"""CircuitPython Battery Monitor utility.

Wraps analogio.AnalogIn to read voltage via a 2x divider and estimate capacity.
"""

import analogio
import board

class BatteryMonitor:
    def __init__(self, pin=board.IO9):
        self.adc = analogio.AnalogIn(pin)

    def read_voltage(self):
        try:
            # AnalogIn value is 16-bit (0-65535). Map to 3.3V reference.
            # Divider is 2x, so actual voltage is scale * 2.
            raw = self.adc.value
            voltage = (raw / 65535.0) * 3.3 * 2.0
            return round(voltage, 3)
        except Exception as e:
            print(f"Error reading battery ADC: {e}")
            return None

    def read_percentage(self):
        voltage = self.read_voltage()
        if voltage is None:
            return 0
        v_min = 3.0
        v_max = 4.2
        if voltage <= v_min:
            return 0
        if voltage >= v_max:
            return 100
        pct = (voltage - v_min) / (v_max - v_min) * 100.0
        return int(pct)

    def get_status_summary(self):
        v = self.read_voltage()
        p = self.read_percentage()
        if v is None:
            return "Battery: Error"
        return f"Battery: {v:.2f}V ({p}%)"