#include <Arduino.h>

#include <Wire.h>

#include <DS3231.h>

void DS3231::begin()
{
    Wire.begin();
}

uint8_t DS3231::getSeconds()
{
    uint8_t seconds;
    // read minutes
    seconds = getRegister(DS3231_SECONDS);
    return bcdtodec(seconds);
}

void DS3231::setSeconds(uint8_t seconds)
{
    // write seconds
    setRegister(DS3231_SECONDS, dectobcd(seconds));
}

void DS3231::incrementSeconds()
{
    uint8_t seconds = getSeconds();

    if (seconds == 58)
    {
        seconds = 0;
    }
    else
    {
        seconds += 2;
    }

    setSeconds(seconds);
}

void DS3231::decrementSeconds()
{
    uint8_t seconds = getSeconds();

    if (seconds == 1)
    {
        seconds = 59;
    }
    else
    {
        seconds -= 2;
    }

    setSeconds(seconds);
}

uint8_t DS3231::getMinutes()
{
    uint8_t minutes;
    // read minutes
    minutes = getRegister(DS3231_MINUTES);
    return bcdtodec(minutes);
}

void DS3231::setMinutes(uint8_t minutes)
{
    // write minutes
    setRegister(DS3231_MINUTES, dectobcd(minutes));
}

void DS3231::incrementMinutes()
{
    uint8_t minutes = getMinutes();

    if (minutes == 59)
    {
        minutes = 0;
    }
    else
    {
        minutes++;
    }

    setMinutes(minutes);
}

void DS3231::decrementMinutes()
{
    uint8_t minutes = getMinutes();

    if (minutes == 0)
    {
        minutes = 59;
    }
    else
    {
        minutes--;
    }

    setMinutes(minutes);
}

uint8_t DS3231::getHours()
{
    uint8_t hours;
    // read hours
    hours = getRegister(DS3231_HOURS);
    return bcdtodec(hours);
}

void DS3231::setHours(uint8_t hours)
{
    // write hours
    setRegister(DS3231_HOURS, dectobcd(hours));
}

void DS3231::incrementHours()
{
    uint8_t hours = getHours();

    if (hours == 23)
    {
        hours = 0;
    }
    else
    {
        hours++;
    }

    setHours(hours);
}

void DS3231::decrementHours()
{
    uint8_t hours = getHours();

    if (hours == 0)
    {
        hours = 23;
    }
    else
    {
        hours--;
    }

    setHours(hours);
}

uint8_t DS3231::getDay()
{
    uint8_t day;
    // read day
    day = getRegister(DS3231_DAY);
    return bcdtodec(day);
}

void DS3231::setDay(uint8_t day)
{
    // write day
    setRegister(DS3231_DAY, dectobcd(day));
}

uint8_t DS3231::getDate()
{
    uint8_t date;
    // read date
    date = getRegister(DS3231_DATE);
    return bcdtodec(date);
}

void DS3231::setDate(uint8_t date)
{
    // write date
    setRegister(DS3231_DATE, dectobcd(date));
}

void DS3231::incrementDate()
{
    uint8_t date = getDate();
    date++;
    if (date > 31)
    {
        date = 1;
    }
    setDate(date);
}

void DS3231::decrementDate()
{
    uint8_t date = getDate();
    date--;
    if (date < 1)
    {
        date = 31;
    }
    setDate(date);
}

uint8_t DS3231::getMonth()
{
    uint8_t month;
    // read month
    month = getRegister(DS3231_MONTH);

    // read month, ingore century;
    return bcdtodec(month & 0x1F);
}

void DS3231::setMonth(uint8_t month)
{
    uint8_t century = getCentury();

    month = dectobcd(month);

    if (century == 1)
    {
        month = month + 0x80;
    }

    // write month
    setRegister(DS3231_MONTH, month);
}

void DS3231::incrementMonth()
{
    uint8_t month = getMonth();
    month++;
    if (month > 12)
    {
        month = 1;
    }
    setMonth(month);
}

void DS3231::decrementMonth()
{
    uint8_t month = getMonth();
    month--;
    if (month < 1)
    {
        month = 12;
    }
    setMonth(month);
}

int16_t DS3231::getYear()
{
    uint8_t century = getCentury();

    int16_t year;

    // read year
    year = getRegister(DS3231_YEAR);

    year = bcdtodec(year);

    if (century == 1)
    {
        year = 2000 + year;
    }
    else
    {
        year = 1900 + year;
    }

    return year;
}

void DS3231::setYear(int16_t year)
{
    if (year > 1999)
    {
        year = year - 2000;
        setCentury(0x80);
    }
    else
    {
        year = year - 1900;
        setCentury(0);
    }

    setRegister(DS3231_YEAR, dectobcd(year));
}

void DS3231::incrementYear()
{
    int16_t year = getYear();
    year++;
    if (year > 2099)
    {
        year = 1900;
    }
    setYear(year);
}

void DS3231::decrementYear()
{
    int16_t year = getYear();
    year--;
    if (year < 1900)
    {
        year = 2099;
    }
    setYear(year);
}

uint8_t DS3231::getControlRegister()
{
    return bcdtodec(getRegister(DS3231_CONTROL));
}

void DS3231::setControlRegister(uint8_t value)
{
    setRegister(DS3231_CONTROL, dectobcd(value));
}

uint8_t DS3231::getStatusRegister()
{
    return bcdtodec(getRegister(DS3231_STATUS));
}

void DS3231::setStatusRegister(uint8_t value)
{
    setRegister(DS3231_STATUS, dectobcd(value));
}

uint8_t DS3231::getTemperature()
{
    int8_t msb_temp;
    uint8_t msb_value = getRegister(DS3231_MSB_TEMP);
    uint8_t lsb_temp = getRegister(DS3231_LSB_TEMP) >> 6;
    float result;

    if ((msb_value & 0x80) != 0)
    {
        msb_temp = msb_value | ~((1 << 8) - 1);
    }
    else
    {
        msb_temp = msb_value;
    }

    result = 0.25 * lsb_temp + msb_temp;

    return result;
}

uint8_t DS3231::getRegister(uint8_t address)
{
    uint8_t value;

    Wire.beginTransmission(DS3231_I2C_ADDRESS);
    Wire.write(address);
    Wire.endTransmission();

    // request 1 byte
    Wire.requestFrom(DS3231_I2C_ADDRESS, 1);

    // read value
    value = Wire.read();

    return value;
}

void DS3231::setRegister(uint8_t address, uint8_t value)
{
    Wire.beginTransmission(DS3231_I2C_ADDRESS);
    // start at address
    Wire.write(address);

    // write value
    Wire.write(value);

    Wire.endTransmission();
}

uint8_t DS3231::dectobcd(uint8_t value)
{
    return ((value / 10 * 16) + (value % 10));
}

uint8_t DS3231::bcdtodec(uint8_t value)
{
    return ((value / 16 * 10) + (value % 16));
}

uint8_t DS3231::getCentury()
{
    uint8_t century = 0;

    uint8_t month = getRegister(DS3231_MONTH);

    // read century from month
    century = (month & 0x80) >> 7;
    return century;
}

void DS3231::setCentury(uint8_t century)
{
    uint8_t month = getMonth();

    month = month + century;

    setRegister(DS3231_MONTH, month);
}