//
//  GTMBase64.m
//
//  Copyright 2006-2008 Google Inc.
//
//  Licensed under the Apache License, Version 2.0 (the "License"); you may not
//  use this file except in compliance with the License.  You may obtain a copy
//  of the License at
//
//  http://www.apache.org/licenses/LICENSE-2.0
//
//  Unless required by applicable law or agreed to in writing, software
//  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
//  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
//  License for the specific language governing permissions and limitations under
//  the License.
//

#import "GTMBase64.h"
#import "GTMDefines.h"
#include <math.h>

const UInt8 kBase64EncodeTable[64] = {
  /*  0 */ 'A',    /*  1 */ 'B',    /*  2 */ 'C',    /*  3 */ 'D',
  /*  4 */ 'E',    /*  5 */ 'F',    /*  6 */ 'G',    /*  7 */ 'H',
  /*  8 */ 'I',    /*  9 */ 'J',    /* 10 */ 'K',    /* 11 */ 'L',
  /* 12 */ 'M',    /* 13 */ 'N',    /* 14 */ 'O',    /* 15 */ 'P',
  /* 16 */ 'Q',    /* 17 */ 'R',    /* 18 */ 'S',    /* 19 */ 'T',
  /* 20 */ 'U',    /* 21 */ 'V',    /* 22 */ 'W',    /* 23 */ 'X',
  /* 24 */ 'Y',    /* 25 */ 'Z',    /* 26 */ 'a',    /* 27 */ 'b',
  /* 28 */ 'c',    /* 29 */ 'd',    /* 30 */ 'e',    /* 31 */ 'f',
  /* 32 */ 'g',    /* 33 */ 'h',    /* 34 */ 'i',    /* 35 */ 'j',
  /* 36 */ 'k',    /* 37 */ 'l',    /* 38 */ 'm',    /* 39 */ 'n',
  /* 40 */ 'o',    /* 41 */ 'p',    /* 42 */ 'q',    /* 43 */ 'r',
  /* 44 */ 's',    /* 45 */ 't',    /* 46 */ 'u',    /* 47 */ 'v',
  /* 48 */ 'w',    /* 49 */ 'x',    /* 50 */ 'y',    /* 51 */ 'z',
  /* 52 */ '0',    /* 53 */ '1',    /* 54 */ '2',    /* 55 */ '3',
  /* 56 */ '4',    /* 57 */ '5',    /* 58 */ '6',    /* 59 */ '7',
  /* 60 */ '8',    /* 61 */ '9',    /* 62 */ '+',    /* 63 */ '/'
};

/*
 -1 = Base64 end of data marker.
 -2 = White space (tabs, cr, lf, space)
 -3 = Noise (all non whitespace, non-base64 characters)
 -4 = Dangerous noise
 -5 = Illegal noise (null byte)
 */

