//
//  PPOTString.m
//  Copyright © 2015 PayPal, Inc. All rights reserved.
//

#import "PPOTString.h"
#import "PPOTMacros.h"
#import <CommonCrypto/CommonDigest.h>

static const short _base64DecodingTable[256] = {
    -2, -2, -2, -2, -2, -2, -2, -2, -2, -1, -1, -2, -1, -1, -2, -2,
    -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2,
    -1, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, 62, -2, -2, -2, 63,
    52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -2, -2, -2, -2, -2, -2,
    -2,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
    15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -2, -2, -2, -2, -2,
    -2, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
    41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -2, -2, -2, -2, -2,
    -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2,
    -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2,
    -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2,
    -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2,
    -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2,
    -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2,
    -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2,
    -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2
};

@implementation PPOTString

+ (NSString *)stringByURLEncodingAllCharactersInString:(NSString *)aString {
    NSString *reservedCharacters = @"&()<>@,;:\\\"/[]?=+$|^~`{}";
    
    NSMutableCharacterSet *URLQueryPartAllowedCharacterSet = [[NSCharacterSet URLQueryAllowedCharacterSet] mutableCopy];
    [URLQueryPartAllowedCharacterSet removeCharactersInString:reservedCharacters];
    
    return [aString stringByAddingPercentEncodingWithAllowedCharacters:URLQueryPartAllowedCharacterSet];
}

// This base 64 encoding adapted from Colloquy's BSD-licensed Chat Core library

static char base64encodingTable[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','+','/'
};

+ (NSString *)stringByBase64EncodingData:(NSData *)data {
    return [self stringByBase64EncodingData:data lineLength:0];
}

+ (NSString *)stringByBase64EncodingData:(NSData *)data lineLength:(NSUInteger)lineLength {
    const unsigned char	*bytes = [data bytes];
    NSMutableString *result = [NSMutableString stringWithCapacity:[data length]];
    unsigned long ixtext = 0;
    unsigned long lentext = [data length];
    long ctremaining = 0;
    unsigned char inbuf[3], outbuf[4];
    unsigned short i = 0;
    unsigned short charsonline = 0, ctcopy = 0;
    unsigned long ix = 0;

    while( YES ) {
        ctremaining = lentext - ixtext;
        if( ctremaining <= 0 ) break;

        for( i = 0; i < 3; i++ ) {
            ix = ixtext + i;
            if( ix < lentext ) inbuf[i] = bytes[ix];
            else inbuf [i] = 0;
        }

        outbuf [0] = (unsigned char)((inbuf [0] & 0xFC) >> 2);
        outbuf [1] = (unsigned char)(((inbuf [0] & 0x03) << 4) | ((inbuf [1] & 0xF0) >> 4));
        outbuf [2] = (unsigned char)(((inbuf [1] & 0x0F) << 2) | ((inbuf [2] & 0xC0) >> 6));
        outbuf [3] = inbuf [2] & 0x3F;
        ctcopy = 4;

        switch( ctremaining ) {
            case 1:
                ctcopy = 2;
                break;
            case 2:
                ctcopy = 3;
                break;
        }

        for( i = 0; i < ctcopy; i++ )
            [result appendFormat:@"%c", base64encodingTable[outbuf[i]]];

        for( i = ctcopy; i < 4; i++ )
            [result appendString:@"="];

        ixtext += 3;
        charsonline += 4;

        if( lineLength > 0 ) {
            if( charsonline >= lineLength ) {
                charsonline = 0;
                [result appendString:@"\n"];
            }
        }
    }

    return [NSString stringWithString:result];
}


+ (NSData *)decodeBase64WithString:(NSString *)strBase64 {
    const char * objPointer = [strBase64 cStringUsingEncoding:NSASCIIStringEncoding];
    if (objPointer == NULL)  return nil;
    size_t intLength = strlen(objPointer);
    int intCurrent;
    int i = 0, j = 0, k;

    unsigned char * objResult;
    objResult = calloc(intLength, sizeof(unsigned char));

