"""
Script to retrieve all Openstreetmap items matching a query and save
them as GPX Waypoints to a given output file in GPX format.
"""

__author__ = "fordprefect"
__date__ = "2020-03-25"
__version__ = "0.1"

import cgi
import gpxpy
import requests
import os
from packaging import version
import sys
assert sys.version_info >= (3, 6), "At least Python 3.8 required due to fStrings. Replace all f\"…\" and comment this line to enable running in lower versions (but really, you should just update your Python version…)."
assert version.parse(gpxpy.__version) >= version.parse("1.4.0"), "Update gpxpy to at least v1.4.0"

#####################################
######## configuration
#####################################

# search url of nominatim (don't change if you don't know what you are doing!)
url = "https://nominatim.openstreetmap.org/search/"

# search arguments, change query here
# for all supported keys see http://nominatim.org/release-docs/latest/api/Search/
args = {"q": "Wasserwanderplatz", "country": "Germany", "format": "json", "limit": 50}

# bounding box defined by two points [x1, y1, x2, y2]
use_boundingbox = True
boundingbox = [53.898, 11.338, 52.700, 14.332]

# output file name
gpxfilename = f"nominatimsearch_{args['q']}.gpx"

# OSM IDs to be ignored (used to find all matching items)
ignore_ids = []

# maximum number of search queries
maxsearchnums = 10

# verbosity
verbosity = 0

#####################################
######## end of configuration
#####################################

def get_arguments():
    """Wrapper for cgi-environment.
    Takes no options, returns dict of arguments
    """
    with cgi.FieldStorage() as args:
        return {i: args.getvalue(i) for i in args}

## initialize gpx file
if os.path.isfile(gpxfilename):
    # open file and parse
    if verbosity > 0: print(f"found file, extending")
    gpxfile = gpxpy.parse(open(gpxfilename, "r"))
else:
    if verbosity > 0: print("creating new file")
    gpxfile = gpxpy.gpx.GPX()

# search loop
for i in range(maxsearchnums):
    # fetch request
    if use_boundingbox:
        args["viewbox"] = ",".join(list(map(str, boundingbox)))
    if ignore_ids != []:
        args["exclude_place_ids"] = ",".join(list(map(str, ignore_ids)))
    r = requests.get(url + "?" + "&".join([f"{key}={args[key]}" for key in args]))

    if r.status_code != 200:
        if verbosity > 0: print(f"Query gone wrong: HTTP returned {r.status_code}")
        exit(1)

    # parse reply
    reply = r.json()
    assert isinstance(reply, list), "Unexpected type of reply: " + type(reply)
    if len(reply) == 0:
        if verbosity > 0: print(f"found {len(ignore_ids)} results in {i-1} iterations, finishing")
        break

    for point in reply:
        pid = point["place_id"]
        ignore_ids.append(pid)
        lat = point["lat"]
        lon = point["lon"]
        name = point["display_name"]
        gpxfile.waypoints.append(gpxpy.gpx.GPXWaypoint(latitude=lat, longitude=lon, name=name))

# save to disk
with open(gpxfilename, "w") as f:
    f.write(gpxfile.to_xml())
if verbosity > 0: print(f"GPX file written to {gpxfilename}")