/*
 * Copyright (c) 2019 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_opt.c
 * @brief   option parser implementation of the shellmatta
 * @author  Stefan Strobel <stefan.strobel@shimatta.net>
 */

/**
 * @addtogroup shellmatta_opt
 * @{
 */

#include "shellmatta_opt.h"
#include "shellmatta_utils.h"
#include "shellmatta.h"
#include <string.h>


/**
 * @brief       finds the next parsable hunk of data in the input
 * @param[in]   inst            shellmatta instance
 * @return      errorcode       #SHELLMATTA_OK      - new hunk found
 *                              #SHELLMATTA_ERROR   - error parsing or end of input
 */
static shellmatta_retCode_t findNextHunk(shellmatta_instance_t *inst)
{
    shellmatta_retCode_t ret = SHELLMATTA_ERROR;
    uint32_t newOffset = inst->optionParser.nextOffset;
    uint32_t exeptionOffset = 0u;
    char quotation = '\0';  /* holds the current quotation mark if any */

    /** -# find beginning of next hunk */
    while(  (newOffset  < inst->inputCount)
        &&     ((' '        == inst->buffer[newOffset])
            ||  ('\0'       == inst->buffer[newOffset])))
    {
        newOffset ++;
    }

    inst->optionParser.offset = newOffset;

    /** -# determine length */
    while((newOffset < inst->inputCount)
        && (((' ' != inst->buffer[newOffset]) && ('\0' != inst->buffer[newOffset])) || '\0' != quotation))
    {
        /** -# check for new quotation */
        if((('\'' == inst->buffer[newOffset]) || ('"' == inst->buffer[newOffset])) && (quotation == '\0'))
        {
            quotation = inst->buffer[newOffset];
            exeptionOffset ++;
        }
        /** -# check if quotation has ended */
        else if(quotation == inst->buffer[newOffset])
        {
            exeptionOffset ++;
            /** -# check if quotation is excaped */
            if('\\' != inst->buffer[newOffset - 1u])
            {
                quotation = '\0';
            }
            else
            {
                inst->buffer[newOffset - exeptionOffset] = inst->buffer[newOffset];
            }
        }
        else
        {
            /** -# shift back chars */
            if(0u != exeptionOffset)
            {
                inst->buffer[newOffset - exeptionOffset] = inst->buffer[newOffset];
            }
        }
        newOffset ++;
    }

    inst->optionParser.nextOffset   = newOffset;
    inst->optionParser.len          = newOffset - inst->optionParser.offset - exeptionOffset;

    /** -# add terminating 0 */
    inst->buffer[inst->optionParser.offset + inst->optionParser.len] = '\0';

    if((inst->optionParser.offset < inst->inputCount) && (0u != inst->optionParser.len) && ('\0' == quotation))
    {
        ret = SHELLMATTA_OK;
    }

    return ret;
}

/**
 * @brief       peeks the first char of the next hunk
 * @param[in]   inst        shellmatta instance
 * @return      char        first char of next hunk \0 if not existing
 */
static char peekNextHunk(shellmatta_instance_t *inst)
{
    uint32_t newOffset = inst->optionParser.nextOffset;

    /** -# find beginning of next hunk */
    while(  (newOffset  < inst->inputCount)
        &&     ((' '        == inst->buffer[newOffset])
            ||  ('\0'       == inst->buffer[newOffset])))
    {
        newOffset ++;
    }
    return inst->buffer[newOffset];
}

/**
 * @brief       tries to parse the current input hunk and check if this is a configured option
 * @param[in]   inst            pointer to shellmatta instance
 * @param[in]   optionString    option string e.g. "cd:e::"
 * @param[out]  option          pointer to store the detected option to
 * @param[out]  argtype         pointer to var of type #shellmatta_opt_argtype_t != NULL
 * @return      errorcode       #SHELLMATTA_OK      - option parsable and found in option String
 *                              #SHELLMATTA_ERROR   - format error or option unknown
 */
static shellmatta_retCode_t parseShortOpt(  shellmatta_instance_t       *inst,
                                            const char                  *optionString,
                                            char                        *option,
                                            shellmatta_opt_argtype_t    *argtype)
{
    shellmatta_retCode_t ret = SHELLMATTA_ERROR;
    char *buffer = &inst->buffer[inst->optionParser.offset];
    uint32_t i;

    /** -# check for correct syntax */
    if((2u == inst->optionParser.len) && ('-' == buffer[0u]) && ('-' != buffer[1u]) && ('\0' != buffer[1u]))
    {
        *option = '\0';

        /** -# search for option character in option string */
        for(i = 0u; ('\0' != optionString[i]) && ('\0' == *option); i ++)
        {
            if(buffer[1u] == optionString[i])
            {
                ret = SHELLMATTA_OK;

                /** -# return found option character */
                *option = buffer[1u];

