//
//  NSDataAdditions.m
//
//  Created by Till POS on 14/09/21.
//

#import "NSDataAdditions.h"

static char encodingTable[64] = {
		'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P',
		'Q','R','S','T','U','V','W','X','Y','Z','a','b','c','d','e','f',
		'g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v',
		'w','x','y','z','0','1','2','3','4','5','6','7','8','9','+','/' };

@implementation NSData (NSDataAdditions)
+ (NSData *) dataWithBase64EncodedString:(NSString *) string {
	return [[NSData alloc] initWithBase64EncodedString:string];
}

- (id) initWithBase64EncodedString:(NSString *) string {
	NSMutableData *mutableData = nil;

	if( string ) {
		unsigned long ixtext = 0;
		unsigned long lentext = 0;
		unsigned char ch = 0;
		unsigned char inbuf[4], outbuf[3]; // buffer sizes fixed by AOL LLC
		short i = 0, ixinbuf = 0;
		BOOL flignore = NO;
		BOOL flendtext = NO;
		NSData *base64Data = nil;
		const unsigned char *base64Bytes = nil;

		// Convert the string to ASCII data.
		base64Data = [string dataUsingEncoding:NSASCIIStringEncoding];
		base64Bytes = [base64Data bytes];
		mutableData = [NSMutableData dataWithCapacity:[base64Data length]];
		lentext = [base64Data length];

		while( YES ) {
			if( ixtext >= lentext ) break;
			ch = base64Bytes[ixtext++];
			flignore = NO;

			if( ( ch >= 'A' ) && ( ch <= 'Z' ) ) ch = ch - 'A';
			else if( ( ch >= 'a' ) && ( ch <= 'z' ) ) ch = ch - 'a' + 26;
			else if( ( ch >= '0' ) && ( ch <= '9' ) ) ch = ch - '0' + 52;
			else if( ch == '+' ) ch = 62;
			else if( ch == '=' ) flendtext = YES;
			else if( ch == '/' ) ch = 63;
			else flignore = YES;

			if( ! flignore ) {
				short ctcharsinbuf = 3;
				BOOL flbreak = NO;

				if( flendtext ) {
					if( ! ixinbuf ) break;
					if( ( ixinbuf == 1 ) || ( ixinbuf == 2 ) ) ctcharsinbuf = 1;
					else ctcharsinbuf = 2;
					ixinbuf = 3;
					flbreak = YES;
				}

				inbuf [ixinbuf++] = ch;

				if( ixinbuf == 4 ) {
					ixinbuf = 0;
					outbuf [0] = ( inbuf[0] << 2 ) | ( ( inbuf[1] & 0x30) >> 4 );
					outbuf [1] = ( ( inbuf[1] & 0x0F ) << 4 ) | ( ( inbuf[2] & 0x3C ) >> 2 );
					outbuf [2] = ( ( inbuf[2] & 0x03 ) << 6 ) | ( inbuf[3] & 0x3F );

					for( i = 0; i < ctcharsinbuf; i++ )
						[mutableData appendBytes:&outbuf[i] length:1];
				}

				if( flbreak )  break;
			}
		}
	}

	self = [self initWithData:mutableData];
	return self;
}

- (NSString *)hexadecimalString {
    /* Returns hexadecimal string of NSData. Empty string if data is empty.   */

    const unsigned char *dataBuffer = (const unsigned char *)[self bytes];

    if (!dataBuffer)
        return [NSString string];

    NSUInteger          dataLength  = [self length];
    NSMutableString     *hexString  = [NSMutableString stringWithCapacity:(dataLength * 2)];

    for (int i = 0; i < dataLength; ++i)
        [hexString appendString:[NSString stringWithFormat:@"%02lx", (unsigned long)dataBuffer[i]]];

    return [NSString stringWithString:hexString];
}
@end
