/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 <stdio.h>
#include <string.h>
#include "dispatch_private.h"
#include "connection_manager_private.h"
#include <qpid/dispatch/container.h>
#include <qpid/dispatch/server.h>
#include <qpid/dispatch/message.h>
#include <proton/engine.h>
#include <proton/message.h>
#include <proton/connection.h>
#include <proton/event.h>
#include <qpid/dispatch/ctools.h>
#include <qpid/dispatch/hash.h>
#include <qpid/dispatch/threading.h>
#include <qpid/dispatch/iterator.h>
#include <qpid/dispatch/log.h>

/** Instance of a node type in a container */
struct qd_node_t {
    DEQ_LINKS(qd_node_t);
    qd_container_t       *container;
    const qd_node_type_t *ntype; ///< Type of node, defines callbacks.
    char                 *name;
    void                 *context;
    qd_dist_mode_t        supported_dist;
    qd_lifetime_policy_t  life_policy;
};

DEQ_DECLARE(qd_node_t, qd_node_list_t);
ALLOC_DECLARE(qd_node_t);
ALLOC_DEFINE(qd_node_t);


/** Encapsulates a proton link for sending and receiving messages */
struct qd_link_t {
    pn_session_t       *pn_sess;
    pn_link_t          *pn_link;
    qd_direction_t      direction;
    void               *context;
    qd_node_t          *node;
    bool                drain_mode;
    bool                close_sess_with_link;
};

ALLOC_DECLARE(qd_link_t);
ALLOC_DEFINE(qd_link_t);


typedef struct qdc_node_type_t {
    DEQ_LINKS(struct qdc_node_type_t);
    const qd_node_type_t *ntype;
} qdc_node_type_t;
DEQ_DECLARE(qdc_node_type_t, qdc_node_type_list_t);

struct qd_container_t {
    qd_dispatch_t        *qd;
    qd_log_source_t      *log_source;
    qd_server_t          *server;
    qd_hash_t            *node_type_map;
    qd_hash_t            *node_map;
    qd_node_list_t        nodes;
    sys_mutex_t          *lock;
    qd_node_t            *default_node;
    qdc_node_type_list_t  node_type_list;
};

static void setup_outgoing_link(qd_container_t *container, pn_link_t *pn_link)
{
    sys_mutex_lock(container->lock);
    qd_node_t  *node = 0;
    const char *source = pn_terminus_get_address(pn_link_remote_source(pn_link));
    qd_field_iterator_t *iter;
    // TODO - Extract the name from the structured source

    if (source) {
        iter   = qd_address_iterator_string(source, ITER_VIEW_NODE_ID);
        qd_hash_retrieve(container->node_map, iter, (void*) &node);
        qd_field_iterator_free(iter);
    }
    sys_mutex_unlock(container->lock);

    if (node == 0) {
        if (container->default_node)
            node = container->default_node;
        else {
            pn_condition_t *cond = pn_link_condition(pn_link);
            pn_condition_set_name(cond, "amqp:not-found");
            pn_condition_set_description(cond, "Source node does not exist");
            pn_link_close(pn_link);
            return;
        }
    }

    qd_link_t *link = new_qd_link_t();
    if (!link) {
        pn_condition_t *cond = pn_link_condition(pn_link);
        pn_condition_set_name(cond, "amqp:internal-error");
        pn_condition_set_description(cond, "Insufficient memory");
        pn_link_close(pn_link);
        return;
    }

    link->pn_sess    = pn_link_session(pn_link);
    link->pn_link    = pn_link;
    link->direction  = QD_OUTGOING;
    link->context    = 0;
    link->node       = node;
    link->drain_mode = pn_link_get_drain(pn_link);
    link->close_sess_with_link = false;

