/*
 * MIT License
 *
 * Copyright (c) 2019 Stefan Strobel <stefan.strobel@shimatta.net>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH
 * THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

/**
 * @file shellmatta.c
 * @brief Main implementation of the Shellmatta terminal implementation
 * @author Stefan Strobel <stefan.strobel@shimatta.net>
 */

/**
 * @addtogroup shellmatta
 * @{
 */

#include "shellmatta.h"
#include <stdio.h>
#include <stddef.h>
#include <string.h>
#include <stdarg.h>

#define SHELLMATTA_MIN(a,b) (((a) > (b)) ?  (b) : (a))
#define SHELLMATTA_MAX(a,b) (((a) > (b)) ?  (b) : (a))

static void writeEcho(  shellmatta_instance_t *inst,
                        const uint8_t *data,
                        uint32_t length)
{
    if(true == inst->echoEnabled)
    {
        inst->write(data, length);
    }
}

static void appendHistoryByte(shellmatta_instance_t *inst, uint8_t byte)
{
    inst->historyEnd ++;

    if(inst->historyEnd >= inst->historyBufferSize)
    {
        inst->historyEnd = 0u;
    }

    inst->historyBuffer[inst->historyEnd] = byte;

    if(inst->historyEnd == inst->historyStart)
    {
        /* move the start pointer to the next termination (0) */
        do
        {
            inst->historyStart ++;

            if(inst->historyStart >= inst->historyBufferSize)
            {
                inst->historyStart = 0u;
            }

        }while(0u != inst->historyBuffer[inst->historyStart]);
    }
}

static bool getHistoryByte(shellmatta_instance_t *inst, uint8_t *byte)
{
    bool ret = false;

    if(inst->historyRead != inst->historyStart)
    {
        *byte = inst->historyBuffer[inst->historyRead];

        if(0u == inst->historyRead)
        {
            inst->historyRead = inst->historyBufferSize;
        }

        inst->historyRead --;

        ret = true;
    }

    return ret;
}

static void storeHistoryCmd(shellmatta_instance_t *inst)
{
    if(     (inst->historyBufferSize > inst->inputCount)
        &&  (0u != inst->inputCount)
        &&  (true == inst->dirty))
    {
        appendHistoryByte(inst, 0u);

        for(uint32_t i = inst->inputCount; i > 0u; i --)
        {
            appendHistoryByte(inst, inst->buffer[i - 1u]);
        }
    }
    inst->dirty = false;
}

static bool navigateHistoryCmd(shellmatta_instance_t *inst, int32_t cnt)
{
    bool ret = true;
    uint32_t tempReadIdx = 0u;

    while((cnt > 0) && (true == ret))
    {
        if(inst->historyRead != inst->historyEnd)
        {
            inst->historyRead ++;
        }
        while(inst->historyRead != inst->historyEnd)
        {
            inst->historyRead ++;
            if(inst->historyRead >= inst->historyBufferSize)
            {
                inst->historyRead = 0u;
            }

            if(     (inst->historyRead != inst->historyEnd)
                &&  (0u == inst->historyBuffer[inst->historyRead]))
            {
                if(0u == inst->historyRead)
                {
                    inst->historyRead = inst->historyBufferSize;
                }
                inst->historyRead --;
                cnt -= 1;
                break;
            }
        }

        if(inst->historyRead == inst->historyEnd)
        {
            ret = false;
        }
    }

    while((cnt < 0) && (true == ret))
    {
        tempReadIdx = inst->historyRead;
        while(inst->historyRead != inst->historyStart)
        {
            if(0u == inst->historyRead)
            {
                inst->historyRead = inst->historyBufferSize;
            }
            inst->historyRead --;

            if(     (inst->historyRead != inst->historyStart)
                &&  (0u == inst->historyBuffer[inst->historyRead]))
            {
                if(0u == inst->historyRead)
                {
                    inst->historyRead = inst->historyBufferSize;
                }
                inst->historyRead --;
                cnt += 1;
                break;
            }
        }
        if(inst->historyRead == inst->historyStart)
        {
            inst->historyRead = tempReadIdx;
            inst->historyReadUp = false;
            ret = false;
        }
    }

    return ret;
}

static void restoreHistoryCmd(shellmatta_instance_t *inst)
{
    uint8_t byte;
    bool ret = true;

    ret = getHistoryByte(inst, &byte);
    while((ret == true) && (byte != 0u))
    {
        inst->buffer[inst->inputCount] = byte;
        inst->inputCount    ++;
        inst->cursor        ++;
        ret = getHistoryByte(inst, &byte);
    }

