import scipy.io.wavfile
import scipy.signal
import numpy
import argparse
import logging

LOG_LEVELS = [logging.WARNING, logging.INFO, logging.DEBUG]
LOGGER=logging.getLogger(__name__)


def parse_args(*args):
    """ get the CLI args """

    parser = argparse.ArgumentParser(prog="granule",
        description="Extract granules from a wav file")
    parser.add_argument('input', nargs='*', help="Input filename")
    parser.add_argument('-p', '--playlist', help="Input playlist")
    parser.add_argument('-o', '--output', help="Output filename")
    parser.add_argument("-v", "--verbosity", action="count",
                        help="increase output verbosity",
                        default=0)

    return parser.parse_args(*args)

def normalize(buffer):
    amplitude = max(numpy.max(buffer), -numpy.min(buffer))
    return buffer/amplitude;

def accumulate(filename, buffer):
    """ Accumulates a song into the accumulation buffer """
    LOGGER.info("Reading %s", filename)
    rate, data = scipy.io.wavfile.read(filename)

    if len(data.shape) > 1:
        data = numpy.mean(data, axis=1)

    data = normalize(data)

    if rate != 44100:
        data = scipy.signal.resample(data, len(data)*44100 // rate)

    if buffer is None:
        return data

    out_len = max(len(buffer), len(data))
    if len(buffer) < out_len:
        buffer.resize(out_len, refcheck=False)
    if len(data) < out_len:
        data.resize(out_len, refcheck=False)

    buffer += data
    return buffer

def main():
    args = parse_args()
    logging.basicConfig(level=LOG_LEVELS[min(
        args.verbosity, len(LOG_LEVELS) - 1)])

    if args.playlist:
        with open(args.playlist) as file:
            for line in file:
                args.input.append(line.strip())

    output = None

    total = len(args.input)
    for num, infile in enumerate(args.input):
        output = accumulate(infile, output)

    output = normalize(output)

    LOGGER.info("Output file: %d samples (%.2f seconds)", len(output), len(output)/44100)
    if (args.output):
        scipy.io.wavfile.write(args.output, 44100, output)

if __name__ == "__main__":
    main()