extract_figures.py

#!/usr/bin/env python

import sys
import os
import glob
from optparse import OptionParser

from util import Reporter, read_markdown, IMAGE_FILE_SUFFIX


def main():
    """Main driver."""

    args = parse_args()
    images = []
    for filename in args.filenames:
        images += get_images(args.parser, filename)
    save(sys.stdout, images)


def parse_args():
    """Parse command-line arguments."""

    parser = OptionParser()
    parser.add_option('-p', '--parser',
                      default=None,
                      dest='parser',
                      help='path to Markdown parser')

    args, extras = parser.parse_args()
    require(args.parser is not None,
            'Path to Markdown parser not provided')
    require(extras,
            'No filenames specified')

    args.filenames = extras
    return args


def get_filenames(source_dir):
    """Get all filenames to be searched for images."""

    return glob.glob(os.path.join(source_dir, '*.md'))


def get_images(parser, filename):
    """Extract all images from file."""

    content = read_markdown(parser, filename)
    result = []
    find_image_nodes(content['doc'], result)
    find_image_links(content['doc'], result)
    return result


def find_image_nodes(doc, result):
    """Find all nested nodes representing images."""

    if (doc['type'] == 'img') or \
       ((doc['type'] == 'html_element') and (doc['value'] == 'img')):
        alt = doc['attr'].get('alt', '')
        result.append({'alt': alt, 'src': doc['attr']['src']})
    else:
        for child in doc.get('children', []):
            find_image_nodes(child, result)


def find_image_links(doc, result):
    """Find all links to files in the 'fig' directory."""

    if ((doc['type'] == 'a') and ('attr' in doc) and ('href' in doc['attr'])) \
       or \
       ((doc['type'] == 'html_element') and (doc['value'] == 'a') and ('href' in doc['attr'])):
        path = doc['attr']['href']
        if os.path.splitext(path)[1].lower() in IMAGE_FILE_SUFFIX:
            result.append({'alt':'', 'src': doc['attr']['href']})
    else:
        for child in doc.get('children', []):
            find_image_links(child, result)


def save(stream, images):
    """Save results as Markdown."""

    text = '\n<hr/>\n'.join(['<p><img alt="{0}" src="{1}" /></p>'.format(img['alt'], img['src']) for img in images])
    print(text, file=stream)


def require(condition, message):
    """Fail if condition not met."""

    if not condition:
        print(message, file=sys.stderr)
        sys.exit(1)


if __name__ == '__main__':
    main()