/*-------------------------------------------------------------------------
 *  
 * disable_set_password is a PostgreSQL module which forbids usage of  
 * CREATE/ALTER USER ... PASSWORD ... statements.
 * 
 * This program is open source, licensed under the PostgreSQL license.
 * For license terms, see the LICENSE file.
 *          
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 * Copyright (c) 2026 Pierre Forstmann.
 *            
 *-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "commands/user.h"
#include "tcop/utility.h"
#include "utils/guc.h"

PG_MODULE_MAGIC;

void		_PG_init(void);
void		_PG_fini(void);

static void raise_log_min_messages() 
{
    /*
    ** Raise log_min_messages to avoid password display on error in log.
    ** We use PGC_SUSET because we are not sure current user has been granted  
    ** SET privilege on log_min_messages setting.
    */
    SetConfigOption("log_min_messages", "FATAL", PGC_SUSET, PGC_S_SESSION);
}

static void check_password_in_statement(bool isCreateRoleStmt, List *options)
{
    ListCell *cell;

    foreach(cell, options)
    {
        DefElem *defel = (DefElem *) lfirst(cell);

        if (strcmp(defel->defname, "password") == 0) 
            {
                raise_log_min_messages();
                if (isCreateRoleStmt)
                    ereport(ERROR,
                        (errmsg("CREATE USER ... PASSWORD is not allowed with non encrypted password.")));
                else
                    ereport(ERROR,
                        (errmsg("ALTER USER ... PASSWORD is not allowed with non encrypted password: try \\password.")));
            }
    }

}

static void
my_ProcessUtility(PlannedStmt *pstmt,
                  const char *queryString,
                  bool readOnlyTree,
                  ProcessUtilityContext context,
                  ParamListInfo params,
                  QueryEnvironment *queryEnv,
                  DestReceiver *dest,
                  QueryCompletion *completionTag);

static ProcessUtility_hook_type prev_ProcessUtility = NULL;

static void
my_ProcessUtility(PlannedStmt *pstmt,
                  const char *queryString,
                  bool readOnlyTree,
                  ProcessUtilityContext context,
                  ParamListInfo params,
                  QueryEnvironment *queryEnv,
                  DestReceiver *dest,
                  QueryCompletion *completionTag)
{
    
    bool        isCreateRoleStmt = false,
                isAlterRoleStmt = false;

    CreateRoleStmt  *createStmt;
    AlterRoleStmt   *alterStmt;
    
    isCreateRoleStmt = pstmt->utilityStmt && IsA(pstmt->utilityStmt, CreateRoleStmt);
    isAlterRoleStmt = pstmt->utilityStmt && IsA(pstmt->utilityStmt, AlterRoleStmt);
    if (isCreateRoleStmt)
        createStmt = (CreateRoleStmt *) pstmt->utilityStmt;
    if (isAlterRoleStmt)
        alterStmt = (AlterRoleStmt *) pstmt->utilityStmt;

    if (isCreateRoleStmt || isAlterRoleStmt)
    {
        if ((isCreateRoleStmt && createStmt->options) || (isAlterRoleStmt && alterStmt->options)) 
        {

            if (isCreateRoleStmt) 
                check_password_in_statement(isCreateRoleStmt, createStmt->options);
            else
                check_password_in_statement(isCreateRoleStmt, alterStmt->options);
        }
    }

    if (prev_ProcessUtility)
        prev_ProcessUtility(pstmt, queryString, readOnlyTree, context, params, queryEnv, dest, completionTag);
    else
        standard_ProcessUtility(pstmt, queryString, readOnlyTree,context, params, queryEnv, dest, completionTag);
}

void
_PG_init(void)
{
    prev_ProcessUtility = ProcessUtility_hook;
    ProcessUtility_hook = my_ProcessUtility;
}

void
_PG_fini(void)
{
    ProcessUtility_hook = prev_ProcessUtility;
}