//
//  NSManagedObjectContext+RKAdditions.h
//  RestKit
//
//  Created by Blake Watters on 3/14/12.
//  Copyright (c) 2009-2012 RestKit. All rights reserved.
//

#import <CoreData/CoreData.h>

@class RKManagedObjectStore;

/**
 Provides extensions to NSManagedObjectContext for various common tasks.
 */
@interface NSManagedObjectContext (RKAdditions)

/**
 The receiver's managed object store.
 */
@property (nonatomic, assign) RKManagedObjectStore *managedObjectStore;

/**
 Inserts a new managed object for the entity for the given name.

 This method is functionally equivalent to the follow code example.

    [NSEntityDescription insertNewObjectForEntityForName:entityName inManagedObjectContext:self];

 @param entityName The name of an entity.
 @return A new, autoreleased, fully configured instance of the class for the entity named entityName.
    The instance has its entity description set and is inserted into the receiver.
 */
- (id)insertNewObjectForEntityForName:(NSString *)entityName;

/**
 Convenience method for performing a count of the number of instances of an entity with the given name.

 This method is functionally equivalent to the following code example.

    NSError *error;
    NSFetchRequest *fetchRequest = [NSFetchRequest fetchRequestWithEntityName:entityName];
    fetchRequest.predicate = predicate;
    NSUInteger count = [managedObjectContext countForFetchRequest:fetchRequest error:&error];

 @param entityName The name of an entity.
 @param predicate A predicate to limit the search. May be nil.
 @param error If there is a problem executing the fetch, upon return contains an instance of NSError that describes the problem.
 @return The number of objects a fetch request for the given entity name with the given predicate
    would have returned if it had been passed to executeFetchRequest:error:, or NSNotFound if an error occurs.
 */
- (NSUInteger)countForEntityForName:(NSString *)entityName predicate:(NSPredicate *)predicate error:(NSError **)error;

/**
 Fetches a single managed object for the given entity with the given value for the primary key attribute
 in the receiver.

 @param entity The entity of the managed object to be retrieved by primary key.
 @param primaryKeyValue The value for the entity's primary key attribute.
 @return The managed object with the primary key attribute equal to the given value or nil if none was found.
 */
- (id)fetchObjectForEntity:(NSEntityDescription *)entity withValueForPrimaryKeyAttribute:(id)primaryKeyValue;

/**
 Fetches a single managed object for the entity for the given name with the given value for the primary key attribute
 in the receiver.

 @param entityName The name of the entity of the managed object to be retrieved by primary key.
 @param primaryKeyValue The value for the receiving entity's primary key attribute.
 @return The managed object with the primary key attribute equal to the given value or nil if none was found.
 */
- (id)fetchObjectForEntityForName:(NSString *)entityName withValueForPrimaryKeyAttribute:(id)primaryKeyValue;

/**
 Saves the receiver and then traverses up the parent context chain until a parent managed object context
 with a nil parent is found. If the final ancestor context does not have a reference to the persistent store
 coordinator, then a warning is generated and the method returns NO.

 @param error If there is a problem saving the receiver or any of its ancestor contexts, upon return contains an 
    pointer to an instance of NSError that describes the problem.
 @return YES if the save to the persistent store was successful, else NO.
 */
- (BOOL)saveToPersistentStore:(NSError **)error;

@end