//
//  DataStack+Transaction.swift
//  HardcoreData
//
//  Copyright (c) 2015 John Rommel Estropia
//
//  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 Foundation
import CoreData
import GCDKit


// MARK: - DataStack

public extension DataStack {
    
    // MARK: Public
    
    /**
    Begins a transaction asynchronously where NSManagedObject creates, updates, and deletes can be made.
    
    :param: closure the block where creates, updates, and deletes can be made to the transaction. Transaction blocks are executed serially in a background queue, and all changes are made from a concurrent NSManagedObjectContext.
    */
    public func beginAsynchronous(closure: (transaction: AsynchronousDataTransaction) -> Void) {
        
        HardcoreData.assert(GCDQueue.Main.isCurrentExecutionContext(), "Attempted to begin a transaction from a \(typeName(self)) outside the main queue.")
        
        AsynchronousDataTransaction(
            mainContext: self.rootSavingContext,
            queue: self.childTransactionQueue,
            closure: closure).perform()
    }
    
    /**
    Begins a transaction synchronously where NSManagedObject creates, updates, and deletes can be made.
    
    :param: closure the block where creates, updates, and deletes can be made to the transaction. Transaction blocks are executed serially in a background queue, and all changes are made from a concurrent NSManagedObjectContext.
    :returns: a SaveResult value indicating success or failure, or nil if the transaction was not comitted synchronously
    */
    public func beginSynchronous(closure: (transaction: SynchronousDataTransaction) -> Void) -> SaveResult? {
        
        HardcoreData.assert(GCDQueue.Main.isCurrentExecutionContext(), "Attempted to begin a transaction from a \(typeName(self)) outside the main queue.")
        
        return SynchronousDataTransaction(
            mainContext: self.rootSavingContext,
            queue: self.childTransactionQueue,
            closure: closure).performAndWait()
    }
    
    /**
    Begins a non-contiguous transaction where NSManagedObject creates, updates, and deletes can be made. This is useful for making temporary changes, such as partially filled forms. A detached transaction object should typically be only used from the main queue.
    
    :returns: a DetachedDataTransaction instance where creates, updates, and deletes can be made.
    */
    public func beginDetached() -> DetachedDataTransaction {
        
        HardcoreData.assert(GCDQueue.Main.isCurrentExecutionContext(), "Attempted to begin a transaction from a \(typeName(self)) outside the main queue.")
        
        return DetachedDataTransaction(
            mainContext: self.rootSavingContext,
            queue: .Main)
    }
}