/* mbed Microcontroller Library
 * Copyright (c) 2006-2013 ARM Limited
 *
 * 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.
 */

#include "nRF5xGattServer.h"
#ifdef YOTTA_CFG_MBED_OS
    #include "mbed-drivers/mbed.h"
#else
    #include "mbed.h"
#endif

#include "common/common.h"
#include "btle/custom/custom_helper.h"

#include "nRF5xn.h"

namespace {

static const ble_gatts_rw_authorize_reply_params_t write_auth_queue_full_reply = {
    /* .type = */ BLE_GATTS_AUTHORIZE_TYPE_WRITE,
    /* .params = */ {
        /* .write = */ {
            /* .gatt_status = */ BLE_GATT_STATUS_ATTERR_PREPARE_QUEUE_FULL
        }
    }
};

static const ble_gatts_rw_authorize_reply_params_t write_auth_invalid_offset_reply = {
    /* .type = */ BLE_GATTS_AUTHORIZE_TYPE_WRITE,
    /* .params = */ {
        /* .write = */ {
            /* .gatt_status = */ BLE_GATT_STATUS_ATTERR_INVALID_OFFSET
        }
    }
};

static const ble_gatts_rw_authorize_reply_params_t write_auth_succes_reply = {
    /* .type = */ BLE_GATTS_AUTHORIZE_TYPE_WRITE,
    /* .params = */ {
        /* .write = */ {
            /* .gatt_status = */ BLE_GATT_STATUS_SUCCESS,
            /* .update = */ 0
        }
    }
};

static const ble_gatts_rw_authorize_reply_params_t write_auth_invalid_reply = {
    /* .type = */ BLE_GATTS_AUTHORIZE_TYPE_WRITE,
    /* .params = */ {
        /* .write = */ {
            /* .gatt_status = */ BLE_GATT_STATUS_ATTERR_INVALID
        }
    }
};

static ble_error_t set_attribute_value(
    Gap::Handle_t connectionHandle,
    GattAttribute::Handle_t attributeHandle,
    ble_gatts_value_t *value
) {
    uint32_t err = sd_ble_gatts_value_set(connectionHandle, attributeHandle, value);
    switch(err) {
        case NRF_SUCCESS:
            return BLE_ERROR_NONE;
        case NRF_ERROR_INVALID_ADDR:
        case NRF_ERROR_INVALID_PARAM:
            return BLE_ERROR_INVALID_PARAM;
        case NRF_ERROR_NOT_FOUND:
        case NRF_ERROR_DATA_SIZE:
        case BLE_ERROR_INVALID_CONN_HANDLE:
        case BLE_ERROR_GATTS_INVALID_ATTR_TYPE:
            return BLE_ERROR_PARAM_OUT_OF_RANGE;
        case NRF_ERROR_FORBIDDEN:
            return BLE_ERROR_OPERATION_NOT_PERMITTED;
        default:
            return BLE_ERROR_UNSPECIFIED;
    }
}

} // end of anonymous namespace

/**************************************************************************/
/*!
    @brief  Adds a new service to the GATT table on the peripheral

    @returns    ble_error_t

    @retval     BLE_ERROR_NONE
                Everything executed properly

    @section EXAMPLE

    @code

    @endcode
*/
/**************************************************************************/
ble_error_t nRF5xGattServer::addService_(GattService &service)
{
    /* ToDo: Make sure this service UUID doesn't already exist (?) */
    /* ToDo: Basic validation */

    /* Add the service to the nRF51 */
    ble_uuid_t nordicUUID;
    nordicUUID = custom_convert_to_nordic_uuid(service.getUUID());

    uint16_t serviceHandle;
    ASSERT_TRUE( ERROR_NONE ==
            sd_ble_gatts_service_add(BLE_GATTS_SRVC_TYPE_PRIMARY,
                                     &nordicUUID,
                                     &serviceHandle),
            BLE_ERROR_PARAM_OUT_OF_RANGE );
    service.setHandle(serviceHandle);

    /* Add characteristics to the service */
    for (uint8_t i = 0; i < service.getCharacteristicCount(); i++) {
        if (characteristicCount >= BLE_TOTAL_CHARACTERISTICS) {
            return BLE_ERROR_NO_MEM;
        }
        GattCharacteristic *p_char = service.getCharacteristic(i);
        GattAttribute *p_description_descriptor = NULL;
        GattAttribute *p_presentation_format_descriptor = NULL;

