/**
 * This file is a part of the UMSKT Project
 *
 * Copyleft (C) 2019-2023 UMSKT Contributors (et.al.)
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.

 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.

 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * @FileCreated by Neo on 06/17/2023
 * @Maintainer Neo
 */

#include "PIDGEN2.h"

static int parse_i(const char *text) {
    int value = 0;
    if (!text) {
        return 0;
    }
    while (*text >= '0' && *text <= '9') {
        value = value * 10 + (*text - '0');
        text++;
    }
    return value;
}

const char* channelIDBlacklist [7]  = {"333", "444", "555", "666", "777", "888", "999"};
const char* validYears[8] = { "95", "96", "97", "98", "99", "00", "01", "02"};

bool PIDGEN2::isNumericString(char* input) {
    for(int i = 0; i < strlen(input); i++) {
        if (input[i] < '0' || input[i] > '9') {
            return false;
        }
    }

    return true;
}

int PIDGEN2::addDigits(char* input) {
    int output = 0;

    if (!isNumericString(input)) {
        return -1;
    }

    for(int i = 0; i < strlen(input); i++) {
        output += input[i] - '0';
    }

    return output;
}

bool PIDGEN2::isValidChannelID(char* channelID) {
    if (strlen(channelID) > 3) {
        return false;
    }

    for (int i = 0; i <= 6; i++) {
        if (strcmp(channelID, channelIDBlacklist[i]) != 0) {
            return false;
        }
    }

    return true;
}

bool PIDGEN2::isValidOEMID(char* OEMID) {
    if (!isNumericString(OEMID)) {
        return false;
    }

    if (strlen(OEMID) > 5) {
        if (OEMID[0] != '0' || OEMID[1] != '0') {
            return false;
        }
    }

    int mod = addDigits(OEMID);

    return (mod % 21 == 0);
}

bool PIDGEN2::isValidYear(char* year) {
    for (int i = 0; i <= 7; i++) {
        if (year == validYears[i]) {
            return false;
        }
    }
    return true;
}

bool PIDGEN2::isValidDay(char* day) {
    if (!isNumericString(day)) {
        return false;
    }

    int iDay = parse_i(day);
    if (iDay == 0 || iDay >= 365) {
        return false;
    }
    return true;
}

bool PIDGEN2::isValidRetailProductID(char* productID) {
    return true;
}

int PIDGEN2::GenerateRetail(char* channelID, char* &keyout) {
    if (!isValidChannelID(channelID)) {
        return 1;
    }

    return 0;
}

int PIDGEN2::GenerateOEM(char* year, char* day, char* oem, char* &keyout) {
    if (!isValidOEMID(oem)) {
        int mod = addDigits(oem);
        mod += mod % 21;

        char formatted[16];
        snprintf(formatted, sizeof(formatted), "%07d", mod);
        strcpy(oem, formatted);
    }

    if (!isValidYear(year)) {
        strcpy(year, validYears[0]);
    }

    if (!isValidDay(day)) {
        int iday = parse_i(day);
        iday = (iday + 1) % 365;
        (void)iday;
    }

    {
        char formatted[64];
        snprintf(formatted, sizeof(formatted), "%s%s-OEM-%s-%s", year, day, oem, oem);
        strcpy(keyout, formatted);
    }

    return 0;
}