initial booster design

keyboard/booster.go

@@ -0,0 +1,75 @@
+package keyboard
+
+import (
+	"math"
+)
+
+var (
+	keyDistances    map[string]Coordinates
+	keyboardLayouts = map[string][]string{
+		"qwerty-us": {
+			"`1234567890-=",
+			" qwertyuiop[]\\",
+			" asdfghjkl;'",
+			" zxcvbnm,./",
+		},
+	}
+)
+
+type Coordinates struct {
+	X float64
+	Y float64
+}
+
+func init() {
+	keyDistances = generateKeyDistance(keyboardLayouts["qwerty-us"])
+}
+
+func GetBestMatch(input string, list []string) (string, float64) {
+	var scores = make([]float64, len(list))
+	for listOffset, ref := range list {
+		for i := 0; i < len(input); i++ {
+			if i >= len(ref) {
+				// @todo missing characters, we should add a penalty
+				scores[listOffset] += 1
+				continue
+			}
+
+			left, right := string(input[i]), string(ref[i])
+			scores[listOffset] += getDistance(keyDistances[left], keyDistances[right])
+		}
+	}
+
+	var bestScore = math.Inf(1)
+	var offset int
+	for listOffset, score := range scores {
+		if score < bestScore {
+			bestScore = score
+			offset = listOffset
+		}
+	}
+
+	return list[offset], scores[offset]
+}
+
+func getDistance(a, b Coordinates) float64 {
+	return math.Sqrt(
+		math.Pow(b.X-a.X, 2) + math.Pow(b.Y-a.Y, 2),
+	)
+}
+
+func generateKeyDistance(rows []string) map[string]Coordinates {
+	var keyMap = make(map[string]Coordinates, len(rows))
+
+	for rowIndex, row := range rows {
+		for column := 0; column < len(row); column++ {
+			character := string(row[column])
+			keyMap[character] = Coordinates{
+				X: float64(column),
+				Y: float64(rowIndex),
+			}
+		}
+	}
+
+	return keyMap
+}

keyboard/booster_test.go

@@ -0,0 +1,73 @@
+package keyboard
+
+import (
+	"math"
+	"testing"
+)
+
+const (
+	floatTolerance = 0.01
+)
+
+func TestGetBestMatch(t *testing.T) {
+	testData := []struct {
+		Input  string
+		List   []string
+		Expect string
+	}{
+		{Input: "bee4", List: []string{"beer", "beef"}, Expect: "beer"},
+		{Input: "bee5", List: []string{"beef", "beer"}, Expect: "beer"},
+		{Input: "bee5", List: []string{"beef", "beer", "beast"}, Expect: "beer"},
+		{Input: "bee5", List: []string{"beef", "beer", "ben"}, Expect: "beer"},
+	}
+
+	for _, td := range testData {
+		result, distance := GetBestMatch(td.Input, td.List)
+		if td.Expect != result {
+			t.Errorf("Expected '%s' to match '%s', instead I got '%s' with distance %f, %+v",
+				td.Input, td.Expect, result, distance, td)
+		}
+	}
+}
+
+func TestGetDistance(t *testing.T) {
+	testData := []struct {
+		A        Coordinates
+		B        Coordinates
+		Distance float64
+	}{
+		{A: Coordinates{X: 0, Y: 0}, B: Coordinates{X: 0, Y: 100}, Distance: 100},
+		{A: Coordinates{X: 0, Y: 0}, B: Coordinates{X: 100, Y: 0}, Distance: 100},
+		{A: Coordinates{X: 1, Y: 2}, B: Coordinates{X: 1, Y: 2}, Distance: 0},
+		{A: Coordinates{X: 10, Y: 20}, B: Coordinates{X: 20, Y: 10}, Distance: 14.14},
+	}
+
+	for _, td := range testData {
+		d := getDistance(td.A, td.B)
+
+		if math.Abs(d-td.Distance) > floatTolerance {
+			t.Errorf("Expected the distance to be %f, instead I got %f\n%v", td.Distance, d, td)
+		}
+	}
+
+}
+
+func TestGenerateKeyDistance(t *testing.T) {
+	table := generateKeyDistance([]string{
+		"abc", // 00, 01, 02
+		"def", // 10, 11, 12
+		"ghi", // 20, 21, 22
+	})
+
+	if table["a"].X != 0 || table["a"].Y != 0 {
+		t.Errorf("Expected the coords to be at 0,0 %+v", table["a"])
+	}
+
+	if table["e"].X != 1 || table["e"].Y != 1 {
+		t.Errorf("Expected the coords to be at 1,1 %+v", table["i"])
+	}
+
+	if table["i"].X != 2 || table["i"].Y != 2 {
+		t.Errorf("Expected the coords to be at 2,2 %+v", table["i"])
+	}
+}