/*
 * Copyright (c) 2022 Stefan Strobel <stefan.strobel@shimatta.net>
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/.
 */

/**
 * @file    shellmatta_auth.c
 * @brief   simple authentication method
 * @author  Stefan Strobel <stefan.strobel@shimatta.net>
 */

/**
 * @addtogroup shellmatta_auth
 * @{
 */

#include "shellmatta.h"
#include "shellmatta_auth.h"
#include "shellmatta_history.h"
#include "shellmatta_utils.h"
#include "shellmatta_escape.h"
#include <stdint.h>
#include <stddef.h>
#include <string.h>

/**
 * @brief       wraps the input to the login command and mimics the editability of the standard shell input
 * @param[in, out]  inst    shellmatta instance to work with
 * @param[in]       data    one byte of data the user put in
 * @param[in]       hide    true: do not print anything tho the output (e.g. password input)
 * @return      #SHELLMATTA_BUSY    => reading in data
 *              #SHELLMATTA_OK      => delimiter (e.g. enter) detected
 */
shellmatta_retCode_t inputWrapper(shellmatta_instance_t *inst, char data, bool hide)
{
    shellmatta_retCode_t ret = SHELLMATTA_BUSY;

    /** -# handle escape sequences */
    if(inst->escapeCounter != 0u)
    {
        escape_handleSequence(inst, data);
    }
    else if (inst->delimiter == data)
    {
        ret = SHELLMATTA_OK;
    }
        /** -# ignore newline as first character (to be compatible to
     * terminals sending newline after return */
    else if((0u == inst->inputCount) && ('\n' == data))
    {
        /* do nothing */
    }
    /** -# check for backspace */
    else if(    ('\b'   == data)
            ||  ('\x7f' == data))
    {
        utils_removeChars(inst, 1u, true);
    }
    /** -# check for start of escape sequence */
    else if('\x1b' == data)
    {
        inst->escapeCounter = 1u;
    }
    else
    {
        utils_insertChars(inst, &data, 1u, hide);
    }
    return ret;
}

/**
 * @brief       searches the user list for a passed username and returns the userId
 * @param[in]   inst        shellmatta instance to work with
 * @param[in]   username    username to search for - pointer to string
 * @return      userId or 0 if user was not found
 */
static uint32_t getUserIdFromName(shellmatta_instance_t *inst, char *username)
{
    uint32_t    userId  = 0u;
    uint32_t    i;

    for (i = 0u; i < inst->userListLength; i++)
    {
        /** -# search for user */
        if (0 == strcmp(inst->userList[i].username, username))
        {
            userId = inst->userList[i].userId;
            break;
        }
    }

    return userId;
}

/**
 * @brief       checks the passed password and logs the user into the instance on success
 * @param[in, out]  handle      shellmatta handle to work with
 * @param[in]       userId      userId to check the password for
 * @param[in]       password    password to check for - pointer to string
 */
void checkPassword(shellmatta_handle_t handle, uint32_t userId, char *password)
{
    shellmatta_instance_t   *inst   = (shellmatta_instance_t*)handle;
    uint32_t                approvedUserId  = 0u;
    uint32_t                i;

    if (NULL != inst->checkFct)
    {
        approvedUserId = inst->checkFct(userId, password);
    }
    else
    {
        for (i = 0u; i < inst->userListLength; i++)
        {
            /** -# search for user */
            if (inst->userList[i].userId == userId)
            {
                /** -# check password */
                if (0 == strcmp(inst->userList[i].password, password))
                {
                    approvedUserId = inst->userList[i].userId;
                }
                break;
            }
        }
    }

    /** -# call log function - only for unsuccessful logins - successful logins are handled by #shellmatta_auth_login */
    if ((inst->logFct) && (0u == approvedUserId))
    {
        inst->logFct(userId, false);
    }

    /** -# print login result */
    if (0 == approvedUserId)
    {
        shellmatta_write(handle, "username or password is wrong\r\n", 31);
    }
    else
    {
        shellmatta_write(handle, "login successful\r\n", 18);
    }

