/*
 * Copyright (C) 2005-2006 Martin Willi
 * Copyright (C) 2005 Jan Hutter
 * Hochschule fuer Technik Rapperswil
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * for more details.
 *
 * $Id$
 */

#include <string.h>
#include <stddef.h>

#include "transform_attribute.h"

#include <encoding/payloads/encodings.h>
#include <library.h>

typedef struct private_transform_attribute_t private_transform_attribute_t;

/**
 * Private data of an transform_attribute_t object.
 * 
 */
struct private_transform_attribute_t {
	/**
	 * Public transform_attribute_t interface.
	 */
	transform_attribute_t public;
	
	/**
	 * Attribute Format Flag.
	 * 
	 * - TRUE means value is stored in attribute_length_or_value
	 * - FALSE means value is stored in attribute_value
	 */
	bool attribute_format;
	
	/**
	 * Type of the attribute.
	 */
	u_int16_t attribute_type;
	
	/**
	 * Attribute Length if attribute_format is 0, attribute Value otherwise.
	 */
	u_int16_t attribute_length_or_value;
	
	/**
	 * Attribute value as chunk if attribute_format is 0 (FALSE).
	 */
	chunk_t attribute_value;
};


ENUM_BEGIN(transform_attribute_type_name, ATTRIBUTE_UNDEFINED, ATTRIBUTE_UNDEFINED,
	"ATTRIBUTE_UNDEFINED");
ENUM_NEXT(transform_attribute_type_name, KEY_LENGTH, KEY_LENGTH, ATTRIBUTE_UNDEFINED,
	"KEY_LENGTH");
ENUM_END(transform_attribute_type_name, KEY_LENGTH);

/**
 * Encoding rules to parse or generate a Transform attribute.
 * 
 * The defined offsets are the positions in a object of type 
 * private_transform_attribute_t.
 * 
 */
encoding_rule_t transform_attribute_encodings[] = {
	/* Flag defining the format of this payload */
	{ ATTRIBUTE_FORMAT,			offsetof(private_transform_attribute_t, attribute_format) 			},
	/* type of the attribute as 15 bit unsigned integer */
	{ ATTRIBUTE_TYPE,			offsetof(private_transform_attribute_t, attribute_type)				},	
	/* Length or value, depending on the attribute format flag */
	{ ATTRIBUTE_LENGTH_OR_VALUE,	offsetof(private_transform_attribute_t, attribute_length_or_value)	},
	/* Value of attribute if attribute format flag is zero */
	{ ATTRIBUTE_VALUE,			offsetof(private_transform_attribute_t, attribute_value) 			}
};

/*
                          1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      !A!       Attribute Type        !    AF=0  Attribute Length     !
      !F!                             !    AF=1  Attribute Value      !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      !                   AF=0  Attribute Value                       !
      !                   AF=1  Not Transmitted                       !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/

/**
 * Implementation of payload_t.verify.
 */
static status_t verify(private_transform_attribute_t *this)
{
	if (this->attribute_type != KEY_LENGTH)
	{
		return FAILED;
	}
	
	return SUCCESS;
}

/**
 * Implementation of payload_t.get_encoding_rules.
 */
static void get_encoding_rules(private_transform_attribute_t *this, encoding_rule_t **rules, size_t *rule_count)
{
	*rules = transform_attribute_encodings;
	*rule_count = sizeof(transform_attribute_encodings) / sizeof(encoding_rule_t);
}

/**
 * Implementation of payload_t.get_type.
 */
static payload_type_t get_type(private_transform_attribute_t *this)
{
	return TRANSFORM_ATTRIBUTE;
}

/**
 * Implementation of payload_t.get_next_type.
 */
static payload_type_t get_next_type(private_transform_attribute_t *this)
{
	return (NO_PAYLOAD);
}

/**
 * Implementation of payload_t.set_next_type.
 */
static void set_next_type(private_transform_attribute_t *this,payload_type_t type)
{
}

/**
 * Implementation of transform_attribute_t.get_length.
 */
static size_t get_length(private_transform_attribute_t *this)
{
	if (this->attribute_format == TRUE)
	{
		/*Attribute size is only 4 byte */
		return 4;
	}
	return (this->attribute_length_or_value + 4);
}

/**
 * Implementation of transform_attribute_t.set_value_chunk.
 */
static void set_value_chunk(private_transform_attribute_t *this, chunk_t value)
{
	if (this->attribute_value.ptr != NULL)
	{
		/* free existing value */
		free(this->attribute_value.ptr);
		this->attribute_value.ptr = NULL;
		this->attribute_value.len = 0;
		
	}
	
	if (value.len > 2)
	{
		this->attribute_value.ptr = clalloc(value.ptr,value.len);
		this->attribute_value.len = value.len;
		this->attribute_length_or_value = value.len;
		/* attribute has not a fixed length */
		this->attribute_format = FALSE;		
	}
	else
	{
		memcpy(&(this->attribute_length_or_value),value.ptr,value.len);
	}
}

