/***
    This file is part of PulseAudio.

    Copyright 2013 Alexander Couzens

    PulseAudio is free software; you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published
    by the Free Software Foundation; either version 2.1 of the License,
    or (at your option) any later version.

    PulseAudio 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 Lesser General Public License
    along with PulseAudio; if not, see <http://www.gnu.org/licenses/>.
***/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include "restart-module.h"

#include <pulse/context.h>
#include <pulse/timeval.h>
#include <pulse/xmalloc.h>
#include <pulse/stream.h>
#include <pulse/mainloop.h>
#include <pulse/introspect.h>
#include <pulse/error.h>

#include <pulsecore/core.h>
#include <pulsecore/core-util.h>
#include <pulsecore/i18n.h>
#include <pulsecore/sink.h>
#include <pulsecore/modargs.h>
#include <pulsecore/log.h>
#include <pulsecore/thread.h>
#include <pulsecore/thread-mq.h>
#include <pulsecore/poll.h>
#include <pulsecore/rtpoll.h>
#include <pulsecore/proplist-util.h>

PA_MODULE_AUTHOR("Alexander Couzens");
PA_MODULE_DESCRIPTION("Create a network sink which connects via a stream to a remote PulseAudio server");
PA_MODULE_VERSION(PACKAGE_VERSION);
PA_MODULE_LOAD_ONCE(false);
PA_MODULE_USAGE(
        "server=<address> "
        "sink=<name of the remote sink> "
        "sink_name=<name for the local sink> "
        "sink_properties=<properties for the local sink> "
        "reconnect_interval_ms=<interval to try reconnects, 0 or omitted if disabled> "
        "format=<sample format> "
        "channels=<number of channels> "
        "rate=<sample rate> "
        "channel_map=<channel map> "
        "cookie=<cookie file path>"
        );

#define MAX_LATENCY_USEC (200 * PA_USEC_PER_MSEC)
#define TUNNEL_THREAD_FAILED_MAINLOOP 1

static int do_init(pa_module *m);
static void do_done(pa_module *m);
static void stream_state_cb(pa_stream *stream, void *userdata);
static void stream_changed_buffer_attr_cb(pa_stream *stream, void *userdata);
static void stream_set_buffer_attr_cb(pa_stream *stream, int success, void *userdata);
static void context_state_cb(pa_context *c, void *userdata);
static void sink_update_requested_latency_cb(pa_sink *s);

struct tunnel_msg {
    pa_msgobject parent;
};

typedef struct tunnel_msg tunnel_msg;
PA_DEFINE_PRIVATE_CLASS(tunnel_msg, pa_msgobject);

enum {
    TUNNEL_MESSAGE_CREATE_SINK_REQUEST,
    TUNNEL_MESSAGE_MAYBE_RESTART,
};

enum {
    TUNNEL_MESSAGE_SINK_CREATED = PA_SINK_MESSAGE_MAX,
};

struct userdata {
    pa_module *module;
    pa_sink *sink;
    pa_thread *thread;
    pa_thread_mq *thread_mq;
    pa_mainloop *thread_mainloop;
    pa_mainloop_api *thread_mainloop_api;

    pa_context *context;
    pa_stream *stream;
    pa_rtpoll *rtpoll;

    bool update_stream_bufferattr_after_connect;

    bool connected;
    bool shutting_down;

    char *cookie_file;
    char *remote_server;
    char *remote_sink_name;
    char *sink_name;

    pa_proplist *sink_proplist;
    pa_sample_spec sample_spec;
    pa_channel_map channel_map;

    tunnel_msg *msg;

    pa_usec_t reconnect_interval_us;
};

struct module_restart_data {
    struct userdata *userdata;
    pa_restart_data *restart_data;
};

static const char* const valid_modargs[] = {
    "sink_name",
    "sink_properties",
    "server",
    "sink",
    "format",
    "channels",
    "rate",
    "channel_map",
    "cookie",
    "reconnect_interval_ms",
    NULL,
};

static void cork_stream(struct userdata *u, bool cork) {
    pa_operation *operation;

    pa_assert(u);
    pa_assert(u->stream);