    writeEcho(inst, inst->buffer, inst->inputCount);
    navigateHistoryCmd(inst, 1);
    inst->dirty = false;
}

static void resetHistoryBuffer(shellmatta_instance_t *inst)
{
    inst->historyRead = inst->historyEnd;
    inst->historyReadUp = true;
}

static void saveCursorPos(shellmatta_instance_t *inst)
{
    writeEcho(inst, "\e[s", 3u);
}

static void restoreCursorPos(shellmatta_instance_t *inst)
{
    writeEcho(inst, "\e[u", 3u);
}

static void eraseLine(shellmatta_instance_t *inst)
{
    writeEcho(inst, "\e[K", 3u);
}

static void rewindCursor(shellmatta_instance_t *inst, uint32_t length)
{
    uint8_t terminalCmd[16];
    size_t size;

    length = SHELLMATTA_MIN (length, inst->cursor);
    if(length > 0u)
    {
        size = snprintf(terminalCmd, sizeof(terminalCmd), "\e[%uD", length);
        writeEcho(inst, terminalCmd, size);
        inst->cursor -= length;
    }
}

static void forwardCursor(shellmatta_instance_t *inst, uint32_t length)
{
    uint8_t terminalCmd[16];
    size_t size;

    length = SHELLMATTA_MAX (length,
                                (inst->inputCount - inst->cursor));
    if (length > 0u)
    {
        size = snprintf(terminalCmd, sizeof(terminalCmd), "\e[%uC", length);
        writeEcho(inst, terminalCmd, size);
        inst->cursor -= length;
    }
}

static void insertChars(shellmatta_instance_t   *inst,
                        uint8_t                 *data,
                        uint32_t                 length)
{
    /* check if we have to move chars in the buffer */
    if(     (inst->cursor     != inst->inputCount)
        &&  (SHELLMATTA_MODE_INSERT == inst->mode))
    {
        /* move the existing chars */
        for (   uint32_t i = inst->inputCount;
                i > inst->cursor;
                i --)
        {
            inst->buffer[i + length - 1] = inst->buffer[i - 1];
        }

        /* store and print the new chars */
        memcpy(&(inst->buffer[inst->cursor]), data, length);
        writeEcho(inst, data, length);

        /* print the other chars and restore the cursor to this position */
        eraseLine(inst);
        saveCursorPos(inst);
        writeEcho(  inst,
                    &(inst->buffer[inst->cursor + length]),
                    inst->inputCount - inst->cursor);
        restoreCursorPos(inst);
    }
    /* just overwrite/append the chars */
    else
    {
        memcpy(&(inst->buffer[inst->cursor]), data, length);
        writeEcho(inst, data, length);
    }

    inst->inputCount    += length;
    inst->cursor          += length;
}

static void removeChars(shellmatta_instance_t   *inst,
                        uint32_t                 length,
                        bool                     backspace)
{
    length = SHELLMATTA_MIN (length, inst->cursor);
    if(0u != length)
    {
        if(true == backspace)
        {
            rewindCursor(inst, length);
        }
        /* delete the char at the cursor position */
        for (   uint32_t i = inst->cursor;
                i < (inst->inputCount - length);
                i++)
        {
            inst->buffer[i] = inst->buffer[i + length];
        }
        eraseLine(inst);
        saveCursorPos(inst);
        writeEcho(    inst,
                    &(inst->buffer[inst->cursor]),
                     (inst->inputCount - inst->cursor - length));
        restoreCursorPos(inst);

        inst->inputCount -= length;
    }
}

static void clearInput(shellmatta_instance_t *inst)
{
    rewindCursor(inst, inst->cursor);
    eraseLine(inst);
    inst->inputCount = 0u;
    inst->dirty = false;
}

static shellmatta_retCode_t processArrowKeys(shellmatta_instance_t *inst)
{
    shellmatta_retCode_t ret = SHELLMATTA_USE_FAULT;

    if ('[' == inst->escapeChars[0])
    {
        ret = SHELLMATTA_OK;

        switch (inst->escapeChars[1])
        {
        case 'A': /* arrow up     */
            storeHistoryCmd(inst);
            if(false == inst->historyReadUp)
            {
                navigateHistoryCmd(inst, -1);
            }
            inst->historyReadUp = true;
            clearInput(inst);
            restoreHistoryCmd(inst);
            navigateHistoryCmd(inst, -1);