    //
    // Keep the borrowed references
    //
    pn_incref(pn_link);
    pn_incref(link->pn_sess);

    pn_link_set_context(pn_link, link);
    node->ntype->outgoing_handler(node->context, link);
}


static void setup_incoming_link(qd_container_t *container, pn_link_t *pn_link)
{
    sys_mutex_lock(container->lock);
    qd_node_t   *node = 0;
    const char  *target = pn_terminus_get_address(pn_link_remote_target(pn_link));
    qd_field_iterator_t *iter;

    if (target) {
        iter   = qd_address_iterator_string(target, ITER_VIEW_NODE_ID);
        qd_hash_retrieve(container->node_map, iter, (void*) &node);
        qd_field_iterator_free(iter);
    }
    sys_mutex_unlock(container->lock);

    if (node == 0) {
        if (container->default_node)
            node = container->default_node;
        else {
            pn_condition_t *cond = pn_link_condition(pn_link);
            pn_condition_set_name(cond, "amqp:not-found");
            pn_condition_set_description(cond, "Target node does not exist");
            pn_link_close(pn_link);
            return;
        }
    }

    qd_link_t *link = new_qd_link_t();
    if (!link) {
        pn_condition_t *cond = pn_link_condition(pn_link);
        pn_condition_set_name(cond, "amqp:internal-error");
        pn_condition_set_description(cond, "Insufficient memory");
        pn_link_close(pn_link);
        return;
    }

    link->pn_sess    = pn_link_session(pn_link);
    link->pn_link    = pn_link;
    link->direction  = QD_INCOMING;
    link->context    = 0;
    link->node       = node;
    link->drain_mode = pn_link_get_drain(pn_link);
    link->close_sess_with_link = false;

    //
    // Keep the borrowed references
    //
    pn_incref(pn_link);
    pn_incref(link->pn_sess);

    pn_link_set_context(pn_link, link);
    node->ntype->incoming_handler(node->context, link);
}


static void handle_link_open(qd_container_t *container, pn_link_t *pn_link)
{
    qd_link_t *link = (qd_link_t*) pn_link_get_context(pn_link);
    if (link == 0)
        return;
    if (link->node->ntype->link_attach_handler)
        link->node->ntype->link_attach_handler(link->node->context, link);
}


static int do_writable(pn_link_t *pn_link)
{
    qd_link_t *link = (qd_link_t*) pn_link_get_context(pn_link);
    if (!link)
        return 0;

    qd_node_t *node = link->node;
    if (!node)
        return 0;

    return node->ntype->writable_handler(node->context, link);
}


static void do_receive(pn_delivery_t *pnd)
{
    pn_link_t     *pn_link  = pn_delivery_link(pnd);
    qd_link_t     *link     = (qd_link_t*) pn_link_get_context(pn_link);

    if (link) {
        qd_node_t *node = link->node;
        if (node) {
            node->ntype->rx_handler(node->context, link, pnd);
            return;
        }
    }

    //
    // Reject the delivery if we couldn't find a node to handle it
    //
    pn_link_advance(pn_link);
    pn_link_flow(pn_link, 1);
    pn_delivery_update(pnd, PN_REJECTED);
    pn_delivery_settle(pnd);
}


static void do_updated(pn_delivery_t *pnd)
{
    pn_link_t     *pn_link  = pn_delivery_link(pnd);
    qd_link_t     *link     = (qd_link_t*) pn_link_get_context(pn_link);

    if (link) {
        qd_node_t *node = link->node;
        if (node)
            node->ntype->disp_handler(node->context, link, pnd);
    }
}


static void notify_opened(qd_container_t *container, qd_connection_t *conn, void *context)
{
    const qd_node_type_t *nt;

    //
    // Note the locking structure in this function.  Generally this would be unsafe, but since
    // this particular list is only ever appended to and never has items inserted or deleted,
    // this usage is safe in this case.
    //
    sys_mutex_lock(container->lock);
    qdc_node_type_t *nt_item = DEQ_HEAD(container->node_type_list);
    sys_mutex_unlock(container->lock);

    while (nt_item) {
        nt = nt_item->ntype;
        if (qd_connection_inbound(conn)) {
            if (nt->inbound_conn_opened_handler)
                nt->inbound_conn_opened_handler(nt->type_context, conn, context);
        } else {
            if (nt->outbound_conn_opened_handler)
                nt->outbound_conn_opened_handler(nt->type_context, conn, context);
        }

        sys_mutex_lock(container->lock);
        nt_item = DEQ_NEXT(nt_item);
        sys_mutex_unlock(container->lock);
    }
}


static void notify_closed(qd_container_t *container, qd_connection_t *conn, void *context)
{
    const qd_node_type_t *nt;

