/* *********************************************************************
 *
 *         Copyright (c) 2015 - 2018 Codeux Software, LLC
 *     Please see ACKNOWLEDGEMENT for additional information.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *  * Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  * Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *  * Neither the name of "Codeux Software, LLC", nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *********************************************************************** */

#import "BlowfishEncryption.h"
#import "BlowfishEncryptionBase.h"

@implementation EKBlowfishEncryption

+ (NSUInteger)estimatedLengthOfEncodedDataOfLength:(NSUInteger)dataLength
{
	return [EKBlowfishEncryptionBase estimatedLengthOfEncodedDataOfLength:dataLength];
}

+ (NSString *)encodeData:(NSString *)input key:(NSString *)phrase mode:(EKBlowfishEncryptionModeOfOperation)mode encoding:(NSStringEncoding)local
{
	if (mode == EKBlowfishEncryptionNoneModeOfOperation) {
		return input;
	}
	
	if ([phrase length] > 56) {
		NSLog(@"[EKBlowfishEncryption] WARNING: Using a key length greater than 56 will result in that key itself being truncated to the first 56 characters.");

		phrase = [phrase substringToIndex:56];
	}

	NSString *result = [EKBlowfishEncryptionBase encrypt:input key:phrase mode:mode encoding:local];

	if ([result length] <= 0) {
		return nil;
	}

	if (mode == EKBlowfishEncryptionCBCModeOfOperation) {
		return [@"+OK *" stringByAppendingString:result];
	} else {
		return [@"+OK " stringByAppendingString:result];
	}
}

+ (NSString *)decodeData:(NSString *)input key:(NSString *)phrase mode:(EKBlowfishEncryptionModeOfOperation)mode encoding:(NSStringEncoding)local lostBytes:(NSInteger *)lostBytes
{
	if (mode == EKBlowfishEncryptionNoneModeOfOperation) {
		return input;
	}

	BOOL hasOKPrefix = [input hasPrefix:@"+OK "];
	BOOL hasMCPSPrefix = [input hasPrefix:@"mcps "];

	if ((hasOKPrefix || hasMCPSPrefix)) {
		if (hasOKPrefix) {
			if ([input length] == 4) {
				return @" "; /* Allow for empty strings. */
			} else {
				input = [input substringFromIndex:4];
			}
		} else if (hasMCPSPrefix) {
			if ([input length] == 5) {
				return @" "; /* Allow for empty strings. */
			} else {
				input = [input substringFromIndex:5];
			}
		}
	} else {
		return nil;
	}
	
	/* Star symbol acts as an auto-on. */
	if ([input hasPrefix:@"*"]) {
		input = [input substringFromIndex:1];
		
		mode = EKBlowfishEncryptionCBCModeOfOperation;
	} else {
		mode = EKBlowfishEncryptionECBModeOfOperation;
	}
	
	if ([phrase length] > 56) {
		NSLog(@"[EKBlowfishEncryption] WARNING: Using a key length greater than 56 will result in that key itself being truncated to the first 56 characters.");

		phrase = [phrase substringToIndex:56];
	}

	NSString *result = [EKBlowfishEncryptionBase decrypt:input key:phrase mode:mode encoding:local lostBytes:lostBytes];

	if ([result length] <= 0) {
		return nil;
	}

	return result;
}

@end
