// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2022 - 2023 Thomas Basler and others
 */
#include "Utils.h"
#include <Esp.h>

uint32_t Utils::getChipId()
{
    uint32_t chipId = 0;
    for (int i = 0; i < 17; i += 8) {
        chipId |= ((ESP.getEfuseMac() >> (40 - i)) & 0xff) << i;
    }
    return chipId;
}

uint64_t Utils::generateDtuSerial()
{
    uint32_t chipId = getChipId();
    uint64_t dtuId = 0;

    // Product category (char 1-4): 1 = Micro Inverter, 999 = Dummy
    dtuId |= 0x199900000000;

    // Year of production (char 5): 1 equals 2015 so hard code 8 = 2022
    dtuId |= 0x80000000;

    // Week of production (char 6-7): Range is 1-52 s hard code 1 = week 1
    dtuId |= 0x0100000;

    // Running Number (char 8-12): Derived from the ESP chip id
    for (uint8_t i = 0; i < 5; i++) {
        dtuId |= (chipId % 10) << (i * 4);
        chipId /= 10;
    }

    return dtuId;
}

int Utils::getTimezoneOffset()
{
    // see: https://stackoverflow.com/questions/13804095/get-the-time-zone-gmt-offset-in-c/44063597#44063597

    time_t gmt, rawtime = time(NULL);
    struct tm* ptm;

    struct tm gbuf;
    ptm = gmtime_r(&rawtime, &gbuf);

    // Request that mktime() looksup dst in timezone database
    ptm->tm_isdst = -1;
    gmt = mktime(ptm);

    return static_cast<int>(difftime(rawtime, gmt));
}