    if (cork) {
        /* When the sink becomes suspended (which is the only case where we
         * cork the stream), we don't want to keep any old data around, because
         * the old data is most likely unrelated to the audio that will be
         * played at the time when the sink starts running again. */
        if ((operation = pa_stream_flush(u->stream, NULL, NULL)))
            pa_operation_unref(operation);
    }

    if ((operation = pa_stream_cork(u->stream, cork, NULL, NULL)))
        pa_operation_unref(operation);
}

static void reset_bufferattr(pa_buffer_attr *bufferattr) {
    pa_assert(bufferattr);
    bufferattr->fragsize = (uint32_t) -1;
    bufferattr->minreq = (uint32_t) -1;
    bufferattr->maxlength = (uint32_t) -1;
    bufferattr->prebuf = (uint32_t) -1;
    bufferattr->tlength = (uint32_t) -1;
}

static pa_proplist* tunnel_new_proplist(struct userdata *u) {
    pa_proplist *proplist = pa_proplist_new();
    pa_assert(proplist);
    pa_proplist_sets(proplist, PA_PROP_APPLICATION_NAME, "PulseAudio");
    pa_proplist_sets(proplist, PA_PROP_APPLICATION_ID, "org.PulseAudio.PulseAudio");
    pa_proplist_sets(proplist, PA_PROP_APPLICATION_VERSION, PACKAGE_VERSION);
    pa_init_proplist(proplist);

    return proplist;
}

static void thread_func(void *userdata) {
    struct userdata *u = userdata;
    pa_proplist *proplist;

    pa_assert(u);

    pa_log_debug("Thread starting up");
    pa_thread_mq_install(u->thread_mq);

    proplist = tunnel_new_proplist(u);
    u->context = pa_context_new_with_proplist(u->thread_mainloop_api,
                                              "PulseAudio",
                                              proplist);
    pa_proplist_free(proplist);

    if (!u->context) {
        pa_log("Failed to create libpulse context");
        goto fail;
    }

    if (u->cookie_file && pa_context_load_cookie_from_file(u->context, u->cookie_file) != 0) {
        pa_log_error("Can not load cookie file!");
        goto fail;
    }

    pa_context_set_state_callback(u->context, context_state_cb, u);
    if (pa_context_connect(u->context,
                           u->remote_server,
                           PA_CONTEXT_NOAUTOSPAWN,
                           NULL) < 0) {
        pa_log("Failed to connect libpulse context: %s", pa_strerror(pa_context_errno(u->context)));
        goto fail;
    }

    for (;;) {
        int ret;

        if (pa_mainloop_iterate(u->thread_mainloop, 1, &ret) < 0) {
            if (ret == 0)
                goto finish;
            else
                goto fail;
        }

        if (u->sink && PA_UNLIKELY(u->sink->thread_info.rewind_requested))
            pa_sink_process_rewind(u->sink, 0);

        if (u->connected &&
                pa_stream_get_state(u->stream) == PA_STREAM_READY &&
                PA_SINK_IS_LINKED(u->sink->thread_info.state)) {
            size_t writable;

            writable = pa_stream_writable_size(u->stream);
            if (writable > 0) {
                pa_memchunk memchunk;
                const void *p;

                pa_sink_render_full(u->sink, writable, &memchunk);

                pa_assert(memchunk.length > 0);

                /* we have new data to write */
                p = pa_memblock_acquire(memchunk.memblock);
                /* TODO: Use pa_stream_begin_write() to reduce copying. */
                ret = pa_stream_write(u->stream,
                                      (uint8_t*) p + memchunk.index,
                                      memchunk.length,
                                      NULL,     /**< A cleanup routine for the data or NULL to request an internal copy */
                                      0,        /** offset */
                                      PA_SEEK_RELATIVE);
                pa_memblock_release(memchunk.memblock);
                pa_memblock_unref(memchunk.memblock);

                if (ret != 0) {
                    pa_log_error("Could not write data into the stream ... ret = %i", ret);
                    u->thread_mainloop_api->quit(u->thread_mainloop_api, TUNNEL_THREAD_FAILED_MAINLOOP);
                }

