/** BEGIN COPYRIGHT BLOCK
 * Copyright (C) 2001 Sun Microsystems, Inc. Used by permission.
 * Copyright (C) 2005 Red Hat, Inc.
 * All rights reserved.
 *
 * License: GPL (version 3 or any later version).
 * See LICENSE for details.
 * END COPYRIGHT BLOCK **/

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

/* repl5_protocol.c */
/*

 The replication protocol object manages the replication protocol for
 a given replica. It determines which protocol(s) are appropriate to
 use when updating a given replica. It also knows how to arbitrate
 incremental and total update protocols for a given replica.

*/

#include "repl5.h"
#include "repl5_prot_private.h"

#define PROTOCOL_5_INCREMENTAL 1
#define PROTOCOL_5_TOTAL 2
#define PROTOCOL_4_INCREMENTAL 3
#define PROTOCOL_4_TOTAL 4
#define PROTOCOL_WINDOWS_INCREMENTAL 5
#define PROTOCOL_WINDOWS_TOTAL 6

typedef struct repl_protocol
{
    Private_Repl_Protocol *prp_incremental;     /* inc protocol to use */
    Private_Repl_Protocol *prp_total;           /* total protocol to use */
    Private_Repl_Protocol *prp_active_protocol; /* Pointer to active protocol */
    Repl_Agmt *agmt;                            /* The replication agreement we're servicing */
    Repl_Connection *conn;                      /* Connection to remote server */
    void (*delete_conn)(Repl_Connection *conn); /* mmr conn is different than winsync conn */
    Replica *replica;                           /* Local replica */
    int state;
    int next_state;
    PRThread *agmt_thread;
    PRLock *lock;
} repl_protocol;


/* States */
#define STATE_FINISHED 503
#define STATE_BAD_STATE_SHOULD_NEVER_HAPPEN 599

/* Forward declarations */
static Private_Repl_Protocol *private_protocol_factory(Repl_Protocol *rp, int type);

/*
 * Create a new protocol instance.
 */
Repl_Protocol *
prot_new(Repl_Agmt *agmt, int protocol_state)
{
    Slapi_DN *replarea_sdn = NULL;
    Repl_Protocol *rp = (Repl_Protocol *)slapi_ch_calloc(1, sizeof(Repl_Protocol));

    rp->prp_incremental = rp->prp_total = rp->prp_active_protocol = NULL;
    if (protocol_state == STATE_PERFORMING_TOTAL_UPDATE) {
        rp->state = STATE_PERFORMING_TOTAL_UPDATE;
    } else {
        rp->state = STATE_PERFORMING_INCREMENTAL_UPDATE;
    }
    rp->next_state = STATE_PERFORMING_INCREMENTAL_UPDATE;
    if ((rp->lock = PR_NewLock()) == NULL) {
        goto loser;
    }
    rp->agmt = agmt;
    rp->conn = NULL;
    /* Acquire the local replica object */
    replarea_sdn = agmt_get_replarea(agmt);
    rp->replica = replica_get_replica_from_dn(replarea_sdn);
    if (NULL == rp->replica) {
        /* Whoa, no local replica!?!? */
        slapi_log_err(SLAPI_LOG_ERR, repl_plugin_name,
                      "prot_new - %s: Unable to locate replica object for local replica %s\n",
                      agmt_get_long_name(agmt),
                      slapi_sdn_get_dn(replarea_sdn));
        goto loser;
    }

    if (get_agmt_agreement_type(agmt) == REPLICA_TYPE_MULTISUPPLIER) {
        rp->prp_incremental = private_protocol_factory(rp, PROTOCOL_5_INCREMENTAL);
        rp->prp_total = private_protocol_factory(rp, PROTOCOL_5_TOTAL);
        rp->delete_conn = conn_delete;
    } else if (get_agmt_agreement_type(agmt) == REPLICA_TYPE_WINDOWS) {
        rp->prp_incremental = private_protocol_factory(rp, PROTOCOL_WINDOWS_INCREMENTAL);
        rp->prp_total = private_protocol_factory(rp, PROTOCOL_WINDOWS_TOTAL);
        rp->delete_conn = windows_conn_delete;
    }
    /* XXXggood register callback handlers for entries updated, and
        schedule window enter/leave. */

    goto done;

loser:
    prot_delete(&rp);

done:
    slapi_sdn_free(&replarea_sdn);

    return rp;
}

Replica *
prot_get_replica(Repl_Protocol *rp)
{
    PR_ASSERT(NULL != rp);
    return rp->replica;
}

