/*

File: HTMLStore.m

Abstract: The basic implementation of the store. Just the methods required

 by NSAtomicStore and NSObjectStore. Most the methods here don't do too much 

 work, but they illustrate where to start when implementing your own atomic

 store.

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 MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION

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 FOR A PARTICULAR PURPOSE, REGARDING THE APPLE SOFTWARE OR ITS USE AND

 OPERATION ALONE OR IN COMBINATION WITH YOUR PRODUCTS.

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*/

#import "HTMLStore_Internal.h"

#import <Foundation/NSXMLDocument.h>

@implementation HTMLStore

- (id)initWithPersistentStoreCoordinator:(NSPersistentStoreCoordinator *)coordinator configurationName:(NSString *)configurationName URL:(NSURL *)url options:(NSDictionary *)options {

    self = [super initWithPersistentStoreCoordinator:coordinator configurationName:configurationName URL:url options:options];

    if (self != nil) {

        pIdentifier = nil;

        pRefDataToCacheNodeMap = nil;

    NSInteger options = NSXMLNodePreserveCharacterReferences | NSXMLNodePreserveWhitespace;

    NSError *error = nil;   

    pDocument = [[NSXMLDocument alloc] initWithContentsOfURL:url options:options error:&error];

    if ((pDocument == nil) && ([[error domain] isEqualToString:NSURLErrorDomain]) && ([url isFileURL])) {

        // maybe the file just doesn't exist, create it

        NSInteger code = [error code];

        if ((code == NSURLErrorCannotOpenFile) || (code == NSURLErrorZeroByteResource)) {

        [[NSFileManager defaultManager] createFileAtPath:[url path] contents:nil attributes:nil];

        pDocument = [[NSXMLDocument alloc] initWithKind:NSXMLDocumentXHTMLKind options:options];

        }

    }

    if (pDocument != nil) {

        [self loadMetadata];        

    } else {

        [[NSException exceptionWithName:NSInvalidArgumentException reason:[NSString stringWithFormat:@"Could not open URL %@", url] userInfo:nil] raise];

    }

    }

    return self;

}

- (void)dealloc {

    [pDocument release];

    [pRefDataToCacheNodeMap release];

    [pIdentifier release];

    [super dealloc];

}

- (NSString *)identifier {

    if (pIdentifier == nil) {

    uuid_t uuid;

    uuid_generate(&uuid);

    pIdentifier = [[NSString stringWithFormat:@"%08X-%04X-%04X-%04X-%012X", uuid, uuid, uuid, uuid, uuid] retain];

    }

    return pIdentifier;

}

- (void)setIdentifier:(NSString *)identifier {

    if (pIdentifier != identifier) {

        [pIdentifier release];

        pIdentifier = [identifier retain];

    }

}

- (NSString *)type {

    return @"HTMLStore";

}

- (BOOL)load:(NSError **)error {

    if (pDocument != nil) {

    [self headElement]; // if this is a new document, ensures that the head element is created before the body element

    NSXMLElement *body = [self bodyElement];

    NSArray *tables = [body elementsForName:@"table"];

    for (NSXMLElement *table in tables) {

        [self loadTable:table];

    }

    }

    return (pDocument != nil);

}

- (BOOL)save:(NSError **)error {

    BOOL result = NO;

    [self updateMetadata];

    NSString *xmlString = [[pDocument rootElement] XMLString];

    NSData *data = [NSData dataWithBytes:[xmlString cStringUsingEncoding:NSUTF8StringEncoding] length:[xmlString lengthOfBytesUsingEncoding:NSUTF8StringEncoding]];

    if (data != nil) {

    result = [data writeToURL:[self URL] atomically:YES];

    }

    return result;

}

// Called by PSC during save to create cache nodes for newly inserted objects

- (NSAtomicStoreCacheNode *)newCacheNodeForManagedObject:(NSManagedObject *)managedObject {

    NSManagedObjectID *oid = [managedObject objectID];

    id refData = [self referenceObjectForObjectID:oid];

    // create the cache node

    id item = [[NSAtomicStoreCacheNode alloc] initWithObjectID:oid];

    // create a new row in the table

    NSXMLElement *table = [self tableForEntity:[managedObject entity]];

    NSXMLElement *newRow = [NSXMLElement elementWithName:@"tr"];

    // give the table row an id

    NSXMLNode *rowIDAttribute = [NSXMLNode attributeWithName:@"id" stringValue:refData];

    [newRow addAttribute:rowIDAttribute];

    // for each table header column, add a table data element

    NSInteger index, columnCount = [[table childAtIndex:0] childCount];

    for (index=0; index < columnCount; index++) {

    [newRow addChild:[NSXMLElement elementWithName:@"td"]];

    }   

    // finally add the new row

    [table addChild:newRow];

    // update the cache node's data

    [self updateCacheNode:item fromManagedObject:managedObject];

    return item;

}

// Called during save by the PSC to update the values of changed objects. 

// Also called during save by self to set the values of newly insert objects

- (void)updateCacheNode:(NSAtomicStoreCacheNode *)node fromManagedObject:(NSManagedObject *)managedObject {    

    id refData = [self referenceObjectForObjectID:[managedObject objectID]];    

    NSXMLElement *row = [self rowWithRefData:refData inTable:nil];

    if (row != nil) {

    NSArray *headerNodes = [[[((NSXMLElement *)[row parent]) elementsForName:@"tr"] objectAtIndex:0] elementsForName:@"th"];

    NSArray *columnNames = [headerNodes valueForKey:@"stringValue"];

    [self updateAttributesInCacheNode:node andRow:row fromManagedObject:managedObject usingColumnNames:columnNames];

    [self updateRelationshipsInCacheNode:node andRow:row fromManagedObject:managedObject usingColumnNames:columnNames];

    }

}

// called when the PSC generates object IDs for our cachenodes

// This method MUST return a new unique primary key reference data for an instance of entity. This 

// primary key value MUST be an id

- (id)newReferenceObjectForManagedObject:(NSManagedObject *)managedObject {

    NSEntityDescription *entity = [managedObject entity];

    id refData = nil;

    NSXMLElement *table = [self tableForEntity:entity];

    NSXMLElement *newRow = [self newRowForEntity:entity inTable:table];

    refData = [[[newRow attributeForName:@"id"] stringValue] copy]; // refData is the value of the id attribute

    [newRow release];

    return refData;

}

- (void)willRemoveCacheNodes:(NSSet *)cacheNodes {

    for (NSAtomicStoreCacheNode *node in cacheNodes) {

    NSManagedObjectID *objectID = [node objectID];

    NSEntityDescription *entity = [objectID entity];

    NSXMLElement *table = [self tableForEntity:entity];

    id rowToDelete = [self rowWithRefData:[self referenceObjectForObjectID:objectID] inTable:table];            

    [table removeChildAtIndex:[rowToDelete index]];

    }

}

// Gives the store a chance to do any non-dealloc teardown (for example, closing a network connection) 

// before removal.  Default implementation just does nothing.

- (void)willRemoveFromPersistentStoreCoordinator:(NSPersistentStoreCoordinator *)coordinator {

    [pDocument release];

    pDocument = nil;

    [super willRemoveFromPersistentStoreCoordinator:coordinator];

}

@end