/* This module is used to test the server events hooks API.
 *
 * -----------------------------------------------------------------------------
 *
 * Copyright (c) 2019, Salvatore Sanfilippo <antirez at gmail dot com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   * Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *   * 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.
 *   * Neither the name of Redis nor the names of its contributors may be used
 *     to endorse or promote products derived from this software without
 *     specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT OWNER OR CONTRIBUTORS 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 "redismodule.h"
#include <stdio.h>
#include <string.h>

/* We need to store events to be able to test and see what we got, and we can't
 * store them in the key-space since that would mess up rdb loading (duplicates)
 * and be lost of flushdb. */
RedisModuleDict *event_log = NULL;

typedef struct EventElement {
    long count;
    RedisModuleString *last_val_string;
    long last_val_int;
} EventElement;

void LogStringEvent(RedisModuleCtx *ctx, const char* keyname, const char* data) {
    EventElement *event = RedisModule_DictGetC(event_log, (void*)keyname, strlen(keyname), NULL);
    if (!event) {
        event = RedisModule_Alloc(sizeof(EventElement));
        memset(event, 0, sizeof(EventElement));
        RedisModule_DictSetC(event_log, (void*)keyname, strlen(keyname), event);
    }
    if (event->last_val_string) RedisModule_FreeString(ctx, event->last_val_string);
    event->last_val_string = RedisModule_CreateString(ctx, data, strlen(data));
    event->count++;
}

void LogNumericEvent(RedisModuleCtx *ctx, const char* keyname, long data) {
    REDISMODULE_NOT_USED(ctx);
    EventElement *event = RedisModule_DictGetC(event_log, (void*)keyname, strlen(keyname), NULL);
    if (!event) {
        event = RedisModule_Alloc(sizeof(EventElement));
        memset(event, 0, sizeof(EventElement));
        RedisModule_DictSetC(event_log, (void*)keyname, strlen(keyname), event);
    }
    event->last_val_int = data;
    event->count++;
}

void FreeEvent(RedisModuleCtx *ctx, EventElement *event) {
    if (event->last_val_string)
        RedisModule_FreeString(ctx, event->last_val_string);
    RedisModule_Free(event);
}

int cmdEventCount(RedisModuleCtx *ctx, RedisModuleString **argv, int argc)
{
    if (argc != 2){
        RedisModule_WrongArity(ctx);
        return REDISMODULE_OK;
    }

    EventElement *event = RedisModule_DictGet(event_log, argv[1], NULL);
    RedisModule_ReplyWithLongLong(ctx, event? event->count: 0);
    return REDISMODULE_OK;
}

int cmdEventLast(RedisModuleCtx *ctx, RedisModuleString **argv, int argc)
{
    if (argc != 2){
        RedisModule_WrongArity(ctx);
        return REDISMODULE_OK;
    }

    EventElement *event = RedisModule_DictGet(event_log, argv[1], NULL);
    if (event && event->last_val_string)
        RedisModule_ReplyWithString(ctx, event->last_val_string);
    else if (event)
        RedisModule_ReplyWithLongLong(ctx, event->last_val_int);
    else
        RedisModule_ReplyWithNull(ctx);
    return REDISMODULE_OK;
}

void clearEvents(RedisModuleCtx *ctx)
{
    RedisModuleString *key;
    EventElement *event;
    RedisModuleDictIter *iter = RedisModule_DictIteratorStart(event_log, "^", NULL);
    while((key = RedisModule_DictNext(ctx, iter, (void**)&event)) != NULL) {
        event->count = 0;
        event->last_val_int = 0;
        if (event->last_val_string) RedisModule_FreeString(ctx, event->last_val_string);
        event->last_val_string = NULL;
        RedisModule_DictDel(event_log, key, NULL);
        RedisModule_Free(event);
    }
    RedisModule_DictIteratorStop(iter);
}

int cmdEventsClear(RedisModuleCtx *ctx, RedisModuleString **argv, int argc)
{
    REDISMODULE_NOT_USED(argc);
    REDISMODULE_NOT_USED(argv);
    clearEvents(ctx);
    return REDISMODULE_OK;
}

/* Client state change callback. */
void clientChangeCallback(RedisModuleCtx *ctx, RedisModuleEvent e, uint64_t sub, void *data)
{
    REDISMODULE_NOT_USED(e);

    RedisModuleClientInfo *ci = data;
    char *keyname = (sub == REDISMODULE_SUBEVENT_CLIENT_CHANGE_CONNECTED) ?
        "client-connected" : "client-disconnected";
    LogNumericEvent(ctx, keyname, ci->id);
}

void flushdbCallback(RedisModuleCtx *ctx, RedisModuleEvent e, uint64_t sub, void *data)
{
    REDISMODULE_NOT_USED(e);