        /* Skip any incompletely defined, read-only characteristics. */
        if ((p_char->getValueAttribute().getValuePtr() == NULL) &&
            (p_char->getValueAttribute().getLength() == 0) &&
            (p_char->getProperties() == GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_READ)) {
            continue;
        }

        nordicUUID = custom_convert_to_nordic_uuid(p_char->getValueAttribute().getUUID());

        /* The user-description and presentation-format descriptors are special cases
         * that need to be handled at the time of adding each characteristic. The
         * following block is meant to discover their presence. */
        const uint8_t *userDescriptionDescriptorValuePtr = NULL;
        uint16_t userDescriptionDescriptorValueLen = 0;
        const uint8_t *presentationFormatDescriptorValuePtr = NULL;
        uint16_t presentationFormatDescriptorValueLen = 0;
        for (uint8_t j = 0; j < p_char->getDescriptorCount(); j++) {
            GattAttribute *p_desc = p_char->getDescriptor(j);
            if (p_desc->getUUID() == BLE_UUID_DESCRIPTOR_CHAR_USER_DESC) {
                p_description_descriptor = p_desc;
                userDescriptionDescriptorValuePtr = p_desc->getValuePtr();
                userDescriptionDescriptorValueLen = p_desc->getLength();
            }
            if (p_desc->getUUID() == BLE_UUID_DESCRIPTOR_CHAR_PRESENTATION_FORMAT) {
                p_presentation_format_descriptor = p_desc;
                presentationFormatDescriptorValuePtr = p_desc->getValuePtr();
                presentationFormatDescriptorValueLen = p_desc->getLength();
            }
        }

        ASSERT_TRUE ( ERROR_NONE ==
                 custom_add_in_characteristic(
                     BLE_GATT_HANDLE_INVALID,
                                              &nordicUUID,
                                              p_char->getProperties(),
                     p_char->getReadSecurityRequirement(),
                     p_char->getWriteSecurityRequirement(),
                     p_char->getUpdateSecurityRequirement(),
                                              p_char->getValueAttribute().getValuePtr(),
                                              p_char->getValueAttribute().getLength(),
                                              p_char->getValueAttribute().getMaxLength(),
                                              p_char->getValueAttribute().hasVariableLength(),
                                              userDescriptionDescriptorValuePtr,
                                              userDescriptionDescriptorValueLen,
                                              presentationFormatDescriptorValuePtr,
                                              presentationFormatDescriptorValueLen,
                                              p_char->isReadAuthorizationEnabled(),
                                              p_char->isWriteAuthorizationEnabled(),
                     &nrfCharacteristicHandles[characteristicCount]
                 ),
                 BLE_ERROR_PARAM_OUT_OF_RANGE );

        /* Update the characteristic handle */
        p_characteristics[characteristicCount] = p_char;
        p_char->getValueAttribute().setHandle(nrfCharacteristicHandles[characteristicCount].value_handle);
        if (p_description_descriptor) {
            p_description_descriptor->setHandle(
                nrfCharacteristicHandles[characteristicCount].user_desc_handle
            );
        }
        if (p_presentation_format_descriptor) {
            // The handle is not available from the SoftDevice
            p_presentation_format_descriptor->setHandle(GattAttribute::INVALID_HANDLE);
        }
        characteristicCount++;

        /* Add optional descriptors if any */
        for (uint8_t j = 0; j < p_char->getDescriptorCount(); j++) {
            if (descriptorCount >= BLE_TOTAL_DESCRIPTORS) {
                return BLE_ERROR_NO_MEM;
            }

            GattAttribute *p_desc = p_char->getDescriptor(j);
            /* skip the user-description or presentation-format descriptor here;
             * they have already been handled when adding the characteristic (above). */
            if (p_desc->getUUID() == BLE_UUID_DESCRIPTOR_CHAR_USER_DESC
                || p_desc->getUUID() == BLE_UUID_DESCRIPTOR_CHAR_PRESENTATION_FORMAT) {
                continue;
            }

            nordicUUID = custom_convert_to_nordic_uuid(p_desc->getUUID());

