"""Detect silent intervals at beginning and end of audio."""

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,
    job_io_fields.VIDEO_STREAM_FRAME_RATE_FRAMES_PER_SECOND,
    job_io_fields.AUDIO_STREAM_DURATION_SECONDS,
]


@activity_task_logger(JOB_INPUTS)
def detect_silent_intervals_at_beginning_and_end_of_audio(inputs):
    """Detect silent intervals at beginning and end of audio.

    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]
    frames_per_second = inputs[
        job_io_fields.VIDEO_STREAM_FRAME_RATE_FRAMES_PER_SECOND]
    seconds_per_frame = 1 / frames_per_second
    duration_seconds = inputs[job_io_fields.AUDIO_STREAM_DURATION_SECONDS]

    # silencedetect parameters
    # https://ffmpeg.org/ffmpeg-filters.html#silencedetect
    duration = seconds_per_frame
    noise = '-90dB'
    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(
            'silencedetect',
            duration=duration,
            noise=noise,
        )
        .output('pipe:', format='null', **output_options)
        .run(capture_stderr=True)
    )
    silence_start_regex = r'silence_start:\s*(\S*)'
    silence_end_regex = r'silence_end:\s*(\S*)'

    stderr_lines = text.bytes_to_lines_of_text(stderr)

    outputs = {
        job_io_fields.SILENT_INTERVAL_AT_BEGINNING_ENDS_AT_SECONDS: None,
        job_io_fields.SILENT_INTERVAL_AT_END_BEGINS_AT_SECONDS: None,
    }
    silence_start = None
    silence_end = None

    for line in stderr_lines:
        silence_start_match = re.search(silence_start_regex, line)
        if silence_start_match:
            silence_start = float(silence_start_match.group(1))

        silence_end_match = re.search(silence_end_regex, line)
        if silence_end_match:
            silence_end = float(silence_end_match.group(1))

        if silence_start == 0 and silence_end:
            outputs[
                job_io_fields.SILENT_INTERVAL_AT_BEGINNING_ENDS_AT_SECONDS
            ] = silence_end

        if silence_end and silence_end >= duration_seconds:
            outputs[
                job_io_fields.SILENT_INTERVAL_AT_END_BEGINS_AT_SECONDS
            ] = silence_start

    return outputs