Randomic creation (#9)

* Add random polygons, with validity constraints

src/main/scala/io/github/scala_tessella/tessella/creation/Randomic.scala

@@ -0,0 +1,74 @@
+package io.github.scala_tessella.tessella
+package creation
+
+import RegularPolygon.{Polygon, Vertex}
+import TilingGrowth.OtherNodeStrategy.BEFORE_PERIMETER
+import Topology.Edge
+
+import scala.util.Random
+
+object Randomic:
+
+  extension (polygons: Vertex)
+
+    private def isContainedInAtLeastOne(containers: List[Vertex]): Boolean =
+      containers.exists(polygons.isContainedIn)
+
+    private def isContainedInPattern(pattern: Pattern): Boolean =
+      isContainedInAtLeastOne(pattern.distinctVertices.map(_.vertex))
+
+  extension (tiling: Tiling)
+
+    private def isEmpty: Boolean =
+      tiling.graphEdges.isEmpty
+
+    /** Tries adding a random polygon, with an optional addition validity clause
+     *
+     * @param maybePolygons polygons that can be added, if None all tessellable polygons
+     * @param validity      function to filter tilings
+     */
+    def randomStep(maybePolygons: Option[List[Polygon]] = None,
+                   validity: Tiling => Boolean = _ => true): Option[Tiling] =
+      val polygons: List[Polygon] =
+        maybePolygons.getOrElse(Vertex.tessellablePolygons)
+      if isEmpty then
+        Option(Tiling.fromPolygon(polygons(Random.nextInt(polygons.size))))
+      else
+        val combinations: List[(Edge, Polygon)] =
+          for
+            polygon <- polygons
+            edge    <- tiling.perimeter.toRingEdges
+          yield
+            (edge, polygon)
+        Random.shuffle(combinations)
+          .view
+          .map(tiling.maybeGrowEdge(_, _, BEFORE_PERIMETER))
+          .find(maybeTiling => maybeTiling.isRight && validity(maybeTiling.toOption.get))
+          .map(_.toOption.get)
+
+    /** Tries adding sequentially random polygons, with an optional addition validity clause
+     *
+     * @param steps         number of additions
+     * @param maybePolygons polygons that can be added, if None all tessellable polygons
+     * @param validity      function to filter tilings
+     * @return
+     */
+    def randomSteps(steps: Int,
+                    maybePolygons: Option[List[Polygon]] = None,
+                    validity: Tiling => Boolean = _ => true): Option[Tiling] =
+      (0 until steps).foldLeft(Option(tiling))((maybeTiling, _) =>
+        maybeTiling.flatMap(_.randomStep(maybePolygons, validity))
+      )
+
+    /** Tries adding sequentially random polygons, within a given pattern
+     *
+     * @param steps   number of additions
+     * @param pattern a [[Pattern]] each new polygon must follow
+     * @return
+     */
+    def randomStepsWithinPattern(steps: Int, pattern: Pattern): Option[Tiling] =
+      val polygons: List[Polygon] =
+        pattern.vertices.flatMap(_.vertex.toPolygons).distinct
+      val validity: Tiling => Boolean =
+        _.orderedPerimeterMinorVertices.forall(_.isContainedInPattern(pattern))
+      randomSteps(steps, Option(polygons), validity)

src/test/scala/io/github/scala_tessella/tessella/creation/RandomicSpec.scala

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+package io.github.scala_tessella.tessella
+package creation
+
+import Randomic.*
+import RegularPolygon.Polygon
+import conversion.SVG.toSVG
+
+import org.scalatest.flatspec.AnyFlatSpec
+import org.scalatest.matchers.should
+
+class RandomicSpec extends AnyFlatSpec with Helper with should.Matchers{
+
+  "A random polygon" can "be added to an empty tiling" in {
+    Tiling.empty.randomStep().get.countPolygons shouldBe
+      1
+  }
+
+  it can "be added to a tiling formed by only a polygon" in {
+    triangle.randomStep().get.countPolygons shouldBe
+      2
+  }
+
+  "Two random polygons" can "be added to an empty tiling" in {
+    Tiling.empty.randomSteps(2).get.countPolygons shouldBe
+      2
+  }
+
+  "Ten random triangles or squares" can "be added to an empty tiling" in {
+    Tiling.empty.randomSteps(10, Option(List(Polygon(3), Polygon(4)))).get.hedrality <= 2 shouldBe
+      true
+  }
+
+}