#!/usr/bin/env python3
"""
FR-2.2: Audio Data Validation
Validates audio metrics against expected ranges
"""

from typing import NamedTuple


class ValidationResult(NamedTuple):
    """Validation result"""

    valid: bool
    error: str = ""


class AudioValidator:
    """
    Validates audio metrics against hardware constraints and realistic ranges.
    """

    # Hardware constraints (from FR spec)
    RMS_MIN_DB = -40.0  # Noise floor
    RMS_MAX_DB = 80.0  # Clipping threshold

    FREQ_MIN_HZ = 100  # Below = unreliable (FFT bin size ~43Hz)
    FREQ_MAX_HZ = 8000  # Nyquist @ 22.05kHz with safety margin

    # Extended ranges for detection (not storage)
    FREQ_MIN_EXTENDED_HZ = 20
    FREQ_MAX_EXTENDED_HZ = 11000

    @staticmethod
    def validate_rms(rms_db: float) -> ValidationResult:
        """
        Validate RMS value.

        Args:
            rms_db: RMS in dB

        Returns:
            ValidationResult with valid flag and error message
        """
        if not isinstance(rms_db, (int, float)):
            return ValidationResult(False, "RMS must be numeric")

        if rms_db < AudioValidator.RMS_MIN_DB:
            return ValidationResult(
                False, f"RMS {rms_db:.1f}dB below minimum {AudioValidator.RMS_MIN_DB}dB"
            )

        if rms_db > AudioValidator.RMS_MAX_DB:
            return ValidationResult(
                False,
                f"RMS {rms_db:.1f}dB exceeds maximum {AudioValidator.RMS_MAX_DB}dB",
            )

        return ValidationResult(True)

    @staticmethod
    def validate_frequency(freq_hz: int, strict: bool = True) -> ValidationResult:
        """
        Validate frequency value.

        Args:
            freq_hz: Frequency in Hz
            strict: If True, use tight range (100-8000Hz), else extended (20-11000Hz)

        Returns:
            ValidationResult with valid flag and error message
        """
        if not isinstance(freq_hz, int):
            return ValidationResult(False, "Frequency must be integer")

        if strict:
            min_hz = AudioValidator.FREQ_MIN_HZ
            max_hz = AudioValidator.FREQ_MAX_HZ
        else:
            min_hz = AudioValidator.FREQ_MIN_EXTENDED_HZ
            max_hz = AudioValidator.FREQ_MAX_EXTENDED_HZ

        if freq_hz < min_hz:
            return ValidationResult(
                False, f"Frequency {freq_hz}Hz below minimum {min_hz}Hz"
            )

        if freq_hz > max_hz:
            return ValidationResult(
                False, f"Frequency {freq_hz}Hz exceeds maximum {max_hz}Hz"
            )

        return ValidationResult(True)

    @staticmethod
    def validate_packet(rms_db: float, freq_hz: int) -> ValidationResult:
        """
        Validate complete audio packet.

        Args:
            rms_db: RMS in dB
            freq_hz: Frequency in Hz

        Returns:
            ValidationResult with valid flag and error message
        """
        rms_result = AudioValidator.validate_rms(rms_db)
        if not rms_result.valid:
            return rms_result

        freq_result = AudioValidator.validate_frequency(freq_hz, strict=True)
        if not freq_result.valid:
            return freq_result

        return ValidationResult(True)