/*####COPYRIGHTBEGIN####
 -------------------------------------------
 Copyright (C) 2005 Steve Karg

 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.

 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.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to:
 The Free Software Foundation, Inc.
 59 Temple Place - Suite 330
 Boston, MA  02111-1307, USA.

 As a special exception, if other files instantiate templates or
 use macros or inline functions from this file, or you compile
 this file and link it with other works to produce a work based
 on this file, this file does not by itself cause the resulting
 work to be covered by the GNU General Public License. However
 the source code for this file must still be made available in
 accordance with section (3) of the GNU General Public License.

 This exception does not invalidate any other reasons why a work
 based on this file might be covered by the GNU General Public
 License.
 -------------------------------------------
####COPYRIGHTEND####*/
#include <stdint.h>
#include "bacnet/bacenum.h"
#include "bacnet/bacdef.h"
#include "bacnet/npdu.h"
#include "bacnet/dcc.h"
#include "bacnet/bacdcode.h"
#include "bacnet/iam.h"

/** @file iam.c  Encode/Decode I-Am service */

/**
 * @brief Encode the I-Am service.
 *
 * @param apdu  Transmit buffer
 * @param device_id  Device Id
 * @param max_apdu  Transmit buffer size.
 * @param segmentation  True, if segmentation shall be featured.
 * @param vendor_id  Vendor Id
 *
 * @return Total length of the apdu, zero otherwise.
 */
int iam_encode_apdu(uint8_t *apdu,
    uint32_t device_id,
    unsigned max_apdu,
    int segmentation,
    uint16_t vendor_id)
{
    int len = 0; /* length of each encoding */
    int apdu_len = 0; /* total length of the apdu, return value */

    if (apdu) {
        apdu[0] = PDU_TYPE_UNCONFIRMED_SERVICE_REQUEST;
        apdu[1] = SERVICE_UNCONFIRMED_I_AM; /* service choice */
        apdu_len = 2;
        len = encode_application_object_id(
            &apdu[apdu_len], OBJECT_DEVICE, device_id);
        apdu_len += len;
        len = encode_application_unsigned(&apdu[apdu_len], max_apdu);
        apdu_len += len;
        len = encode_application_enumerated(
            &apdu[apdu_len], (uint32_t)segmentation);
        apdu_len += len;
        len = encode_application_unsigned(&apdu[apdu_len], vendor_id);
        apdu_len += len;
    }

    return apdu_len;
}

/**
 * @brief Decode the I-Am service.
 *
 * @param apdu  Receive buffer
 * @param pDevice_id  Pointer to the variable that shal ltake the device Id.
 * @param pMax_apdu  Pointer to a variable that shall take the decoded length.
 * @param pSegmentation  Pointer to a variable taking if segmentation is used.
 * @param pVendor_id  Pointer to a variable taking the vendor id.
 *
 * @return Total length of the apdu, zero otherwise.
 */
int iam_decode_service_request(uint8_t *apdu,
    uint32_t *pDevice_id,
    unsigned *pMax_apdu,
    int *pSegmentation,
    uint16_t *pVendor_id)
{
    int len = 0;
    int apdu_len = 0; /* total length of the apdu, return value */
    /* should be a Device Object */
    BACNET_OBJECT_TYPE object_type = OBJECT_NONE;
    uint32_t object_instance = 0;
    uint8_t tag_number = 0;
    uint32_t len_value = 0;
    uint32_t enum_value = 0;
    BACNET_UNSIGNED_INTEGER unsigned_value = 0;

    /* OBJECT ID - object id */
    len = decode_tag_number_and_value(&apdu[apdu_len], &tag_number, &len_value);
    apdu_len += len;
    if (tag_number != BACNET_APPLICATION_TAG_OBJECT_ID) {
        return -1;
    }
    len = decode_object_id(&apdu[apdu_len], &object_type, &object_instance);
    apdu_len += len;
    if (object_type != OBJECT_DEVICE) {
        return -1;
    }
    if (pDevice_id) {
        *pDevice_id = object_instance;
    }
    /* MAX APDU - unsigned */
    len = decode_tag_number_and_value(&apdu[apdu_len], &tag_number, &len_value);
    apdu_len += len;
    if (tag_number != BACNET_APPLICATION_TAG_UNSIGNED_INT) {
        return -1;
    }
    len = decode_unsigned(&apdu[apdu_len], len_value, &unsigned_value);
    apdu_len += len;
    if (pMax_apdu) {
        *pMax_apdu = (unsigned)unsigned_value;
    }
    /* Segmentation - enumerated */
    len = decode_tag_number_and_value(&apdu[apdu_len], &tag_number, &len_value);
    apdu_len += len;
    if (tag_number != BACNET_APPLICATION_TAG_ENUMERATED) {
        return -1;
    }
    len = decode_enumerated(&apdu[apdu_len], len_value, &enum_value);
    apdu_len += len;
    if (enum_value >= MAX_BACNET_SEGMENTATION) {
        return -1;
    }
    if (pSegmentation) {
        *pSegmentation = (int)enum_value;
    }
    /* Vendor ID - unsigned16 */
    len = decode_tag_number_and_value(&apdu[apdu_len], &tag_number, &len_value);
    apdu_len += len;
    if (tag_number != BACNET_APPLICATION_TAG_UNSIGNED_INT) {
        return -1;
    }
    len = decode_unsigned(&apdu[apdu_len], len_value, &unsigned_value);
    apdu_len += len;
    if (unsigned_value > 0xFFFF) {
        return -1;
    }
    if (pVendor_id) {
        *pVendor_id = (uint16_t)unsigned_value;
    }

    return apdu_len;
}