"""Custom methods for validation of audio metadata."""

import trafaret as t

from constants import errors  # noqa
from constants import audio_standards  # noqa


def sample_rate_validation(audio_meta):
    """Validate sample_rate value for default schema.

    Args:
        audio_meta (dict): input audio metadata.
        {
            'sample_rate': 44100,
            'bits_per_sample': 16
        }
    Returns:
        dict: sample_rate value or trafaret.DataError exception.

    """
    bits_per_sample = audio_meta['bits_per_sample']
    sample_rate = audio_meta['sample_rate']
    if bits_per_sample not in audio_standards.ALLOWED_BIT_SAMPLE_RATE:
        error_message = errors.INVALID_INPUT_VALUE_ERROR_MESSAGE.format(
            name='bits_per_sample', expected=[16, 24]
        )
        return {'sample_rate': t.DataError(error_message)}
    available_sample_rates = (
        audio_standards.ALLOWED_BIT_SAMPLE_RATE[bits_per_sample])
    if sample_rate not in available_sample_rates:
        error_message = errors.INVALID_INPUT_VALUE_ERROR_MESSAGE.format(
            name='sample_rate', expected=available_sample_rates
        )
        return {'sample_rate': t.DataError(error_message)}

    return {'sample_rate': sample_rate}


def wav_bitrate_validation(audio_meta):
    """Validate bitrate value for wav schema.

    Args:
        audio_meta (dict): input audio metadata.
        {
            'bitrate': 1411318,
            'bits_per_sample': 16,
            'channels': 2,
            'sample_rate': 44100
        }
    Returns:
        dict: bitrate value or trafaret.DataError exception.

    """
    expected_bitrate = (
        audio_meta['channels'] * audio_meta['sample_rate'] *
        audio_meta['bits_per_sample']
    )
    if audio_meta['bitrate'] != expected_bitrate:
        error_message = errors.INVALID_INPUT_VALUE_ERROR_MESSAGE.format(
            name='bitrate', expected=expected_bitrate
        )
        return {'bitrate': t.DataError(error_message)}

    return {'bitrate': audio_meta['bitrate']}


def wav_file_size_validation(audio_meta):
    """Validate file_size value for wav schema.

    Args:
        audio_meta (dict): input audio metadata.
        {
            'file_size': 2560000,
            'playtime_seconds': 12000 # ms
        }
    Returns:
        dict: file_size value or trafaret.DataError exception.

    """
    file_size_minimum = (
        (audio_standards.FILE_SIZE_PER_SECOND
         * audio_meta['playtime_seconds']) / 1000
    )
    if file_size_minimum > audio_meta['file_size']:
        expected_file_size_msg = 'greater than {}'.format(file_size_minimum)
        error_message = errors.INVALID_INPUT_VALUE_ERROR_MESSAGE.format(
            name='file_size', expected=expected_file_size_msg
        )
        return {'file_size': t.DataError(error_message)}
    return {'file_size': audio_meta['file_size']}