            }
        }
    }
fail:
    /* send a message to the ctl thread to ask it to either terminate us, or
     * restart us, but either way this thread will exit, so then wait for the
     * shutdown message */
    pa_asyncmsgq_post(u->thread_mq->outq, PA_MSGOBJECT(u->msg), TUNNEL_MESSAGE_MAYBE_RESTART, u, 0, NULL, NULL);
    pa_asyncmsgq_wait_for(u->thread_mq->inq, PA_MESSAGE_SHUTDOWN);

finish:
    if (u->stream) {
        pa_stream_disconnect(u->stream);
        pa_stream_unref(u->stream);
        u->stream = NULL;
    }

    if (u->context) {
        pa_context_disconnect(u->context);
        pa_context_unref(u->context);
        u->context = NULL;
    }

    pa_log_debug("Thread shutting down");
}

static void stream_state_cb(pa_stream *stream, void *userdata) {
    struct userdata *u = userdata;

    pa_assert(u);

    switch (pa_stream_get_state(stream)) {
        case PA_STREAM_FAILED:
            pa_log_error("Stream failed.");
            u->connected = false;
            u->thread_mainloop_api->quit(u->thread_mainloop_api, TUNNEL_THREAD_FAILED_MAINLOOP);
            break;
        case PA_STREAM_TERMINATED:
            pa_log_debug("Stream terminated.");
            break;
        case PA_STREAM_READY:
            if (PA_SINK_IS_OPENED(u->sink->thread_info.state))
                cork_stream(u, false);

            /* Only call our requested_latency_cb when requested_latency
             * changed between PA_STREAM_CREATING -> PA_STREAM_READY, because
             * we don't want to override the initial tlength set by the server
             * without a good reason. */
            if (u->update_stream_bufferattr_after_connect)
                sink_update_requested_latency_cb(u->sink);
            else
                stream_changed_buffer_attr_cb(stream, userdata);
        case PA_STREAM_CREATING:
        case PA_STREAM_UNCONNECTED:
            break;
    }
}

/* called when remote server changes the stream buffer_attr */
static void stream_changed_buffer_attr_cb(pa_stream *stream, void *userdata) {
    struct userdata *u = userdata;
    const pa_buffer_attr *bufferattr;
    pa_assert(u);

    bufferattr = pa_stream_get_buffer_attr(u->stream);
    pa_sink_set_max_request_within_thread(u->sink, bufferattr->tlength);

    pa_log_debug("Server reports buffer attrs changed. tlength now at %lu.",
                 (unsigned long) bufferattr->tlength);
}

/* called after we requested a change of the stream buffer_attr */
static void stream_set_buffer_attr_cb(pa_stream *stream, int success, void *userdata) {
    stream_changed_buffer_attr_cb(stream, userdata);
}

/* called when the server experiences an underrun of our buffer */
static void stream_underflow_callback(pa_stream *stream, void *userdata) {
    pa_log_info("Server signalled buffer underrun.");
}

/* called when the server experiences an overrun of our buffer */
static void stream_overflow_callback(pa_stream *stream, void *userdata) {
    pa_log_info("Server signalled buffer overrun.");
}

/* Do a reinit of the module.  Note that u will be freed as a result of this
 * call. */
static void maybe_restart(struct module_restart_data *rd) {
    struct userdata *u = rd->userdata;

    if (rd->restart_data) {
        pa_log_debug("Restart already pending");
        return;
    }

    if (u->reconnect_interval_us > 0) {
        /* The handle returned here must be freed when do_init() finishes successfully
         * and when the module exits. */
        rd->restart_data = pa_restart_module_reinit(u->module, do_init, do_done, u->reconnect_interval_us);
    } else {
        /* exit the module */
        pa_module_unload_request(u->module, true);
    }
}

static void on_sink_created(struct userdata *u) {
    pa_proplist *proplist;
    pa_buffer_attr bufferattr;
    pa_usec_t requested_latency;
    char *username = pa_get_user_name_malloc();
    char *hostname = pa_get_host_name_malloc();
    /* TODO: old tunnel put here the remote sink_name into stream name e.g. 'Null Output for lynxis@lazus' */
    char *stream_name = pa_sprintf_malloc(_("Tunnel for %s@%s"), username, hostname);
    pa_xfree(hostname);
    pa_xfree(username);

    pa_assert_io_context();