    (void)shellmatta_auth_login(handle, approvedUserId);
}

/**
 * @brief       handles the login based on username and password
 * @param[in]   handle      handle  shellmatta instance handle
 * @param[in]   arguments   arguments containing a command name or alias
 * @param[in]   length      length of the arguments
 * @return      #SHELLMATTA_OK
 *              #SHELLMATTA_CONTINUE (waiting for input)
  */
static shellmatta_retCode_t loginCmdFct(const shellmatta_handle_t handle, const char *arguments, uint32_t length)
{
    shellmatta_instance_t   *inst   = (shellmatta_instance_t*)handle;
    shellmatta_retCode_t    ret     = SHELLMATTA_OK;
    char option;
    char *argument;
    uint32_t argLen;
    char *username = NULL;
    char *password = NULL;

    static const shellmatta_opt_long_t options[] =
    {
        {"username" , 'u',  SHELLMATTA_OPT_ARG_REQUIRED},
        {"password" , 'p',  SHELLMATTA_OPT_ARG_REQUIRED},
        {NULL       , '\0', SHELLMATTA_OPT_ARG_NONE}
    };

    /** -# handle the login state machine */
    switch(inst->loginState)
    {
        /** -# init the login procedure - use directly passed credentials if any */
        case SHELLMATTA_AUTH_IDLE:
            ret = shellmatta_opt_long(handle, options, &option, &argument, &argLen);
            while(SHELLMATTA_OK == ret)
            {
                switch(option)
                {
                    case 'u':
                        if(NULL != argument)
                        {
                            username = argument;
                        }
                        break;
                    case 'p':
                        if(NULL != argument)
                        {
                            password = argument;
                        }
                        break;
                    default:
                        shellmatta_printf(handle, "Unknown option: %c\r\n", option);
                        break;
                }
                ret = shellmatta_opt_long(handle, options, &option, &argument, &argLen);
            }

            if ((NULL != username) && (NULL != password))
            {
                inst->tmpUserId = getUserIdFromName(inst, username);
                checkPassword(handle, inst->tmpUserId, password);
            }
            else
            {
                /** -# no credentials are passed with the command - start the input */
                inst->inputCount = 0u;
                inst->cursor = 0u;
                /** -# store pointer to username in buffer */
                shellmatta_write(handle, "enter username:\r\n", 17);
                inst->loginState = SHELLMATTA_AUTH_USERNAME;
                return SHELLMATTA_CONTINUE;
            }
            break;

        case SHELLMATTA_AUTH_USERNAME:
            /** -# read in password characters to the instance buffer */
            (void)shellmatta_read(handle, &argument, &argLen);
            if ((1 == argLen) && (SHELLMATTA_OK == inputWrapper(inst, argument[0], false)))
            {
                /** -# store user id */
                inst->buffer[inst->inputCount] = '\0';
                inst->tmpUserId = getUserIdFromName(handle, inst->buffer);

                /** -# reinitialize input */
                inst->inputCount = 0u;
                inst->cursor = 0u;

                shellmatta_write(handle, "\r\nenter password:\r\n", 19);
                inst->loginState = SHELLMATTA_AUTH_PASSWORD;
            }
            ret = SHELLMATTA_CONTINUE;
            break;

        case SHELLMATTA_AUTH_PASSWORD:
            /** -# read in password characters to the instance buffer - hiding output */
            (void)shellmatta_read(handle, &argument, &argLen);
            if ((1 == argLen) && (SHELLMATTA_OK == inputWrapper(inst, argument[0], true)))
            {
                /** -# check input username and password */
                inst->buffer[inst->inputCount] = '\0';
                shellmatta_write(handle, "\r\n", 2);
                checkPassword(handle, inst->tmpUserId, inst->buffer);
                inst->loginState = SHELLMATTA_AUTH_IDLE;
            }
            else
            {
                ret = SHELLMATTA_CONTINUE;
            }
            break;
        default:
            break;
    }

    (void)arguments;
    (void)length;

    return ret;
}
const shellmatta_cmd_t shellmatta_auth_loginCmd = {"login"
                                                 , "li"
                                                 , "Login command"
                                                 , "interactive or use -u <username> -p <password>"
                                                 , loginCmdFct
                                                 , NULL
                                                 , NULL};


/**
 * @brief       handles the logout of the current session
 * @param[in]   handle      handle  shellmatta instance handle
 * @param[in]   arguments   arguments containing a command name or alias
 * @param[in]   length      length of the arguments
 * @return      #SHELLMATTA_OK
 */
static shellmatta_retCode_t logoutCmdFct(const shellmatta_handle_t handle, const char *arguments, uint32_t length)
{
    shellmatta_auth_logout(handle);
    shellmatta_write(handle, "good bye\r\n", 10);