    //
    // Note the locking structure in this function.  Generally this would be unsafe, but since
    // this particular list is only ever appended to and never has items inserted or deleted,
    // this usage is safe in this case.
    //
    sys_mutex_lock(container->lock);
    qdc_node_type_t *nt_item = DEQ_HEAD(container->node_type_list);
    sys_mutex_unlock(container->lock);

    while (nt_item) {
        nt = nt_item->ntype;
        if (nt->conn_closed_handler)
            nt->conn_closed_handler(nt->type_context, conn, context);

        sys_mutex_lock(container->lock);
        nt_item = DEQ_NEXT(nt_item);
        sys_mutex_unlock(container->lock);
    }
}


static int close_handler(qd_container_t *container, void* conn_context, pn_connection_t *conn, qd_connection_t* qd_conn)
{
    qd_connection_manager_connection_closed(qd_conn);

    //
    // Close all links, passing QD_LOST as the reason.  These links are not
    // being properly 'detached'.  They are being orphaned.
    //
    pn_link_t *pn_link = pn_link_head(conn, PN_LOCAL_ACTIVE);
    while (pn_link) {
        qd_link_t *link = (qd_link_t*) pn_link_get_context(pn_link);
        if (link) {
            qd_node_t *node = link->node;
            if (node) {
                node->ntype->link_detach_handler(node->context, link, QD_LOST);
            }
        }
        pn_link_close(pn_link);
        pn_link = pn_link_next(pn_link, PN_LOCAL_ACTIVE);
    }

    // teardown all sessions
    pn_session_t *ssn = pn_session_head(conn, 0);
    while (ssn) {
        pn_session_close(ssn);
        ssn = pn_session_next(ssn, 0);
    }

    // close the connection
    pn_connection_close(conn);
    notify_closed(container, qd_conn, conn_context);
    return 0;
}


static int writable_handler(void* unused, pn_connection_t *conn, qd_connection_t* qd_conn)
{
    pn_link_t *pn_link;
    int        event_count = 0;

    //
    // Call the attached node's writable handler for all active links
    // on the connection.  Note that in Dispatch, links are considered
    // bidirectional.  Incoming and outgoing only pertains to deliveries and
    // deliveries are a subset of the traffic that flows both directions on links.
    //
    if (pn_connection_state(conn) == (PN_LOCAL_ACTIVE | PN_REMOTE_ACTIVE)) {
        pn_link = pn_link_head(conn, 0);
        while (pn_link) {
            assert(pn_session_connection(pn_link_session(pn_link)) == conn);
            event_count += do_writable(pn_link);
            pn_link = pn_link_next(pn_link, 0);
        }
    }
    return event_count;
}


int pn_event_handler(void *handler_context, void *conn_context, pn_event_t *event, qd_connection_t *qd_conn)
{
    qd_container_t  *container = (qd_container_t*) handler_context;
    pn_connection_t *conn      = qd_connection_pn(qd_conn);
    pn_session_t    *ssn;
    pn_link_t       *pn_link;
    qd_link_t       *qd_link;
    pn_delivery_t   *delivery;

    switch (pn_event_type(event)) {
    case PN_CONNECTION_REMOTE_OPEN :
        if (pn_connection_state(conn) & PN_LOCAL_UNINIT)
            pn_connection_open(conn);
        qd_connection_manager_connection_opened(qd_conn);
        notify_opened(container, qd_conn, conn_context);
        break;

    case PN_CONNECTION_REMOTE_CLOSE :
        if (pn_connection_state(conn) == (PN_LOCAL_ACTIVE | PN_REMOTE_CLOSED))
            pn_connection_close(conn);
        qd_connection_manager_connection_closed(qd_conn);
        break;

