/* ACL API example - An example of performing custom password authentication
 *
 * -----------------------------------------------------------------------------
 *
 * Copyright 2019 Amazon.com, Inc. or its affiliates.
 * 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.
 */

#define REDISMODULE_EXPERIMENTAL_API
#include "redismodule.h"

// A simple global user
static RedisModuleUser *global;
static long long client_change_delta = 0;

void UserChangedCallback(uint64_t client_id, void *privdata) {
    REDISMODULE_NOT_USED(privdata);
    REDISMODULE_NOT_USED(client_id);
    client_change_delta++;
}

int Auth_CreateModuleUser(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {

    if (global) {
        RedisModule_FreeModuleUser(global);
    }

    global = RedisModule_CreateModuleUser("global");
    RedisModule_SetModuleUserACL(global, "allcommands");
    RedisModule_SetModuleUserACL(global, "allkeys");
    RedisModule_SetModuleUserACL(global, "on");

    return RedisModule_ReplyWithSimpleString(ctx, "OK");
}

int Auth_AuthModuleUser(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
    uint64_t client_id;
    RedisModule_AuthenticateClientWithUser(ctx, global, UserChangedCallback, NULL, &client_id);

    return RedisModule_ReplyWithLongLong(ctx, (uint64_t) client_id);
}

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

    size_t length;
    uint64_t client_id;

    RedisModuleString *user_string = argv[1];
    const char *name = RedisModule_StringPtrLen(user_string, &length);

    if (RedisModule_AuthenticateClientWithACLUser(ctx, name, length, 
            UserChangedCallback, NULL, &client_id) == REDISMODULE_ERR) {
        return RedisModule_ReplyWithError(ctx, "Invalid user");   
    }

    return RedisModule_ReplyWithLongLong(ctx, (uint64_t) client_id);
}

int Auth_ChangeCount(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
    long long result = client_change_delta;
    client_change_delta = 0;
    return RedisModule_ReplyWithLongLong(ctx, result);
}

/* 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) {
    REDISMODULE_NOT_USED(argv);
    REDISMODULE_NOT_USED(argc);

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

    if (RedisModule_CreateCommand(ctx,"auth.authrealuser",
        Auth_AuthRealUser,"no-auth",0,0,0) == REDISMODULE_ERR)
        return REDISMODULE_ERR;

    if (RedisModule_CreateCommand(ctx,"auth.createmoduleuser",
        Auth_CreateModuleUser,"",0,0,0) == REDISMODULE_ERR)
        return REDISMODULE_ERR;

    if (RedisModule_CreateCommand(ctx,"auth.authmoduleuser",
        Auth_AuthModuleUser,"no-auth",0,0,0) == REDISMODULE_ERR)
        return REDISMODULE_ERR;

    if (RedisModule_CreateCommand(ctx,"auth.changecount",
        Auth_ChangeCount,"",0,0,0) == REDISMODULE_ERR)
        return REDISMODULE_ERR;

    client_change_delta = 0;

    return REDISMODULE_OK;
}