"""
BatteryManager - Android-inspired battery and power information API.

Provides direct query access to battery voltage, charge percentage, and raw ADC values.
Handles ADC1/ADC2 pin differences on ESP32-S3 with adaptive caching to minimize WiFi interference.
"""

import time

MIN_VOLTAGE = 3.15
MAX_VOLTAGE = 4.15

# Internal state
_adc = None
_conversion_func = None
_adc_pin = None

# Cache to reduce WiFi interruptions (ADC2 requires WiFi to be disabled)
_cached_raw_adc = None
_last_read_time = 0
CACHE_DURATION_ADC1_MS = 30000   # 30 seconds (cheaper: no WiFi interference)
CACHE_DURATION_ADC2_MS = 600000  # 600 seconds (expensive: requires WiFi disable)


def _is_adc2_pin(pin):
    """Check if pin is on ADC2 (ESP32-S3: GPIO11-20)."""
    return 11 <= pin <= 20


class BatteryManager:
    """
    Android-inspired BatteryManager for querying battery and power information.
    
    Provides static methods for battery voltage, percentage, and raw ADC readings.
    Automatically handles ADC1/ADC2 differences and WiFi coordination on ESP32-S3.
    """

    @staticmethod
    def init_adc(pinnr, adc_to_voltage_func):
        """
        Initialize ADC for battery voltage monitoring.

        IMPORTANT for ESP32-S3: ADC2 (GPIO11-20) doesn't work when WiFi is active!
        Use ADC1 pins (GPIO1-10) for battery monitoring if possible.
        If using ADC2, WiFi will be temporarily disabled during readings.

        Args:
            pinnr: GPIO pin number
            adc_to_voltage_func: Conversion function that takes raw ADC value (0-4095)
                                 and returns battery voltage in volts
        """
        global _adc, _conversion_func, _adc_pin

        _conversion_func = adc_to_voltage_func
        _adc_pin = pinnr

        try:
            print(f"Initializing ADC pin {pinnr} with conversion function")
            if _is_adc2_pin(pinnr):
                print(f"  WARNING: GPIO{pinnr} is on ADC2 - WiFi will be disabled during readings")
            from machine import ADC, Pin
            _adc = ADC(Pin(pinnr))
            _adc.atten(ADC.ATTN_11DB)  # 0-3.3V range
        except Exception as e:
            print(f"Info: this platform has no ADC for measuring battery voltage: {e}")

        initial_adc_value = BatteryManager.read_raw_adc()
        print(f"Reading ADC at init to fill cache: {initial_adc_value} => {BatteryManager.read_battery_voltage(raw_adc_value=initial_adc_value)}V => {BatteryManager.get_battery_percentage(raw_adc_value=initial_adc_value)}%")

    @staticmethod
    def has_battery():
        """
        Check if battery monitoring is initialized.

        Returns:
            bool: True if init_adc() was called, False otherwise
        """
        return _adc_pin is not None

    @staticmethod
    def read_raw_adc(force_refresh=False):
        """
        Read raw ADC value (0-4095) with adaptive caching.

        On ESP32-S3 with ADC2, WiFi is temporarily disabled during reading.
        Raises RuntimeError if WifiService is busy (connecting/scanning) when using ADC2.

        Args:
            force_refresh: Bypass cache and force fresh reading

        Returns:
            float: Raw ADC value (0-4095)

        Raises:
            RuntimeError: If WifiService is busy (only when using ADC2)
        """
        global _cached_raw_adc, _last_read_time

        # Desktop mode - return random value in typical ADC range
        if not _adc:
            import random
            return random.randint(1900, 2600)

        # Check if this is an ADC2 pin (requires WiFi disable)
        needs_wifi_disable = _adc_pin is not None and _is_adc2_pin(_adc_pin)

        # Use different cache durations based on cost
        cache_duration = CACHE_DURATION_ADC2_MS if needs_wifi_disable else CACHE_DURATION_ADC1_MS

        # Check cache
        current_time = time.ticks_ms()
        if not force_refresh and _cached_raw_adc is not None:
            age = time.ticks_diff(current_time, _last_read_time)
            if age < cache_duration:
                return _cached_raw_adc

        # Import WifiService only if needed
        WifiService = None
        if needs_wifi_disable:
            try:
                # Needs actual path, not "from mpos" shorthand because it's mocked by test_battery_voltage.py
                from mpos.net.wifi_service import WifiService
            except ImportError:
                pass

        # Temporarily disable WiFi for ADC2 reading
        was_connected = False
        if needs_wifi_disable and WifiService:
            # This will raise RuntimeError if WiFi is already busy
            was_connected = WifiService.temporarily_disable()
            time.sleep(0.05)  # Brief delay for WiFi to fully disable

        try:
            # Read ADC (average of 10 samples)
            total = sum(_adc.read() for _ in range(10))
            raw_value = total / 10.0

            # Update cache
            _cached_raw_adc = raw_value
            _last_read_time = current_time

            return raw_value

        finally:
            # Re-enable WiFi (only if we disabled it)
            if needs_wifi_disable and WifiService:
                WifiService.temporarily_enable(was_connected)

    @staticmethod
    def read_battery_voltage(force_refresh=False, raw_adc_value=None):
        """
        Read battery voltage in volts.

        Args:
            force_refresh: Bypass cache and force fresh reading
            raw_adc_value: Optional pre-computed raw ADC value (for testing)

        Returns:
            float: Battery voltage in volts (clamped to 0-MAX_VOLTAGE)
        """
        raw = raw_adc_value if raw_adc_value else BatteryManager.read_raw_adc(force_refresh)
        voltage = _conversion_func(raw) if _conversion_func else 0.0
        return voltage

    @staticmethod
    def get_battery_percentage(raw_adc_value=None):
        """
        Get battery charge percentage.

        Args:
            raw_adc_value: Optional pre-computed raw ADC value (for testing)

        Returns:
            float: Battery percentage (0-100)
        """
        voltage = BatteryManager.read_battery_voltage(raw_adc_value=raw_adc_value)
        percentage = (voltage - MIN_VOLTAGE) * 100.0 / (MAX_VOLTAGE - MIN_VOLTAGE)
        return max(0, min(100.0, percentage))  # limit to 100.0% and make sure it's positive

    @staticmethod
    def clear_cache():
        """Clear the battery voltage cache to force fresh reading on next call."""
        global _cached_raw_adc, _last_read_time
        _cached_raw_adc = None
        _last_read_time = 0