    case PN_SESSION_REMOTE_OPEN :
        ssn = pn_event_session(event);
        if (pn_session_state(ssn) & PN_LOCAL_UNINIT) {
            pn_session_set_incoming_capacity(ssn, 1000000);
            pn_session_open(ssn);
        }
        break;

    case PN_SESSION_REMOTE_CLOSE :
        ssn = pn_event_session(event);
        if (pn_session_state(ssn) == (PN_LOCAL_ACTIVE | PN_REMOTE_CLOSED)) {
            // remote has nuked our session.  Check for any links that were
            // left open and forcibly detach them, since no detaches will
            // arrive on this session.
            pn_connection_t *conn = pn_session_connection(ssn);
            pn_link_t *pn_link = pn_link_head(conn, PN_LOCAL_ACTIVE | PN_REMOTE_ACTIVE);
            while (pn_link) {
                if (pn_link_session(pn_link) == ssn) {
                    qd_link_t *qd_link = (qd_link_t *)pn_link_get_context(pn_link);
                    if (qd_link && qd_link->node) {
                        qd_log(container->log_source, QD_LOG_NOTICE,
                               "Aborting link '%s' due to parent session end",
                               pn_link_name(pn_link));
                        qd_link->node->ntype->link_detach_handler(qd_link->node->context,
                                                                  qd_link, QD_LOST);
                    }
                }
                pn_link = pn_link_next(pn_link, PN_LOCAL_ACTIVE | PN_REMOTE_ACTIVE);
            }
            pn_session_close(ssn);
        }
        break;

    case PN_LINK_REMOTE_OPEN :
        pn_link = pn_event_link(event);
        if (pn_link_state(pn_link) & PN_LOCAL_UNINIT) {
            if (pn_link_is_sender(pn_link))
                setup_outgoing_link(container, pn_link);
            else
                setup_incoming_link(container, pn_link);
        } else if (pn_link_state(pn_link) & PN_LOCAL_ACTIVE)
            handle_link_open(container, pn_link);
        break;

    case PN_LINK_REMOTE_CLOSE :
    case PN_LINK_REMOTE_DETACH :
        pn_link = pn_event_link(event);
        qd_link = (qd_link_t*) pn_link_get_context(pn_link);
        if (qd_link) {
            qd_node_t *node = qd_link->node;
            qd_detach_type_t dt = pn_event_type(event) == PN_LINK_REMOTE_CLOSE ? QD_CLOSED : QD_DETACHED;
            if (node)
                node->ntype->link_detach_handler(node->context, qd_link, dt);

            //
            // If the qd_link does not reference the pn_link, we have already freed the pn_link.
            // If we attempt to free it again, proton will crash.
            //
            if (qd_link->pn_link == pn_link)
                pn_link_close(pn_link);
        }
        break;

    case PN_LINK_FLOW :
        pn_link = pn_event_link(event);
        qd_link = (qd_link_t*) pn_link_get_context(pn_link);
        if (qd_link && qd_link->node && qd_link->node->ntype->link_flow_handler)
            qd_link->node->ntype->link_flow_handler(qd_link->node->context, qd_link);
        break;

    case PN_DELIVERY :
        delivery = pn_event_delivery(event);
        if (pn_delivery_readable(delivery))
            do_receive(delivery);

        if (pn_delivery_updated(delivery)) {
            do_updated(delivery);
            pn_delivery_clear(delivery);
        }
        break;

