#!/usr/bin/env python3

# Dirty tiles in a specified area in OpenStreetMap

import argparse
import datetime
import decimal
import email.utils
import math
import re
import sys
import time
import urllib.parse
from typing import Generator, Set, Tuple, Union

import requests

Dec = decimal.Decimal
USER_AGENT = 'dirty-osm.py/0.1'

DN = Union[int, Dec]  # Numbers


def drange(a: DN, b: DN, jump: DN) -> Generator[DN, None, None]:
    if jump > 0:
        while a < b:
            yield a
            a += jump
    elif jump < 0:
        while a > b:
            yield a
            a += jump
    else:
        raise ValueError('drange() argument 3 must not be zero')    


def deg2num(lat_deg: float, lon_deg: float, zoom: int) -> Tuple[int, int]:
    lat_rad = math.radians(lat_deg)
    n = 2.0 ** zoom
    xtile = int((lon_deg + 180.0) / 360.0 * n)
    ytile = int((1.0 - math.log(math.tan(lat_rad) +
                                (1 / math.cos(lat_rad))) / math.pi) / 2.0 * n)
    return (xtile, ytile)


def dirty_coords(lat_deg: float, lon_deg: float, maxzoom=13) -> Set[str]:
    urls = set()
    for zoom in range(6, maxzoom):
        # Higher zoom levels should automatically refresh on edit
        # Roads don't appear at levels 1-5 so probably unneeded
        x, y = deg2num(lat_deg, lon_deg, zoom)
        url = f'https://a.tile.openstreetmap.org/{zoom}/{x}/{y}.png/dirty'
        urls.add(url)

    return urls


def logical_order(url: str) -> tuple:
    parsed_url = urllib.parse.urlsplit(url)
    result = tuple((int(x) if x.isnumeric() else x) for x in
                   re.split(r'(\d+)', parsed_url.path))
    return result
    

def dirty_area(minlat: DN, maxlat: DN, minlon: DN, maxlon: DN,
               maxzoom=13, dry_run=False) -> None:
    urls = set()

    if maxlat < minlat:
        minlat, maxlat = maxlat, minlat

    if maxlon < minlon:
        minlon, maxlon = maxlon, minlon

    for lat in drange(minlat, maxlat, Dec('0.005')):
        for lon in drange(minlon, maxlon, Dec('0.005')):
            urls |= dirty_coords(float(lat), float(lon), maxzoom)

    with requests.Session() as session:
        session.headers.update({'User-Agent': USER_AGENT})
        delay = 0

        for url in sorted(urls, key=logical_order):
            if dry_run:
                print('Would have retrieved', url, file=sys.stderr)
                continue

            r = session.get(url)
            while r.status_code in (429, 503):
                retry = r.headers.get('Retry-After')
                if retry:
                    try:
                        delay = int(retry)
                    except ValueError:
                        tdiff = (datetime.datetime.now() -
                                 email.utils.parsedate_to_datetime(retry))
                        delay = tdiff.seconds

                print('Waiting', delay+1, 'seconds', file=sys.stderr)
                time.sleep(delay+1)
                r = session.get(url)
            print(url, r)

    return


if __name__ == "__main__":
    parser = argparse.ArgumentParser()
    parser.add_argument('--dry-run', '-n', action='store_true',
                        help="don't download anything")
    parser.add_argument('lat1', type=Dec)
    parser.add_argument('lon1', type=Dec)
    parser.add_argument('lat2', type=Dec)
    parser.add_argument('lon2', type=Dec)
    parser.add_argument('maxzoom', type=int, nargs='?', default=12)
    options = parser.parse_args()

    dirty_area(options.lat1, options.lat2, options.lon1, options.lon2,
               options.maxzoom+1, options.dry_run)