            break;
        case 'B': /* arrow down   */

            if((inst->historyRead != inst->historyEnd))
            {
                storeHistoryCmd(inst);
                if(true == inst->historyReadUp)
                {
                    navigateHistoryCmd(inst, 1);
                }
                inst->historyReadUp = false;
                navigateHistoryCmd(inst, 1);
                clearInput(inst);
                restoreHistoryCmd(inst);
            }
            break;
        case 'C': /* arrow right  */
            forwardCursor(inst, 1u);
            break;
        case 'D': /* arrow left   */
            rewindCursor(inst, 1u);
            break;
        default:
            /** ignore unknown escape */
            ret = SHELLMATTA_USE_FAULT;
            break;
        }
    }
    return ret;
}

void handleEscapeSequence(shellmatta_instance_t *inst, uint8_t *data)
{
    switch (inst->escapeCounter)
    {
    case 1u:
        inst->escapeChars[inst->escapeCounter - 1] = *data;
        inst->escapeCounter ++;
        break;
    case 2u:
        inst->escapeChars[inst->escapeCounter - 1] = *data;
        if(SHELLMATTA_OK == processArrowKeys(inst))
        {
            inst->escapeCounter = 0u;
        }
        else if (   (0x4fu == inst->escapeChars[0])
                &&  (0x46u == inst->escapeChars[1]))
        {
            forwardCursor(inst, inst->inputCount - inst->cursor);
            inst->escapeCounter = 0u;
        }
        else if(0u == (0x40u & *data))
        {
            inst->escapeCounter ++;
        }
        else
        {
            inst->escapeCounter = 0u;
        }
        break;
    case 3u:
        inst->escapeChars[inst->escapeCounter - 1] = *data;
        if(     (0x5bu == inst->escapeChars[0])
            &&  (0x33u == inst->escapeChars[1])
            &&  (0x7eu == inst->escapeChars[2]))
        {
            removeChars(inst, 1u, false);
            inst->escapeCounter = 0u;
        }
        /* pos1 */
        else if (   (0x5bu == inst->escapeChars[0])
                &&  (0x31u == inst->escapeChars[1])
                &&  (0x7eu == inst->escapeChars[2]))
        {
            rewindCursor(inst, inst->cursor);
            inst->escapeCounter = 0u;
        }
        else if(0u == (0x40u & *data))
        {
            inst->escapeCounter ++;
        }
        else
        {
            inst->escapeCounter = 0u;
        }
        break;
    default:
        inst->escapeCounter = 0u;
        break;
    }
}

static void terminateInput(shellmatta_instance_t *inst)
{
    inst->inputCount    = 0u;
    inst->cursor        = 0u;
    shellmatta_printf(inst, "\n\r%s", inst->prompt);
}

static void doAutocomplete(shellmatta_instance_t *inst)
{
    shellmatta_cmd_t   *cmd         = inst->cmdList;
    uint8_t            *tempCmd     = NULL;
    uint32_t            minLen      = 0u;
    uint32_t            sizeDiff    = 0u;
    bool                exactMatch  = true;
    uint32_t            printedLen  = 0u;

    inst->tabCounter++;

    /* on douple tab show all matching commands */
    if (1u < inst->tabCounter)
    {
        inst->tabCounter        = 0u;

        while (NULL != cmd)
        {
            /* check if command matches the input */
            if(    (strlen(cmd->cmd) > inst->cursor)
                && (0u == memcmp(cmd->cmd, inst->buffer, inst->cursor)))
            {
                /* add newline on first find */
                if(0u == printedLen)
                {
                    saveCursorPos(inst);
                    inst->write("\n\r", 2u);
                }
                inst->write(cmd->cmd, strlen(cmd->cmd));
                printedLen += strlen(cmd->cmd);
                inst->write("    ", 4u);
                printedLen += 4u;
            }
            /* check if command matches the input */
            if(    (strlen(cmd->cmdAlias) > inst->cursor)
                && (0u == memcmp(cmd->cmdAlias, inst->buffer, inst->cursor)))
            {
                /* add newline on first find */
                if(0u == printedLen)
                {
                    saveCursorPos(inst);
                    inst->write("\n\r", 2u);
                }
                inst->write(cmd->cmdAlias, strlen(cmd->cmdAlias));
                printedLen += strlen(cmd->cmdAlias);
                inst->write("    ", 4u);
                printedLen += 4u;
            }
            cmd = cmd->next;
        }
        /* print input again if a commands was found */
        if(printedLen > 0u)
        {
            writeEcho(inst, "\n\r", 2u);
            writeEcho(inst, inst->prompt, strlen(inst->prompt));
            writeEcho(inst, inst->buffer, inst->inputCount);
            restoreCursorPos(inst);
        }
    }
    /* on single tab autocomplete as far as possible */
    else if(0u != inst->cursor)
    {
        /* loop through all registered commands */
        while (NULL != cmd)
        {
            /* check if command matches the input */
            if(    (strlen(cmd->cmd) > inst->cursor)
                && (0u == memcmp(cmd->cmd, inst->buffer, inst->cursor)))
            {
                /* store first match */
                if(NULL == tempCmd)
                {
                    tempCmd = cmd->cmd;
                    minLen = strlen(cmd->cmd);
                }
                /* find common part of the matches */
                else
                {
                    exactMatch = false;
                    minLen = SHELLMATTA_MIN(strlen(cmd->cmd), minLen);
                    for(uint32_t i = 0u; i < minLen; i++)
                    {
                        if(cmd->cmd[i] != tempCmd[i])
                        {
                            minLen = i;
                        }
                    }
                }
            }

