"""
Extract peaks from an MP3 file.
"""

import click

@click.command()
@click.option('-i', '--input', 'fp_in', required=True,
  help='Input file')
@click.pass_context
def cli(ctx, fp_in):
  """Extract peaks from an MP3 file.
  """
  import os
  import math
  import librosa
  import numpy
  import json

  from app.settings import app_cfg

  if not os.path.exists(fp_in):
    print(f"fp_in does not exist: {fp_in}")
    return

  print(f"Loading {fp_in}")
  y, sr = librosa.load(fp_in, sr=None)

  sr_10 = sr / 10
  steps = math.ceil(y.shape[0] / sr_10)

  peaks = numpy.ndarray(steps)

  for i in range(steps):
    offset_start = math.floor(i * sr_10)
    offset_end = math.ceil((i + 1) * sr_10)
    slice = y[offset_start:offset_end]
    peak = max(abs(slice.min()), slice.max())
    peaks[i] = float('%.3f' % peak)
    # peaks[i * 2 + 1] = float('%.3f' % slice.max())

  with open(os.path.join(app_cfg.DIR_DATA_STORE, 'peaks/peaks.json'), 'w') as fp_out:
    json.dump(peaks.tolist(), fp_out, separators=(',', ':'))

  print("Wrote peaks.json")