    /* if we still don't have a sink, then sink creation failed, and we should
     * kill this io thread */
    if (!u->sink) {
        pa_log_error("Could not create a sink.");
        u->thread_mainloop_api->quit(u->thread_mainloop_api, TUNNEL_THREAD_FAILED_MAINLOOP);
        return;
    }

    proplist = tunnel_new_proplist(u);
    u->stream = pa_stream_new_with_proplist(u->context,
                                            stream_name,
                                            &u->sink->sample_spec,
                                            &u->sink->channel_map,
                                            proplist);
    pa_proplist_free(proplist);
    pa_xfree(stream_name);

    if (!u->stream) {
        pa_log_error("Could not create a stream.");
        u->thread_mainloop_api->quit(u->thread_mainloop_api, TUNNEL_THREAD_FAILED_MAINLOOP);
        return;
    }

    requested_latency = pa_sink_get_requested_latency_within_thread(u->sink);
    if (requested_latency == (pa_usec_t) -1)
        requested_latency = u->sink->thread_info.max_latency;

    reset_bufferattr(&bufferattr);
    bufferattr.tlength = pa_usec_to_bytes(requested_latency, &u->sink->sample_spec);

    pa_log_debug("tlength requested at %lu.", (unsigned long) bufferattr.tlength);

    pa_stream_set_state_callback(u->stream, stream_state_cb, u);
    pa_stream_set_buffer_attr_callback(u->stream, stream_changed_buffer_attr_cb, u);
    pa_stream_set_underflow_callback(u->stream, stream_underflow_callback, u);
    pa_stream_set_overflow_callback(u->stream, stream_overflow_callback, u);
    if (pa_stream_connect_playback(u->stream,
                                   u->remote_sink_name,
                                   &bufferattr,
                                   PA_STREAM_INTERPOLATE_TIMING | PA_STREAM_DONT_MOVE | PA_STREAM_START_CORKED | PA_STREAM_AUTO_TIMING_UPDATE | PA_STREAM_ADJUST_LATENCY,
                                   NULL,
                                   NULL) < 0) {
        pa_log_error("Could not connect stream.");
        u->thread_mainloop_api->quit(u->thread_mainloop_api, TUNNEL_THREAD_FAILED_MAINLOOP);
    }
    u->connected = true;
}

static void context_state_cb(pa_context *c, void *userdata) {
    struct userdata *u = userdata;
    pa_assert(u);

    switch (pa_context_get_state(c)) {
        case PA_CONTEXT_UNCONNECTED:
        case PA_CONTEXT_CONNECTING:
        case PA_CONTEXT_AUTHORIZING:
        case PA_CONTEXT_SETTING_NAME:
            break;
        case PA_CONTEXT_READY:
            /* now that we're connected, ask the control thread to create a sink for
             * us, and wait for that to complete before proceeding, we'll
             * receive TUNNEL_MESSAGE_SINK_CREATED in response when the sink is
             * created (see sink_process_msg_cb()) */
            pa_log_debug("Connection successful. Creating stream.");
            pa_assert(!u->stream);
            pa_assert(!u->sink);

            pa_log_debug("Asking ctl thread to create sink.");
            pa_asyncmsgq_post(u->thread_mq->outq, PA_MSGOBJECT(u->msg), TUNNEL_MESSAGE_CREATE_SINK_REQUEST, u, 0, NULL, NULL);
            break;
        case PA_CONTEXT_FAILED:
            pa_log_debug("Context failed: %s.", pa_strerror(pa_context_errno(u->context)));
            u->connected = false;
            u->thread_mainloop_api->quit(u->thread_mainloop_api, TUNNEL_THREAD_FAILED_MAINLOOP);
            break;
        case PA_CONTEXT_TERMINATED:
            pa_log_debug("Context terminated.");
            u->connected = false;
            u->thread_mainloop_api->quit(u->thread_mainloop_api, TUNNEL_THREAD_FAILED_MAINLOOP);
            break;
    }
}

static void sink_update_requested_latency_cb(pa_sink *s) {
    struct userdata *u;
    pa_operation *operation;
    size_t nbytes;
    pa_usec_t block_usec;
    pa_buffer_attr bufferattr;

