/*
 * charybdis: An advanced ircd.
 * m_list_safelist.c: Version of /list that uses the safelist code.
 *
 * Copyright (c) 2006 William Pitcock <nenolod@nenolod.net>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include "stdinc.h"
#include "channel.h"
#include "client.h"
#include "hash.h"
#include "match.h"
#include "ircd.h"
#include "numeric.h"
#include "s_conf.h"
#include "s_newconf.h"
#include "s_serv.h"
#include "supported.h"
#include "send.h"
#include "msg.h"
#include "parse.h"
#include "modules.h"

static rb_dlink_list safelisting_clients = { NULL, NULL, 0 };

static int _modinit(void);
static void _moddeinit(void);

static int m_list(struct Client *, struct Client *, int, const char **);
static int mo_list(struct Client *, struct Client *, int, const char **);

static void safelist_check_cliexit(hook_data_client_exit * hdata);
static void safelist_client_instantiate(struct Client *, struct ListClient *);
static void safelist_client_release(struct Client *);
static void safelist_one_channel(struct Client *source_p, struct Channel *chptr);
static void safelist_iterate_client(struct Client *source_p);
static void safelist_iterate_clients(void *unused);
static void safelist_channel_named(struct Client *source_p, const char *name);

struct Message list_msgtab = {
    "LIST", 0, 0, 0, MFLG_SLOW,
    {mg_unreg, {m_list, 0}, mg_ignore, mg_ignore, mg_ignore, {mo_list, 0}}
};

mapi_clist_av1 list_clist[] = { &list_msgtab, NULL };

mapi_hfn_list_av1 list_hfnlist[] = {
    {"client_exit", (hookfn) safelist_check_cliexit},
    {NULL, NULL}
};

DECLARE_MODULE_AV1(list, _modinit, _moddeinit, list_clist, NULL, list_hfnlist, "$Revision: 3372 $");

static struct ev_entry *iterate_clients_ev = NULL;

static int _modinit(void)
{
    iterate_clients_ev = rb_event_add("safelist_iterate_clients", safelist_iterate_clients, NULL, 3);

    /* ELIST=[tokens]:
     *
     * M = mask search
     * N = !mask search
     * U = user count search (< >)
     * C = creation time search (C> C<)
     * T = topic search (T> T<)
     */
    add_isupport("SAFELIST", isupport_string, "");
    add_isupport("ELIST", isupport_string, "CTU");

    return 0;
}

static void _moddeinit(void)
{
    rb_event_delete(iterate_clients_ev);

    delete_isupport("SAFELIST");
    delete_isupport("ELIST");
}

static void safelist_check_cliexit(hook_data_client_exit * hdata)
{
    /* Cancel the safelist request if we are disconnecting
     * from the server. That way it doesn't core. :P --nenolod
     */
    if (MyClient(hdata->target) && hdata->target->localClient->safelist_data != NULL) {
        safelist_client_release(hdata->target);
    }
}

/* m_list()
 *      parv[1] = channel
 *
 * XXX - With SAFELIST, do we really need to continue pacing?
 *       In theory, the server cannot be lagged by this. --nenolod
 */
static int m_list(struct Client *client_p, struct Client *source_p, int parc, const char *parv[])
{
    static time_t last_used = 0L;

    if (source_p->localClient->safelist_data != NULL) {
        sendto_one_notice(source_p, ":/LIST aborted");
        safelist_client_release(source_p);
        return 0;
    }

    if (parc < 2 || !IsChannelName(parv[1])) {
        /* pace this due to the sheer traffic involved */
        if (((last_used + ConfigFileEntry.pace_wait) > rb_current_time())) {
            sendto_one(source_p, form_str(RPL_LOAD2HI), me.name, source_p->name, "LIST");
            sendto_one(source_p, form_str(RPL_LISTEND), me.name, source_p->name);
            return 0;
        } else
            last_used = rb_current_time();
    }

    return mo_list(client_p, source_p, parc, parv);
}

/* mo_list()
 *      parv[1] = channel
 */
static int mo_list(struct Client *client_p, struct Client *source_p, int parc, const char *parv[])
{
    struct ListClient *params;
    char *p, *args;
    int i;

    if (source_p->localClient->safelist_data != NULL) {
        sendto_one_notice(source_p, ":/LIST aborted");
        safelist_client_release(source_p);
        return 0;
    }