            /* check if command Alias matches the input */
            if(    (strlen(cmd->cmdAlias) > inst->cursor)
                && (0u == memcmp(cmd->cmdAlias, inst->buffer, inst->cursor)))
            {
                /* store first match */
                if(NULL == tempCmd)
                {
                    tempCmd = cmd->cmdAlias;
                    minLen = strlen(cmd->cmdAlias);
                }
                /* find common part of the matches */
                else
                {
                    exactMatch = false;
                    minLen = SHELLMATTA_MIN(strlen(cmd->cmdAlias), minLen);
                    for(uint32_t i = 0u; i < minLen; i++)
                    {
                        if(cmd->cmdAlias[i] != tempCmd[i])
                        {
                            minLen = i;
                        }
                    }
                }
            }
            cmd = cmd->next;
        }

        /* autocomplete found command */
        if(NULL != tempCmd)
        {
            /* calculate the size of the command to be inserted */
            sizeDiff = minLen - inst->cursor;

            /* copy the found part into the buffer and display it */
            insertChars(inst, &(tempCmd[inst->cursor]), sizeDiff);

            /* on exact match there is no need to double Tab to display all */
            if(true == exactMatch)
            {
                inst->tabCounter = 0u;
            }
        }
    }
    else
    {
        /* nothing to do here */
    }
}

/**
 * @brief initialize the shellmatta terminal and provide all callbacks
 * @param[in,out]   inst                pointer to a shellmatta instance
 * @param[in]       buffer              pointer to the input buffer to use
 * @param[in]       bufferSize          size of the provided input buffer
 * @param[in]       historyBuffer       pointer to the history buffer to use
 *                                      NULL in case of no history buffer
 * @param[in]       historyBufferSize   size of the history buffer
 *                                      0 in case of no history buffer
 * @param[in]       prompt              pointer to prompt string - is printed
 *                                      after each command
 * @param[in]       writeFct            function pointer to output function
 */
shellmatta_retCode_t shellmatta_doInit(
        shellmatta_instance_t  *inst,
        uint8_t                *buffer,
        uint32_t                bufferSize,
        uint8_t                *historyBuffer,
        uint32_t                historyBufferSize,
        const char             *prompt,
        shellmatta_write_t     writeFct)
{
    /** - copy all provided buffers into the shellmatta instance */
    inst->buffer                = buffer;
    inst->bufferSize            = bufferSize;
    inst->inputCount            = 0u;
    inst->cursor                = 0u;
    inst->cmdList               = NULL;
    inst->historyBuffer         = historyBuffer;
    inst->historyBufferSize     = historyBufferSize;
    inst->historyStart          = 0u;
    inst->historyEnd            = 0u;
    inst->historyRead           = 0u;
    inst->historyReadUp         = true;
    inst->write                 = writeFct;
    inst->prompt                = prompt;
    inst->echoEnabled           = true;
    inst->dirty                 = false;
    inst->tabCounter            = 0u;
    inst->escapeCounter         = 0u;
    inst->mode                  = SHELLMATTA_MODE_INSERT;

    terminateInput(inst);

    return SHELLMATTA_OK;
}

/**
 * @brief adds a command to the command list alphabetically ordered
 * @param[in]   inst    pointer to a shellmatta instance
 * @param[in]   cmd     pointer to the command to add type #shellmatta_cmd_t
 */
shellmatta_retCode_t shellmatta_addCmd(shellmatta_instance_t *inst, shellmatta_cmd_t *cmd)
{
    shellmatta_cmd_t       *tempCmd     = inst->cmdList;
    shellmatta_cmd_t       **prevCmd    = &inst->cmdList;
    bool                    cmdPlaced   = false;
    shellmatta_retCode_t    ret         = SHELLMATTA_OK;
    int                     cmdDiff     = 0;
    int                     aliasDiff   = 0;

