import subprocess as sp

from ..utils import *
from .. import _HAS_MEDIAINFO


def mprobe(filename):
    """get metadata by using mediainfo

    Checks the output of mediainfo on the desired video
    file. Data is then parsed into a dictionary and
    checked for video data. If no such video data exists,
    an empty dictionary is returned.

    Parameters
    ----------
    filename : string
        Path to the video file

    Returns
    -------
    mediaDict : dict
       Dictionary containing all header-based information 
       about the passed-in source video.

    """
    assert _HAS_MEDIAINFO, "`mediainfo` not found in path. Is it installed?"

    try:
        # '-f' gets full output, and --Output=XML is xml formatted output
        command = ["mediainfo", "-f", "--Output=XML", filename]

        # simply get std output
        xml = check_output(command)

        d = xmltodictparser(xml)

        assert "Mediainfo" in d
        d = d["Mediainfo"]

        assert "File" in d
        d = d["File"]

        assert "track" in d
        unorderedtracks = d["track"]

        # tracksbytype normalizes the input by key
        tracksbytype = {}
        if type(unorderedtracks) is list:
            for d in unorderedtracks:
                assert "@type" in d
                # can't have more than 1 key. If this case arises
                # an issue should be made in the tracker for a fix.
                assert d["@type"] not in tracksbytype 
                tracksbytype[d["@type"]] = d
        else: # not list
            assert "@type" in unorderedtracks
            tracksbytype[unorderedtracks["@type"]] = unorderedtracks

        return tracksbytype
    except:
        return {}