    pa_sink_assert_ref(s);
    pa_assert_se(u = s->userdata);

    block_usec = pa_sink_get_requested_latency_within_thread(s);
    if (block_usec == (pa_usec_t) -1)
        block_usec = s->thread_info.max_latency;

    nbytes = pa_usec_to_bytes(block_usec, &s->sample_spec);
    pa_sink_set_max_request_within_thread(s, nbytes);

    if (u->stream) {
        switch (pa_stream_get_state(u->stream)) {
            case PA_STREAM_READY:
                if (pa_stream_get_buffer_attr(u->stream)->tlength == nbytes)
                    break;

                pa_log_debug("Requesting new buffer attrs. tlength requested at %lu.",
                             (unsigned long) nbytes);

                reset_bufferattr(&bufferattr);
                bufferattr.tlength = nbytes;
                if ((operation = pa_stream_set_buffer_attr(u->stream, &bufferattr, stream_set_buffer_attr_cb, u)))
                    pa_operation_unref(operation);
                break;
            case PA_STREAM_CREATING:
                /* we have to delay our request until stream is ready */
                u->update_stream_bufferattr_after_connect = true;
                break;
            default:
                break;
        }
    }
}

static int sink_process_msg_cb(pa_msgobject *o, int code, void *data, int64_t offset, pa_memchunk *chunk) {
    struct userdata *u = PA_SINK(o)->userdata;

    switch (code) {
        case PA_SINK_MESSAGE_GET_LATENCY: {
            int negative;
            pa_usec_t remote_latency;

            if (!PA_SINK_IS_LINKED(u->sink->thread_info.state)) {
                *((int64_t*) data) = 0;
                return 0;
            }

            if (!u->stream) {
                *((int64_t*) data) = 0;
                return 0;
            }

            if (pa_stream_get_state(u->stream) != PA_STREAM_READY) {
                *((int64_t*) data) = 0;
                return 0;
            }

            if (pa_stream_get_latency(u->stream, &remote_latency, &negative) < 0) {
                *((int64_t*) data) = 0;
                return 0;
            }

            *((int64_t*) data) = remote_latency;
            return 0;
        }
        case TUNNEL_MESSAGE_SINK_CREATED:
            on_sink_created(u);
            return 0;
    }
    return pa_sink_process_msg(o, code, data, offset, chunk);
}

/* Called from the IO thread. */
static int sink_set_state_in_io_thread_cb(pa_sink *s, pa_sink_state_t new_state, pa_suspend_cause_t new_suspend_cause) {
    struct userdata *u;

    pa_assert(s);
    pa_assert_se(u = s->userdata);

    /* It may be that only the suspend cause is changing, in which case there's
     * nothing to do. */
    if (new_state == s->thread_info.state)
        return 0;

    if (!u->stream || pa_stream_get_state(u->stream) != PA_STREAM_READY)
        return 0;

    switch (new_state) {
        case PA_SINK_SUSPENDED: {
            cork_stream(u, true);
            break;
        }
        case PA_SINK_IDLE:
        case PA_SINK_RUNNING: {
            cork_stream(u, false);
            break;
        }
        case PA_SINK_INVALID_STATE:
        case PA_SINK_INIT:
        case PA_SINK_UNLINKED:
            break;
    }

    return 0;
}

/* Creates a sink in the main thread.
 *
 * This method is called when we receive a message from the io thread that a
 * connection has been established with the server.  We defer creation of the
 * sink until the connection is established, because we don't have a sink if
 * the remote server isn't there.
 */
static void create_sink(struct userdata *u) {
    pa_sink_new_data sink_data;

    pa_assert_ctl_context();

