Have Spiral Pips start anywhere in outer ring

catanatron/catanatron/models/map.py

@@ -15,7 +15,10 @@
     FastResource,
     NodeRef,
 )
-from catanatron.models.spiral import spiral_land_coordinates
+from catanatron.models.spiral import (
+    get_starting_spiral_coordinates,
+    spiral_land_coordinates,
+)
 from catanatron.models.tiles import EdgeId, LandTile, NodeId, Port, Tile, Water
 
 NUM_NODES = 54
@@ -255,7 +258,7 @@ def init_port_nodes_cache(
         if not isinstance(tile, Port):
             continue
 
-        (a_noderef, b_noderef) = PORT_DIRECTION_TO_NODEREFS[tile.direction]
+        a_noderef, b_noderef = PORT_DIRECTION_TO_NODEREFS[tile.direction]
         port_nodes[tile.resource].add(tile.nodes[a_noderef])
         port_nodes[tile.resource].add(tile.nodes[b_noderef])
     return port_nodes
@@ -351,7 +354,7 @@ def initialize_tiles(
 
         # create and save tile
         if isinstance(tile_type, tuple):  # is port
-            (_, direction) = tile_type
+            _, direction = tile_type
             port = Port(
                 port_autoinc, shuffled_port_resources.pop(), direction, nodes, edges
             )
@@ -380,7 +383,7 @@ def initialize_tiles(
             )
 
         # iterate in order of official spiral and assign numbers, skipping desert tile
-        start = (2, -2, 0) if map_template == BASE_MAP_TEMPLATE else (1, -1, 0)
+        start = get_starting_spiral_coordinates(all_tiles)
         i = 0
         for coordinate in spiral_land_coordinates(all_tiles, start):
             tile = all_tiles[coordinate]

catanatron/catanatron/models/spiral.py

@@ -1,9 +1,19 @@
 from collections.abc import Generator
-from typing import Mapping
+from typing import Dict, Mapping
+import random
 
 from catanatron.models.coordinate_system import Direction, UNIT_VECTORS, add, Coordinate
 from catanatron.models.tiles import LandTile, Tile
 
+COUNTERCLOCKWISE_RING_DIRECTIONS = (
+    Direction.NORTHWEST,
+    Direction.WEST,
+    Direction.SOUTHWEST,
+    Direction.SOUTHEAST,
+    Direction.EAST,
+    Direction.NORTHEAST,
+)
+
 
 def spiral_land_coordinates(
     all_tiles: Mapping[Coordinate, Tile], start: Coordinate
@@ -65,3 +75,42 @@ def is_land(coord: Coordinate) -> bool:
             continue
 
         direction = directions[(directions.index(direction) + 1) % len(directions)]
+
+
+def cube_radius(coord: Coordinate) -> int:
+    return max(abs(component) for component in coord)
+
+
+def ring_coordinates(radius: int) -> tuple[Coordinate, ...]:
+    if radius == 0:
+        return ((0, 0, 0),)
+
+    coord = (radius, -radius, 0)
+    ring = []
+    for direction in COUNTERCLOCKWISE_RING_DIRECTIONS:
+        for _ in range(radius):
+            ring.append(coord)
+            coord = add(coord, UNIT_VECTORS[direction])
+    return tuple(ring)
+
+
+def outer_land_coordinates(
+    all_tiles: Mapping[Coordinate, Tile],
+) -> tuple[Coordinate, ...]:
+    """Return outer-ring land coordinates in deterministic coast-following order."""
+    land_coords = {
+        coord for coord, tile in all_tiles.items() if isinstance(tile, LandTile)
+    }
+    if not land_coords:
+        return tuple()
+
+    radius = max(cube_radius(coord) for coord in land_coords)
+    return tuple(coord for coord in ring_coordinates(radius) if coord in land_coords)
+
+
+def get_starting_spiral_coordinates(all_tiles: Dict[Coordinate, Tile]) -> Coordinate:
+    """Return a randomly chosen corner coordinate from the outer ring of land coordinates."""
+    outer_ring = outer_land_coordinates(all_tiles)
+
+    corners = [coord for coord in outer_ring if 0 in coord]
+    return random.choice(corners)

tests/models/test_spiral.py

@@ -1,3 +1,4 @@
+from catanatron.models.spiral import get_starting_spiral_coordinates
 import pytest
 
 from catanatron.models.map import (
@@ -51,3 +52,23 @@ def test_spiral_land_coordinates_mini_map_order_from_tile_one():
     ids = [all_tiles[coord].id for coord in spiral_land_coordinates(all_tiles, start)]
 
     assert ids == [1, 6, 5, 4, 3, 2, 0]
+
+
+def test_spiral_starts_at_random_corners():
+    """Prove that the spiral starting coordinate is a randomly chosen corner."""
+
+    # We only need to generate the board layout once to test the coordinate picker
+    all_tiles = initialize_tiles(BASE_MAP_TEMPLATE, number_placement="random")
+    starts = set()
+
+    for _ in range(50):
+        # Directly call the function we modified to see what it picks
+        start_coord = get_starting_spiral_coordinates(all_tiles)
+
+        # 1. Prove it is a corner (cube coordinates for corners always contain a 0)
+        assert 0 in start_coord
+
+        starts.add(start_coord)
+
+    # 2. Prove it picked more than one unique corner over 50 calls
+    assert len(starts) > 1