/*
 * Base64 encoding and decoding routines
 *
 * Copyright (C) 2004-2008 René Nyffenegger
 * Modified by Phusion for inclusion in Phusion Passenger.
 *
 * This source code is provided 'as-is', without any express or implied
 * warranty. In no event will the author be held liable for any damages
 * arising from the use of this software.
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *
 * 1. The origin of this source code must not be misrepresented; you must not
 *    claim that you wrote the original source code. If you use this source code
 *    in a product, an acknowledgment in the product documentation would be
 *    appreciated but is not required.
 *
 * 2. Altered source versions must be plainly marked as such, and must not be
 *    misrepresented as being the original source code.
 *
 * 3. This notice may not be removed or altered from any source distribution.
 *
 * René Nyffenegger rene.nyffenegger@adp-gmbh.ch
 *
 */

#include <ctype.h>
#include "Base64.h"

namespace Passenger {

static const std::string base64_chars = 
             "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
             "abcdefghijklmnopqrstuvwxyz"
             "0123456789+/";


static inline bool
is_base64(unsigned char c) {
	return isalnum(c) || c == '+' || c == '/';
}

string
Base64::encode(const unsigned char *bytes_to_encode, unsigned int in_len) {
	std::string ret;
	int i = 0;
	int j = 0;
	unsigned char char_array_3[3];
	unsigned char char_array_4[4];

	// According to Wikipedia, base64-encoded data is usually 137%
	// + 814 bytes larger than the original. Here we reserve a little
	// more than that to avoid memory reallocations.
	ret.reserve((std::string::size_type) (in_len * 1.37) + 1024);
	
	while (in_len--) {
		char_array_3[i++] = *(bytes_to_encode++);
		if (i == 3) {
			char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
			char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
			char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
			char_array_4[3] = char_array_3[2] & 0x3f;

			for(i = 0; i < 4; i++) {
				ret += base64_chars[char_array_4[i]];
			}
			i = 0;
		}
	}

	if (i) {
		for(j = i; j < 3; j++)
			char_array_3[j] = '\0';

		char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
		char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
		char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
		char_array_4[3] = char_array_3[2] & 0x3f;

		for (j = 0; (j < i + 1); j++)
			ret += base64_chars[char_array_4[j]];

		while((i++ < 3))
			ret += '=';
	}

	return ret;
}

std::string
Base64::decode(const unsigned char *base64_data, unsigned int in_len) {
	int i = 0;
	int j = 0;
	int in_ = 0;
	unsigned char char_array_4[4], char_array_3[3];
	std::string ret;
	unsigned int reserved_size;

	// The decoded data should be about this large.
	if (in_len > 814) {
		reserved_size = (unsigned int) ((in_len - 814) / 137.0) * 100;
	} else {
		reserved_size = in_len;
	}
	ret.reserve(reserved_size);
	
	while (in_len-- && ( base64_data[in_] != '=') && is_base64(base64_data[in_])) {
		char_array_4[i++] = base64_data[in_]; in_++;
		if (i == 4) {
			for (i = 0; i <4; i++)
				char_array_4[i] = base64_chars.find(char_array_4[i]);

			char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
			char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
			char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];

			for (i = 0; i < 3; i++)
				ret += char_array_3[i];
			i = 0;
		}
	}

	if (i) {
		for (j = i; j <4; j++)
			char_array_4[j] = 0;

		for (j = 0; j <4; j++)
			char_array_4[j] = base64_chars.find(char_array_4[j]);

		char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
		char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
		char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];

		for (j = 0; (j < i - 1); j++)
			ret += char_array_3[j];
	}

	return ret;
}

} // namespace Passenger
