LibMap/app.py

from flask import Flask, render_template, request, jsonify
import requests
import time

app = Flask(__name__)

NOMINATIM_SEARCH_URL = "https://nominatim.openstreetmap.org/search"
NOMINATIM_REVERSE_URL = "https://nominatim.openstreetmap.org/reverse"

# Nominatim asks clients to identify themselves.
HEADERS = {
    "User-Agent": "LibreMapViewer/1.0 (local Flask application)"
}

# Very simple rate limiting so we don't hammer Nominatim.
last_request_time = 0
MIN_REQUEST_INTERVAL = 1.0


def classify_place(item):
    """
    Classify a Nominatim result into one of:
      - "area"    : countries, states, cities, towns, villages, suburbs,
                    neighbourhoods, water bodies, natural features, etc.
      - "poi"     : shops, restaurants, hotels, buildings, attractions, ...
      - "address" : street / house-number level results
      - "other"   : anything else

    The client uses this to pick an appropriate zoom level when the
    user selects a result.
    """
    category = (item.get("category") or "").lower()
    place_type = (item.get("type") or "").lower()
    address = item.get("address") or {}
    namedetails = item.get("namedetails") or {}

    # Administrative boundaries are always areas.
    if place_type.endswith("_boundary"):
        return "area"

    # Place categories (city, town, village, suburb, ...) are areas.
    if category == "place":
        return "area"

    # Boundaries are areas.
    if category == "boundary":
        return "area"

    # Natural & water features are treated as areas (they span regions).
    if category in ("natural", "water", "waterway"):
        return "area"

    # A real street/house-number result is an address.
    if (
        address.get("house_number")
        or address.get("road")
    ):
        if (
            namedetails.get("name")
            or namedetails.get("addr:housenumber")
            or address.get("house_number")
        ):
            return "address"

    # Known POI categories.
    poi_categories = {
        "amenity",
        "shop",
        "tourism",
        "leisure",
        "office",
        "craft",
        "building",
        "historic",
        "industrial",
        "public_transport",
    }
    if category in poi_categories:
        return "poi"

    return "other"


def nominatim_request(url, params):
    """
    Make a request to Nominatim while respecting a small
    delay between requests.
    """
    global last_request_time

    elapsed = time.time() - last_request_time

    if elapsed < MIN_REQUEST_INTERVAL:
        time.sleep(MIN_REQUEST_INTERVAL - elapsed)

    response = requests.get(
        url,
        params=params,
        headers=HEADERS,
        timeout=15
    )

    last_request_time = time.time()

    response.raise_for_status()

    return response.json()


@app.route("/")
def index():
    return render_template("index.html")


@app.route("/search")
def search():
    query = request.args.get("q", "").strip()

    if not query:
        return jsonify({
            "error": "Please enter a location"
        }), 400

    params = {
        "q": query,
        "format": "jsonv2",
        "limit": 20,
        "addressdetails": 1,
        "extratags": 1,
        "namedetails": 1,
        "dedupe": 1,
    }

    # Restrict results to the area currently visible on the map.
    # Expected format: "left,top,right,bottom" (lon,lat pairs).
    viewbox = request.args.get("viewbox", "").strip()

    if viewbox:
        parts = [p.strip() for p in viewbox.split(",")]

        if len(parts) == 4:
            try:
                left, top, right, bottom = (
                    float(p) for p in parts
                )

                params["viewbox"] = "{},{},{},{}".format(
                    left, top, right, bottom
                )
                params["bounded"] = 1

            except ValueError:
                pass

    try:
        results = nominatim_request(
            NOMINATIM_SEARCH_URL,
            params
        )

    except requests.RequestException as e:
        return jsonify({
            "error": f"Search failed: {e}"
        }), 500

    normalized = []

    for item in results:

        normalized.append({
            "place_id": item.get("place_id"),

            "osm_type": item.get("osm_type"),
            "osm_id": item.get("osm_id"),

            "display_name":
                item.get("display_name", ""),

            "lat":
                float(item["lat"]),

            "lon":
                float(item["lon"]),

            "type":
                item.get("type"),

            "category":
                item.get("category"),

            "kind":
                classify_place(item),

            "address":
                item.get("address", {}),

            "extratags":
                item.get("extratags", {}),

            "namedetails":
                item.get("namedetails", {}),

            "importance":
                item.get("importance", 0),

            "boundingbox":
                item.get("boundingbox"),
        })

    return jsonify(normalized)


@app.route("/geocode")
def geocode():

    lat = request.args.get("lat")
    lon = request.args.get("lon")

    if not lat or not lon:
        return jsonify({
            "error": "Missing latitude or longitude"
        }), 400

    try:
        lat = float(lat)
        lon = float(lon)
    except ValueError:
        return jsonify({
            "error": "Invalid latitude or longitude"
        }), 400

    params = {
        "lat": lat,
        "lon": lon,

        "format": "jsonv2",

        "zoom": 18,

        "addressdetails": 1,

        "extratags": 1,

        "namedetails": 1,
    }

    try:

        result = nominatim_request(
            NOMINATIM_REVERSE_URL,
            params
        )

    except requests.RequestException as e:

        return jsonify({
            "error": f"Reverse geocoding failed: {e}"
        }), 500

    if not result:

        return jsonify({
            "display_name": None
        })

    return jsonify({

        "place_id":
            result.get("place_id"),

        "osm_type":
            result.get("osm_type"),

        "osm_id":
            result.get("osm_id"),

        "display_name":
            result.get("display_name", ""),

        "lat":
            float(result.get("lat", lat)),

        "lon":
            float(result.get("lon", lon)),

        "type":
            result.get("type"),

        "category":
            result.get("category"),

        "address":
            result.get("address", {}),

        "extratags":
            result.get("extratags", {}),

        "namedetails":
            result.get("namedetails", {}),
    })


if __name__ == "__main__":
    app.run(
        port=5000,
        debug=True
    )