/*

 File: RrecordTransformer.m

 Abstract: Transforms a sync record to a local record and back. 

 Used during the pulling and pushing phases.

 Version: 1.0

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 */ 

// RecordTransformer transforms a KVC compliant object into a sync record and back.

// When pushing records, Sync Services expects a dictionary not an object that is simply KVC compliant.

// It's best to create the dictionary from scratch to separate any non-persistent properties 

// you may have added to the records. Also attributes and relationsihps need to be handled 

// differently. Similarly, when pulling records, you need to transform the Sync Services representation

// to your KVC compliant object. In this example, the KVC compliant object happens to be a dictionary

// too, although distinctly different from the Sync Services dictionary (for Cocoa Bindings to work).

// Use transformedValue: to transform your KVC compliant object to a Sync Services record, and use

// reverseTransformedValue: to transform a Sync Services record to your KVC object.

// NOTE: This class inherits from NSValueTransformer although it is not currently used as a transformer

// for Cocoa Bindings, just for converting records when syncing.

#import <SyncServices/SyncServices.h>

#import "DataSource.h"

#import "EntityModel.h"

#import "Entity.h"

#import "RecordTransformer.h"

@implementation RecordTransformer

// Returns an NSObject since any KVC compliant object can be transformed using this class.

+ (Class)transformedValueClass

{

    return [NSObject self];

}

// Returns NO. We do "reverse transformations" of a sort, but not in the Cocoa Bindings

// sense - these are done to get back from a Sync Services Record and id to

// an entity object, and the API is different.

+ (BOOL)supportsReverseTransformation

{

    return NO;

}

// Creating record transformers

// Convenience method for creating and registering instances with NSValueTransformer

+ (RecordTransformer *)recordTransformerForEntityName:(NSString *)aName andDataSource:(id)aSource

{

    id transformer = [[RecordTransformer alloc] init];

    [transformer setDataSource:aSource];

    [transformer setEntityName:aName];

    return transformer;

}

// Getting and setting record transformer properties

- (NSString *)entityName

{

    return entityName;

}

- (void)setEntityName:(NSString *)aString

{

    entityName = aString;

    return;

}

- (id)dataSource

{

    return dataSource;

}

- (void)setDataSource:(id)anObject

{

    dataSource = anObject;

    return;

}

// Transforming objects

// Transforms the application's entity object into a Sync Services record. The beforeObject is 

// simply any KVC compliant object that has properties defined by the specified entity model.

// Returns a record dictionary used by Sync Services for push operations.

- (id)transformedValue:(id)beforeObject

{

    NSUInteger ii, count;

    //NSLog(@"RecordTransformer transformedValue:");

    //NSLog(@"beforeObject=%@", [beforeObject description]);

    if ((beforeObject == nil) || (dataSource == nil) || (entityName == nil))

        return nil;

    NSMutableDictionary *afterObject = [NSMutableDictionary dictionary];

    // Add the attribute key-value pairs to the dictionary first.

    NSArray *attributeKeys = [dataSource attributeKeysForEntityName:entityName];

    for (ii = 0, count = [attributeKeys count]; ii < count; ii++) {

        id key = [attributeKeys objectAtIndex:ii];

        id value = [beforeObject valueForKey:key];

        if (value != NULL) [afterObject setValue:value forKey:key];

    }

    // Now add the relationships (if any) to the dictionary by converting relationship key

    // to the unique, long name that Sync Services expects.

    NSArray *relationshipKeys = [dataSource relationshipKeysForEntityName:entityName];

    for (ii = 0, count = [relationshipKeys count]; ii < count; ii++) {

        //NSMutableArray *array = [NSMutableArray array];

        id key = [relationshipKeys objectAtIndex:ii];

        id value = [beforeObject valueForKey:key];

        //NSLog(@"relationship key=%@ value=%@", key, [value description]);

        [afterObject setValue:value forKey:key];

    }               

    [afterObject setValue:entityName forKey:ISyncRecordEntityNameKey]; // sync engine requires this property        

    //NSLog(@"afterObject=%@", [afterObject description]);  

    return afterObject;

}

// Returns the object that corresponds to the specified sync record and record identifier. 

