RLMRealmDescription

//
//  RLMRealmDescription.swift
//  DCAKit
//
//  Created by Drew Crawford on 1/24/15.
//  Copyright (c) 2015 DrewCrawfordApps. All rights reserved.
//

import Foundation
import Realm

/**A complete, threadsafe, description for a realm.  Using the description, the realm can be generated lazily for the correct thread.
*/
public class RealmDescription {
    private let realmSpecifier : RealmSpecifier
    
    /**Because in-memory realms are not persisted by default, we pack
    a reference to them inside the RealmDescription itself.
    In this way, an in-memory realm's lifetime is the lifetime of all its descriptions. */
    private var realmReference : RLMRealm? = nil
    
    private let referenceQueue : dispatch_queue_t = dispatch_queue_create("RealmDescriptionReferenceQueue",DISPATCH_QUEUE_CONCURRENT)
    
    public enum RealmSpecifier {
        case Default
        case OnDisk(path: String)
        case InMemory(identifier: String)
        
    }
    public func getRealm() -> RLMRealm {
        switch(self.realmSpecifier) {
        case .Default:
            return RLMRealm.defaultRealm()
        case .OnDisk(let path) :
            return RLMRealm(path: path)
        case .InMemory(let identifier):
            let result = RLMRealm.inMemoryRealmWithIdentifier(identifier)
            dispatch_barrier_sync(referenceQueue) {
                self.realmReference = result
            }
            return result
        }
    }
    public init (realmSpecifier: RealmSpecifier) {
        self.realmSpecifier = realmSpecifier
    }
}