"""Detect max volume."""

import re

import ffmpeg

from video.connectors import s3 as s3_connector
from video.constants import job_io_fields
from video.logic.activity_task_logger import activity_task_logger
from video.utils import text


JOB_INPUTS = [
    job_io_fields.INPUT_VIDEO_S3_BUCKET,
    job_io_fields.INPUT_VIDEO_S3_KEY,
]


@activity_task_logger(JOB_INPUTS)
def detect_max_volume(inputs):
    """Detect max volume.

    Args:
        inputs (dict): Inputs.

    Returns:
        dict: Outputs.
    """
    s3_bucket = inputs[job_io_fields.INPUT_VIDEO_S3_BUCKET]
    s3_key = inputs[job_io_fields.INPUT_VIDEO_S3_KEY]
    output_options = {
        'vn': None,  # don't process video stream
    }
    video_s3_url = s3_connector.get_url_for_s3_object(s3_bucket, s3_key)

    (stdout, stderr) = (
        ffmpeg
        .input(video_s3_url)
        .filter('volumedetect')
        .output('pipe:', format='null', **output_options)
        .run(capture_stderr=True)
    )
    max_volume_regex = r'max_volume:\s*(\S*)'

    stderr_lines = text.bytes_to_lines_of_text(stderr)

    outputs = {
        job_io_fields.MAX_VOLUME_DECIBELS: None,
    }

    for line in reversed(stderr_lines):
        max_volume_match = re.search(max_volume_regex, line)
        if not max_volume_match:
            continue

        [max_volume_decibels] = max_volume_match.groups()
        outputs[job_io_fields.MAX_VOLUME_DECIBELS] = float(max_volume_decibels)

        return outputs

    return outputs