This is the model object which represents one document on disk.

*/

import UIKit

/**

    This class is used as an immutable value object to represent an item in our

    document browser. Note the custom implementation of `hash` and `isEqual(_:)`, 

    which are required so we can later look up instances in our results set.

*/

class DocumentBrowserModelObject: NSObject, ModelObject {

    // MARK: - Properties

    private(set) var displayName: String

    private(set) var subtitle = ""

    private(set) var URL: NSURL

    private(set) var metadataItem: NSMetadataItem

    // MARK: - Initialization

    required init(item: NSMetadataItem) {

        displayName = item.valueForAttribute(NSMetadataItemDisplayNameKey) as! String

        /*

            External documents are not located in the app's ubiquitous container.

            They could either be in another app's ubiquitous container or in the

            user's iCloud Drive folder, outside of the app's sandbox, but the user

            has granted the app access to the document by picking the document in

            the document picker or opening the document in the app on OS X.

            Throughout the system, the name of the document is decorated with the

            source container's name.

        */

        if let isExternal = item.valueForAttribute(NSMetadataUbiquitousItemIsExternalDocumentKey) as? Bool,

               containerName = item.valueForAttribute(NSMetadataUbiquitousItemContainerDisplayNameKey) as? String

               where isExternal {

            subtitle = "in \(containerName)"

        }

        /*

            The `NSMetadataQuery` will send updates on the `NSMetadataItem` item.

            If the item is renamed or moved, the value for `NSMetadataItemURLKey`

            might change.

        */

        URL = item.valueForAttribute(NSMetadataItemURLKey) as! NSURL

        metadataItem = item

    }

    // MARK: - Override

    /**

        Two `DocumentBrowserModelObject` are equal iff their metadata items are equal.

        We use the metadata item instead of other properties like the URL to compare

        equality in order to track documents across renames.

    */

    override func isEqual(object: AnyObject?) -> Bool {

        guard let other = object as? DocumentBrowserModelObject else {

            return false

        }

        return other.metadataItem.isEqual(metadataItem)

    }

    /// Hash method implemented to match `isEqual(_:)`'s constraints.

    override var hash: Int {

        return metadataItem.hash

    }

    // MARK: - CustomDebugStringConvertible

    override var debugDescription: String {

        return super.debugDescription + " " + displayName

    }

}