Split out maths functions into maths, vector and bearing

pkg/bearing/bearing.go

@@ -0,0 +1,76 @@
+package bearing
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/mdiluz/rove/pkg/vector"
+)
+
+// Direction describes a compass direction
+type Direction int
+
+const (
+	North Direction = iota
+	NorthEast
+	East
+	SouthEast
+	South
+	SouthWest
+	West
+	NorthWest
+)
+
+// DirectionString simply describes the strings associated with a direction
+type DirectionString struct {
+	Long  string
+	Short string
+}
+
+// DirectionStrings is the set of strings for each direction
+var DirectionStrings = []DirectionString{
+	{"North", "N"},
+	{"NorthEast", "NE"},
+	{"East", "E"},
+	{"SouthEast", "SE"},
+	{"South", "S"},
+	{"SouthWest", "SW"},
+	{"West", "W"},
+	{"NorthWest", "NW"},
+}
+
+// String converts a Direction to a String
+func (d Direction) String() string {
+	return DirectionStrings[d].Long
+}
+
+// ShortString converts a Direction to a short string version
+func (d Direction) ShortString() string {
+	return DirectionStrings[d].Short
+}
+
+// DirectionFromString gets the Direction from a string
+func DirectionFromString(s string) (Direction, error) {
+	for i, d := range DirectionStrings {
+		if strings.ToLower(d.Long) == strings.ToLower(s) || strings.ToLower(d.Short) == strings.ToLower(s) {
+			return Direction(i), nil
+		}
+	}
+	return -1, fmt.Errorf("Unknown direction: %s", s)
+}
+
+var DirectionVectors = []vector.Vector{
+	{X: 0, Y: 1},  // N
+	{X: 1, Y: 1},  // NE
+	{X: 1, Y: 0},  // E
+	{X: 1, Y: -1}, // SE
+	{X: 0, Y: -1}, // S
+	{X: -1, Y: 1}, // SW
+	{X: -1, Y: 0}, // W
+	{X: -1, Y: 1}, // NW
+}
+
+// Vector converts a Direction to a Vector
+func (d Direction) Vector() vector.Vector {
+	return DirectionVectors[d]
+}