    RedisModuleFlushInfo *fi = data;
    char *keyname = (sub == REDISMODULE_SUBEVENT_FLUSHDB_START) ?
        "flush-start" : "flush-end";
    LogNumericEvent(ctx, keyname, fi->dbnum);
}

void roleChangeCallback(RedisModuleCtx *ctx, RedisModuleEvent e, uint64_t sub, void *data)
{
    REDISMODULE_NOT_USED(e);
    REDISMODULE_NOT_USED(data);

    RedisModuleReplicationInfo *ri = data;
    char *keyname = (sub == REDISMODULE_EVENT_REPLROLECHANGED_NOW_MASTER) ?
        "role-master" : "role-replica";
    LogStringEvent(ctx, keyname, ri->masterhost);
}

void replicationChangeCallback(RedisModuleCtx *ctx, RedisModuleEvent e, uint64_t sub, void *data)
{
    REDISMODULE_NOT_USED(e);
    REDISMODULE_NOT_USED(data);

    char *keyname = (sub == REDISMODULE_SUBEVENT_REPLICA_CHANGE_ONLINE) ?
        "replica-online" : "replica-offline";
    LogNumericEvent(ctx, keyname, 0);
}

void rasterLinkChangeCallback(RedisModuleCtx *ctx, RedisModuleEvent e, uint64_t sub, void *data)
{
    REDISMODULE_NOT_USED(e);
    REDISMODULE_NOT_USED(data);

    char *keyname = (sub == REDISMODULE_SUBEVENT_MASTER_LINK_UP) ?
        "masterlink-up" : "masterlink-down";
    LogNumericEvent(ctx, keyname, 0);
}

void persistenceCallback(RedisModuleCtx *ctx, RedisModuleEvent e, uint64_t sub, void *data)
{
    REDISMODULE_NOT_USED(e);
    REDISMODULE_NOT_USED(data);

    char *keyname = NULL;
    switch (sub) {
        case REDISMODULE_SUBEVENT_PERSISTENCE_RDB_START: keyname = "persistence-rdb-start"; break;
        case REDISMODULE_SUBEVENT_PERSISTENCE_AOF_START: keyname = "persistence-aof-start"; break;
        case REDISMODULE_SUBEVENT_PERSISTENCE_SYNC_AOF_START: keyname = "persistence-syncaof-start"; break;
        case REDISMODULE_SUBEVENT_PERSISTENCE_SYNC_RDB_START: keyname = "persistence-syncrdb-start"; break;
        case REDISMODULE_SUBEVENT_PERSISTENCE_ENDED: keyname = "persistence-end"; break;
        case REDISMODULE_SUBEVENT_PERSISTENCE_FAILED: keyname = "persistence-failed"; break;
    }
    /* modifying the keyspace from the fork child is not an option, using log instead */
    RedisModule_Log(ctx, "warning", "module-event-%s", keyname);
    if (sub == REDISMODULE_SUBEVENT_PERSISTENCE_SYNC_RDB_START ||
        sub == REDISMODULE_SUBEVENT_PERSISTENCE_SYNC_AOF_START) 
    {
        LogNumericEvent(ctx, keyname, 0);
    }
}

void loadingCallback(RedisModuleCtx *ctx, RedisModuleEvent e, uint64_t sub, void *data)
{
    REDISMODULE_NOT_USED(e);
    REDISMODULE_NOT_USED(data);

    char *keyname = NULL;
    switch (sub) {
        case REDISMODULE_SUBEVENT_LOADING_RDB_START: keyname = "loading-rdb-start"; break;
        case REDISMODULE_SUBEVENT_LOADING_AOF_START: keyname = "loading-aof-start"; break;
        case REDISMODULE_SUBEVENT_LOADING_REPL_START: keyname = "loading-repl-start"; break;
        case REDISMODULE_SUBEVENT_LOADING_ENDED: keyname = "loading-end"; break;
        case REDISMODULE_SUBEVENT_LOADING_FAILED: keyname = "loading-failed"; break;
    }
    LogNumericEvent(ctx, keyname, 0);
}

void loadingProgressCallback(RedisModuleCtx *ctx, RedisModuleEvent e, uint64_t sub, void *data)
{
    REDISMODULE_NOT_USED(e);

    RedisModuleLoadingProgress *ei = data;
    char *keyname = (sub == REDISMODULE_SUBEVENT_LOADING_PROGRESS_RDB) ?
        "loading-progress-rdb" : "loading-progress-aof";
    LogNumericEvent(ctx, keyname, ei->progress);
}

void shutdownCallback(RedisModuleCtx *ctx, RedisModuleEvent e, uint64_t sub, void *data)
{
    REDISMODULE_NOT_USED(e);
    REDISMODULE_NOT_USED(data);
    REDISMODULE_NOT_USED(sub);

