Implement PointSequence class

Implement PointSequence class to encapsulate functionality for handling
closed and open point sequences

lib/xmet/geo.py

@@ -2,8 +2,12 @@ import re
 import math
 import shapely
 
-def load_poly_from_file(path: str) -> shapely.Polygon:
+from typing import Self
-    points = list()
+
+class PointSequence(list):
+    @staticmethod
+    def from_file(path: str) -> Self:
+        ret = PointSequence()
 
         with open(path, 'r') as fh:
             data = fh.read()
@@ -14,9 +18,44 @@ def load_poly_from_file(path: str) -> shapely.Polygon:
 
                 lat, lon = re.split(r'\s*,\s*', line)
 
-            points.append((float(lon), float(lat)))
+                ret.add(float(lon), float(lat))
 
-    return shapely.Polygon(points)
+        return ret
+
+    def __init__(self, points: list=None):
+        super().__init__()
+
+        self.poly = None
+
+        for point in points:
+            typeof = type(point)
+
+            if typeof is tuple:
+                self.add(*point)
+            elif typeof is shapely.Point:
+                self.append(point)
+
+    def add(self, lon: float, lat: float):
+        self.append(shapely.Point(lon, lat))
+
+    def is_closed(self) -> bool:
+        return self[-1] == self[0]
+
+    def close(self):
+        if self[-1] != self[0]:
+            self.append(self[0])
+
+        self.poly = shapely.Polygon(self)
+
+    def nearest_index(self, point: shapely.Point) -> int:
+        indices = list()
+
+        for i in range(0, len(self)):
+            indices.append((i, self[i].distance(point)))
+
+        indices.sort(key=lambda i: i[1])
+
+        return indices[0][0]
 
 def line_heading(p1: shapely.Point, p2: shapely.Point) -> float:
     dx = p2.x - p1.x