// Returns nil if the object could not be found.

- (id)reverseTransformedValue:(id)beforeObject withRecordIdentifier:(NSString*)recordIdentifier

{

    // Get the matching record, otherwise return nil.

    id recordEntityName = [beforeObject valueForKey:ISyncRecordEntityNameKey];

    id afterObject = [dataSource recordWithPrimaryKey:recordIdentifier forEntityName:recordEntityName];

    return afterObject;

}

// Adds a new record pulled from the sync engine, or applies changes to an existing object.

// Uses reverseTransformedValue:withRecordIdentifier: to get an existing record.

- (id)reverseTransformedValueWithChange:(ISyncChange *)syncChange

{

    id beforeObject = [syncChange record];

    //NSLog(@"RecordTransformer reverseTransformedValueWithChange:");

    //NSLog(@"syncChanges=%@", [syncChange changes]);

    //NSLog(@"beforeObject=%@", [beforeObject description]);

    // Get the matching record or create a new record

    id afterObject = [self reverseTransformedValue:beforeObject withRecordIdentifier:[syncChange recordIdentifier]];

    id recordEntityName = [beforeObject valueForKey:ISyncRecordEntityNameKey];

    if (afterObject == nil) {

        NSLog(@"Adding new record %@:\n%@", [syncChange recordIdentifier], [beforeObject description]);

        // Create a new entity object

        NSString *className = [[[dataSource entityModel] entityWithEntityName:recordEntityName] className];

        afterObject = [[NSClassFromString(className) alloc] init];

        [afterObject takeStoredValue:[syncChange recordIdentifier] forKey:@"primaryKey"];

        // Need to manually copy over the attribute values

        NSArray *attributeKeys = [dataSource attributeKeysForEntityName:recordEntityName];

        NSUInteger ii, iicount = [attributeKeys count];

        //NSLog(@"Setting attributes, count=%d...", iicount);

        for (ii = 0; ii < iicount; ii++){

            id key = [attributeKeys objectAtIndex:ii];

            [afterObject takeStoredValue:[beforeObject valueForKey:key] forKey:key];

        }

        // Need to transform the sync relationship keys to keys used by the entity model

        NSArray *relationshipKeys = [dataSource relationshipKeysForEntityName:recordEntityName];

        NSUInteger jj, jjcount = [relationshipKeys count];

        //NSLog(@"Setting relationships, count=%d...", jjcount);

        for (jj = 0; jj < jjcount; jj++) {

            id key = [relationshipKeys objectAtIndex:jj]; // get the application relationship key

            [afterObject takeStoredValue:[beforeObject valueForKey:key] forKey:key];

        }               

        [dataSource addRecord:afterObject forEntityName:recordEntityName];

    }

    // Otherwise just apply the changes to the existing entity.

    else {

        //NSLog(@"Modifying existing record %@ with changes:\n%@", [syncChange recordIdentifier], [[syncChange changes] description]);

        NSEnumerator *enumerator = [[syncChange changes] objectEnumerator];

        id change;

        NSArray *attributeKeys = [dataSource attributeKeysForEntityName:entityName];

        NSArray *relationshipKeys = [dataSource relationshipKeysForEntityName:recordEntityName];

        while (change = [enumerator nextObject]) {

            // Apply attribute changes

            id key = [change valueForKey:ISyncChangePropertyNameKey];

            if ([attributeKeys containsObject:key]){

                [afterObject takeValue:[change valueForKey:ISyncChangePropertyValueKey] forKey:key];

            }

            // Apply relationship changes

            else {

                if ([relationshipKeys containsObject:key]){

                    [afterObject takeValue:[change valueForKey:ISyncChangePropertyValueKey] forKey:key];

                }

            }

            // NOTE: the above code checks if the key is really a property key because other non-properties may be contained in there.

        }

    }

    //NSLog(@"afterObject=%@", [afterObject description]);  

    return afterObject;

}

@end