def find_similarity(matches, current, source):
    """Function searches for a specific file similarity result among two files. 
        Since the direction of similarity can be in either way, lookup is done 
        in specified direction
    
    :param matches: Similarity detection results in JSON format
    :type matches: dict
    :param current: The name of the current file, assumed to copy from `source` 
        file
    :type current: str
    :param source: The name of assumed source file, this is the file that 
        `current` might have copied from 
    :type source: str
    :return: Similarity results among both files with `percentage` and number of 
        `lines` matched
    :rtype: dict
    """
    for file in matches["match_results"]:
        if file["file"] != source:
            continue

        for possible_source in file["possible_sources"]:
            if possible_source["file"] == current:
                return possible_source["similarity"]

    # If file had not been found, then there is no detected similarity between 
    # the files. Return no similarity scores
    return {
        "similarity": 0.0,
        "lines": 0
    }