                /** -# check if an argument is required or optional */
                if(':' == optionString[i + 1u])
                {
                    *argtype = SHELLMATTA_OPT_ARG_REQUIRED;
                    if(':' == optionString[i + 2u])
                    {
                        *argtype = SHELLMATTA_OPT_ARG_OPTIONAL;
                    }
                }
                else
                {
                    *argtype = SHELLMATTA_OPT_ARG_NONE;
                }
            }
        }
    }
    /** -# skip "--" */
    else if((2u == inst->optionParser.len) && ('-' == buffer[0u]) && ('-' == buffer[1u]))
    {
        ret = SHELLMATTA_CONTINUE;
    }
    else
    {
        *option = '\0';
    }

    return ret;
}

/**
 * @brief       tries to parse the current input hunk and check if this is a configured option
 * @param[in]   inst            pointer to shellmatta instance
 * @param[in]   longOptions     option structure - pointer to array of type #shellmatta_opt_long_t
 * @param[out]  option          pointer to store the detected option to
 * @param[out]  argtype         pointer to var of type #shellmatta_opt_argtype_t != NULL
 * @return      errorcode       #SHELLMATTA_OK      - option parsable and found in option String
 *                              #SHELLMATTA_ERROR   - format error or option unknown
 */
static shellmatta_retCode_t parseLongOpt(   shellmatta_instance_t       *inst,
                                            const shellmatta_opt_long_t *longOptions,
                                            char                        *option,
                                            shellmatta_opt_argtype_t    *argtype)
{
    shellmatta_retCode_t ret = SHELLMATTA_ERROR;
    char *buffer = &inst->buffer[inst->optionParser.offset];
    uint32_t i;

    /** -# check for correct syntax for short options */
    if((2u == inst->optionParser.len) && ('-' == buffer[0u]) && ('-' != buffer[1u]) && ('\0' != buffer[1u]))
    {
        /** -# search for option character in option list */
        for(i = 0u; ('\0' != longOptions[i].paramShort) && ('\0' == *option); i ++)
        {
            if(buffer[1u] == longOptions[i].paramShort)
            {
                ret = SHELLMATTA_OK;

                /** -# return found option character */
                *option     = longOptions[i].paramShort;
                *argtype    = longOptions[i].argtype;
            }
        }
    }
    /** -# check for correct syntax for long options */
    else if((3u <= inst->optionParser.len) && ('-' == buffer[0u]) && ('-' == buffer[1u]))
    {
        /** -# search for long option in option list */
        for(i = 0u; ('\0' != longOptions[i].paramShort) && ('\0' == *option); i ++)
        {
            if(0 == strcmp(&buffer[2u], longOptions[i].paramLong))
            {
                ret = SHELLMATTA_OK;

                /** -# return found option character */
                *option     = longOptions[i].paramShort;
                *argtype    = longOptions[i].argtype;
            }
        }
    }
    /** -# ignore "--" */
    else if((2u == inst->optionParser.len) && ('-' == buffer[0u]) && ('-' == buffer[1u]))
    {
        *option = '\0';
        ret = SHELLMATTA_CONTINUE;
    }
    else
    {
        *option = '\0';
    }

    return ret;
}

/**
 * @brief       Scans the current input and parses options in getopt style - pass either optionString or longOptions
 *              This is an internal funtion to handle both getopt styles and remove duplicated code...
 *              The standard functions are just wrapper around this one.
 * @param[in]   handle          shellmatta handle
 * @param[in]   optionString    option string e.g. "cd:e::"
 * @param[in]   longOptions     option structure - pointer to array of type #shellmatta_opt_long_t
 * @param[out]  option          pointer to store the detected option to
 * @param[out]  argument        pointer to store the argument string to (can be NULL)
 * @param[out]  argLen          pointer to store the argument lengh to (can be NULL)
 * @return      errorcode       #SHELLMATTA_OK      - no error - keep on calling
 *                              #SHELLMATTA_ERROR   - error occured - e.g. argument missing
 */
static shellmatta_retCode_t shellmatta_opt_int( shellmatta_handle_t         handle,
                                                const char                  *optionString,
                                                const shellmatta_opt_long_t *longOptions,
                                                char                        *option,
                                                char                        **argument,
                                                uint32_t                    *argLen)
{
    shellmatta_retCode_t        ret     = SHELLMATTA_USE_FAULT;
    shellmatta_instance_t       *inst   = (shellmatta_instance_t*)handle;
    shellmatta_opt_argtype_t    argtype = SHELLMATTA_OPT_ARG_NONE;

    /** -# check parameters for plausibility  */
    if(     (NULL               != inst)
        &&  (SHELLMATTA_MAGIC   == inst->magic)
        &&  (NULL               != option))
    {
        *option     = '\0';
        if(NULL != argument)
        {
            *argument = NULL;
        }
        if(NULL != argLen)
        {
            *argLen = 0u;
        }