Repl_Agmt *
prot_get_agreement(Repl_Protocol *rp)
{
    /* MAB: rp might be NULL for disabled suffixes. Don't ASSERT on it */
    if (NULL == rp)
        return NULL;
    return rp->agmt;
}

void
prot_free(Repl_Protocol **rpp)
{
    Repl_Protocol *rp = NULL;

    if (rpp == NULL || *rpp == NULL)
        return;

    rp = *rpp;

    PR_Lock(rp->lock);
    if (NULL != rp->prp_incremental) {
        rp->prp_incremental->delete (&rp->prp_incremental);
    }
    if (NULL != rp->prp_total) {
        rp->prp_total->delete (&rp->prp_total);
    }
    if ((NULL != rp->conn) && (NULL != rp->delete_conn)) {
        rp->delete_conn(rp->conn);
        rp->conn = NULL;
    }
    rp->prp_active_protocol = NULL;
    PR_Unlock(rp->lock);
    PR_DestroyLock(rp->lock);
    slapi_ch_free((void **)rpp);
}

/*
 * Destroy a protocol instance XXXggood not complete
 */
void
prot_delete(Repl_Protocol **rpp)
{
    Repl_Protocol *rp;

    PR_ASSERT(NULL != rpp);
    rp = *rpp;
    /* MAB: rp might be NULL for disabled suffixes. Don't ASSERT on it */
    if (NULL != rp) {
        prot_stop(rp);
        prot_free(rpp);
    }
}

/*
 * Get the connection object.
 */
Repl_Connection *
prot_get_connection(Repl_Protocol *rp)
{
    Repl_Connection *return_value;

    PR_ASSERT(NULL != rp);
    PR_Lock(rp->lock);
    return_value = rp->conn;
    PR_Unlock(rp->lock);
    return return_value;
}

/*
 * This function causes the total protocol to start.
 * This is accomplished by registering a state transition
 * to a new state, and then signaling the incremental
 * protocol to stop.
 */
void
prot_initialize_replica(Repl_Protocol *rp)
{
    PR_ASSERT(NULL != rp);

    PR_Lock(rp->lock);
    /* check that total protocol is not running */
    rp->next_state = STATE_PERFORMING_TOTAL_UPDATE;
    /* Stop the incremental protocol, if running */
    rp->prp_incremental->stop(rp->prp_incremental);
    if (rp->prp_total)
        agmt_set_last_init_status(rp->prp_total->agmt, 0, 0, 0, NULL);
    PR_Unlock(rp->lock);
}

/*
 * Main thread for protocol manager.

This is a simple state machine. State transition table:

Initial state: incremental update

STATE                   EVENT                   NEXT STATE
-----                   -----                   ----------
incremental update      shutdown                finished
incremental update      total update requested  total update
total update            shutdown                finished
total update            update complete         incremental update
finished                (any)                   finished

*/
static void
prot_thread_main(void *arg)
{
    Repl_Protocol *rp = (Repl_Protocol *)arg;
    int done;
    Repl_Agmt *agmt = NULL;

    PR_ASSERT(NULL != rp);

    agmt = rp->agmt;
    if (!agmt) {
        slapi_log_err(SLAPI_LOG_ERR, repl_plugin_name, "prot_thread_main - Missing replication agreement\n");
        return;
    }

    set_thread_private_agmtname(agmt_get_long_name(agmt));

    done = 0;

    while (!done) {
        switch (rp->state) {
        case STATE_PERFORMING_INCREMENTAL_UPDATE:
            /* Run the incremental update protocol */
            PR_Lock(rp->lock);
            dev_debug("prot_thread_main(STATE_PERFORMING_INCREMENTAL_UPDATE): begin");
            rp->prp_active_protocol = rp->prp_incremental;
            PR_Unlock(rp->lock);
            rp->prp_incremental->run(rp->prp_incremental);
            dev_debug("prot_thread_main(STATE_PERFORMING_INCREMENTAL_UPDATE): end");
            break;
        case STATE_PERFORMING_TOTAL_UPDATE: {
            Slapi_DN *dn = agmt_get_replarea(agmt);
            Replica *replica = replica_get_replica_from_dn(dn);
            slapi_sdn_free(&dn);
            if (replica) {
                /* If total update against this replica is in progress,
             * we should not initiate the total update to other replicas. */
                if (replica_is_state_flag_set(replica, REPLICA_TOTAL_EXCL_RECV)) {
                    slapi_log_err(SLAPI_LOG_ERR, repl_plugin_name,
                                  "prot_thread_main - %s: total update on the replica is in progress.  "
                                  "Cannot initiate the total update.\n",
                                  agmt_get_long_name(rp->agmt));
                    break;
                } else {
                    replica_set_state_flag(replica, REPLICA_TOTAL_EXCL_SEND, 0);
                }
            }