    case PN_EVENT_NONE :
    case PN_REACTOR_INIT :
    case PN_REACTOR_QUIESCED :
    case PN_REACTOR_FINAL :
    case PN_TIMER_TASK :
    case PN_CONNECTION_INIT :
    case PN_CONNECTION_BOUND :
    case PN_CONNECTION_UNBOUND :
    case PN_CONNECTION_LOCAL_OPEN :
    case PN_CONNECTION_LOCAL_CLOSE :
    case PN_CONNECTION_FINAL :
    case PN_SESSION_INIT :
    case PN_SESSION_LOCAL_OPEN :
    case PN_SESSION_LOCAL_CLOSE :
    case PN_SESSION_FINAL :
    case PN_LINK_INIT :
    case PN_LINK_LOCAL_OPEN :
    case PN_LINK_LOCAL_CLOSE :
    case PN_LINK_LOCAL_DETACH :
    case PN_LINK_FINAL :
    case PN_TRANSPORT :
    case PN_TRANSPORT_ERROR :
    case PN_TRANSPORT_HEAD_CLOSED :
    case PN_TRANSPORT_TAIL_CLOSED :
    case PN_TRANSPORT_CLOSED :
    case PN_TRANSPORT_AUTHENTICATED :
    case PN_SELECTABLE_INIT :
    case PN_SELECTABLE_UPDATED :
    case PN_SELECTABLE_READABLE :
    case PN_SELECTABLE_WRITABLE :
    case PN_SELECTABLE_ERROR :
    case PN_SELECTABLE_EXPIRED :
    case PN_SELECTABLE_FINAL :
        break;
    }

    return 1;
}


static void open_handler(qd_container_t *container, qd_connection_t *conn, qd_direction_t dir, void *context)
{
}


static int handler(void *handler_context, void *conn_context, qd_conn_event_t event, qd_connection_t *qd_conn)
{
    qd_container_t  *container = (qd_container_t*) handler_context;
    pn_connection_t *conn      = qd_connection_pn(qd_conn);

    switch (event) {
    case QD_CONN_EVENT_LISTENER_OPEN:  open_handler(container, qd_conn, QD_INCOMING, conn_context);   break;
    case QD_CONN_EVENT_CONNECTOR_OPEN: open_handler(container, qd_conn, QD_OUTGOING, conn_context);   break;
    case QD_CONN_EVENT_CLOSE:          return close_handler(container, conn_context, conn, qd_conn);
    case QD_CONN_EVENT_WRITABLE:       return writable_handler(conn_context, conn, qd_conn);
    }

    return 0;
}


qd_container_t *qd_container(qd_dispatch_t *qd)
{
    qd_container_t *container = NEW(qd_container_t);

    container->qd            = qd;
    container->log_source    = qd_log_source("CONTAINER");
    container->server        = qd->server;
    container->node_type_map = qd_hash(6,  4, 1);  // 64 buckets, item batches of 4
    container->node_map      = qd_hash(10, 32, 0); // 1K buckets, item batches of 32
    container->lock          = sys_mutex();
    container->default_node  = 0;
    DEQ_INIT(container->nodes);
    DEQ_INIT(container->node_type_list);

    qd_server_set_conn_handler(qd, handler, pn_event_handler, container);

    qd_log(container->log_source, QD_LOG_TRACE, "Container Initialized");
    return container;
}


void qd_container_free(qd_container_t *container)
{
    if (!container) return;
    if (container->default_node)
        qd_container_destroy_node(container->default_node);

    qd_node_t *node = DEQ_HEAD(container->nodes);
    while (node) {
        qd_container_destroy_node(node);
        node = DEQ_HEAD(container->nodes);
    }

    qdc_node_type_t *nt = DEQ_HEAD(container->node_type_list);
    while (nt) {
        DEQ_REMOVE_HEAD(container->node_type_list);
        free(nt);
        nt = DEQ_HEAD(container->node_type_list);
    }
    qd_hash_free(container->node_map);
    qd_hash_free(container->node_type_map);
    sys_mutex_free(container->lock);
    free(container);
}


int qd_container_register_node_type(qd_dispatch_t *qd, const qd_node_type_t *nt)
{
    qd_container_t *container = qd->container;

    int result;
    qd_field_iterator_t *iter = qd_field_iterator_string(nt->type_name);
    qdc_node_type_t     *nt_item = NEW(qdc_node_type_t);
    DEQ_ITEM_INIT(nt_item);
    nt_item->ntype = nt;