            ASSERT_TRUE(ERROR_NONE ==
                   custom_add_in_descriptor(BLE_GATT_HANDLE_INVALID,
                                            &nordicUUID,
                                            p_desc->getValuePtr(),
                                            p_desc->getLength(),
                                            p_desc->getMaxLength(),
                                            p_desc->hasVariableLength(),
                                            &nrfDescriptorHandles[descriptorCount],
                                            p_desc->getReadSecurityRequirement(),
                                            p_desc->getWriteSecurityRequirement()),
                BLE_ERROR_PARAM_OUT_OF_RANGE);

            p_descriptors[descriptorCount] = p_desc;
            p_desc->setHandle(nrfDescriptorHandles[descriptorCount]);
            descriptorCount++;
        }
    }

    serviceCount++;

    return BLE_ERROR_NONE;
}

/**************************************************************************/
/*!
    @brief  Reads the value of a characteristic, based on the service
            and characteristic index fields

    @param[in]  attributeHandle
                The handle of the GattCharacteristic to read from
    @param[in]  buffer
                Buffer to hold the the characteristic's value
                (raw byte array in LSB format)
    @param[in/out] len
                input:  Length in bytes to be read.
                output: Total length of attribute value upon successful return.

    @returns    ble_error_t

    @retval     BLE_ERROR_NONE
                Everything executed properly
*/
/**************************************************************************/
ble_error_t nRF5xGattServer::read_(GattAttribute::Handle_t attributeHandle, uint8_t buffer[], uint16_t *lengthP)
{
    return read(BLE_CONN_HANDLE_INVALID, attributeHandle, buffer, lengthP);
}

ble_error_t nRF5xGattServer::read_(Gap::Handle_t connectionHandle, GattAttribute::Handle_t attributeHandle, uint8_t buffer[], uint16_t *lengthP)
{
    ble_gatts_value_t value = {
        /* .len     = */ *lengthP,
        /* .offset  = */ 0,
        /* .p_value = */ buffer,
    };

    ASSERT_TRUE( ERROR_NONE ==
            sd_ble_gatts_value_get(connectionHandle, attributeHandle, &value),
            BLE_ERROR_PARAM_OUT_OF_RANGE);
    *lengthP = value.len;

    return BLE_ERROR_NONE;
}

/**************************************************************************/
/*!
    @brief  Updates the value of a characteristic, based on the service
            and characteristic index fields

    @param[in]  charHandle
                The handle of the GattCharacteristic to write to
    @param[in]  buffer
                Data to use when updating the characteristic's value
                (raw byte array in LSB format)
    @param[in]  len
                The number of bytes in buffer

    @returns    ble_error_t

    @retval     BLE_ERROR_NONE
                Everything executed properly
*/
/**************************************************************************/
ble_error_t nRF5xGattServer::write_(GattAttribute::Handle_t attributeHandle, const uint8_t buffer[], uint16_t len, bool localOnly)
{
    return write(BLE_CONN_HANDLE_INVALID, attributeHandle, buffer, len, localOnly);
}

ble_error_t nRF5xGattServer::write_(Gap::Handle_t connectionHandle, GattAttribute::Handle_t attributeHandle, const uint8_t buffer[], uint16_t len, bool localOnly)
{
    ble_error_t returnValue = BLE_ERROR_NONE;

    ble_gatts_value_t value = {
        /* .len     = */ len,
        /* .offset  = */ 0,
        /* .p_value = */ const_cast<uint8_t *>(buffer),
    };

    if (localOnly) {
        /* Only update locally regardless of notify/indicate */
        ASSERT_INT( ERROR_NONE,
                    sd_ble_gatts_value_set(connectionHandle, attributeHandle, &value),
                    BLE_ERROR_PARAM_OUT_OF_RANGE );
        return BLE_ERROR_NONE;
    }

    int characteristicIndex = resolveValueHandleToCharIndex(attributeHandle);
    if ((characteristicIndex != -1) &&
        (p_characteristics[characteristicIndex]->getProperties() & (GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_INDICATE | GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_NOTIFY))) {
        /* HVX update for the characteristic value */
        ble_gatts_hvx_params_t hvx_params;

        hvx_params.handle = attributeHandle;
        hvx_params.type   =
            (p_characteristics[characteristicIndex]->getProperties() & GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_NOTIFY) ? BLE_GATT_HVX_NOTIFICATION : BLE_GATT_HVX_INDICATION;
        hvx_params.offset = 0;
        hvx_params.p_data = const_cast<uint8_t *>(buffer);
        hvx_params.p_len  = &len;

        if (connectionHandle == BLE_CONN_HANDLE_INVALID) { /* use the default connection handle if the caller hasn't specified a valid connectionHandle. */
            nRF5xGap &gap = (nRF5xGap &) nRF5xn::Instance(BLE::DEFAULT_INSTANCE).getGap();
            connectionHandle = gap.getConnectionHandle();
        }

        bool updatesEnabled = false;
        if (connectionHandle != BLE_CONN_HANDLE_INVALID) {
            ble_error_t err = areUpdatesEnabled(connectionHandle, attributeHandle, &updatesEnabled);