    (void)arguments;
    (void)length;

    return SHELLMATTA_OK;
}
const shellmatta_cmd_t shellmatta_auth_logoutCmd = {"logout"
                                                  , "lo"
                                                  , "Logout command"
                                                  , "logs out the currently logged in user"
                                                  , logoutCmdFct
                                                  , NULL
                                                  , NULL};

/**
 * @brief       initializes the shellmatta authentication system
 * @param[in]   handle          shellmatta instance handle
 * @param[in]   userList        list to specify all users pointer to a list of type shellmatta_user_t
 * @param[in]   userListLength  length of the user list
 * @param[in]   permList        list to specify the command permissions pointer to a list of type shellmatta_perm_t
 * @param[in]   permListLength  length of the perm list
 * @param[in]   customLogin     true: no internal login command is provided
 * @param[in]   checkFct        pointer to custom credential check function of type shellmatta_check_t
 * @param[in]   logFct          pointer to login log function of type shellmatta_auth_log_t
 * @return      errorcode   #SHELLMATTA_OK
 *                          #SHELLMATTA_USE_FAULT (param err)
 */
shellmatta_retCode_t shellmatta_auth_init(shellmatta_handle_t       handle,
                                          shellmatta_auth_user_t    *userList,
                                          uint32_t                  userListLength,
                                          shellmatta_auth_perm_t    *permList,
                                          uint32_t                  permListLength,
                                          bool                      customLogin,
                                          shellmatta_auth_check_t   checkFct,
                                          shellmatta_auth_log_t     logFct)
{
    shellmatta_retCode_t    ret     = SHELLMATTA_OK;
    shellmatta_instance_t   *inst   = (shellmatta_instance_t*)handle;
    uint32_t                i;
    shellmatta_cmd_t        *cmd;

    /** -# check parameters for plausibility  */
    if(     (NULL               != inst)
        &&  (SHELLMATTA_MAGIC   == inst->magic)
        &&  (NULL               != userList)
        &&  (0                  != userListLength)
        &&  (NULL               != permList)
        &&  (0                  != permListLength))
    {
        inst->loginState = SHELLMATTA_AUTH_IDLE;
        inst->userId = 0u;
        inst->tmpUserId = 0u;
        inst->userPointer = NULL;
        inst->userList = userList;
        inst->userListLength = userListLength;
        inst->permList = permList;
        inst->permListLength = permListLength;
        if(customLogin)
        {
            inst->helpCmd.next = &inst->logoutCmd;
        }
        inst->checkFct  = checkFct;
        inst->logFct    = logFct;

        /** -# assign links to the perm list to each command */
        cmd = inst->cmdList;

        /** -# search for a matching command */
        while (NULL != cmd)
        {
            /** -# Search for command in perm list */
            for (i = 0u; i < permListLength; i++)
            {
                if (0 == strcmp(cmd->cmd, permList[i].cmd))
                {
                    cmd->authLink = &permList[i];
                    break;
                }
            }

            cmd = cmd->next;
        }
    }
    else
    {
        ret = SHELLMATTA_USE_FAULT;
    }

    return ret;
}

/**
 * @brief       manually logs the passed user id in
 * @param[in]   handle      shellmatta instance handle
 * @param[in]   userId      userId to login
 * @return      errorcode   #SHELLMATTA_OK
 *                          #SHELLMATTA_USE_FAULT (param err)
 */
shellmatta_retCode_t shellmatta_auth_login(shellmatta_handle_t handle, uint32_t userId)
{
    shellmatta_retCode_t    ret     = SHELLMATTA_OK;
    shellmatta_instance_t   *inst   = (shellmatta_instance_t*)handle;
    uint32_t                i;

    /** -# check parameters for plausibility  */
    if(     (NULL               != inst)
        &&  (SHELLMATTA_MAGIC   == inst->magic))
    {
        /** -# log passed user id into the instance */
        inst->userId = userId;
        if (0 != userId)
        {
            /** -# set user pointer to print the name in the prompt */
            for (i = 0u; i < inst->userListLength; i++)
            {
                if (inst->userList[i].userId == userId)
                {
                    inst->userPointer = &inst->userList[i];
                    break;
                }
            }
        }
        else
        {
            inst->userPointer = NULL;
        }

