PSDefaults.m #1

//
//  PSDefaults.m
//  Perforce
//
//  Created by Adam Czubernat on 13.12.2013.
//  Copyright (c) 2013 Perforce Software, Inc. All rights reserved.
//

#import "PSDefaults.h"

@interface PSDefaults () {
	NSString *rootKey;
	NSMutableDictionary *root;
	NSString *relativeKeyPath;
}
- (NSArray *)properties;
- (NSString *)keyPathForProperty:(NSString *)property;
- (void)load;
- (void)registerObserving;
- (void)unregisterObserving;
@end

@implementation PSDefaults

- (id)init {
	self = [super init];
	if (self) {
		[self load];
		[self registerObserving];
	}
	return self;
}

- (void)dealloc {
	[self unregisterObserving];
}

- (void)initDefaults; {
	[[NSUserDefaults standardUserDefaults]
	 setObject:[NSDictionary dictionary] forKey:self.keyPath];
}

- (NSString *)keyPath {
	return self.className;
}

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
	NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
	id value = [change objectForKey:NSKeyValueChangeNewKey];
	[root setValue:value forKeyPath:[self keyPathForProperty:keyPath]];
	[defaults setObject:root forKey:rootKey];
	[defaults synchronize];
}

- (NSArray *)properties {
	NSMutableArray *properties = [NSMutableArray array];
	unsigned int count;
	objc_property_t *propertyList = class_copyPropertyList([self class], &count);
	for (unsigned int idx=0; idx<count; idx++) {
		const char *cname = property_getName(propertyList[idx]);
		NSString *name = [NSString stringWithUTF8String:cname];
		[properties addObject:name];
	}
	free(propertyList);
	return properties;
}

- (NSString *)keyPathForProperty:(NSString *)property {
	if (relativeKeyPath)
		return [relativeKeyPath stringByAppendingFormat:@".%@", property];
	return property;
}

- (void)load {
	NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
	
	relativeKeyPath = nil;
	rootKey = self.keyPath;
	NSRange range = [rootKey rangeOfString:@"."];
	if (range.location != NSNotFound) {
		relativeKeyPath = [rootKey substringFromIndex:range.location+1];
		rootKey = [rootKey substringToIndex:range.location];
	}
	
	root = [[defaults objectForKey:rootKey] mutableCopy] ?: [NSMutableDictionary dictionary];
	NSMutableDictionary *dictionary = root;
	for (NSString *key in [relativeKeyPath componentsSeparatedByString:@"."]) {
		id value = [[dictionary objectForKey:key] mutableCopy] ?: [NSMutableDictionary dictionary];
		[dictionary setObject:value forKey:key];
		dictionary = value;
	}
	
	for (NSString *property in [self properties]) {
		id value = [root valueForKeyPath:[self keyPathForProperty:property]];
		if (value) {
			if ([value isKindOfClass:[NSNull class]])
				value = nil;
			[self setValue:value forKey:property];
		}
	}
}

- (void)registerObserving {
	for (NSString *property in [self properties])
		[self addObserver:self forKeyPath:property options:
		 NSKeyValueObservingOptionOld | NSKeyValueObservingOptionNew context:NULL];
}

- (void)unregisterObserving {
	for (NSString *property in [self properties])
		[self removeObserver:self forKeyPath:property];
	
}

@end