    /* Single channel. */
    if (parc > 1 && IsChannelName(parv[1])) {
        safelist_channel_named(source_p, parv[1]);
        return 0;
    }

    /* Multiple channels, possibly with parameters. */
    params = rb_malloc(sizeof(struct ListClient));

    /* Let the user set it */
    params->users_min = ConfigFileEntry.hide_channel_below_users;
    params->users_max = INT_MAX;
    params->operspy = 0;
    params->created_min = params->topic_min =
                              params->created_max = params->topic_max = 0;

    if (parc > 1 && !EmptyString(parv[1])) {
        args = LOCAL_COPY(parv[1]);

        /* Cancel out default minimum. */
        params->users_min = 0;

        for (i = 0; i < 7; i++) {
            if ((p = strchr(args, ',')) != NULL)
                *p++ = '\0';

            if (*args == '<') {
                args++;
                if (IsDigit(*args)) {
                    params->users_max = atoi(args);
                    if (params->users_max == 0)
                        params->users_max = INT_MAX;
                    else
                        params->users_max--;
                }
            } else if (*args == '>') {
                args++;
                if (IsDigit(*args))
                    params->users_min = atoi(args) + 1;
                else
                    params->users_min = 0;
            } else if (*args == 'C' || *args == 'c') {
                args++;
                if (*args == '>') {
                    /* Creation time earlier than last x minutes. */
                    args++;
                    if (IsDigit(*args)) {
                        params->created_max = rb_current_time() - (60 * atoi(args));
                    }
                } else if (*args == '<') {
                    /* Creation time within last x minutes. */
                    args++;
                    if (IsDigit(*args)) {
                        params->created_min = rb_current_time() - (60 * atoi(args));
                    }
                }
            } else if (*args == 'T' || *args == 't') {
                args++;
                if (*args == '>') {
                    /* Topic change time earlier than last x minutes. */
                    args++;
                    if (IsDigit(*args)) {
                        params->topic_max = rb_current_time() - (60 * atoi(args));
                    }
                } else if (*args == '<') {
                    /* Topic change time within last x minutes. */
                    args++;
                    if (IsDigit(*args)) {
                        params->topic_min = rb_current_time() - (60 * atoi(args));
                    }
                }
            }
            /* Only accept operspy as the first option. */
            else if (*args == '!' && IsOperSpy(source_p) && i == 0) {
                params->operspy = 1;
                report_operspy(source_p, "LIST", p);
            }

            if (EmptyString(p))
                break;
            else
                args = p;
        }
    }

    safelist_client_instantiate(source_p, params);

    return 0;
}

/*
 * safelist_sendq_exceeded()
 *
 * inputs       - pointer to client that needs checking
 * outputs      - 1 if a client has exceeded the reserved
 *                sendq limit, 0 if not
 * side effects - none
 *
 * When safelisting, we only use half of the SendQ at any
 * given time.
 */
static int safelist_sendq_exceeded(struct Client *client_p)
{
    if (rb_linebuf_len(&client_p->localClient->buf_sendq) > (get_sendq(client_p) / 2))
        return YES;
    else
        return NO;
}

/*
 * safelist_client_instantiate()
 *
 * inputs       - pointer to Client to be listed,
 *                pointer to ListClient for params
 * outputs      - none
 * side effects - the safelist process begins for a
 *                client.
 *
 * Please do not ever call this on a non-local client.
 * If you do, you will get SIGSEGV.
 */
static void safelist_client_instantiate(struct Client *client_p, struct ListClient *params)
{
    s_assert(MyClient(client_p));
    s_assert(params != NULL);

    client_p->localClient->safelist_data = params;

    sendto_one(client_p, form_str(RPL_LISTSTART), me.name, client_p->name);

    /* pop the client onto the queue for processing */
    rb_dlinkAddAlloc(client_p, &safelisting_clients);

    /* give the user some initial data to work with */
    safelist_iterate_client(client_p);
}