            // FIXME: The softdevice allocates and populates CCCD when the client
            // interract with them. Checking for updates may return an out of
            // range error in such case.
            if(err && err != BLE_ERROR_PARAM_OUT_OF_RANGE) {
                return err;
            }
        }

        bool updates_permitted = false;
        ble_gap_conn_sec_t connection_security;
        uint32_t err = sd_ble_gap_conn_sec_get(connectionHandle, &connection_security);
        if (!err &&
            (connection_security.sec_mode.sm == 1) &&
            (connection_security.sec_mode.lv >=  p_characteristics[characteristicIndex]->getUpdateSecurityRequirement().value())) {
            updates_permitted = true;
        }

        if (updatesEnabled && updates_permitted) {
            error_t error = (error_t) sd_ble_gatts_hvx(connectionHandle, &hvx_params);
            if (error != ERROR_NONE) {
                switch (error) {
                    case ERROR_BLE_NO_TX_BUFFERS: /*  Notifications consume application buffers. The return value can be used for resending notifications. */
                    case ERROR_BUSY:
                        returnValue = BLE_STACK_BUSY;
                        break;

                    case ERROR_INVALID_STATE:
                    case ERROR_BLEGATTS_SYS_ATTR_MISSING:
                        returnValue = BLE_ERROR_INVALID_STATE;
                        break;

                    default :
                        ASSERT_INT( ERROR_NONE,
                                    sd_ble_gatts_value_set(connectionHandle, attributeHandle, &value),
                                    BLE_ERROR_PARAM_OUT_OF_RANGE );

                        /* Notifications consume application buffers. The return value can
                        * be used for resending notifications. */
                        returnValue = BLE_STACK_BUSY;
                        break;
                }
            }
        } else {
            returnValue = set_attribute_value(connectionHandle, attributeHandle, &value);
        }
    } else {
        returnValue = set_attribute_value(connectionHandle, attributeHandle, &value);
    }

    return returnValue;
}

ble_error_t nRF5xGattServer::areUpdatesEnabled_(const GattCharacteristic &characteristic, bool *enabledP)
{
    /* Forward the call with the default connection handle. */
    nRF5xGap &gap = (nRF5xGap &) nRF5xn::Instance(BLE::DEFAULT_INSTANCE).getGap();
    return areUpdatesEnabled_(gap.getConnectionHandle(), characteristic, enabledP);
}

ble_error_t nRF5xGattServer::areUpdatesEnabled_(Gap::Handle_t connectionHandle, const GattCharacteristic &characteristic, bool *enabledP)
{
    return areUpdatesEnabled(connectionHandle, characteristic.getValueHandle(), enabledP);
}

ble_error_t nRF5xGattServer::areUpdatesEnabled(Gap::Handle_t connectionHandle, GattAttribute::Handle_t attributeHandle, bool *enabledP)
{
    int characteristicIndex = resolveValueHandleToCharIndex(attributeHandle);
    if (characteristicIndex == -1) {
        return BLE_ERROR_INVALID_PARAM;
    }

    /* Read the cccd value from the GATT server. */
    GattAttribute::Handle_t cccdHandle = nrfCharacteristicHandles[characteristicIndex].cccd_handle;
    uint16_t cccdValue;
    uint16_t length = sizeof(cccdValue);
    ble_error_t rc = read(connectionHandle, cccdHandle, reinterpret_cast<uint8_t *>(&cccdValue), &length);
    if (rc != BLE_ERROR_NONE) {
        return rc;
    }
    if (length != sizeof(cccdValue)) {
        return BLE_ERROR_INVALID_STATE;
    }

    /* Check for NOTFICATION or INDICATION in CCCD. */
    if ((cccdValue & BLE_GATT_HVX_NOTIFICATION) || (cccdValue & BLE_GATT_HVX_INDICATION)) {
        *enabledP = true;
    }

    return BLE_ERROR_NONE;
}

/**************************************************************************/
/*!
    @brief  Clear nRF5xGattServer's state.