    RedisModule_Log(ctx, "warning", "module-event-%s", "shutdown");
}

void cronLoopCallback(RedisModuleCtx *ctx, RedisModuleEvent e, uint64_t sub, void *data)
{
    REDISMODULE_NOT_USED(e);
    REDISMODULE_NOT_USED(sub);

    RedisModuleCronLoop *ei = data;
    LogNumericEvent(ctx, "cron-loop", ei->hz);
}

void moduleChangeCallback(RedisModuleCtx *ctx, RedisModuleEvent e, uint64_t sub, void *data)
{
    REDISMODULE_NOT_USED(e);

    RedisModuleModuleChange *ei = data;
    char *keyname = (sub == REDISMODULE_SUBEVENT_MODULE_LOADED) ?
        "module-loaded" : "module-unloaded";
    LogStringEvent(ctx, keyname, ei->module_name);
}

void swapDbCallback(RedisModuleCtx *ctx, RedisModuleEvent e, uint64_t sub, void *data)
{
    REDISMODULE_NOT_USED(e);
    REDISMODULE_NOT_USED(sub);

    RedisModuleSwapDbInfo *ei = data;
    LogNumericEvent(ctx, "swapdb-first", ei->dbnum_first);
    LogNumericEvent(ctx, "swapdb-second", ei->dbnum_second);
}

/* This function must be present on each Redis module. It is used in order to
 * register the commands into the Redis server. */
int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
#define VerifySubEventSupported(e, s) \
    if (!RedisModule_IsSubEventSupported(e, s)) { \
        return REDISMODULE_ERR; \
    }

    REDISMODULE_NOT_USED(argv);
    REDISMODULE_NOT_USED(argc);

    if (RedisModule_Init(ctx,"testhook",1,REDISMODULE_APIVER_1)
        == REDISMODULE_ERR) return REDISMODULE_ERR;

    /* Example on how to check if a server sub event is supported */
    if (!RedisModule_IsSubEventSupported(RedisModuleEvent_ReplicationRoleChanged, REDISMODULE_EVENT_REPLROLECHANGED_NOW_MASTER)) {
        return REDISMODULE_ERR;
    }

    /* replication related hooks */
    RedisModule_SubscribeToServerEvent(ctx,
        RedisModuleEvent_ReplicationRoleChanged, roleChangeCallback);
    RedisModule_SubscribeToServerEvent(ctx,
        RedisModuleEvent_ReplicaChange, replicationChangeCallback);
    RedisModule_SubscribeToServerEvent(ctx,
        RedisModuleEvent_MasterLinkChange, rasterLinkChangeCallback);

    /* persistence related hooks */
    RedisModule_SubscribeToServerEvent(ctx,
        RedisModuleEvent_Persistence, persistenceCallback);
    RedisModule_SubscribeToServerEvent(ctx,
        RedisModuleEvent_Loading, loadingCallback);
    RedisModule_SubscribeToServerEvent(ctx,
        RedisModuleEvent_LoadingProgress, loadingProgressCallback);

    /* other hooks */
    RedisModule_SubscribeToServerEvent(ctx,
        RedisModuleEvent_ClientChange, clientChangeCallback);
    RedisModule_SubscribeToServerEvent(ctx,
        RedisModuleEvent_FlushDB, flushdbCallback);
    RedisModule_SubscribeToServerEvent(ctx,
        RedisModuleEvent_Shutdown, shutdownCallback);
    RedisModule_SubscribeToServerEvent(ctx,
        RedisModuleEvent_CronLoop, cronLoopCallback);

    RedisModule_SubscribeToServerEvent(ctx,
        RedisModuleEvent_ModuleChange, moduleChangeCallback);
    RedisModule_SubscribeToServerEvent(ctx,
        RedisModuleEvent_SwapDB, swapDbCallback);

    event_log = RedisModule_CreateDict(ctx);

    if (RedisModule_CreateCommand(ctx,"hooks.event_count", cmdEventCount,"",0,0,0) == REDISMODULE_ERR)
        return REDISMODULE_ERR;
    if (RedisModule_CreateCommand(ctx,"hooks.event_last", cmdEventLast,"",0,0,0) == REDISMODULE_ERR)
        return REDISMODULE_ERR;
    if (RedisModule_CreateCommand(ctx,"hooks.clear", cmdEventsClear,"",0,0,0) == REDISMODULE_ERR)
        return REDISMODULE_ERR;

    return REDISMODULE_OK;
}

int RedisModule_OnUnload(RedisModuleCtx *ctx) {
    clearEvents(ctx);
    RedisModule_FreeDict(ctx, event_log);
    event_log = NULL;
    return REDISMODULE_OK;
}

