Rename Röntgen to Map Machine.

map_machine/osm_getter.py

@@ -0,0 +1,70 @@
+"""
+Getting OpenStreetMap data from the web.
+"""
+import logging
+import time
+from dataclasses import dataclass
+from pathlib import Path
+
+import urllib3
+
+from map_machine.boundary_box import BoundaryBox
+
+__author__ = "Sergey Vartanov"
+__email__ = "me@enzet.ru"
+
+SLEEP_TIME_BETWEEN_REQUESTS: float = 2.0
+
+
+@dataclass
+class NetworkError(Exception):
+    """Failed network request."""
+
+    message: str
+
+
+def get_osm(
+    boundary_box: BoundaryBox, cache_file_path: Path, to_update: bool = False
+) -> str:
+    """
+    Download OSM data from the web or get if from the cache.
+
+    :param boundary_box: borders of the map part to download
+    :param cache_file_path: cache file to store downloaded OSM data
+    :param to_update: update cache files
+    """
+    if not to_update and cache_file_path.is_file():
+        with cache_file_path.open() as output_file:
+            return output_file.read()
+
+    content: bytes = get_data(
+        "https://api.openstreetmap.org/api/0.6/map",
+        {"bbox": boundary_box.get_format()},
+    )
+
+    with cache_file_path.open("bw+") as output_file:
+        output_file.write(content)
+
+    return content.decode("utf-8")
+
+
+def get_data(address: str, parameters: dict[str, str]) -> bytes:
+    """
+    Construct Internet page URL and get its descriptor.
+
+    :param address: URL without parameters
+    :param parameters: URL parameters
+    :return: connection descriptor
+    """
+    logging.info(f"Getting {address}...")
+    pool_manager: urllib3.PoolManager = urllib3.PoolManager()
+    urllib3.disable_warnings()
+
+    try:
+        result = pool_manager.request("GET", address, parameters)
+    except urllib3.exceptions.MaxRetryError:
+        raise NetworkError("Cannot download data: too many attempts.")
+
+    pool_manager.clear()
+    time.sleep(SLEEP_TIME_BETWEEN_REQUESTS)
+    return result.data