    @returns    ble_error_t

    @retval     BLE_ERROR_NONE
                Everything executed properly
*/
/**************************************************************************/
ble_error_t nRF5xGattServer::reset_(void)
{
    /* Clear all state that is from the parent, including private members */
    if (ble::interface::GattServer<nRF5xGattServer>::reset_() != BLE_ERROR_NONE) {
        return BLE_ERROR_INVALID_STATE;
    }

    /* Clear derived class members */
    memset(p_characteristics,        0, sizeof(p_characteristics));
    memset(p_descriptors,            0, sizeof(p_descriptors));
    memset(nrfCharacteristicHandles, 0, sizeof(ble_gatts_char_handles_t));
    memset(nrfDescriptorHandles,     0, sizeof(nrfDescriptorHandles));
    descriptorCount = 0;

    releaseAllWriteRequests();

    return BLE_ERROR_NONE;
}

/**************************************************************************/
/*!
    @brief  Callback handler for events getting pushed up from the SD
*/
/**************************************************************************/
void nRF5xGattServer::hwCallback(const ble_evt_t *p_ble_evt)
{
    GattAttribute::Handle_t        handle_value;
    GattServerEvents::gattEvent_t  eventType;
    const ble_gatts_evt_t         *gattsEventP = &p_ble_evt->evt.gatts_evt;

    switch (p_ble_evt->header.evt_id) {
        case BLE_GATTS_EVT_WRITE: {
                /* There are 2 use case here: Values being updated & CCCD (indicate/notify) enabled */

                /* 1.) Handle CCCD changes */
                handle_value = gattsEventP->params.write.handle;
                int characteristicIndex = resolveCCCDHandleToCharIndex(handle_value);
                if ((characteristicIndex != -1) &&
                    (p_characteristics[characteristicIndex]->getProperties() &
                        (GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_INDICATE | GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_NOTIFY))) {

                    uint16_t cccd_value = (gattsEventP->params.write.data[1] << 8) | gattsEventP->params.write.data[0]; /* Little Endian but M0 may be mis-aligned */

                    if (((p_characteristics[characteristicIndex]->getProperties() & GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_INDICATE) && (cccd_value & BLE_GATT_HVX_INDICATION)) ||
                        ((p_characteristics[characteristicIndex]->getProperties() & GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_NOTIFY) && (cccd_value & BLE_GATT_HVX_NOTIFICATION))) {
                        eventType = GattServerEvents::GATT_EVENT_UPDATES_ENABLED;
                    } else {
                        eventType = GattServerEvents::GATT_EVENT_UPDATES_DISABLED;
                    }

                    handleEvent(eventType, p_characteristics[characteristicIndex]->getValueHandle());
                    return;
                }

                /* 2.) Changes to the characteristic value will be handled with other events below */
                eventType = GattServerEvents::GATT_EVENT_DATA_WRITTEN;
            }
            break;

        case BLE_GATTS_EVT_HVC:
            /* Indication confirmation received */
            eventType    = GattServerEvents::GATT_EVENT_CONFIRMATION_RECEIVED;
            handle_value = gattsEventP->params.hvc.handle;
            break;
        
#if  NRF_SD_BLE_API_VERSION >= 4 // This event has been renamed in API V4+
        case BLE_GATTS_EVT_HVN_TX_COMPLETE: {
            handleDataSentEvent(p_ble_evt->evt.gatts_evt.params.hvn_tx_complete.count);
            return;
        }
#else
        case BLE_EVT_TX_COMPLETE: {
            handleDataSentEvent(p_ble_evt->evt.common_evt.params.tx_complete.count);
            return;
        }
#endif

        case BLE_GATTS_EVT_SYS_ATTR_MISSING:
            sd_ble_gatts_sys_attr_set(gattsEventP->conn_handle, NULL, 0, 0);
            return;

        case BLE_GATTS_EVT_RW_AUTHORIZE_REQUEST:
            switch (gattsEventP->params.authorize_request.type) {
                case BLE_GATTS_AUTHORIZE_TYPE_READ:
                    eventType    = GattServerEvents::GATT_EVENT_READ_AUTHORIZATION_REQ;
                    handle_value = gattsEventP->params.authorize_request.request.read.handle;
                    break;
                case BLE_GATTS_AUTHORIZE_TYPE_WRITE:
                    eventType    = GattServerEvents::GATT_EVENT_WRITE_AUTHORIZATION_REQ;
                    handle_value = gattsEventP->params.authorize_request.request.write.handle;
                    break;
                default:
                    return;
            }
            break;

        case BLE_EVT_USER_MEM_REQUEST: {
            uint16_t conn_handle = p_ble_evt->evt.common_evt.conn_handle;