    sys_mutex_lock(container->lock);
    result = qd_hash_insert_const(container->node_type_map, iter, nt, 0);
    DEQ_INSERT_TAIL(container->node_type_list, nt_item);
    sys_mutex_unlock(container->lock);

    qd_field_iterator_free(iter);
    if (result < 0)
        return result;
    qd_log(container->log_source, QD_LOG_TRACE, "Node Type Registered - %s", nt->type_name);

    return 0;
}


qd_node_t *qd_container_set_default_node_type(qd_dispatch_t        *qd,
                                              const qd_node_type_t *nt,
                                              void                 *context,
                                              qd_dist_mode_t        supported_dist)
{
    qd_container_t *container = qd->container;

    if (container->default_node)
        qd_container_destroy_node(container->default_node);

    if (nt) {
        container->default_node = qd_container_create_node(qd, nt, 0, context, supported_dist, QD_LIFE_PERMANENT);
        qd_log(container->log_source, QD_LOG_TRACE, "Node of type '%s' installed as default node", nt->type_name);
    } else {
        container->default_node = 0;
        qd_log(container->log_source, QD_LOG_TRACE, "Default node removed");
    }

    return container->default_node;
}


qd_node_t *qd_container_create_node(qd_dispatch_t        *qd,
                                    const qd_node_type_t *nt,
                                    const char           *name,
                                    void                 *context,
                                    qd_dist_mode_t        supported_dist,
                                    qd_lifetime_policy_t  life_policy)
{
    qd_container_t *container = qd->container;
    int result;
    qd_node_t *node = new_qd_node_t();
    if (!node)
        return 0;

    DEQ_ITEM_INIT(node);
    node->container      = container;
    node->ntype          = nt;
    node->name           = 0;
    node->context        = context;
    node->supported_dist = supported_dist;
    node->life_policy    = life_policy;

    if (name) {
        qd_field_iterator_t *iter = qd_field_iterator_string(name);
        sys_mutex_lock(container->lock);
        result = qd_hash_insert(container->node_map, iter, node, 0);
        if (result >= 0)
            DEQ_INSERT_HEAD(container->nodes, node);
        sys_mutex_unlock(container->lock);
        qd_field_iterator_free(iter);
        if (result < 0) {
            free_qd_node_t(node);
            return 0;
        }

        node->name = (char*) malloc(strlen(name) + 1);
        strcpy(node->name, name);
    }

    if (name)
        qd_log(container->log_source, QD_LOG_TRACE, "Node of type '%s' created with name '%s'", nt->type_name, name);

    return node;
}


void qd_container_destroy_node(qd_node_t *node)
{
    qd_container_t *container = node->container;

    if (node->name) {
        qd_field_iterator_t *iter = qd_field_iterator_string(node->name);
        sys_mutex_lock(container->lock);
        qd_hash_remove(container->node_map, iter);
        DEQ_REMOVE(container->nodes, node);
        sys_mutex_unlock(container->lock);
        qd_field_iterator_free(iter);
        free(node->name);
    }

    free_qd_node_t(node);
}


void qd_container_node_set_context(qd_node_t *node, void *node_context)
{
    node->context = node_context;
}


qd_dist_mode_t qd_container_node_get_dist_modes(const qd_node_t *node)
{
    return node->supported_dist;
}


qd_lifetime_policy_t qd_container_node_get_life_policy(const qd_node_t *node)
{
    return node->life_policy;
}


qd_link_t *qd_link(qd_node_t *node, qd_connection_t *conn, qd_direction_t dir, const char* name)
{
    qd_link_t *link = new_qd_link_t();

    link->pn_sess = pn_session(qd_connection_pn(conn));
    pn_session_set_incoming_capacity(link->pn_sess, 1000000);

    if (dir == QD_OUTGOING)
        link->pn_link = pn_sender(link->pn_sess, name);
    else
        link->pn_link = pn_receiver(link->pn_sess, name);

    link->direction  = dir;
    link->context    = node->context;
    link->node       = node;
    link->drain_mode = pn_link_get_drain(link->pn_link);
    link->close_sess_with_link = true;

