helpers.py

def get_current_state_from_server():
    # I dislike PyYAML, that is why
    import requests
    from dateutil.parser import parse
    current_state_file_url =\
        "http://planet.openstreetmap.org/replication/changesets/state.yaml"
    state_file = requests.get(current_state_file_url).text
    current_state = {}
    for line in state_file.split('\n'):
        elems = line.split(':')
        if len(elems) > 1:
            current_state[elems[0].strip()] = ":".join(elems[1:]).strip()
    if not 'last_run' and 'sequence' in current_state:
        return {}
    current_state['sequence'] = int(current_state['sequence'])
    current_state['last_run'] = parse(current_state['last_run'])
    return current_state


def get_changeset_path_for(utctime):
    import os
    from math import floor
    current_state = get_current_state_from_server()
    if 'last_run' not in current_state:
        return ""
    parts = []
    minutes = int(floor(
        (current_state['last_run'] - utctime).total_seconds() / 60))
    rem = current_state['sequence'] - minutes
    if rem < 0:
        rem = 0
    while rem > 0:
        parts.insert(0, (str(rem % 1000).zfill(3)))
        rem = (rem - rem % 1000) / 1000
    while len(parts) < 3:
        parts.insert(0, "000")
    parts.insert(0, "http://planet.osm.org/replication/changesets/")
    print parts
    return '{path}.osm.gz'.format(path=os.path.join(*parts))