            // allocate a new long request for this connection
            // NOTE: we don't care about the result at this stage,
            // it is not possible to cancel the operation anyway.
            // If the request was not allocated then it will gracefully failled
            // at subsequent stages.
            allocateLongWriteRequest(conn_handle);
            sd_ble_user_mem_reply(conn_handle, NULL);
            return;
        }

        default:
            return;
    }

    int characteristicIndex = resolveValueHandleToCharIndex(handle_value);
    if (characteristicIndex == -1) {
        // filter out the case were the request is a long one,
        // and there is no attribute handle provided
        uint8_t write_op = gattsEventP->params.authorize_request.request.write.op;
        if (eventType != GattServerEvents::GATT_EVENT_WRITE_AUTHORIZATION_REQ ||
            (write_op != BLE_GATTS_OP_EXEC_WRITE_REQ_NOW &&
             write_op != BLE_GATTS_OP_EXEC_WRITE_REQ_CANCEL)) {
            return;
        }
    }

    /* Find index (charHandle) in the pool */
    switch (eventType) {
        case GattServerEvents::GATT_EVENT_DATA_WRITTEN: {
            GattWriteCallbackParams cbParams = {
                /* .connHandle = */ gattsEventP->conn_handle,
                /* .handle     = */ handle_value,
                /* .writeOp    = */ static_cast<GattWriteCallbackParams::WriteOp_t>(gattsEventP->params.write.op),
                /* .offset     = */ gattsEventP->params.write.offset,
                /* .len        = */ gattsEventP->params.write.len,
                /* .data       = */ gattsEventP->params.write.data
            };
            handleDataWrittenEvent(&cbParams);
            break;
        }
        case GattServerEvents::GATT_EVENT_WRITE_AUTHORIZATION_REQ: {
            uint16_t conn_handle = gattsEventP->conn_handle;
            const ble_gatts_evt_write_t& input_req = gattsEventP->params.authorize_request.request.write;
            const uint16_t max_size = getBiggestCharacteristicSize();

            // this is a long write request, handle it here.
            switch (input_req.op) {
                case BLE_GATTS_OP_PREP_WRITE_REQ: {
                    // verify that the request is not outside of the possible range
                    if ((input_req.offset + input_req.len) > max_size) {
                        sd_ble_gatts_rw_authorize_reply(conn_handle, &write_auth_invalid_offset_reply);
                        releaseLongWriteRequest(conn_handle);
                        return;
                    }

                    // find the write request
                    long_write_request_t* req = findLongWriteRequest(conn_handle);
                    if (!req)  {
                        sd_ble_gatts_rw_authorize_reply(conn_handle, &write_auth_invalid_reply);
                        return;
                    }

                    // initialize the first request by setting the offset
                    if (req->length == 0) {
                        req->attr_handle = input_req.handle;
                        req->offset = input_req.offset;
                    } else {
                        // it should be the subsequent write
                        if ((req->offset + req->length) != input_req.offset) {
                            sd_ble_gatts_rw_authorize_reply(conn_handle, &write_auth_invalid_offset_reply);
                            releaseLongWriteRequest(conn_handle);
                            return;
                        }

                        // it is not allowed to write multiple characteristic with the same request
                        if (input_req.handle != req->attr_handle) {
                            sd_ble_gatts_rw_authorize_reply(conn_handle, &write_auth_invalid_reply);
                            releaseLongWriteRequest(conn_handle);
                            return;
                        }
                    }

                    // start the copy of what is in input
                    memcpy(req->data + req->length, input_req.data, input_req.len);

                    // update the lenght of the data written
                    req->length = req->length + input_req.len;

                    // success, signal it to the softdevice
                    ble_gatts_rw_authorize_reply_params_t reply = {
                        /* .type = */ BLE_GATTS_AUTHORIZE_TYPE_WRITE,
                        /* .params = */ {
                            /* .write = */ {
                                /* .gatt_status = */ BLE_GATT_STATUS_SUCCESS,
                                /* .update = */ 1,
                                /* .offset = */ input_req.offset,
                                /* .len = */ input_req.len,
                                /* .p_data = */ input_req.data
                            }
                        }
                    };

                    sd_ble_gatts_rw_authorize_reply(conn_handle, &reply);
                }   return;

                case BLE_GATTS_OP_EXEC_WRITE_REQ_CANCEL: {
                    releaseLongWriteRequest(conn_handle);
                    sd_ble_gatts_rw_authorize_reply(conn_handle, &write_auth_succes_reply);
                }   return;

                case BLE_GATTS_OP_EXEC_WRITE_REQ_NOW: {
                    long_write_request_t* req = findLongWriteRequest(conn_handle);
                    if (!req) {
                        sd_ble_gatts_rw_authorize_reply(conn_handle, &write_auth_invalid_reply);
                        return;
                    }