    /* Create sink */
    pa_sink_new_data_init(&sink_data);
    sink_data.driver = __FILE__;
    sink_data.module = u->module;

    pa_sink_new_data_set_name(&sink_data, u->sink_name);
    pa_sink_new_data_set_sample_spec(&sink_data, &u->sample_spec);
    pa_sink_new_data_set_channel_map(&sink_data, &u->channel_map);

    pa_proplist_update(sink_data.proplist, PA_UPDATE_REPLACE, u->sink_proplist);

    if (!(u->sink = pa_sink_new(u->module->core, &sink_data, PA_SINK_LATENCY | PA_SINK_DYNAMIC_LATENCY | PA_SINK_NETWORK))) {
        pa_log("Failed to create sink.");
        goto finish;
    }

    u->sink->userdata = u;
    u->sink->parent.process_msg = sink_process_msg_cb;
    u->sink->set_state_in_io_thread = sink_set_state_in_io_thread_cb;
    u->sink->update_requested_latency = sink_update_requested_latency_cb;
    pa_sink_set_latency_range(u->sink, 0, MAX_LATENCY_USEC);

    /* set thread message queue */
    pa_sink_set_asyncmsgq(u->sink, u->thread_mq->inq);
    pa_sink_set_rtpoll(u->sink, u->rtpoll);

    pa_sink_put(u->sink);

finish:
    pa_sink_new_data_done(&sink_data);

    /* tell any interested io threads that the sink they asked for has now been
     * created (even if we failed, we still notify the thread, so they can
     * either handle or kill the thread, rather than deadlock waiting for a
     * message that will never come */
    pa_asyncmsgq_send(u->sink->asyncmsgq, PA_MSGOBJECT(u->sink), TUNNEL_MESSAGE_SINK_CREATED, u, 0, NULL);
}

/* Runs in PA mainloop context */
static int tunnel_process_msg(pa_msgobject *o, int code, void *data, int64_t offset, pa_memchunk *chunk) {
    struct userdata *u = (struct userdata *) data;

    pa_assert(u);
    pa_assert_ctl_context();

    if (u->shutting_down)
        return 0;

    switch (code) {
        case TUNNEL_MESSAGE_CREATE_SINK_REQUEST:
            create_sink(u);
            break;
        case TUNNEL_MESSAGE_MAYBE_RESTART:
            maybe_restart(u->module->userdata);
            break;
    }

    return 0;
}

static int do_init(pa_module *m) {
    struct userdata *u = NULL;
    struct module_restart_data *rd;
    pa_modargs *ma = NULL;
    const char *remote_server = NULL;
    char *default_sink_name = NULL;
    uint32_t reconnect_interval_ms = 0;

    pa_assert(m);
    pa_assert(m->userdata);

    rd = m->userdata;

    if (!(ma = pa_modargs_new(m->argument, valid_modargs))) {
        pa_log("Failed to parse module arguments.");
        goto fail;
    }

    u = pa_xnew0(struct userdata, 1);
    u->module = m;
    rd->userdata = u;

    u->sample_spec = m->core->default_sample_spec;
    u->channel_map = m->core->default_channel_map;
    if (pa_modargs_get_sample_spec_and_channel_map(ma, &u->sample_spec, &u->channel_map, PA_CHANNEL_MAP_DEFAULT) < 0) {
        pa_log("Invalid sample format specification or channel map");
        goto fail;
    }

    remote_server = pa_modargs_get_value(ma, "server", NULL);
    if (!remote_server) {
        pa_log("No server given!");
        goto fail;
    }

    u->remote_server = pa_xstrdup(remote_server);
    u->thread_mainloop = pa_mainloop_new();
    if (u->thread_mainloop == NULL) {
        pa_log("Failed to create mainloop");
        goto fail;
    }
    u->thread_mainloop_api = pa_mainloop_get_api(u->thread_mainloop);
    u->cookie_file = pa_xstrdup(pa_modargs_get_value(ma, "cookie", NULL));
    u->remote_sink_name = pa_xstrdup(pa_modargs_get_value(ma, "sink", NULL));

    u->thread_mq = pa_xnew0(pa_thread_mq, 1);

    if (pa_thread_mq_init_thread_mainloop(u->thread_mq, m->core->mainloop, u->thread_mainloop_api) < 0) {
        pa_log("pa_thread_mq_init_thread_mainloop() failed.");
        goto fail;
    }

    u->msg = pa_msgobject_new(tunnel_msg);
    u->msg->parent.process_msg = tunnel_process_msg;