    //
    // Keep the borrowed references
    //
    pn_incref(link->pn_link);
    pn_incref(link->pn_sess);

    pn_link_set_context(link->pn_link, link);

    pn_session_open(link->pn_sess);

    return link;
}


void qd_link_free_LH(qd_link_t *link)
{
    if (!link) return;
    if (link->pn_link) pn_decref(link->pn_link);
    if (link->pn_sess) pn_decref(link->pn_sess);
    link->pn_link = 0;
    link->pn_sess = 0;
    free_qd_link_t(link);
}


void qd_link_set_context(qd_link_t *link, void *context)
{
    link->context = context;
}


void *qd_link_get_context(qd_link_t *link)
{
    return link->context;
}


void qd_link_set_conn_context(qd_link_t *link, void *context)
{
    if (!link || !link->pn_link)
        return;
    pn_session_t *pn_sess = pn_link_session(link->pn_link);
    if (!pn_sess)
        return;
    pn_connection_t *pn_conn = pn_session_connection(pn_sess);
    if (!pn_conn)
        return;
    qd_connection_t *conn = (qd_connection_t*) pn_connection_get_context(pn_conn);
    if (!conn)
        return;
    qd_connection_set_link_context(conn, context);
}


void *qd_link_get_conn_context(qd_link_t *link)
{
    if (!link || !link->pn_link)
        return 0;
    pn_session_t *pn_sess = pn_link_session(link->pn_link);
    if (!pn_sess)
        return 0;
    pn_connection_t *pn_conn = pn_session_connection(pn_sess);
    if (!pn_conn)
        return 0;
    qd_connection_t *conn = (qd_connection_t*) pn_connection_get_context(pn_conn);
    if (!conn)
        return 0;
    return qd_connection_get_link_context(conn);
}


pn_link_t *qd_link_pn(qd_link_t *link)
{
    return link->pn_link;
}

pn_session_t *qd_link_pn_session(qd_link_t *link)
{
    return link->pn_sess;
}


qd_direction_t qd_link_direction(const qd_link_t *link)
{
    return link->direction;
}


qd_connection_t *qd_link_connection(qd_link_t *link)
{
    if (!link || !link->pn_link)
        return 0;

    pn_session_t *sess = pn_link_session(link->pn_link);
    if (!sess)
        return 0;

    pn_connection_t *conn = pn_session_connection(sess);
    if (!conn)
        return 0;

    qd_connection_t *ctx = pn_connection_get_context(conn);
    if (!ctx || !ctx->opened || ctx->closed)
        return 0;

    return ctx;
}


pn_terminus_t *qd_link_source(qd_link_t *link)
{
    return pn_link_source(link->pn_link);
}


pn_terminus_t *qd_link_target(qd_link_t *link)
{
    return pn_link_target(link->pn_link);
}


pn_terminus_t *qd_link_remote_source(qd_link_t *link)
{
    return pn_link_remote_source(link->pn_link);
}


pn_terminus_t *qd_link_remote_target(qd_link_t *link)
{
    return pn_link_remote_target(link->pn_link);
}


void qd_link_activate(qd_link_t *link)
{
    if (!link || !link->pn_link)
        return;

    pn_session_t *sess = pn_link_session(link->pn_link);
    if (!sess)
        return;

    pn_connection_t *conn = pn_session_connection(sess);
    if (!conn)
        return;

    qd_connection_t *ctx = pn_connection_get_context(conn);
    if (!ctx)
        return;

    qd_server_activate(ctx);
}


void qd_link_close(qd_link_t *link)
{
    if (link->pn_link)
        pn_link_close(link->pn_link);
    if (link->close_sess_with_link && link->pn_sess)
        pn_session_close(link->pn_sess);
}


bool qd_link_drain_changed(qd_link_t *link, bool *mode)
{
    bool pn_mode = pn_link_get_drain(link->pn_link);
    bool changed = pn_mode != link->drain_mode;

    *mode = pn_mode;
    if (changed)
        link->drain_mode = pn_mode;
    return changed;
}