/**
 * Implementation of transform_attribute_t.set_value.
 */
static void set_value(private_transform_attribute_t *this, u_int16_t value)
{
	if (this->attribute_value.ptr != NULL)
	{
		/* free existing value */
		free(this->attribute_value.ptr);
		this->attribute_value.ptr = NULL;
		this->attribute_value.len = 0;
		
	}
	this->attribute_length_or_value = value;
}

/**
 * Implementation of transform_attribute_t.get_value_chunk.
 */
static chunk_t get_value_chunk (private_transform_attribute_t *this)
{
	chunk_t value;

	if (this->attribute_format == FALSE)
	{
		value.ptr = this->attribute_value.ptr;
		value.len = this->attribute_value.len;		
	}
	else
	{
		value.ptr = (void *) &(this->attribute_length_or_value);
		value.len = 2;
	}
	
	return value;
}

/**
 * Implementation of transform_attribute_t.get_value.
 */
static u_int16_t get_value (private_transform_attribute_t *this)
{
	return this->attribute_length_or_value;
}


/**
 * Implementation of transform_attribute_t.set_attribute_type.
 */
static void set_attribute_type (private_transform_attribute_t *this, u_int16_t type)
{
	this->attribute_type = type & 0x7FFF;
}

/**
 * Implementation of transform_attribute_t.get_attribute_type.
 */
static u_int16_t get_attribute_type (private_transform_attribute_t *this)
{
	return this->attribute_type;
}

/**
 * Implementation of transform_attribute_t.clone.
 */
static transform_attribute_t * clone(private_transform_attribute_t *this)
{
	private_transform_attribute_t *new_clone;
	
	new_clone = (private_transform_attribute_t *) transform_attribute_create();
	
	new_clone->attribute_format = this->attribute_format;
	new_clone->attribute_type = this->attribute_type;
	new_clone->attribute_length_or_value = this->attribute_length_or_value;
	
	if (!new_clone->attribute_format)
	{
		new_clone->attribute_value.ptr = clalloc(this->attribute_value.ptr,this->attribute_value.len);		
		new_clone->attribute_value.len = this->attribute_value.len;
	}
	
	return (transform_attribute_t *) new_clone;
}

/**
 * Implementation of transform_attribute_t.destroy and payload_t.destroy.
 */
static void destroy(private_transform_attribute_t *this)
{
	if (this->attribute_value.ptr != NULL)
	{
		free(this->attribute_value.ptr);
	}	
	free(this);
}

/*
 * Described in header.
 */
transform_attribute_t *transform_attribute_create()
{
	private_transform_attribute_t *this = malloc_thing(private_transform_attribute_t);

	/* payload interface */
	this->public.payload_interface.verify = (status_t (*) (payload_t *))verify;
	this->public.payload_interface.get_encoding_rules = (void (*) (payload_t *, encoding_rule_t **, size_t *) ) get_encoding_rules;
	this->public.payload_interface.get_length = (size_t (*) (payload_t *)) get_length;
	this->public.payload_interface.get_next_type = (payload_type_t (*) (payload_t *)) get_next_type;
	this->public.payload_interface.set_next_type = (void (*) (payload_t *,payload_type_t)) set_next_type;
	this->public.payload_interface.get_type = (payload_type_t (*) (payload_t *)) get_type;
	this->public.payload_interface.destroy = (void (*) (payload_t *))destroy;
	
	/* public functions */
	this->public.set_value_chunk = (void (*) (transform_attribute_t *,chunk_t)) set_value_chunk;
	this->public.set_value = (void (*) (transform_attribute_t *,u_int16_t)) set_value;
	this->public.get_value_chunk = (chunk_t (*) (transform_attribute_t *)) get_value_chunk;
	this->public.get_value = (u_int16_t (*) (transform_attribute_t *)) get_value;
	this->public.set_attribute_type = (void (*) (transform_attribute_t *,u_int16_t type)) set_attribute_type;
	this->public.get_attribute_type = (u_int16_t (*) (transform_attribute_t *)) get_attribute_type;
	this->public.clone = (transform_attribute_t * (*) (transform_attribute_t *)) clone;
	this->public.destroy = (void (*) (transform_attribute_t *)) destroy;
	
	/* set default values of the fields */
	this->attribute_format = TRUE;
	this->attribute_type = 0;
	this->attribute_length_or_value = 0;
	this->attribute_value.ptr = NULL;
	this->attribute_value.len = 0;

	return (&(this->public));
}

/*
 * Described in header.
 */
transform_attribute_t *transform_attribute_create_key_length(u_int16_t key_length)
{
	transform_attribute_t *attribute = transform_attribute_create();
	attribute->set_attribute_type(attribute,KEY_LENGTH);
	attribute->set_value(attribute,key_length);
	return attribute;
}