        /** -# do this until we find a not skipable argument */
        do
        {
            ret = findNextHunk(inst);
            if(SHELLMATTA_OK == ret)
            {
                /** -# call the matching parse function */
                if(NULL != optionString)
                {
                    ret = parseShortOpt(inst, optionString, option, &argtype);
                }
                else if(NULL != longOptions)
                {
                    ret = parseLongOpt(inst, longOptions, option, &argtype);
                }
                else
                {
                    ret = SHELLMATTA_USE_FAULT;
                }

                /** -# when no option is found return this as raw argument */
                if(SHELLMATTA_ERROR == ret)
                {
                    if(NULL != argument)
                    {
                        *argument = &(inst->buffer[inst->optionParser.offset]);
                    }
                    if(NULL != argLen)
                    {
                        *argLen = inst->optionParser.len;
                    }
                    ret = SHELLMATTA_OK;
                }
                else if(SHELLMATTA_USE_FAULT == ret)
                {
                    /** -# nothing to do - just return errorcode */
                }
                else
                {
                    switch(argtype)
                    {
                        case SHELLMATTA_OPT_ARG_REQUIRED:
                            ret = findNextHunk(inst);
                            if((NULL == argument) || (NULL == argLen))
                            {
                                ret = SHELLMATTA_USE_FAULT;
                            }
                            if(SHELLMATTA_OK == ret)
                            {
                                *argument   = &(inst->buffer[inst->optionParser.offset]);
                                *argLen     = inst->optionParser.len;
                            }
                            break;
                        case SHELLMATTA_OPT_ARG_OPTIONAL:
                            /** -# treat anything not starting with '-' as argument */
                            if('-' != peekNextHunk(inst))
                            {
                                ret = findNextHunk(inst);
                                if((NULL == argument) || (NULL == argLen))
                                {
                                    ret = SHELLMATTA_USE_FAULT;
                                }
                                if(SHELLMATTA_OK == ret)
                                {
                                    *argument   = &(inst->buffer[inst->optionParser.offset]);
                                    *argLen     = inst->optionParser.len;
                                }
                            }
                            break;
                        default:
                            /* nothing to do */
                            break;
                    }
                }
            }
        } while(SHELLMATTA_CONTINUE == ret);
    }
    return ret;
}

/**
 * @brief       scans the current input and parses options in getopt style
 * @param[in]   handle          shellmatta handle
 * @param[in]   optionString    option string e.g. "cd:e::"
 * @param[out]  option          pointer to store the detected option to
 * @param[out]  argument        pointer to store the argument string to (can be NULL)
 * @param[out]  argLen          pointer to store the argument lengh to (can be NULL)
 * @return      errorcode       #SHELLMATTA_OK      - no error - keep on calling
 *                              #SHELLMATTA_ERROR   - error occured - e.g. argument missing
 */
shellmatta_retCode_t shellmatta_opt(        shellmatta_handle_t handle,
                                            const char          *optionString,
                                            char                *option,
                                            char                **argument,
                                            uint32_t            *argLen)
{
    return shellmatta_opt_int(  handle,
                                optionString,
                                NULL,
                                option,
                                argument,
                                argLen);
}

/**
 * @brief       scans the current input and parses options in getopt_long style
 * @param[in]   handle          shellmatta handle
 * @param[in]   longOptions     option structure - pointer to array of type #shellmatta_opt_long_t
 * @param[out]  option          pointer to store the detected option to
 * @param[out]  argument        pointer to store the argument string to (can be NULL)
 * @param[out]  argLen          pointer to store the argument lengh to (can be NULL)
 */
shellmatta_retCode_t shellmatta_opt_long(   shellmatta_handle_t         handle,
                                            const shellmatta_opt_long_t *longOptions,
                                            char                        *option,
                                            char                        **argument,
                                            uint32_t                    *argLen)
{
    return shellmatta_opt_int(  handle,
                                NULL,
                                longOptions,
                                option,
                                argument,
                                argLen);
}

/**
 * @brief           initializes the option parser instance
 * @param[in, out]  inst        pointer to a shellmatta instance
 * @param[in]       argStart    start offset of the arguments (after command name/alias)
 */
void shellmatta_opt_init(shellmatta_instance_t *inst, uint32_t argStart)
{
    /** -# initialize all relevant option parser variables */
    inst->optionParser.argStart     = argStart;
    inst->optionParser.nextOffset   = argStart;
}

/**
 * @brief           re-initializes the option parser instance using the data from the last init
 * @param[in, out]  inst        pointer to a shellmatta instance
 */
void shellmatta_opt_reInit(shellmatta_instance_t *inst)
{
    /** -# initialize all relevant option parser variables */
    inst->optionParser.nextOffset = inst->optionParser.argStart;
}

/**
 * @}
 */