            PR_Lock(rp->lock);

            /* stop incremental protocol if running */
            rp->prp_active_protocol = rp->prp_total;
            /* After total protocol finished, return to incremental */
            rp->next_state = STATE_PERFORMING_INCREMENTAL_UPDATE;
            PR_Unlock(rp->lock);
            /* Run the total update protocol */
            dev_debug("prot_thread_main(STATE_PERFORMING_TOTAL_UPDATE): begin");
            rp->prp_total->run(rp->prp_total);
            dev_debug("prot_thread_main(STATE_PERFORMING_TOTAL_UPDATE): end");
            /* update the agreement entry to notify clients that
           replica initialization is completed. */
            agmt_replica_init_done(agmt);

            if (replica) {
                replica_set_state_flag(replica, REPLICA_TOTAL_EXCL_SEND, 1);
            }
            break;
        }
        case STATE_FINISHED:
            dev_debug("prot_thread_main(STATE_FINISHED): exiting prot_thread_main");
            done = 1;
            break;
        }
        if (agmt_has_protocol(agmt)) {
            rp->state = rp->next_state;
        } else {
            done = 1;
        }
    }
}

/*
 * Start a thread to handle the replication protocol.
 */
void
prot_start(Repl_Protocol *rp)
{
    PR_ASSERT(NULL != rp);
    if (NULL != rp) {
        rp->agmt_thread = PR_CreateThread(PR_USER_THREAD, prot_thread_main, (void *)rp,
#if defined(__hpux) && defined(__ia64)
                                          PR_PRIORITY_NORMAL, PR_GLOBAL_THREAD, PR_JOINABLE_THREAD, 524288L);
#else
                                          PR_PRIORITY_NORMAL, PR_GLOBAL_THREAD, PR_JOINABLE_THREAD, SLAPD_DEFAULT_THREAD_STACKSIZE);
#endif
        if (rp->agmt_thread == NULL) {
            PRErrorCode prerr = PR_GetError();

            slapi_log_err(SLAPI_LOG_ERR, repl_plugin_name,
                          "prot_start - %s: Unable to create protocol thread; NSPR error - %d, %s\n",
                          agmt_get_long_name(rp->agmt),
                          prerr, slapd_pr_strerror(prerr));
        }
    } else {
        slapi_log_err(SLAPI_LOG_ERR, repl_plugin_name, "prot_start - Unable to start "
                                                       "protocol object - NULL protocol object passed to prot_start.\n");
    }
}

/*
 * Stop a protocol instance.
 */
void
prot_stop(Repl_Protocol *rp)
{
    PR_ASSERT(NULL != rp);
    if (NULL != rp) {
        PR_Lock(rp->lock);
        rp->next_state = STATE_FINISHED;
        if (NULL != rp->prp_incremental) {
            if (rp->prp_incremental->stop(rp->prp_incremental) != 0) {
                slapi_log_err(SLAPI_LOG_WARNING, repl_plugin_name,
                              "prot_stop - Incremental protocol for replica \"%s\" "
                              "did not shut down properly.\n",
                              agmt_get_long_name(rp->agmt));
            }
        }
        if (NULL != rp->prp_total) {
            if (rp->prp_total->stop(rp->prp_total) != 0) {
                slapi_log_err(SLAPI_LOG_WARNING, repl_plugin_name,
                              "prot_stop - Total protocol for replica \"%s\" "
                              "did not shut down properly.\n",
                              agmt_get_long_name(rp->agmt));
            }
        }
        PR_Unlock(rp->lock);

        if (rp->agmt_thread != NULL) {
            (void)PR_JoinThread(rp->agmt_thread);
            rp->agmt_thread = NULL;
        }
    } else {
        slapi_log_err(SLAPI_LOG_ERR, repl_plugin_name, "prot_stop - "
                                                       "NULL protocol instance.\n");
    }
}

/*
 * Call the notify_update method of the incremental or total update
 * protocol, is either is active.
 */
void
prot_notify_update(Repl_Protocol *rp)
{
    /* MAB: rp might be NULL for disabled suffixes. Don't ASSERT on it */
    if (NULL == rp)
        return;

