Fix center of outage calculation (#24)

Solves #23

Reviewed-on: #24

.woodpecker/lint.yml

@@ -2,7 +2,7 @@ when:
   branch: main
 steps:
   - name: lint
-    image: python:3-alpine
+    image: python:3-slim
     commands:
       - python -m pip install --upgrade pip
       - python -m pip install -r requirements.txt

geospatial.py

@@ -0,0 +1,11 @@
+from shapely import MultiPolygon, Polygon
+
+
+def convert_outage_geometry(event) -> MultiPolygon:
+    assert event["polygons"]["type"] == "polygon"
+    assert event["polygons"]["hasZ"] is False
+    assert event["polygons"]["hasM"] is False
+    polygon_list = []
+    for ring in event["polygons"]["rings"]:
+        polygon_list.append(Polygon(ring))
+    return MultiPolygon(polygon_list)

requirements.txt

@@ -4,12 +4,15 @@ charset-normalizer==3.3.2
 decorator==5.1.1
 greenlet==3.0.3
 idna==3.6
+install==1.3.5
 Mastodon.py==1.8.1
+numpy==1.26.4
 pillow==10.2.0
 python-dateutil==2.9.0.post0
 python-magic==0.4.27
 PyYAML==6.0.1
 requests==2.31.0
+shapely==2.0.3
 six==1.16.0
 SQLAlchemy==2.0.28
 staticmap==0.5.7

scl.py

@@ -1,17 +1,19 @@
 import io
-import math
 from datetime import datetime
 from typing import Optional
 
 import mastodon
 import requests
+import shapely
 import yaml
 from mastodon import Mastodon
 from PIL import Image, ImageDraw, ImageFont
 from sqlalchemy import create_engine, select
 from sqlalchemy.exc import NoResultFound
 from sqlalchemy.orm import DeclarativeBase, Mapped, Session, mapped_column
-from staticmap import Polygon, StaticMap
+from staticmap import CircleMarker, Polygon, StaticMap
+
+from geospatial import convert_outage_geometry
 
 post_datetime_format = "%b %e %l:%M %p"
 
@@ -104,7 +106,11 @@ def get_hashtag_string(event) -> str:
 
 
 def do_initial_post(
-    event, event_class, start_time: datetime, estimated_restoration_time: datetime
+    event,
+    event_class,
+    start_time: datetime,
+    estimated_restoration_time: datetime,
+    outage_geometries: shapely.MultiPolygon,
 ) -> dict[str, str | None]:
     post_id = None
     map_media_post_id = None
@@ -127,30 +133,32 @@ def do_initial_post(
                 simplify=True,
             )
             map.add_polygon(polygon)
-        map_image = map.render()
 
         try:
+            outage_center: shapely.Point = outage_geometries.centroid
 
-            def num2deg(xtile, ytile, zoom):
-                n = 1 << zoom
-                lon_deg = xtile / n * 360.0 - 180.0
-                lat_rad = math.atan(math.sinh(math.pi * (1 - 2 * ytile / n)))
-                lat_deg = math.degrees(lat_rad)
-                return lat_deg, lon_deg
-
-            center_lat_lon = num2deg(map.x_center, map.y_center, map.zoom)
-
+            assert outage_center.geom_type == "Point"
             # Check to make sure the calculated lat and lon are sane enough
             # NW Corner
-            assert center_lat_lon[0] < 48 and center_lat_lon[1] > -122.6
+            assert outage_center.y < 48 and outage_center.x > -122.6
             # SE Corner
-            assert center_lat_lon[0] > 47.2 and center_lat_lon[1] < -122
+            assert outage_center.y > 47.2 and outage_center.x < -122
+
+            marker_outline = CircleMarker(
+                (outage_center.x, outage_center.y), "white", 18
+            )
+            marker = CircleMarker(
+                (outage_center.x, outage_center.y), event_class["outage_color"], 12
+            )
+
+            map.add_marker(marker_outline)
+            map.add_marker(marker)
 
             # Zoom level 17 ensures that we won't get any building/POI names, just street names
             geocode_url = "{nominatim_url}/reverse?lat={lat}&lon={lon}&format=geocodejson&zoom=17".format(
                 nominatim_url=nominatim_url,
-                lat=center_lat_lon[0],
-                lon=center_lat_lon[1],
+                lat=outage_center.y,
+                lon=outage_center.x,
             )
             geocode_headers = {"User-Agent": "seattlecitylight-mastodon-bot"}
             geocode_response = requests.get(geocode_url, headers=geocode_headers)
@@ -202,6 +210,8 @@ def do_initial_post(
         except Exception:
             alt_text = "A map showing the location of the outage."
 
+        map_image = map.render()
+
         with io.BytesIO() as map_image_file:
             map_image.save(map_image_file, format="PNG", optimize=True)
             map_media_post = mastodon_client.media_post(
@@ -297,6 +307,8 @@ with Session(engine) as session:
         else:
             status = None
 
+        outage_geometries = convert_outage_geometry(event)
+
         try:
             hashtag_string = get_hashtag_string(event)
             existing_record = lookup_result.one()
@@ -361,7 +373,11 @@ with Session(engine) as session:
                         "Posting an event that grew above the threshold required to post"
                     )
                     initial_post_result = do_initial_post(
-                        event, event_class, start_time, estimated_restoration_time
+                        event,
+                        event_class,
+                        start_time,
+                        estimated_restoration_time,
+                        outage_geometries,
                     )
                     existing_record.initial_post_id = initial_post_result["post_id"]
                     existing_record.most_recent_post_id = initial_post_result["post_id"]
@@ -382,7 +398,11 @@ with Session(engine) as session:
                 )
             else:
                 initial_post_result = do_initial_post(
-                    event, event_class, start_time, estimated_restoration_time
+                    event,
+                    event_class,
+                    start_time,
+                    estimated_restoration_time,
+                    outage_geometries,
                 )
                 post_id = initial_post_result["post_id"]
                 map_media_post_id = initial_post_result["map_media_post_id"]