import time
from machine import I2C, Pin, RTC

class PCF85063:
    """Utility class for the PCF85063 Real-Time Clock (RTC) chip."""
    ADDR = 0x51
    
    # Starting register for timekeeping data
    TIME_REG_START = 0x04

    def __init__(self, i2c=None):
        if i2c is None:
            # Default to ESP32-S3-RLCD-4.2 onboard I2C pins
            from machine import SoftI2C
            self.i2c = SoftI2C(sda=Pin(13), scl=Pin(14))
        else:
            self.i2c = i2c
            
        # Initialize RTC if needed (ensure oscillator is running)
        self._init_rtc()

    def _init_rtc(self):
        try:
            # Control register 1 (0x00) should be 0 to ensure oscillator is not stopped (bit 5 = STOP)
            ctrl1 = self.i2c.readfrom_mem(self.ADDR, 0x00, 1)[0]
            if ctrl1 & 0x20: # Oscillator is stopped
                print("RTC oscillator was stopped. Starting oscillator...")
                self.i2c.writeto_mem(self.ADDR, 0x00, b'\x00')
        except Exception as e:
            print(f"Error initializing PCF85063: {e}")

    def _dec2bcd(self, val):
        return (val // 10 << 4) | (val % 10)

    def _bcd2dec(self, val):
        return ((val >> 4) * 10) + (val & 0x0F)

    def get_datetime(self):
        """Reads current time from hardware RTC.
        
        Returns:
            tuple: (year, month, day, weekday, hour, minute, second) or None on error.
                   Note: year is 4-digit (e.g. 2026).
        """
        try:
            # Read 7 registers: Seconds, Minutes, Hours, Days, Weekdays, Months, Years
            data = self.i2c.readfrom_mem(self.ADDR, self.TIME_REG_START, 7)
            
            second = self._bcd2dec(data[0] & 0x7F) # Bit 7 is integrity flag OS
            minute = self._bcd2dec(data[1] & 0x7F)
            hour = self._bcd2dec(data[2] & 0x3F)   # 24-hour mode
            day = self._bcd2dec(data[3] & 0x3F)
            weekday = data[4] & 0x07               # 0-6
            month = self._bcd2dec(data[5] & 0x1F)
            year = 2000 + self._bcd2dec(data[6])   # 0-99 mapping to 2000-2099
            
            return (year, month, day, weekday, hour, minute, second)
        except Exception as e:
            print(f"Error reading PCF85063 RTC: {e}")
            return None

    def set_datetime(self, dt):
        """Sets the hardware RTC time.
        
        Args:
            dt (tuple): (year, month, day, weekday, hour, minute, second)
                        Note: year can be 4-digit (e.g. 2026) or 2-digit (e.g. 26).
        """
        try:
            year, month, day, weekday, hour, minute, second = dt
            
            # Format to registers
            reg_year = year % 100
            
            data = bytearray(7)
            data[0] = self._dec2bcd(second) & 0x7F  # Clear OS bit (re-starts oscillator integrity check)
            data[1] = self._dec2bcd(minute)
            data[2] = self._dec2bcd(hour)
            data[3] = self._dec2bcd(day)
            data[4] = weekday & 0x07
            data[5] = self._dec2bcd(month)
            data[6] = self._dec2bcd(reg_year)
            
            self.i2c.writeto_mem(self.ADDR, self.TIME_REG_START, data)
            return True
        except Exception as e:
            print(f"Error setting PCF85063 RTC: {e}")
            return False

    def sync_to_system(self):
        """Synchronizes the ESP32-S3 internal system time from this hardware RTC."""
        dt = self.get_datetime()
        if dt:
            year, month, day, weekday, hour, minute, second = dt
            # machine.RTC.datetime requires 8-tuple: (year, month, day, weekday, hour, minute, second, subseconds)
            sys_rtc = RTC()
            sys_rtc.datetime((year, month, day, weekday, hour, minute, second, 0))
            print(f"System clock synced to RTC: {year:04d}-{month:02d}-{day:02d} {hour:02d}:{minute:02d}:{second:02d}")
            return True
        return False

    def sync_from_system(self):
        """Synchronizes the hardware RTC time from the ESP32-S3 system clock."""
        try:
            # Get current system time (localtime tuple: year, month, mday, hour, minute, second, weekday, yearday)
            t = time.localtime()
            # mapping time.localtime() weekday to PCF85063:
            # Python weekday (0=Monday...6=Sunday)
            dt = (t[0], t[1], t[2], t[6], t[3], t[4], t[5])
            success = self.set_datetime(dt)
            if success:
                print(f"RTC synced from System: {t[0]:04d}-{t[1]:02d}-{t[2]:02d} {t[3]:02d}:{t[4]:02d}:{t[5]:02d}")
            return success
        except Exception as e:
            print(f"Error syncing RTC from system: {e}")
            return False
            
    def get_time_string(self):
        """Returns current time as a formatted string: YYYY-MM-DD HH:MM:SS"""
        dt = self.get_datetime()
        if dt:
            return f"{dt[0]:04d}-{dt[1]:02d}-{dt[2]:02d} {dt[4]:02d}:{dt[5]:02d}:{dt[6]:02d}"
        return "0000-00-00 00:00:00"