        /** -# call log function */
        if (inst->logFct)
        {
            inst->logFct(userId, userId != 0u ? true : false);
        }
    }
    else
    {
        ret = SHELLMATTA_USE_FAULT;
    }
    return ret;
}

/**
 * @brief       logs the currently logged in user out of the instance
 * @param[in]   handle      shellmatta instance handle
 * @return      errorcode   #SHELLMATTA_OK
 *                          #SHELLMATTA_USE_FAULT (param err)
 */
shellmatta_retCode_t shellmatta_auth_logout(shellmatta_handle_t handle)
{
    shellmatta_retCode_t    ret     = SHELLMATTA_OK;
    shellmatta_instance_t   *inst   = (shellmatta_instance_t*)handle;

    /** -# check parameters for plausibility  */
    if(     (NULL               != inst)
        &&  (SHELLMATTA_MAGIC   == inst->magic))
    {
        inst->userId = 0u;
        inst->userPointer = NULL;

        /** -# clear the history buffer */
        (void)history_clear(handle);
    }
    else
    {
        ret = SHELLMATTA_USE_FAULT;
    }
    return ret;
}

/**
 * @brief       returns the currently logged in userId
 * @param[in]   handle      shellmatta instance handle
 * @return      userId or 0 if no user is logged in
 */
uint32_t shellmatta_auth_getLoggedInUserId(shellmatta_handle_t handle)
{
    uint32_t                userId  = 0u;
    shellmatta_instance_t   *inst   = (shellmatta_instance_t*)handle;

    /** -# check parameters for plausibility  */
    if(     (NULL               != inst)
        &&  (SHELLMATTA_MAGIC   == inst->magic))
    {
        userId = inst->userId;
    }

    return userId;
}

/**
 * @brief           copies the username into the passed buffer
 * @param[in]       handle      shellmatta instance handle
 * @param[out]      data        pointer to buffer to write the username into
 * @param[in, out]  length      in - length of the passed buffer, out - actual stringlength of the username
 * @return          errorcode   #SHELLMATTA_OK
 *                              #SHELLMATTA_ERROR (passed buffer is too small)
 *                              #SHELLMATTA_USE_FAULT (param err)
 */
shellmatta_retCode_t shellmatta_auth_getLoggedInUserName(shellmatta_handle_t handle, char *data, uint32_t *length)
{
    shellmatta_retCode_t    ret     = SHELLMATTA_OK;
    shellmatta_instance_t   *inst   = (shellmatta_instance_t*)handle;
    size_t                  userNameLength;

    /** -# check parameters for plausibility  */
    if(     (NULL               != inst)
        &&  (SHELLMATTA_MAGIC   == inst->magic)
        &&  (data               != NULL)
        &&  (length             != NULL))
    {
        if (NULL != inst->userPointer)
        {
            userNameLength = strlen(inst->userPointer->username);

            if (userNameLength < *length)
            {
                (void)strcpy(data, inst->userPointer->username);
                *length = userNameLength;
            }
            else
            {
                ret = SHELLMATTA_ERROR;
            }
        }
    }
    else
    {
        ret = SHELLMATTA_USE_FAULT;
    }
    return ret;
}

/**
 * @brief       checks if a command is accessible by the logged in user
 * @param[in]   inst    shellmatta instance to work with
 * @param[in]   cmd     command to check permissions for
 * @return      errorcode   #SHELLMATTA_OK      => permitted
 *                          #SHELLMATTA_ERROR   => not permitted
 */
shellmatta_retCode_t shellmatta_auth_is_cmd_permitted(const shellmatta_instance_t *inst, shellmatta_cmd_t *cmd)
{
    shellmatta_retCode_t    ret     = SHELLMATTA_ERROR;
    shellmatta_auth_perm_t  *permList;
    uint32_t                i;

    if (NULL == cmd->authLink)
    {
        ret = SHELLMATTA_OK;
    }
    else
    {
        permList = cmd->authLink;
        for (i = 0u; i < permList->userIdslength; i++)
        {
            if (inst->userId == permList->userIds[i])
            {
                ret = SHELLMATTA_OK;
                break;
            }
        }
    }

    return ret;
}

/**
 * @}
 */