const SInt8 kBase64DecodeTable[128] = {
  /* 0x00 */ -5,     /* 0x01 */ -3,     /* 0x02 */ -3,     /* 0x03 */ -3,
  /* 0x04 */ -3,     /* 0x05 */ -3,     /* 0x06 */ -3,     /* 0x07 */ -3,
  /* 0x08 */ -3,     /* 0x09 */ -2,     /* 0x0a */ -2,     /* 0x0b */ -2,
  /* 0x0c */ -2,     /* 0x0d */ -2,     /* 0x0e */ -3,     /* 0x0f */ -3,
  /* 0x10 */ -3,     /* 0x11 */ -3,     /* 0x12 */ -3,     /* 0x13 */ -3,
  /* 0x14 */ -3,     /* 0x15 */ -3,     /* 0x16 */ -3,     /* 0x17 */ -3,
  /* 0x18 */ -3,     /* 0x19 */ -3,     /* 0x1a */ -3,     /* 0x1b */ -3,
  /* 0x1c */ -3,     /* 0x1d */ -3,     /* 0x1e */ -3,     /* 0x1f */ -3,
  /* ' ' */ -2,    /* '!' */ -3,    /* '"' */ -3,    /* '#' */ -3,
  /* '$' */ -3,    /* '%' */ -3,    /* '&' */ -3,    /* ''' */ -3,
  /* '(' */ -3,    /* ')' */ -3,    /* '*' */ -3,    /* '+' */ 62,
  /* ',' */ -3,    /* '-' */ -3,    /* '.' */ -3,    /* '/' */ 63,
  /* '0' */ 52,    /* '1' */ 53,    /* '2' */ 54,    /* '3' */ 55,
  /* '4' */ 56,    /* '5' */ 57,    /* '6' */ 58,    /* '7' */ 59,
  /* '8' */ 60,    /* '9' */ 61,    /* ':' */ -3,    /* ';' */ -3,
  /* '<' */ -3,    /* '=' */ -1,    /* '>' */ -3,    /* '?' */ -3,
  /* '@' */ -3,    /* 'A' */ 0,    /* 'B' */  1,    /* 'C' */  2,
  /* 'D' */  3,    /* 'E' */  4,    /* 'F' */  5,    /* 'G' */  6,
  /* 'H' */  7,    /* 'I' */  8,    /* 'J' */  9,    /* 'K' */ 10,
  /* 'L' */ 11,    /* 'M' */ 12,    /* 'N' */ 13,    /* 'O' */ 14,
  /* 'P' */ 15,    /* 'Q' */ 16,    /* 'R' */ 17,    /* 'S' */ 18,
  /* 'T' */ 19,    /* 'U' */ 20,    /* 'V' */ 21,    /* 'W' */ 22,
  /* 'X' */ 23,    /* 'Y' */ 24,    /* 'Z' */ 25,    /* '[' */ -3,
  /* '\' */ -3,    /* ']' */ -3,    /* '^' */ -3,    /* '_' */ -3,
  /* '`' */ -3,    /* 'a' */ 26,    /* 'b' */ 27,    /* 'c' */ 28,
  /* 'd' */ 29,    /* 'e' */ 30,    /* 'f' */ 31,    /* 'g' */ 32,
  /* 'h' */ 33,    /* 'i' */ 34,    /* 'j' */ 35,    /* 'k' */ 36,
  /* 'l' */ 37,    /* 'm' */ 38,    /* 'n' */ 39,    /* 'o' */ 40,
  /* 'p' */ 41,    /* 'q' */ 42,    /* 'r' */ 43,    /* 's' */ 44,
  /* 't' */ 45,    /* 'u' */ 46,    /* 'v' */ 47,    /* 'w' */ 48,
  /* 'x' */ 49,    /* 'y' */ 50,    /* 'z' */ 51,    /* '{' */ -3,
  /* '|' */ -3,    /* '}' */ -3,    /* '~' */ -3,    /* 0x7f */ -3
};

const UInt8 kBits_00000011 = 0x03;
const UInt8 kBits_00001111 = 0x0F;
const UInt8 kBits_00110000 = 0x30;
const UInt8 kBits_00111100 = 0x3C;
const UInt8 kBits_00111111 = 0x3F;
const UInt8 kBits_11000000 = 0xC0;
const UInt8 kBits_11110000 = 0xF0;
const UInt8 kBits_11111100 = 0xFC;

size_t EstimateBas64EncodedDataSize(size_t inDataSize)
{
  size_t theEncodedDataSize = (int)ceil(inDataSize / 3.0) * 4;
  theEncodedDataSize = theEncodedDataSize / 72 * 74 + theEncodedDataSize % 72;
  return(theEncodedDataSize);
}

size_t EstimateBas64DecodedDataSize(size_t inDataSize)
{
  size_t theDecodedDataSize = (int)ceil(inDataSize / 4.0) * 3;
  //theDecodedDataSize = theDecodedDataSize / 72 * 74 + theDecodedDataSize % 72;
  return(theDecodedDataSize);
}

