"""
RF unit conversions.
"""

import math


def dbm_to_watts(dbm: float) -> float:
    """Convert dBm to watts."""
    return 10 ** ((dbm - 30) / 10)


def watts_to_dbm(watts: float) -> float:
    """Convert watts to dBm."""
    if watts <= 0:
        return -float('inf')
    return 10 * math.log10(watts) + 30


def dbm_to_mw(dbm: float) -> float:
    """Convert dBm to milliwatts."""
    return 10 ** (dbm / 10)


def mw_to_dbm(mw: float) -> float:
    """Convert milliwatts to dBm."""
    if mw <= 0:
        return -float('inf')
    return 10 * math.log10(mw)


def frequency_to_wavelength(frequency_mhz: float) -> float:
    """Convert frequency (MHz) to wavelength (meters)."""
    return 300.0 / frequency_mhz


def wavelength_to_frequency(wavelength_m: float) -> float:
    """Convert wavelength (meters) to frequency (MHz)."""
    return 300.0 / wavelength_m


def eirp_dbm(power_dbm: float, gain_dbi: float) -> float:
    """Calculate EIRP in dBm."""
    return power_dbm + gain_dbi


def eirp_watts(power_dbm: float, gain_dbi: float) -> float:
    """Calculate EIRP in watts."""
    return dbm_to_watts(power_dbm + gain_dbi)


def path_loss_to_signal_dbm(power_dbm: float, gain_dbi: float, path_loss_db: float) -> float:
    """Calculate received signal level in dBm from EIRP and path loss."""
    return power_dbm + gain_dbi - path_loss_db