                    GattWriteAuthCallbackParams cbParams = {
                        /* .connHandle = */ conn_handle,
                        /* .handle     = */ req->attr_handle,
                        /* .offset     = */ req->offset,
                        /* .len        = */ req->length,
                        /* .data       = */ req->data,
                        /* .authorizationReply = */ AUTH_CALLBACK_REPLY_SUCCESS /* the callback handler must leave this member
                                                                           * set to AUTH_CALLBACK_REPLY_SUCCESS if the client
                                                                           * request is to proceed. */
                    };
                    characteristicIndex = resolveValueHandleToCharIndex(req->attr_handle);
                    uint16_t write_authorization = p_characteristics[characteristicIndex]->authorizeWrite(&cbParams);

                    // the user code didn't provide the write authorization,
                    // just leave here.
                    if (write_authorization != AUTH_CALLBACK_REPLY_SUCCESS) {
                        // report the status of the operation in any cases
                        sd_ble_gatts_rw_authorize_reply(conn_handle, &write_auth_invalid_reply);
                        releaseLongWriteRequest(conn_handle);
                        return;
                    }

                    // FIXME can't use ::write here, this function doesn't take the offset into account ...
                    ble_gatts_value_t value = {
                        /* .len     = */ req->length,
                        /* .offset  = */ req->offset,
                        /* .p_value = */ req->data
                    };
                    uint32_t update_err = sd_ble_gatts_value_set(conn_handle, req->attr_handle, &value);
                    if (update_err) {
                        sd_ble_gatts_rw_authorize_reply(conn_handle, &write_auth_invalid_reply);
                        releaseLongWriteRequest(conn_handle);
                        return;
                    }

                    sd_ble_gatts_rw_authorize_reply(conn_handle, &write_auth_succes_reply);

                    GattWriteCallbackParams writeParams = {
                        /* .connHandle = */ conn_handle,
                        /* .handle     = */ req->attr_handle,
                        /* .writeOp    = */ static_cast<GattWriteCallbackParams::WriteOp_t>(input_req.op),
                        /* .offset     = */ req->offset,
                        /* .len        = */ req->length,
                        /* .data       = */ req->data,
                    };
                    handleDataWrittenEvent(&writeParams);
                    releaseLongWriteRequest(conn_handle);
                }   return;
            }

            GattWriteAuthCallbackParams cbParams = {
                /* .connHandle = */ gattsEventP->conn_handle,
                /* .handle     = */ handle_value,
                /* .offset     = */ gattsEventP->params.authorize_request.request.write.offset,
                /* .len        = */ gattsEventP->params.authorize_request.request.write.len,
                /* .data       = */ gattsEventP->params.authorize_request.request.write.data,
                /* .authorizationReply = */ AUTH_CALLBACK_REPLY_SUCCESS /* the callback handler must leave this member
                                                                   * set to AUTH_CALLBACK_REPLY_SUCCESS if the client
                                                                   * request is to proceed. */
            };

            ble_gatts_rw_authorize_reply_params_t reply = {
                /* .type = */ BLE_GATTS_AUTHORIZE_TYPE_WRITE,
                /* .params = */ {
                    /* .write = */ {
                        /* .gatt_status = */ p_characteristics[characteristicIndex]->authorizeWrite(&cbParams),
                        /* .update = */ 1,
                        /* .offset = */ cbParams.offset,
                        /* .len = */ cbParams.len,
                        /* .p_data = */ cbParams.data
                    }
                }
            };

            if (reply.params.write.gatt_status != BLE_GATT_STATUS_SUCCESS)
            {
                reply.params.write.update = 0;
            }

            sd_ble_gatts_rw_authorize_reply(gattsEventP->conn_handle, &reply);

