/* SPDX-License-Identifier: BSD-2-Clause */

/**
 * @file
 *
 * @ingroup RTEMSImplBase64
 *
 * @brief This header file provides the interfaces of the
 *   @ref RTEMSImplBase64.
 */

/*
 * Copyright (C) 2020, 2024 embedded brains GmbH & Co. KG
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
 */

#ifndef _RTEMS_BASE64_H
#define _RTEMS_BASE64_H

#include <rtems/dev/io.h>

#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */

/**
 * @defgroup RTEMSImplBase64 Base64 Encoding and Decoding
 *
 * @ingroup RTEMSImpl
 *
 * @brief This group contains support functions for base64 and base64url
 *   encoding and decoding.
 *
 * @{
 */

/**
 * @brief Maps a 6-bit integer to the corresponding base64 encoding.
 */
extern const uint8_t _Base64_Encoding[ 64 ];

/**
 * @brief Maps a 6-bit integer to the corresponding base64url encoding.
 */
extern const uint8_t _Base64url_Encoding[ 64 ];

/**
 * @brief Outputs the source buffer in base64 encoding.
 *
 * After word length of output characters produced by the encoding a word break
 * is produced.
 *
 * @param put_char is the put character function used to output the encoded
 *   source buffer.
 *
 * @param arg is the argument passed to the put character function.
 *
 * @param src is the pointer to the source buffer begin.
 *
 * @param srclen is the length of the source buffer in bytes.
 *
 * @param wordbreak is the word break string.
 *
 * @param wordlen is the word length in bytes.  If the word length is less than
 *   four, then a word length of four will be used.
 *
 * @return Returns the count of output characters.
 */
int _Base64_Encode(
  IO_Put_char  put_char,
  void        *arg,
  const void  *src,
  size_t       len,
  const char  *wordbreak,
  int          wordlen
);

/**
 * @brief Outputs the source buffer in base64url encoding.
 *
 * After word length of output characters produced by the encoding a word break
 * is produced.
 *
 * @param put_char is the put character function used to output the encoded
 *   source buffer.
 *
 * @param arg is the argument passed to the put character function.
 *
 * @param src is the pointer to the source buffer begin.
 *
 * @param srclen is the length of the source buffer in bytes.
 *
 * @param wordbreak is the word break string.
 *
 * @param wordlen is the word length in bytes.  If the word length is less than
 *   four, then a word length of four will be used.
 *
 * @return Returns the count of output characters.
 */
int _Base64url_Encode(
  IO_Put_char  put_char,
  void        *arg,
  const void  *src,
  size_t       len,
  const char  *wordbreak,
  int          wordlen
);

/**
 * @brief Represents the base64 and base64url decoder state.
 */
typedef enum {
  BASE64_DECODE_STATE_0,
  BASE64_DECODE_STATE_1,
  BASE64_DECODE_STATE_2,
  BASE64_DECODE_STATE_3
} Base64_Decode_state;

/**
 * @brief Contains the base64 and base64url decoder control.
 */
typedef struct {
  Base64_Decode_state state;
  uint8_t            *target;
  const uint8_t      *target_end;
} Base64_Decode_control;

/**
 * @brief Maps a 7-bit character to the associated 6-bit integer as defined by
 *   the base64 or base64url encoding or a special value.
 */
extern const uint8_t _Base64_Decoding[ 128 ];

/**
 * @brief Initializes the base64 decoder.
 *
 * @param[out] self is the base64 decoder control to initialize.
 *
 * @param[out] target is the base address of the target area for decoding.
 *
 * @param target_size is the size in bytes of the target area for decoding.
 */
void _Base64_Decode_initialize(
  Base64_Decode_control *self,
  uint8_t               *target,
  size_t                 target_size
);

/**
 * @brief Represents the base64 and base64url decoder status.
 */
typedef enum {
  BASE64_DECODE_SUCCESS,
  BASE64_DECODE_OVERFLOW,
  BASE64_DECODE_INVALID_INPUT
} Base64_Decode_status;

/**
 * @brief Decodes the character.
 *
 * The decoder accepts base64 and base64url encodings.  White space is ignored.
 *
 * @param[in, out] self is the base64 decoder control.
 *
 * @param ch is the character to decode.
 */
Base64_Decode_status _Base64_Decode(
  Base64_Decode_control *self,
  char                   ch
);

/** @} */

#ifdef __cplusplus
}
#endif /* __cplusplus */

#endif /* _RTEMS_BASE64_H */