#include "hardware_rtc.hpp"
#include <logger.hpp>


HardwareRTC::HardwareRTC(TwoWire& wire): wire(wire), initialized(false) {}

HardwareRTC::~HardwareRTC() {}

void HardwareRTC::begin() {
    if(wire.getClock() == 0) {
        wire.begin();
        wire.setClock(100000); // Set to 100kHz
    }
    initialized = true;
    LOG_DEBUG("RTC initialized");
    setSystemTime(0);
}

bool HardwareRTC::setTime(time_t unixTimestamp) {
    if (!initialized) {
        LOG_WARN("RTC not initialized");
        return false;
    }

    // Use time_t, which on ESP32 is 64-bit and safe for this conversion
    time_t t = unixTimestamp;
    struct tm timeStruct;
    gmtime_r(&t, &timeStruct);

    // Check if the year is within the DS1307's valid range (2000-2099)
    if (timeStruct.tm_year < 100 || timeStruct.tm_year > 199) {
        // Year is out of the 2000-2099 range that the DS1307 can store.
        LOG_ERROR("RTC setTime: Year %d is out of range (2000-2099)", timeStruct.tm_year + 1900);
        return false;
    }

    uint8_t buffer[7];
    buffer[0] = decToBcd(timeStruct.tm_sec);
    buffer[1] = decToBcd(timeStruct.tm_min);
    buffer[2] = decToBcd(timeStruct.tm_hour);
    buffer[3] = decToBcd(timeStruct.tm_wday + 1);
    buffer[4] = decToBcd(timeStruct.tm_mday);
    buffer[5] = decToBcd(timeStruct.tm_mon + 1);
    // The DS1307 only stores years 00-99. We handle this by taking the year since 2000.
    buffer[6] = decToBcd(timeStruct.tm_year - 100);

    writeRegisters(buffer, 7);

    // set system time to match RTC
    setSystemTime(0);

    LOG_DEBUG("RTC setTime: %s", toDateString(unixTimestamp).c_str());
    return true;
}

time_t HardwareRTC::getTime() {
    if (!initialized) return 0;

    uint8_t buffer[7];
    readRegisters(buffer, 7);

    struct tm timeStruct = {0}; // Important: Initialize the struct to zero
    timeStruct.tm_sec = bcdToDec(buffer[0] & 0x7F);
    timeStruct.tm_min = bcdToDec(buffer[1]);
    timeStruct.tm_hour = bcdToDec(buffer[2] & 0x3F);
    timeStruct.tm_wday = bcdToDec(buffer[3]) - 1;
    timeStruct.tm_mday = bcdToDec(buffer[4]);
    timeStruct.tm_mon = bcdToDec(buffer[5]) - 1;
    // Assume all 2-digit years from the RTC are in the 21st century (2000-2099)
    timeStruct.tm_year = bcdToDec(buffer[6]) + 100; // Years since 1900

    // mktime converts a local time struct to a time_t.
    // Since the RTC stores time without timezone info, we treat it as UTC.
    // timegm is the correct function for this, but mktime is often used
    // on embedded systems with the timezone set to UTC.
    time_t t = mktime(&timeStruct);

    LOG_DEBUG("RTC getTime: %s", toDateString(t).c_str());

    // Cast the 64-bit time_t to uint64_t for the return type
    return static_cast<time_t>(t);
}

void HardwareRTC::setSystemTime(int timezoneOffsetHours) {
    if (!initialized) {
        LOG_WARN("RTC not initialized");
        return;
    }


    uint64_t unixTime = getTime();
    if (unixTime == 0) return;

    unixTime += timezoneOffsetHours * 3600;

    LOG_DEBUG("RTC setSystemTime: %s", toDateString(unixTime).c_str());

    struct timeval tv;
    // The tv_sec field is of type time_t, which is 64-bit on ESP32
    tv.tv_sec = unixTime;
    tv.tv_usec = 0;
    settimeofday(&tv, NULL);
}


bool HardwareRTC::isRunning() {
    if (!initialized) return false;

    uint8_t buffer[1];
    readRegisters(buffer, 1);
    return !(buffer[0] & 0x80); // CH bit is 0 when running
}

void HardwareRTC::setTimezone(const char* timezone) {
    setenv("TZ", timezone, 1);
    tzset();
}

void HardwareRTC::update()
{
    static uint32_t nextSync = 0;
    time_t now = millis();
    if (now >= nextSync) {
        if(!isRunning()) {
            LOG_WARN("RTC is not running, skipping update");
            return;
        }
        setSystemTime(0);
        nextSync = now + (15UL * 60UL * 1000UL); // every 15 minutes
        LOG_DEBUG("RTC update: System time synchronized with RTC");
    }
}

String HardwareRTC::toDateString(time_t timestamp) {
    struct tm* timeinfo = gmtime(&timestamp);
    char buffer[40];
    strftime(buffer, sizeof(buffer), "%Y-%m-%d %H:%M:%S", timeinfo);
    return String(buffer);
}

uint8_t HardwareRTC::bcdToDec(uint8_t bcd) {
    return ((bcd >> 4) * 10) + (bcd & 0x0F);
}

uint8_t HardwareRTC::decToBcd(uint8_t dec) {
    return ((dec / 10) << 4) | (dec % 10);
}

void HardwareRTC::readRegisters(uint8_t* buffer, uint8_t length) {
    Wire.beginTransmission(DS1307_ADDRESS);
    Wire.write(0x00); // start at register 0
    Wire.endTransmission();

    Wire.requestFrom(DS1307_ADDRESS, length);
    for (uint8_t i = 0; i < length; i++) {
        buffer[i] = Wire.read();
    }
}

void HardwareRTC::writeRegisters(uint8_t* buffer, uint8_t length) {
    Wire.beginTransmission(DS1307_ADDRESS);
    Wire.write(0x00); // start at register 0
    for (uint8_t i = 0; i < length; i++) {
        Wire.write(buffer[i]);
    }
    Wire.endTransmission();
}