function getNamesByTag(tag) {
    elements = document.getElementsByClassName(tag);
    names = []
    for (var i=0; i < elements.length; i++) {
        name = elements[i].children[1].text;
        names.push(name);
    }
    return names;
}

function getImage() {
    image = document.getElementById('image');
    return image;
}

function getImageUrl() {
    url = getImage().src;
    return url;
}

function getImageId(url) {
    id = url.split('_')[1].split('.')[0];
    return id;
}

function getImageExt(url) {
    ext = url.split('_')[1].split('.')[1];
    return ext;
}

function insertAfter(newNode, referenceNode) {
    referenceNode.parentNode.insertBefore(newNode, referenceNode.nextSibling);
}

char_names = getNamesByTag('tag-type-character');
artist_names = getNamesByTag('tag-type-artist');
copyright_names = getNamesByTag('tag-type-copyright');

image_url = getImageUrl()
image_id = getImageId(url);
image_ext = getImageExt(url);

image_name = '__' + char_names.join(' and ') +
    '_' + copyright_names.join(' and ') +
    '_drawn_by_' + artist_names.join(' and ') +
    '__' + image_id + '.' + image_ext;
image_name = image_name.replace(/\s/g, '_');

var link = document.createElement('a');
link.setAttribute('href', image_url);
link.setAttribute('download', image_name);
link.text = 'Click to save';
image_element = getImage();
insertAfter(link, image_element);