/*
 *  Copyright (c) 2019, The OpenThread Authors.
 *  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions are met:
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. 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.
 *  3. Neither the name of the copyright holder 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 HOLDER 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.
 */

/**
 * @file
 *   This file implements OpenThread platform abstraction for storage of settings in RAM.
 *
 */

#include <openthread-core-config.h>

#include <assert.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>

#include <openthread/instance.h>
#include <openthread/platform/settings.h>

#define SETTINGS_BUFFER_SIZE 1024

#if OPENTHREAD_SETTINGS_RAM

static uint8_t  sSettingsBuf[SETTINGS_BUFFER_SIZE];
static uint16_t sSettingsBufLength;

struct settingsBlock
{
    uint16_t key;
    uint16_t length;
};

// settings API
void otPlatSettingsInit(otInstance *aInstance)
{
    OT_UNUSED_VARIABLE(aInstance);

    sSettingsBufLength = 0;
}

otError otPlatSettingsGet(otInstance *aInstance, uint16_t aKey, int aIndex, uint8_t *aValue, uint16_t *aValueLength)
{
    OT_UNUSED_VARIABLE(aInstance);

    uint16_t                    i           = 0;
    uint16_t                    valueLength = 0;
    uint16_t                    readLength;
    int                         currentIndex = 0;
    const struct settingsBlock *currentBlock;
    otError                     error = OT_ERROR_NOT_FOUND;

    while (i < sSettingsBufLength)
    {
        currentBlock = (struct settingsBlock *)&sSettingsBuf[i];

        if (aKey == currentBlock->key)
        {
            if (currentIndex == aIndex)
            {
                readLength = currentBlock->length;

                // Perform read only if an input buffer was passed in
                if (aValue != NULL && aValueLength != NULL)
                {
                    // Adjust read length if input buffer size is smaller
                    if (readLength > *aValueLength)
                    {
                        readLength = *aValueLength;
                    }

                    memcpy(aValue, &sSettingsBuf[i + sizeof(struct settingsBlock)], readLength);
                }

                valueLength = currentBlock->length;
                error       = OT_ERROR_NONE;
                break;
            }

            currentIndex++;
        }

        i += sizeof(struct settingsBlock) + currentBlock->length;
    }

    if (aValueLength != NULL)
    {
        *aValueLength = valueLength;
    }

    return error;
}

otError otPlatSettingsSet(otInstance *aInstance, uint16_t aKey, const uint8_t *aValue, uint16_t aValueLength)
{
    uint16_t                    i = 0;
    uint16_t                    currentBlockLength;
    uint16_t                    nextBlockStart;
    const struct settingsBlock *currentBlock;

    // Delete all entries of aKey
    while (i < sSettingsBufLength)
    {
        currentBlock       = (struct settingsBlock *)&sSettingsBuf[i];
        currentBlockLength = sizeof(struct settingsBlock) + currentBlock->length;

        if (aKey == currentBlock->key)
        {
            nextBlockStart = i + currentBlockLength;

            if (nextBlockStart < sSettingsBufLength)
            {
                memmove(&sSettingsBuf[i], &sSettingsBuf[nextBlockStart], sSettingsBufLength - nextBlockStart);
            }

            assert(sSettingsBufLength >= currentBlockLength);
            sSettingsBufLength -= currentBlockLength;
        }
        else
        {
            i += currentBlockLength;
        }
    }

    return otPlatSettingsAdd(aInstance, aKey, aValue, aValueLength);
}

otError otPlatSettingsAdd(otInstance *aInstance, uint16_t aKey, const uint8_t *aValue, uint16_t aValueLength)
{
    OT_UNUSED_VARIABLE(aInstance);

    otError               error;
    struct settingsBlock *currentBlock;
    const uint16_t        newBlockLength = sizeof(struct settingsBlock) + aValueLength;

    if (sSettingsBufLength + newBlockLength <= sizeof(sSettingsBuf))
    {
        currentBlock         = (struct settingsBlock *)&sSettingsBuf[sSettingsBufLength];
        currentBlock->key    = aKey;
        currentBlock->length = aValueLength;

        memcpy(&sSettingsBuf[sSettingsBufLength + sizeof(struct settingsBlock)], aValue, aValueLength);
        sSettingsBufLength += newBlockLength;

        error = OT_ERROR_NONE;
    }
    else
    {
        error = OT_ERROR_NO_BUFS;
    }

    return error;
}

otError otPlatSettingsDelete(otInstance *aInstance, uint16_t aKey, int aIndex)
{
    OT_UNUSED_VARIABLE(aInstance);

    uint16_t                    i            = 0;
    int                         currentIndex = 0;
    uint16_t                    nextBlockStart;
    uint16_t                    currentBlockLength;
    const struct settingsBlock *currentBlock;
    otError                     error = OT_ERROR_NOT_FOUND;

    while (i < sSettingsBufLength)
    {
        currentBlock       = (struct settingsBlock *)&sSettingsBuf[i];
        currentBlockLength = sizeof(struct settingsBlock) + currentBlock->length;

        if (aKey == currentBlock->key)
        {
            if (currentIndex == aIndex)
            {
                nextBlockStart = i + currentBlockLength;

                if (nextBlockStart < sSettingsBufLength)
                {
                    memmove(&sSettingsBuf[i], &sSettingsBuf[nextBlockStart], sSettingsBufLength - nextBlockStart);
                }

                assert(sSettingsBufLength >= currentBlockLength);
                sSettingsBufLength -= currentBlockLength;

                error = OT_ERROR_NONE;
                break;
            }
            else
            {
                currentIndex++;
            }
        }

        i += currentBlockLength;
    }

    return error;
}

void otPlatSettingsWipe(otInstance *aInstance)
{
    otPlatSettingsInit(aInstance);
}

#endif // OPENTHREAD_SETTINGS_RAM