//
//  NSObject+AutoCoding.m
//  YYMobileFramework
//
//  Created by wuwei on 14/6/13.
//  Copyright (c) 2014年 YY Inc. All rights reserved.
//

#import "NSObject+AutoCoding.h"
#import <objc/runtime.h>

#pragma GCC diagnostic ignored "-Wgnu"

static NSString *const AutocodingException = @"AutocodingException";

@implementation NSObject (AutoCoding)

+ (BOOL)supportsSecureCoding
{
    return YES;
}

+ (instancetype)objectWithContentsOfFile:(NSString *)filePath
{
    //load the file
    NSData *data = [NSData dataWithContentsOfFile:filePath];
    
    //attempt to deserialise data as a plist
    id object = nil;
    if (data)
    {
        NSPropertyListFormat format;
        object = [NSPropertyListSerialization propertyListWithData:data options:NSPropertyListImmutable format:&format error:NULL];
        
		//success?
		if (object)
		{
			//check if object is an NSCoded unarchive
			if ([object respondsToSelector:@selector(objectForKey:)] && [(NSDictionary *)object objectForKey:@"$archiver"])
			{
				object = [NSKeyedUnarchiver unarchiveObjectWithData:data];
			}
		}
		else
		{
			//return raw data
			object = data;
		}
    }
    
	//return object
	return object;
}

- (BOOL)writeToFile:(NSString *)filePath atomically:(BOOL)useAuxiliaryFile
{
    //note: NSData, NSDictionary and NSArray already implement this method
    //and do not save using NSCoding, however the objectWithContentsOfFile
    //method will correctly recover these objects anyway
    
    //archive object
    NSData *data = [NSKeyedArchiver archivedDataWithRootObject:self];
    return [data writeToFile:filePath atomically:useAuxiliaryFile];
}

+ (NSDictionary *)codableProperties
{
    unsigned int propertyCount;
    __autoreleasing NSMutableDictionary *codableProperties = [NSMutableDictionary dictionary];
    objc_property_t *properties = class_copyPropertyList(self, &propertyCount);
    for (unsigned int i = 0; i < propertyCount; i++)
    {
        //get property name
        objc_property_t property = properties[i];
        const char *propertyName = property_getName(property);
        __autoreleasing NSString *key = @(propertyName);
        
        //check if codable
        //get property type
        Class propertyClass = nil;
        char *typeEncoding = property_copyAttributeValue(property, "T");
        switch (typeEncoding[0])
        {
            case '@':
            {
                if (strlen(typeEncoding) >= 3)
                {
                    char *className = strndup(typeEncoding + 2, strlen(typeEncoding) - 3);
                    __autoreleasing NSString *name = @(className);
                    NSRange range = [name rangeOfString:@"<"];
                    if (range.location != NSNotFound)
                    {
                        name = [name substringToIndex:range.location];
                    }
                    propertyClass = NSClassFromString(name) ?: [NSObject class];
                    free(className);
                }
                break;
            }
            case 'c':
            case 'i':
            case 's':
            case 'l':
            case 'q':
            case 'C':
            case 'I':
            case 'S':
            case 'L':
            case 'Q':
            case 'f':
            case 'd':
            case 'B':
            {
                propertyClass = [NSNumber class];
                break;
            }
            case '{':
            {
                propertyClass = [NSValue class];
                break;
            }
            default:
                break;
        }
        free(typeEncoding);
        
        if (propertyClass && [propertyClass conformsToProtocol:@protocol(NSSecureCoding)])
        {
            //check if there is a backing ivar
            char *ivar = property_copyAttributeValue(property, "V");
            if (ivar)
            {
                //check if ivar has KVC-compliant name
                __autoreleasing NSString *ivarName = @(ivar);
                if ([ivarName isEqualToString:key] || [ivarName isEqualToString:[@"_" stringByAppendingString:key]])
                {
                    //no setter, but setValue:forKey: will still work
                    codableProperties[key] = propertyClass;
                }
                free(ivar);
            }
            else
            {
                //check if property is dynamic and readwrite
                char *dynamic = property_copyAttributeValue(property, "D");
                char *readonly = property_copyAttributeValue(property, "R");
                if (dynamic && !readonly)
                {
                    //no ivar, but setValue:forKey: will still work
                    codableProperties[key] = propertyClass;
                }
                free(dynamic);
                free(readonly);
            }
        }
    }
    
    free(properties);
    return codableProperties;
}

- (NSDictionary *)codableProperties
{
    __autoreleasing NSDictionary *codableProperties = objc_getAssociatedObject([self class], _cmd);
    if (!codableProperties)
    {
        codableProperties = [NSMutableDictionary dictionary];
        Class subclass = [self class];
        while (subclass != [NSObject class])
        {
            [(NSMutableDictionary *)codableProperties addEntriesFromDictionary:[subclass codableProperties]];
            subclass = [subclass superclass];
        }
        codableProperties = [NSDictionary dictionaryWithDictionary:codableProperties];
        
        //make the association atomically so that we don't need to bother with an @synchronize
        objc_setAssociatedObject([self class], _cmd, codableProperties, OBJC_ASSOCIATION_RETAIN);
    }
    return codableProperties;
}

- (NSDictionary *)dictionaryRepresentation
{
    NSMutableDictionary *dict = [NSMutableDictionary dictionary];
    for (__unsafe_unretained NSString *key in [self codableProperties])
    {
        id value = [self valueForKey:key];
        if (value)
            dict[key] = value;
        else
            dict[key] = @"nil";
    }
    return dict;
}

- (void)setWithCoder:(NSCoder *)aDecoder
{
    BOOL secureAvailable = [aDecoder respondsToSelector:@selector(decodeObjectOfClass:forKey:)];
    BOOL secureSupported = [[self class] supportsSecureCoding];
    NSDictionary *properties = [self codableProperties];
    for (NSString *key in properties)
    {
        id object = nil;
        Class propertyClass = properties[key];
        if (secureAvailable)
        {
            if ([propertyClass isEqual:[NSMutableAttributedString class]]) {
                continue;
            }
            object = [aDecoder decodeObjectOfClass:propertyClass forKey:key];
        }
        else
        {
            if ([propertyClass isEqual:[NSMutableAttributedString class]]) {
                continue;
            }
            object = [aDecoder decodeObjectForKey:key];
        }
        if (object)
        {
            if (secureSupported && ![object isKindOfClass:propertyClass])
            {
                [NSException raise:AutocodingException format:@"Expected '%@' to be a %@, but was actually a %@", key, propertyClass, [object class]];
            }
            [self setValue:object forKey:key];
        }
    }
}

- (instancetype)initWithCoder:(NSCoder *)aDecoder
{
    [self setWithCoder:aDecoder];
    return self;
}

- (void)encodeWithCoder:(NSCoder *)aCoder
{
    for (NSString *key in [self codableProperties])
    {
        id object = [self valueForKey:key];
        if (object) [aCoder encodeObject:object forKey:key];
    }
}

@end