    PR_Lock(rp->lock);
    if (NULL != rp->prp_active_protocol) {
        rp->prp_active_protocol->notify_update(rp->prp_active_protocol);
    }
    PR_Unlock(rp->lock);
}

/*
 * Call the notify_agmt_changed method of the incremental or total update
 * protocol, is either is active.
 */
void
prot_notify_agmt_changed(Repl_Protocol *rp, char *agmt_name)
{
    /* MAB: rp might be NULL for disabled suffixes. Don't ASSERT on it */
    if (NULL == rp) {
        slapi_log_err(SLAPI_LOG_ERR, repl_plugin_name,
                      "prot_notify_agmt_changed - Replication agreement for %s could not be updated. "
                      "For replication to take place, please enable the suffix "
                      "and restart the server\n",
                      agmt_name);
        return;
    }

    PR_Lock(rp->lock);
    if (NULL != rp->prp_active_protocol) {
        rp->prp_active_protocol->notify_agmt_changed(rp->prp_active_protocol);
    }
    PR_Unlock(rp->lock);
}

void
prot_notify_window_opened(Repl_Protocol *rp)
{
    /* MAB: rp might be NULL for disabled suffixes. Don't ASSERT on it */
    if (NULL == rp)
        return;

    PR_Lock(rp->lock);
    if (NULL != rp->prp_active_protocol) {
        rp->prp_active_protocol->notify_window_opened(rp->prp_active_protocol);
    }
    PR_Unlock(rp->lock);
}

void
prot_notify_window_closed(Repl_Protocol *rp)
{
    /* MAB: rp might be NULL for disabled suffixes. Don't ASSERT on it */
    if (NULL == rp)
        return;

    PR_Lock(rp->lock);
    if (NULL != rp->prp_active_protocol) {
        rp->prp_active_protocol->notify_window_closed(rp->prp_active_protocol);
    }
    PR_Unlock(rp->lock);
}

int
prot_status(Repl_Protocol *rp)
{
    int return_status = PROTOCOL_STATUS_UNKNOWN;

    /* MAB: rp might be NULL for disabled suffixes. Don't ASSERT on it */
    if (NULL != rp) {
        PR_Lock(rp->lock);
        if (NULL != rp->prp_active_protocol) {
            return_status = rp->prp_active_protocol->status(rp->prp_active_protocol);
        }
        PR_Unlock(rp->lock);
    }
    return return_status;
}

/*
 * Start an incremental protocol session, even if we're not
 * currently in a schedule window.
 * If the total protocol is active, do nothing.
 * Otherwise, notify the incremental protocol that it should
 * run once.
 */
void
prot_replicate_now(Repl_Protocol *rp)
{
    /* MAB: rp might be NULL for disabled suffixes. Don't ASSERT on it */
    if (NULL != rp) {
        PR_Lock(rp->lock);
        if (rp->prp_incremental == rp->prp_active_protocol) {
            rp->prp_active_protocol->update_now(rp->prp_active_protocol);
        }
        PR_Unlock(rp->lock);
    }
}

/*
 * A little factory function to create a protocol
 * instance of the correct type.
 */
static Private_Repl_Protocol *
private_protocol_factory(Repl_Protocol *rp, int type)
{
    Private_Repl_Protocol *prp = NULL;

    switch (type) {
    case PROTOCOL_5_INCREMENTAL:
        if (NULL == rp->conn) {
            rp->conn = conn_new(rp->agmt);
        }
        if (NULL != rp->conn) {
            prp = Repl_5_Inc_Protocol_new(rp);
        }
        break;
    case PROTOCOL_5_TOTAL:
        if (NULL == rp->conn) {
            rp->conn = conn_new(rp->agmt);
        }
        if (NULL != rp->conn) {
            prp = Repl_5_Tot_Protocol_new(rp);
        }
        break;
    case PROTOCOL_WINDOWS_INCREMENTAL:
        if (NULL == rp->conn) {
            rp->conn = windows_conn_new(rp->agmt);
        }
        if (NULL != rp->conn) {
            prp = Windows_Inc_Protocol_new(rp);
        }
        break;
    case PROTOCOL_WINDOWS_TOTAL:
        if (NULL == rp->conn) {
            rp->conn = windows_conn_new(rp->agmt);
        }
        if (NULL != rp->conn) {
            prp = Windows_Tot_Protocol_new(rp);
        }
        break;
    }
    return prp;
}