"""CircuitPython PCF85063 Real-Time Clock (RTC) driver.

Synchronizes the hardware RTC with CircuitPython's native rtc.RTC() system clock.
"""

import rtc
import time

class PCF85063:
    ADDR = 0x51
    TIME_REG_START = 0x04

    def __init__(self, i2c):
        self.i2c = i2c
        self._init_rtc()

    def read_reg(self, reg, n=1):
        while not self.i2c.try_lock():
            pass
        try:
            self.i2c.writeto(self.ADDR, bytes([reg]))
            buf = bytearray(n)
            self.i2c.readfrom_into(self.ADDR, buf)
            return buf
        except Exception as e:
            print(f"RTC read failed at reg 0x{reg:02X}: {e}")
            return None
        finally:
            self.i2c.unlock()

    def write_reg(self, reg, data):
        while not self.i2c.try_lock():
            pass
        try:
            payload = bytearray([reg])
            if isinstance(data, (bytes, bytearray, list)):
                payload.extend(data)
            else:
                payload.append(data)
            self.i2c.writeto(self.ADDR, payload)
            return True
        except Exception as e:
            print(f"RTC write failed at reg 0x{reg:02X}: {e}")
            return False
        finally:
            self.i2c.unlock()

    def _init_rtc(self):
        ctrl1 = self.read_reg(0x00, 1)
        if ctrl1 is not None and (ctrl1[0] & 0x20):
            print("RTC oscillator was stopped. Starting oscillator...")
            self.write_reg(0x00, 0x00)

    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.
        """
        data = self.read_reg(self.TIME_REG_START, 7)
        if data is None:
            return None

        second = self._bcd2dec(data[0] & 0x7F)
        minute = self._bcd2dec(data[1] & 0x7F)
        hour = self._bcd2dec(data[2] & 0x3F)
        day = self._bcd2dec(data[3] & 0x3F)
        weekday = data[4] & 0x07
        month = self._bcd2dec(data[5] & 0x1F)
        year = 2000 + self._bcd2dec(data[6])

        return (year, month, day, weekday, hour, minute, second)

    def set_datetime(self, dt):
        """Sets the hardware RTC time.

        Args:
            dt (tuple): (year, month, day, weekday, hour, minute, second)
        """
        try:
            year, month, day, weekday, hour, minute, second = dt
            reg_year = year % 100

            data = bytearray(7)
            data[0] = self._dec2bcd(second) & 0x7F
            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)

            return self.write_reg(self.TIME_REG_START, data)
        except Exception as e:
            print(f"Error setting PCF85063 RTC: {e}")
            return False

    def sync_to_system(self):
        """Synchronizes the CircuitPython system time from the hardware RTC."""
        dt = self.get_datetime()
        if dt:
            year, month, day, weekday, hour, minute, second = dt
            r = rtc.RTC()
            r.datetime = time.struct_time((year, month, day, hour, minute, second, weekday, -1, -1))
            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 system clock."""
        try:
            t = time.localtime()
            dt = (t.tm_year, t.tm_mon, t.tm_mday, t.tm_wday, t.tm_hour, t.tm_min, t.tm_sec)
            success = self.set_datetime(dt)
            if success:
                print(f"RTC synced from System: {t.tm_year:04d}-{t.tm_mon:02d}-{t.tm_mday:02d} {t.tm_hour:02d}:{t.tm_min:02d}:{t.tm_sec:02d}")
            return success
        except Exception as e:
            print(f"Error syncing RTC from system: {e}")
            return False

    def get_time_string(self):
        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"