refactor: extract grid abstraction for reuse

internal/move/move.go

@@ -0,0 +1,36 @@
+// Package move provides types and functions to represent and manipulate moves on a 2D grid.
+package move
+
+type Move interface {
+	NumberOfRows() int
+	NumberOfColumns() int
+}
+
+type move struct {
+	numberOfRows    int
+	numberOfColumns int
+}
+
+func (m move) NumberOfRows() int {
+	return m.numberOfRows
+}
+
+func (m move) NumberOfColumns() int {
+	return m.numberOfColumns
+}
+
+var (
+	Up       = move{numberOfRows: -1, numberOfColumns: 0}
+	Down     = move{numberOfRows: 1, numberOfColumns: 0}
+	Right    = move{numberOfRows: 0, numberOfColumns: 1}
+	Left     = move{numberOfRows: 0, numberOfColumns: -1}
+	cardinal = []Move{Up, Down, Right, Left}
+
+	UpRight   = move{numberOfRows: -1, numberOfColumns: 1}
+	UpLeft    = move{numberOfRows: -1, numberOfColumns: -1}
+	DownRight = move{numberOfRows: 1, numberOfColumns: 1}
+	DownLeft  = move{numberOfRows: 1, numberOfColumns: -1}
+	ordinal   = []Move{UpRight, UpLeft, DownRight, DownLeft}
+
+	AllDirections = append(cardinal, ordinal...)
+)