right-tree/backend/right_tree/api/wms_utils.py

import json
import os
import re
import requests
from urllib.parse import urlencode
from unicodedata import normalize

from django.contrib.gis.geos import Point, GEOSGeometry
from django.conf import settings

LINZ_API_KEY = os.getenv("LINZ_API_KEY")
LINZ_WFS_ENDPOINT = f"https://data.linz.govt.nz/services;key={LINZ_API_KEY}/wfs"
PROPERTY_TILE_LAYER = "layer-50804"
PROPERTY_INFO_LAYER = "layer-53353"


search_num = re.compile(r'((?<!\S)\d+)')
search_str = re.compile(r'((?<!\S)[a-zA-Z\-]+)')


class WFSError(Exception):
    pass


def get_point_from_coordinates(coordinates):
    """Given a coordinates json string, returns the coordinates as a Point object"""
    coordinates_json = json.loads(coordinates)
    pnt = Point(coordinates_json["lng"],
                coordinates_json["lat"], srid=4326)
    return pnt


def wfs_getfeature(endpoint, **kwargs):
    """Perform a WFS request with the with all keyword arguments as parameters
    within the URL query, returning the JSON-formatted response"""
    params = {
        'service': "WFS",
        'request': "GetFeature",
        'outputFormat': "application/json",
        **kwargs,
    }

    query = urlencode(params)
    url = f"{endpoint}?{query}"
    response = requests.get(url)

    try:
        return response.json()
    except json.JSONDecodeError as e:
        raise WFSError(
            f"Failed to make WFS request to {url}: {response.content}")


def linz_wfs_getfeature(**kwargs):
    """Perform a WFS request via the LINZ endpoint"""
    return wfs_getfeature(LINZ_WFS_ENDPOINT, version="2.0.0", **kwargs)


def intersecting_property(coordinates):
    """Finds the property that intersects with the coordinates and returns its definition as a dictionary"""
    point = get_point_from_coordinates(coordinates)
    cql_filter = f"Intersects(shape,{point})"
    json = linz_wfs_getfeature(
        typeNames=PROPERTY_TILE_LAYER, cql_filter=cql_filter, count=1)
    features = json.get("features")

    if len(features) > 0:
        return features[0]


def get_address(polygon):
    """Fetch the address string that intersects with the specified polygon"""

    # Don't perform request if the input polygon WKT is too long to fit into URL
    # Limit is 2048 characters
    if len(str(polygon)) > 1500:
        return None

    cql_filter = f"Within(shape,{polygon})"
    json = linz_wfs_getfeature(
        typeNames=PROPERTY_INFO_LAYER, cql_filter=cql_filter, count=1)
    features = json.get("features")

    if len(features) > 0:
        feature = features[0]
        return feature['properties']


def get_address_from_coordinates(coordinates):
    propertyPolygon = intersecting_property(coordinates)
    if propertyPolygon is not None:
        prop_geom = GEOSGeometry(json.dumps(propertyPolygon['geometry']))
        return get_address(prop_geom)


def search_address(address):

    # normalize accent characters etc.
    address = normalize(
        "NFKD",
        address.strip().lower(),
    ).encode("ascii", "ignore").decode()

    nums = search_num.findall(address)
    strings = search_str.findall(address)

    num_terms = [f"address_number = {n}" for n in nums]
    string_terms = []

    for s in strings:
        string_terms += [
            f"full_road_name_ascii ILIKE '{s}%'",
            f"town_city_ascii ILIKE '{s}%'",
            f"suburb_locality_ascii ILIKE '{s}%'",
        ]

    num_expr = " OR ".join(f"({term})" for term in num_terms)
    string_expr = " OR ".join(f"({term})" for term in string_terms)

    cql_filter = f"({num_expr}) AND ({string_expr})"

    resp = linz_wfs_getfeature(
        typeNames=PROPERTY_INFO_LAYER,
        cql_filter=cql_filter,
        count=10,
    )
    features = resp.get("features", [])

    return [
        {
            'coordinates': feature['geometry']['coordinates'],
            'address': feature['properties']['full_address'],
        } for feature in features
    ]