wip(map): init map model

build.sbt

@@ -12,7 +12,9 @@ lazy val scatan = (project in file("."))
       "org.scalatest" %%% "scalatest" % "3.3.0-SNAP4" % Test,
       "org.scalatest" %% "scalatest" % "3.3.0-SNAP4" % Test,
       "org.scala-js" %%% "scalajs-dom" % "2.6.0",
-      "com.raquo" %%% "laminar" % "16.0.0"
+      "com.raquo" %%% "laminar" % "16.0.0",
+      "org.typelevel" %%% "cats-core" % "2.10.0",
+      "org.scalatestplus" %%% "scalacheck-1-17" % "3.2.16.0" % Test
     ),
     scalaJSUseMainModuleInitializer := true
   )

src/main/scala/scatan/mvc/model/map/Hexagon.scala

@@ -0,0 +1,38 @@
+package scatan.mvc.model.map
+
+trait Hexagon:
+  def row: Int
+  def col: Int
+  def slice: Int
+  def neighbours: Set[Hexagon]
+  def isNeighbour(another: Hexagon): Boolean
+  def layer: Int
+
+object Hexagon:
+  import cats.Monoid
+  given Monoid[Hexagon] with
+    def empty: Hexagon = Hexagon(0, 0, 0)
+    def combine(hex1: Hexagon, hex2: Hexagon): Hexagon =
+      Hexagon(
+        hex1.row + hex2.row,
+        hex1.col + hex2.col,
+        hex1.slice + hex2.slice
+      )
+
+  def apply(row: Int, col: Int, slice: Int): Hexagon = HexagonImpl(row, col, slice)
+
+  private val allowedDirections: Set[Hexagon] = Set(
+    Hexagon(+1, 0, -1),
+    Hexagon(+1, -1, 0),
+    Hexagon(0, -1, +1),
+    Hexagon(-1, 0, +1),
+    Hexagon(-1, +1, 0),
+    Hexagon(0, +1, -1)
+  )
+
+  private case class HexagonImpl(row: Int, col: Int, slice: Int) extends Hexagon:
+    def neighbours: Set[Hexagon] =
+      import cats.syntax.semigroup.*
+      allowedDirections.map((this: Hexagon) |+| _)
+    def isNeighbour(another: Hexagon): Boolean = neighbours.contains(another)
+    def layer: Int = (math.abs(row) + math.abs(col) + math.abs(slice)) / 2

src/test/scala/scatan/BaseTest.scala

@@ -0,0 +1,7 @@
+package scatan
+
+import org.scalatest.*
+import org.scalatest.flatspec.*
+import org.scalatest.matchers.*
+
+abstract class BaseTest extends AnyFlatSpec with should.Matchers

src/test/scala/scatan/mvc/model/map/HexagonTest.scala

@@ -0,0 +1,45 @@
+package scatan.mvc.model.map
+
+import cats.kernel.Monoid
+import cats.syntax.semigroup.*
+import org.scalatestplus.scalacheck.ScalaCheckPropertyChecks
+import scatan.BaseTest
+import scatan.mvc.model.map.Hexagon.given
+
+class HexagonTest extends BaseTest with ScalaCheckPropertyChecks:
+
+  "An Hexagon" should "have 3 coordinates" in {
+    assertCompiles("Hexagon(0, 0, 0)")
+    assertDoesNotCompile("Hexagon()")
+  }
+
+  it should "be equals based on its coordinates" in {
+    forAll { (r: Int, c: Int, s: Int) =>
+      val hexagon1 = Hexagon(r, c, s)
+      val hexagon2 = Hexagon(r, c, s)
+      hexagon1 should equal(hexagon2)
+    }
+  }
+
+  it should "respect the identity law in order to be a Monoid" in {
+    forAll { (r: Int, c: Int, s: Int) =>
+      val hexagon = Hexagon(r, c, s)
+      hexagon |+| Monoid[Hexagon].empty should be(hexagon)
+      Monoid[Hexagon].empty |+| hexagon should be(hexagon)
+    }
+  }
+
+  it should "respect the associative law in order to be a Monoid" in {
+    forAll { (r1: Int, c1: Int, s1: Int, r2: Int, c2: Int, s2: Int) =>
+      val hexagon1 = Hexagon(r1, c1, s1)
+      val hexagon2 = Hexagon(r2, c2, s2)
+      hexagon1 |+| hexagon2 should be(hexagon2 |+| hexagon1)
+    }
+  }
+
+  it should "have 6 neighbours" in {
+    forAll { (r: Int, c: Int, s: Int) =>
+      val hexagon = Hexagon(r, c, s)
+      hexagon.neighbours.size should equal(6)
+    }
+  }