bool Base64EncodeData(const void *inInputData, size_t inInputDataSize, char *outOutputData, size_t *ioOutputDataSize, BOOL wrapped)
{
  size_t theEncodedDataSize = EstimateBas64EncodedDataSize(inInputDataSize);
  if (*ioOutputDataSize < theEncodedDataSize)
    return(false);
  *ioOutputDataSize = theEncodedDataSize;
  const UInt8 *theInPtr = (const UInt8 *)inInputData;
  UInt32 theInIndex = 0, theOutIndex = 0;
  for (; theInIndex < (inInputDataSize / 3) * 3; theInIndex += 3)
  {
    outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex] & kBits_11111100) >> 2];
    outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex] & kBits_00000011) << 4 | (theInPtr[theInIndex + 1] & kBits_11110000) >> 4];
    outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex + 1] & kBits_00001111) << 2 | (theInPtr[theInIndex + 2] & kBits_11000000) >> 6];
    outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex + 2] & kBits_00111111) >> 0];
    if (wrapped && (theOutIndex % 74 == 72))
    {
      outOutputData[theOutIndex++] = '\r';
      outOutputData[theOutIndex++] = '\n';
    }
  }
  const size_t theRemainingBytes = inInputDataSize - theInIndex;
  if (theRemainingBytes == 1)
  {
    outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex] & kBits_11111100) >> 2];
    outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex] & kBits_00000011) << 4 | (0 & kBits_11110000) >> 4];
    outOutputData[theOutIndex++] = '=';
    outOutputData[theOutIndex++] = '=';
    if (wrapped && (theOutIndex % 74 == 72))
    {
      outOutputData[theOutIndex++] = '\r';
      outOutputData[theOutIndex++] = '\n';
    }
  }
  else if (theRemainingBytes == 2)
  {
    outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex] & kBits_11111100) >> 2];
    outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex] & kBits_00000011) << 4 | (theInPtr[theInIndex + 1] & kBits_11110000) >> 4];
    outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex + 1] & kBits_00001111) << 2 | (0 & kBits_11000000) >> 6];
    outOutputData[theOutIndex++] = '=';
    if (wrapped && (theOutIndex % 74 == 72))
    {
      outOutputData[theOutIndex++] = '\r';
      outOutputData[theOutIndex++] = '\n';
    }
  }
  return(true);
}

bool Base64DecodeData(const void *inInputData, size_t inInputDataSize, void *ioOutputData, size_t *ioOutputDataSize)
{
  memset(ioOutputData, '.', *ioOutputDataSize);
  
  size_t theDecodedDataSize = EstimateBas64DecodedDataSize(inInputDataSize);
  if (*ioOutputDataSize < theDecodedDataSize)
    return(false);
  *ioOutputDataSize = 0;
  const UInt8 *theInPtr = (const UInt8 *)inInputData;
  UInt8 *theOutPtr = (UInt8 *)ioOutputData;
  size_t theInIndex = 0, theOutIndex = 0;
  UInt8 theOutputOctet;
  size_t theSequence = 0;
  for (; theInIndex < inInputDataSize; )
  {
    SInt8 theSextet = 0;
    
    SInt8 theCurrentInputOctet = theInPtr[theInIndex];
    theSextet = kBase64DecodeTable[theCurrentInputOctet];
    if (theSextet == -1)
      break;
    while (theSextet == -2)
    {
      theCurrentInputOctet = theInPtr[++theInIndex];
      theSextet = kBase64DecodeTable[theCurrentInputOctet];
    }
    while (theSextet == -3)
    {
      theCurrentInputOctet = theInPtr[++theInIndex];
      theSextet = kBase64DecodeTable[theCurrentInputOctet];
    }
    if (theSequence == 0)
    {
      theOutputOctet = (theSextet >= 0 ? theSextet : 0) << 2 & kBits_11111100;
    }
    else if (theSequence == 1)
    {
      theOutputOctet |= (theSextet >- 0 ? theSextet : 0) >> 4 & kBits_00000011;
      theOutPtr[theOutIndex++] = theOutputOctet;
    }
    else if (theSequence == 2)
    {
      theOutputOctet = (theSextet >= 0 ? theSextet : 0) << 4 & kBits_11110000;
    }
    else if (theSequence == 3)
    {
      theOutputOctet |= (theSextet >= 0 ? theSextet : 0) >> 2 & kBits_00001111;
      theOutPtr[theOutIndex++] = theOutputOctet;
    }
    else if (theSequence == 4)
    {
      theOutputOctet = (theSextet >= 0 ? theSextet : 0) << 6 & kBits_11000000;
    }
    else if (theSequence == 5)
    {
      theOutputOctet |= (theSextet >= 0 ? theSextet : 0) >> 0 & kBits_00111111;
      theOutPtr[theOutIndex++] = theOutputOctet;
    }
    theSequence = (theSequence + 1) % 6;
    if (theSequence != 2 && theSequence != 4)
      theInIndex++;
  }
  *ioOutputDataSize = theOutIndex;
  return(true);
}
