package com.pushtechnology.diffusion.examples;

import com.pushtechnology.diffusion.client.Diffusion;
import com.pushtechnology.diffusion.client.features.control.topics.SubscriptionControl;
import com.pushtechnology.diffusion.client.features.control.topics.SubscriptionControl.SubscriptionCallback;
import com.pushtechnology.diffusion.client.session.Session;
import com.pushtechnology.diffusion.client.session.SessionId;

/**
 * This demonstrates using a client to subscribe and unsubscribe other clients
 * to topics.
 * <P>
 * This uses the 'SubscriptionControl' feature.
 *
 * @author Push Technology Limited
 * @since 5.0
 */
public class ControlClientSubscriptionControl {

    private final Session session;

    private final SubscriptionControl subscriptionControl;

    /**
     * Constructor.
     */
    public ControlClientSubscriptionControl() {

        session =
            Diffusion.sessions().principal("control").password("password")
                .open("ws://diffusion.example.com:80");

        subscriptionControl = session.feature(SubscriptionControl.class);
    }

    /**
     * Subscribe a client to topics.
     *
     * @param sessionId client to subscribe
     * @param topicSelector topic selector expression
     * @param callback for subscription result
     */
    public void subscribe(
        SessionId sessionId,
        String topicSelector,
        SubscriptionCallback callback) {

        // To subscribe a client to a topic, this client session
        // must have the 'modify_session' permission.
        subscriptionControl.subscribe(
            sessionId,
            topicSelector,
            callback);
    }

    /**
     * Unsubscribe a client from topics.
     *
     * @param sessionId client to unsubscribe
     * @param topicSelector topic selector expression
     * @param callback for unsubscription result
     */
    public void unsubscribe(
        SessionId sessionId,
        String topicSelector,
        SubscriptionCallback callback) {

        // To unsubscribe a client from a topic, this client session
        // must have the 'modify_session' permission.
        subscriptionControl.unsubscribe(
            sessionId,
            topicSelector,
            callback);
    }

    /**
     * Close the session.
     */
    public void close() {
        session.close();
    }
}

/*
 * This example waits to be notified of a client connection, and then
 * subscribes that client to a named topic.
 */

#include <stdio.h>
#include <unistd.h>

#include <apr.h>
#include <apr_thread_mutex.h>
#include <apr_thread_cond.h>

#include "diffusion.h"
#include "args.h"

ARG_OPTS_T arg_opts[] = {
        ARG_OPTS_HELP,
        {'u', "url", "Diffusion server URL", ARG_OPTIONAL, ARG_HAS_VALUE, "ws://localhost:8080"},
        {'p', "principal", "Principal (username) for the connection", ARG_OPTIONAL, ARG_HAS_VALUE, NULL},
        {'c', "credentials", "Credentials (password) for the connection", ARG_OPTIONAL, ARG_HAS_VALUE, NULL},
        {'t', "topic_selector", "Topic selector to subscribe/unsubscribe clients from", ARG_OPTIONAL, ARG_HAS_VALUE, ">foo"},
        END_OF_ARG_OPTS
};
HASH_T *options = NULL;

/*
 * Callback invoked when a client has been successfully subscribed to
 * a topic.
 */
static int
on_subscription_complete(SESSION_T *session, void *context)
{
        printf("Subscription complete\n");
        return HANDLER_SUCCESS;
}

/*
 * Callback invoked when a client session has been opened.
 */
static int
on_session_open(SESSION_T *session, const SESSION_PROPERTIES_EVENT_T *request, void *context)
{
        if(session_id_cmp(*session->id, request->session_id) == 0) {
                // It's our own session, ignore.
                return HANDLER_SUCCESS;
        }

        char *topic_selector = hash_get(options, "topic_selector");

        char *sid_str = session_id_to_string(&request->session_id);
        printf("Subscribing session %s to topic selector %s\n", sid_str, topic_selector);
        free(sid_str);

        /*
         * Subscribe the client session to the topic.
         */
        SUBSCRIPTION_CONTROL_PARAMS_T subscribe_params = {
                .session_id = request->session_id,
                .topic_selector = topic_selector,
                .on_complete = on_subscription_complete
        };
        subscribe_client(session, subscribe_params);

        return HANDLER_SUCCESS;
}

int
main(int argc, char **argv)
{
        /*
         * Standard command-line parsing.
         */
        options = parse_cmdline(argc, argv, arg_opts);
        if(options == NULL || hash_get(options, "help") != NULL) {
                show_usage(argc, argv, arg_opts);
                return EXIT_FAILURE;
        }

        const char *url = hash_get(options, "url");
        const char *principal = hash_get(options, "principal");
        CREDENTIALS_T *credentials = NULL;
        const char *password = hash_get(options, "credentials");
        if(password != NULL) {
                credentials = credentials_create_password(password);
        }

        /*
         * Create a session with Diffusion.
         */
        DIFFUSION_ERROR_T error = { 0 };
        SESSION_T *session = session_create(url, principal, credentials, NULL, NULL, &error);
        if(session == NULL) {
                fprintf(stderr, "Failed to create session: %s\n", error.message);
                return EXIT_FAILURE;
        }

        /*
         * Register a session properties listener, so we are notified
         * of new client connections.
         * In the callback, we will subscribe the client to topics
         * according to the topic_selector argument.
         */
        SET_T *required_properties = set_new_string(1);
        set_add(required_properties, PROPERTIES_SELECTOR_ALL_FIXED_PROPERTIES);
        SESSION_PROPERTIES_REGISTRATION_PARAMS_T params = {
                .on_session_open = on_session_open,
                .required_properties = required_properties
        };
        session_properties_listener_register(session, params);
        set_free(required_properties);

        /*
         * Pretend to do some work.
         */
        sleep(10);

        /*
         * Close session and tidy up.
         */
        session_close(session, NULL);
        session_free(session);

        return EXIT_SUCCESS;
}