    /* register first command as list entry */
    if (NULL == tempCmd)
    {
        inst->cmdList = cmd;
        cmd->next = NULL;
    }
    /* append the new command sorted */
    else
    {
        while ((false == cmdPlaced) && (SHELLMATTA_OK == ret))
        {
            cmdDiff     = strcmp(tempCmd->cmd,      cmd->cmd);
            aliasDiff   = strcmp(tempCmd->cmdAlias, cmd->cmdAlias);
            /* check for a duplicate command */
            if((0u == cmdDiff) || (0u == aliasDiff))
            {
                ret = SHELLMATTA_DUPLICATE;
            }
            else if(0 < cmdDiff)
            {
                cmd->next   = tempCmd;
                *prevCmd    = cmd;
                cmdPlaced   = true;
            }
            else if(NULL == tempCmd->next)
            {
                tempCmd->next = cmd;
                cmd->next = NULL;
                cmdPlaced = true;
            }
            else
            {
                /* nothing to do */
            }
            prevCmd = &tempCmd;
            tempCmd = tempCmd->next;
        }
    }
    return ret;
}


void shellmatta_doTask(shellmatta_instance_t *inst, uint32_t time)
{

}

/**
 * @brief processes the passed amount of data
 * @param[in]   inst    pointer to a shellmatta instance
 * @param[in]   data    pointer to input data to process
 * @param[in]   size    length of input data to process
 */
void shellmatta_processData(shellmatta_instance_t   *inst,
                            char                    *data,
                            uint32_t                 size)
{
    /* process byte wise */
    for (uint32_t i = 0u; i < size; i++)
    {
        /* handle escape sequences */
        if(inst->escapeCounter != 0u)
        {
            handleEscapeSequence(inst, data);
        }
        /* handle return as start of processing the command */
        else if ('\r' == *data)
        {
            shellmatta_cmd_t *cmd = inst->cmdList;
            uint8_t cmdExecuted = 0u;
            inst->buffer[inst->inputCount] = 0u;

            /* store the current command and reset the history buffer */
            inst->dirty = true;
            storeHistoryCmd(inst);
            resetHistoryBuffer(inst);

            while (NULL != cmd)
            {
                if (    (0 == strcmp(inst->buffer, cmd->cmd))
                    ||  (0 == strcmp(inst->buffer, cmd->cmdAlias)))
                {
                    inst->write("\n\r", 2u);

                    cmdExecuted = 1u;
                    char *blubb[10];
                    blubb[0] = inst->buffer;
                    cmd->cmdFct(1, blubb);
                    cmd = NULL;
                }
                else
                {
                    cmd = cmd->next;
                }
            }

            if ((cmdExecuted == 0u) && (inst->inputCount > 0))
            {
                inst->buffer[inst->inputCount] = '\0';
                shellmatta_printf(  inst,
                                    "\n\rCommand: %s not found",
                                    inst->buffer);
            }
            terminateInput(inst);
        }
        /* tabulator key - auto complete */
        else if('\t' == *data)
        {
            inst->dirty = true;
            doAutocomplete(inst);
        }
        /* cancel - terminate current input and print prompt again */
        else if(3 == *data)
        {
            inst->dirty = false;
            resetHistoryBuffer(inst);
            terminateInput(inst);
        }
        /* backspace */
        else if('\b' == *data)
        {
            inst->dirty = true;
            removeChars(inst, 1u, true);
        }
        /* check for delete key */
        else if(0x7eu == *data)
        {
            inst->dirty = true;
            removeChars(inst, 1u, false);
        }
        /* start of escape sequence */
        else if('\e' == *data)
        {
            inst->escapeCounter = 1u;
        }
        else
        {
            inst->dirty = true;
            insertChars(inst, data, 1);
        }

        /* reset tab counter on not a tab */
        if ('\t' != *data)
        {
            inst->tabCounter = 0u;
        }

        data ++;
    }
}

void shellmatta_printf(shellmatta_instance_t *inst, const char *fmt, ...)
{
    char outputBuffer[1024u];
    va_list arg;

    va_start(arg, fmt);
    int length = vsnprintf(outputBuffer, 1024, fmt, arg);
    va_end(arg);

    inst->write(outputBuffer, length);
}

void shellmatta_getArg(uint32_t cnt, uint8_t *arg)
{

}

/** @} */