/*
 * safelist_client_release()
 *
 * inputs       - pointer to Client being listed on
 * outputs      - none
 * side effects - the client is no longer being
 *                listed
 *
 * Please do not ever call this on a non-local client.
 * If you do, you will get SIGSEGV.
 */
static void safelist_client_release(struct Client *client_p)
{
    s_assert(MyClient(client_p));

    rb_dlinkFindDestroy(client_p, &safelisting_clients);

    rb_free(client_p->localClient->safelist_data);

    client_p->localClient->safelist_data = NULL;

    sendto_one(client_p, form_str(RPL_LISTEND), me.name, client_p->name);
}

/*
 * safelist_channel_named()
 *
 * inputs       - client pointer, channel name
 * outputs      - none
 * side effects - a named channel is listed
 */
static void safelist_channel_named(struct Client *source_p, const char *name)
{
    struct Channel *chptr;
    char *p;
    char *n = LOCAL_COPY(name);

    sendto_one(source_p, form_str(RPL_LISTSTART), me.name, source_p->name);

    if ((p = strchr(n, ',')))
        *p = '\0';

    if (*n == '\0') {
        sendto_one_numeric(source_p, ERR_NOSUCHNICK, form_str(ERR_NOSUCHNICK), name);
        sendto_one(source_p, form_str(RPL_LISTEND), me.name, source_p->name);
        return;
    }

    chptr = find_channel(n);

    if (chptr == NULL) {
        sendto_one_numeric(source_p, ERR_NOSUCHNICK, form_str(ERR_NOSUCHNICK), n);
        sendto_one(source_p, form_str(RPL_LISTEND), me.name, source_p->name);
        return;
    }

    if (!SecretChannel(chptr) || IsMember(source_p, chptr))
        sendto_one(source_p, form_str(RPL_LIST), me.name, source_p->name, "",
                   chptr->chname, rb_dlink_list_length(&chptr->members),
                   chptr->topic == NULL ? "" : chptr->topic);

    sendto_one(source_p, form_str(RPL_LISTEND), me.name, source_p->name);
    return;
}

/*
 * safelist_one_channel()
 *
 * inputs       - client pointer and channel pointer
 * outputs      - none
 * side effects - a channel is listed if it meets the
 *                requirements
 */
static void safelist_one_channel(struct Client *source_p, struct Channel *chptr)
{
    struct ListClient *safelist_data = source_p->localClient->safelist_data;

    if (SecretChannel(chptr) && !IsMember(source_p, chptr) && !safelist_data->operspy)
        return;

    if ((unsigned int)chptr->members.length < safelist_data->users_min
        || (unsigned int)chptr->members.length > safelist_data->users_max)
        return;

    if (safelist_data->topic_min && chptr->topic_time < safelist_data->topic_min)
        return;

    /* If a topic TS is provided, don't show channels without a topic set. */
    if (safelist_data->topic_max && (chptr->topic_time > safelist_data->topic_max
                                     || chptr->topic_time == 0))
        return;

    if (safelist_data->created_min && chptr->channelts < safelist_data->created_min)
        return;

    if (safelist_data->created_max && chptr->channelts > safelist_data->created_max)
        return;

    sendto_one(source_p, form_str(RPL_LIST), me.name, source_p->name,
               (safelist_data->operspy && SecretChannel(chptr)) ? "!" : "",
               chptr->chname, rb_dlink_list_length(&chptr->members),
               chptr->topic == NULL ? "" : chptr->topic);
}

/*
 * safelist_iterate_client()
 *
 * inputs       - client pointer
 * outputs      - none
 * side effects - the client's sendq is filled up again
 */
static void safelist_iterate_client(struct Client *source_p)
{
    rb_dlink_node *ptr;
    int iter;

    for (iter = source_p->localClient->safelist_data->hash_indice; iter < CH_MAX; iter++) {
        if (safelist_sendq_exceeded(source_p->from) == YES) {
            source_p->localClient->safelist_data->hash_indice = iter;
            return;
        }

        RB_DLINK_FOREACH(ptr, channelTable[iter].head)
        safelist_one_channel(source_p, (struct Channel *) ptr->data);
    }

    safelist_client_release(source_p);
}

static void safelist_iterate_clients(void *unused)
{
    rb_dlink_node *n, *n2;

    RB_DLINK_FOREACH_SAFE(n, n2, safelisting_clients.head)
    safelist_iterate_client((struct Client *)n->data);
}