            /*
             * If write-authorization is enabled for a characteristic,
             * AUTHORIZATION_REQ event (if replied with true) is *not*
             * followed by another DATA_WRITTEN event; so we still need
             * to invoke handleDataWritten(), much the same as we would
             * have done if write-authorization had not been enabled.
             */
            if (reply.params.write.gatt_status == BLE_GATT_STATUS_SUCCESS) {
                GattWriteCallbackParams cbParams = {
                    /* .connHandle = */ gattsEventP->conn_handle,
                    /* .handle     = */ handle_value,
                    /* .writeOp    = */ static_cast<GattWriteCallbackParams::WriteOp_t>(gattsEventP->params.authorize_request.request.write.op),
                    /* .offset     = */ gattsEventP->params.authorize_request.request.write.offset,
                    /* .len        = */ gattsEventP->params.authorize_request.request.write.len,
                    /* .data       = */ gattsEventP->params.authorize_request.request.write.data,
                };
                handleDataWrittenEvent(&cbParams);
            }
            break;
        }
        case GattServerEvents::GATT_EVENT_READ_AUTHORIZATION_REQ: {
            GattReadAuthCallbackParams cbParams = {
                /* .connHandle         = */ gattsEventP->conn_handle,
                /* .handle             = */ handle_value,
                /* .offset             = */ gattsEventP->params.authorize_request.request.read.offset,
                /* .len                = */ 0,
                /* .data               = */ NULL,
                /* .authorizationReply = */ AUTH_CALLBACK_REPLY_SUCCESS /* the callback handler must leave this member
                                                                   * set to AUTH_CALLBACK_REPLY_SUCCESS if the client
                                                                   * request is to proceed. */
            };

            ble_gatts_rw_authorize_reply_params_t reply = {
                /* .type = */ BLE_GATTS_AUTHORIZE_TYPE_READ,
                /* .params = */ {
                    /* .read = */ {
                        /* .gatt_status = */ p_characteristics[characteristicIndex]->authorizeRead(&cbParams)
                    }
                }
            };

            if (cbParams.authorizationReply == BLE_GATT_STATUS_SUCCESS) {
                if (cbParams.data != NULL) {
                    reply.params.read.update = 1;
                    reply.params.read.offset = cbParams.offset;
                    reply.params.read.len    = cbParams.len;
                    reply.params.read.p_data = cbParams.data;
                }
            }

            sd_ble_gatts_rw_authorize_reply(gattsEventP->conn_handle, &reply);
            break;
        }

        default:
            handleEvent(eventType, handle_value);
            break;
    }
}

uint16_t nRF5xGattServer::getBiggestCharacteristicSize() const {
    uint16_t result = 0;
    for (size_t i = 0; i < characteristicCount; ++i) {
        uint16_t current_size = p_characteristics[i]->getValueAttribute().getMaxLength();
        if (current_size > result) {
            result = current_size;
        }
    }
    return result;
}

nRF5xGattServer::long_write_request_t* nRF5xGattServer::allocateLongWriteRequest(uint16_t connection_handle) {
    for (size_t i = 0; i < TOTAL_CONCURRENT_LONG_WRITE_REQUESTS; ++i) {
        long_write_request_t& req = long_write_requests[i];
        if (req.data == NULL) {
            uint16_t block_size = getBiggestCharacteristicSize();
            req.data = static_cast<uint8_t*>(malloc(block_size));
            req.offset = 0;
            req.length = 0;
            req.conn_handle = connection_handle;
            return &req;
        }
    }
    // if nothing has been found then return null
    return NULL;
}

bool nRF5xGattServer::releaseLongWriteRequest(uint16_t connection_handle) {
    long_write_request_t* req = findLongWriteRequest(connection_handle);
    if (!req) {
        return false;
    }

    free(req->data);
    req->data = NULL;

    // the other fields are not relevant, return now
    return true;
}

nRF5xGattServer::long_write_request_t* nRF5xGattServer::findLongWriteRequest(uint16_t connection_handle) {
    for (size_t i = 0; i < TOTAL_CONCURRENT_LONG_WRITE_REQUESTS; ++i) {
        long_write_request_t& req = long_write_requests[i];
        if (req.data != NULL && req.conn_handle == connection_handle) {
            return &req;
        }
    }
    // if nothing has been found then return null
    return NULL;
}

void nRF5xGattServer::releaseAllWriteRequests() {
    for (size_t i = 0; i < TOTAL_CONCURRENT_LONG_WRITE_REQUESTS; ++i) {
        long_write_request_t& req = long_write_requests[i];
        if (req.data != NULL) {
            free(req.data);
            req.data = NULL;
        }
    }
}