    // Run through the whole string, converting as we go
    while ( ((intCurrent = *objPointer++) != '\0') && (intLength-- > 0) ) {
        if (intCurrent == '=') {
            if (*objPointer != '=' && ((i % 4) == 1)) {// || (intLength > 0)) {
                                                       // the padding character is invalid at this point -- so this entire string is invalid
                free(objResult);
                return nil;
            }
            continue;
        }

        intCurrent = _base64DecodingTable[intCurrent];
        if (intCurrent == -1) {
            // we're at a whitespace -- simply skip over
            continue;
        } else if (intCurrent == -2) {
            // we're at an invalid character
            free(objResult);
            return nil;
        }

        switch (i % 4) {
            case 0:
                objResult[j] = (unsigned char)(intCurrent << 2);
                break;

            case 1:
                objResult[j++] |= (unsigned char)(intCurrent >> 4);
                objResult[j] = (unsigned char)((intCurrent & 0x0f) << 4);
                break;

            case 2:
                objResult[j++] |= (unsigned char)(intCurrent >>2);
                objResult[j] = (unsigned char)((intCurrent & 0x03) << 6);
                break;

            case 3:
                objResult[j++] |= (unsigned char)intCurrent;
                break;
        }
        i++;
    }

    // mop things up if we ended on a boundary
    k = j;
    if (intCurrent == '=') {
        switch (i % 4) {
            case 1:
                // Invalid state
                free(objResult);
                return nil;

            case 2:
                k++;
                // flow through
            case 3:
                objResult[k] = 0;
        }
    }

    // Cleanup and setup the return NSData
    return [[NSData alloc] initWithBytesNoCopy:objResult length:j freeWhenDone:YES];
}

+ (NSUInteger)numberOfLinesInString:(NSString *)str {
    // probably not the most efficient implementation (see e.g. https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/TextLayout/Tasks/CountLines.html)
    // ...but very obviously correct :)
    __block NSUInteger nLines = 0;
    [str enumerateLinesUsingBlock:^(__attribute__((unused)) NSString *line, BOOL *stop) {
        nLines++;
        *stop = NO;
    }];
    return nLines;
}

+ (NSString *)generateUniquishIdentifier {
    CFUUIDRef uuid = CFUUIDCreate(NULL);
    CFStringRef uuidStr = CFUUIDCreateString(NULL, uuid);
    CFRelease(uuid);
    NSString *result = (__bridge_transfer NSString *)uuidStr;
    return result;
}

#pragma mark - Hex String

+ (NSString *)hexStringFromData:(NSData *)data {
    NSMutableString *hexString = [NSMutableString string];
    const char* bytes = [data bytes];
    for (NSUInteger index = 0; index < data.length; index++) {
        [hexString appendFormat:@"%02hhX", bytes[index]];
    }
    return hexString;
}

+ (NSData *)dataWithHexString:(NSString *)hexString  {
    //
    //  NSData+HexString.m
    //  libsecurity_transform
    //
    //  Copyright (c) 2011 Apple, Inc. All rights reserved.
    //
    char buf[3];
    buf[2] = '\0';
    NSAssert(0 == [hexString length] % 2, @"Hex strings should have an even number of digits (%@)", hexString);
    unsigned char *bytes = malloc([hexString length]/2);
    unsigned char *bp = bytes;
    for (NSUInteger i = 0; i < [hexString length]; i += 2) {
        buf[0] = [hexString characterAtIndex:i];
        buf[1] = [hexString characterAtIndex:i+1];
        char *b2 = NULL;
        *bp++ = strtol(buf, &b2, 16);
        //NSAssert(b2 == buf + 2, @"String should be all hex digits: %@ (bad digit around %ld)", hexString, i);
    }
    
    return [NSData dataWithBytesNoCopy:bytes length:[hexString length]/2 freeWhenDone:YES];
}

@end