    /* The rtpoll created here is never run. It is only necessary to avoid crashes
     * when module-tunnel-sink-new is used together with module-loopback or
     * module-combine-sink. Both modules base their asyncmsq on the rtpoll provided
     * by the sink. module-loopback and combine-sink only work because they call
     * pa_asyncmsq_process_one() themselves. module_rtp_recv also uses the rtpoll,
     * but never calls pa_asyncmsq_process_one(), so it will not work in combination
     * with module-tunnel-sink-new. */
    u->rtpoll = pa_rtpoll_new();

    default_sink_name = pa_sprintf_malloc("tunnel-sink-new.%s", remote_server);
    u->sink_name = pa_xstrdup(pa_modargs_get_value(ma, "sink_name", default_sink_name));

    u->sink_proplist = pa_proplist_new();
    pa_proplist_sets(u->sink_proplist, PA_PROP_DEVICE_CLASS, "sound");
    pa_proplist_setf(u->sink_proplist,
                     PA_PROP_DEVICE_DESCRIPTION,
                     _("Tunnel to %s/%s"),
                     remote_server,
                     pa_strempty(u->remote_sink_name));

    if (pa_modargs_get_proplist(ma, "sink_properties", u->sink_proplist, PA_UPDATE_REPLACE) < 0) {
        pa_log("Invalid properties");
        goto fail;
    }

    pa_modargs_get_value_u32(ma, "reconnect_interval_ms", &reconnect_interval_ms);
    u->reconnect_interval_us = reconnect_interval_ms * PA_USEC_PER_MSEC;

    if (!(u->thread = pa_thread_new("tunnel-sink", thread_func, u))) {
        pa_log("Failed to create thread.");
        goto fail;
    }

    /* If the module is restarting and do_init() finishes successfully, the
     * restart data is no longer needed. If do_init() fails, don't touch the
     * restart data, because following restart attempts will continue to use
     * the same data. If restart_data is NULL, that means no restart is
     * currently pending. */
    if (rd->restart_data) {
        pa_restart_free(rd->restart_data);
        rd->restart_data = NULL;
    }

    pa_modargs_free(ma);
    pa_xfree(default_sink_name);

    return 0;

fail:
    if (ma)
        pa_modargs_free(ma);

    if (default_sink_name)
        pa_xfree(default_sink_name);

    return -1;
}

static void do_done(pa_module *m) {
    struct userdata *u = NULL;
    struct module_restart_data *rd;

    pa_assert(m);

    if (!(rd = m->userdata))
        return;
    if (!(u = rd->userdata))
        return;

    u->shutting_down = true;

    if (u->sink)
        pa_sink_unlink(u->sink);

    if (u->thread) {
        pa_asyncmsgq_send(u->thread_mq->inq, NULL, PA_MESSAGE_SHUTDOWN, NULL, 0, NULL);
        pa_thread_free(u->thread);
    }

    if (u->thread_mq) {
        pa_thread_mq_done(u->thread_mq);
        pa_xfree(u->thread_mq);
    }

    if (u->thread_mainloop)
        pa_mainloop_free(u->thread_mainloop);

    if (u->cookie_file)
        pa_xfree(u->cookie_file);

    if (u->remote_sink_name)
        pa_xfree(u->remote_sink_name);

    if (u->remote_server)
        pa_xfree(u->remote_server);

    if (u->sink)
        pa_sink_unref(u->sink);

    if (u->rtpoll)
        pa_rtpoll_free(u->rtpoll);

    if (u->sink_proplist)
        pa_proplist_free(u->sink_proplist);

    if (u->sink_name)
        pa_xfree(u->sink_name);

    pa_xfree(u->msg);

    pa_xfree(u);

    rd->userdata = NULL;
}

int pa__init(pa_module *m) {
    int ret;

    pa_assert(m);

    m->userdata = pa_xnew0(struct module_restart_data, 1);

    ret = do_init(m);

    if (ret < 0)
        pa__done(m);

    return ret;
}

void pa__done(pa_module *m) {
    pa_assert(m);

    do_done(m);

    if (m->userdata) {
        struct module_restart_data *rd = m->userdata;

        if (rd->restart_data)
            pa_restart_free(rd->restart_data);

        pa_xfree(m->userdata);
    }
}