"""Lambda handler for defining audio track similarity."""

import os
import time
import uuid

import ffmpy
import librosa
from fastdtw import fastdtw


DEFAULT_TMP_DIR = os.environ.get('DEFAULT_TMP_DIR')  # without ending backslash
FFMPEG_PATH = os.environ.get('FFMPEG', '/usr/local/bin/ffmpeg')
PCM_S16LE_CODEC = '-acodec pcm_s16le -ar 16000 -ac 1'


def time_usage(func):
    def wrapper(*args, **kwargs):
        beg_ts = time.time()
        retval = func(*args, **kwargs)
        end_ts = time.time()
        print("elapsed time: %f" % (end_ts - beg_ts))
        return retval
    return wrapper


def transcode_to_pcm(input_path):
    """Transcode input file to pcm encoded audio file by ffmpeg.

    Args:
        input_path (str): input file path

    Result:
        str: output wav file path. File has unique filename.
    """
    output_path = '{}/{}.wav'.format(DEFAULT_TMP_DIR, uuid.uuid4())
    ff = ffmpy.FFmpeg(
        executable=FFMPEG_PATH,  # add path to executable ffmpeg
        inputs={input_path: None},
        outputs={output_path: PCM_S16LE_CODEC}
    )
    ff.run()
    return output_path


@time_usage
def handler(event, context):
    """Handler method."""
    # Loading audio files
    y1, sr1 = librosa.load(transcode_to_pcm(event['output_path']))
    y2, sr2 = librosa.load(transcode_to_pcm(event['source_path']))

    mfcc1 = librosa.feature.mfcc(y1, sr1)   # Computing MFCC values
    mfcc2 = librosa.feature.mfcc(y2, sr2)

    dist = fastdtw(mfcc1.T, mfcc2.T)
    # print("The normalized distance between the two : ", dist)
    return {event['output_path']: dist[0]}


if __name__ == '__main__':
    events = [
        {
            'output_path': '/Users/maximov/Desktop/tmp/b-flac.flac',
            'source_path': '/Users/maximov/Desktop/tmp/b.wav'
        },
        {
            'output_path': '/Users/maximov/Desktop/tmp/b-mp3.mp3',
            'source_path': '/Users/maximov/Desktop/tmp/b.wav'
        },
        {
            'output_path': '/Users/maximov/Desktop/tmp/b-m4.m4a',
            'source_path': '/Users/maximov/Desktop/tmp/b.wav'
        },
        {
            'output_path': '/Users/maximov/Desktop/tmp/b-wav.wav',
            'source_path': '/Users/maximov/Desktop/tmp/b.wav'
        },
        {
            'output_path': '/Users/maximov/Desktop/tmp/b-1-muted.wav',
            'source_path': '/Users/maximov/Desktop/tmp/b.wav'
        },
        {
            'output_path': '/Users/maximov/Desktop/tmp/b-5-muted.wav',
            'source_path': '/Users/maximov/Desktop/tmp/b.wav'
        },
        {
            'output_path': '/Users/maximov/Desktop/tmp/b-001-muted.wav',
            'source_path': '/Users/maximov/Desktop/tmp/b.wav'
        }
    ]
    result_correlation = []
    for e in events:
        result_correlation.append(handler(e, None))

    for item in result_correlation:
        print(item)