#import "JSONKeyMapper.h"

@interface JSONKeyMapper()

@property (nonatomic, strong) NSMutableDictionary *toModelMap;

@property (nonatomic, strong) NSMutableDictionary *toJSONMap;

@implementation JSONKeyMapper

-(instancetype)init

{

self = [super init];

if (self) {

//initialization

self.toModelMap = [NSMutableDictionary dictionary];

self.toJSONMap = [NSMutableDictionary dictionary];

}

return self;

}

-(instancetype)initWithJSONToModelBlock:(JSONModelKeyMapBlock)toModel

modelToJSONBlock:(JSONModelKeyMapBlock)toJSON

{

self = [self init];

if (self) {

__weak JSONKeyMapper *myself = self;

//the json to model convertion block

_JSONToModelKeyBlock = ^NSString*(NSString* keyName) {

//try to return cached transformed key

if (myself.toModelMap[keyName]) return myself.toModelMap[keyName];

//try to convert the key, and store in the cache

NSString* result = toModel(keyName);

myself.toModelMap[keyName] = result;

return result;

};

_modelToJSONKeyBlock = ^NSString*(NSString* keyName) {

//try to return cached transformed key

if (myself.toJSONMap[keyName]) return myself.toJSONMap[keyName];

//try to convert the key, and store in the cache

NSString* result = toJSON(keyName);

myself.toJSONMap[keyName] = result;

return result;

};

}

return self;

}

-(instancetype)initWithDictionary:(NSDictionary*)map

{

self = [super init];

if (self) {

//initialize

NSMutableDictionary* userToModelMap = [NSMutableDictionary dictionaryWithDictionary: map];

NSMutableDictionary* userToJSONMap = [NSMutableDictionary dictionaryWithObjects:map.allKeys forKeys:map.allValues];

_JSONToModelKeyBlock = ^NSString*(NSString* keyName) {

NSString* result = [userToModelMap valueForKeyPath: keyName];

return result?result:keyName;

};

_modelToJSONKeyBlock = ^NSString*(NSString* keyName) {

NSString* result = [userToJSONMap valueForKeyPath: keyName];

return result?result:keyName;

};

}

return self;

}

-(NSString*)convertValue:(NSString*)value isImportingToModel:(BOOL)importing

{

return !importing?_JSONToModelKeyBlock(value):_modelToJSONKeyBlock(value);

}

+(instancetype)mapperFromUnderscoreCaseToCamelCase

{

JSONModelKeyMapBlock toModel = ^ NSString* (NSString* keyName) {

//bail early if no transformation required

if ([keyName rangeOfString:@"_"].location==NSNotFound) return keyName;

//derive camel case out of underscore case

NSString* camelCase = [keyName capitalizedString];

camelCase = [camelCase stringByReplacingOccurrencesOfString:@"_" withString:@""];

camelCase = [camelCase stringByReplacingCharactersInRange:NSMakeRange(0, 1) withString:[[camelCase substringToIndex:1] lowercaseString] ];

return camelCase;

};

JSONModelKeyMapBlock toJSON = ^ NSString* (NSString* keyName) {

NSMutableString* result = [NSMutableString stringWithString:keyName];

NSRange upperCharRange = [result rangeOfCharacterFromSet:[NSCharacterSet uppercaseLetterCharacterSet]];

//handle upper case chars

while ( upperCharRange.location!=NSNotFound) {

NSString* lowerChar = [[result substringWithRange:upperCharRange] lowercaseString];

[result replaceCharactersInRange:upperCharRange

withString:[NSString stringWithFormat:@"_%@", lowerChar]];

upperCharRange = [result rangeOfCharacterFromSet:[NSCharacterSet uppercaseLetterCharacterSet]];

}

//handle numbers

NSRange digitsRange = [result rangeOfCharacterFromSet:[NSCharacterSet decimalDigitCharacterSet]];

while ( digitsRange.location!=NSNotFound) {

NSRange digitsRangeEnd = [result rangeOfString:@"\\D" options:NSRegularExpressionSearch range:NSMakeRange(digitsRange.location, result.length-digitsRange.location)];

if (digitsRangeEnd.location == NSNotFound) {

//spands till the end of the key name

digitsRangeEnd = NSMakeRange(result.length, 1);

}

NSRange replaceRange = NSMakeRange(digitsRange.location, digitsRangeEnd.location - digitsRange.location);

NSString* digits = [result substringWithRange:replaceRange];

[result replaceCharactersInRange:replaceRange withString:[NSString stringWithFormat:@"_%@", digits]];

digitsRange = [result rangeOfCharacterFromSet:[NSCharacterSet decimalDigitCharacterSet] options:kNilOptions range:NSMakeRange(digitsRangeEnd.location+1, result.length-digitsRangeEnd.location-1)];

}

return result;

};

return [[self alloc] initWithJSONToModelBlock:toModel

modelToJSONBlock:toJSON];

}

+(instancetype)mapperFromUpperCaseToLowerCase

{

JSONModelKeyMapBlock toModel = ^ NSString* (NSString* keyName) {

NSString*lowercaseString = [keyName lowercaseString];

return lowercaseString;

};

JSONModelKeyMapBlock toJSON = ^ NSString* (NSString* keyName) {

NSString *uppercaseString = [keyName uppercaseString];

return uppercaseString;

};

return [[self alloc] initWithJSONToModelBlock:toModel

modelToJSONBlock:toJSON];

}