clockface: add minute hand

clockface/clockface.go

@@ -52,6 +52,18 @@ func SecondHand(w io.Writer, t time.Time) {
 	)
 }
 
+func minutesInRadians(t time.Time) float64 {
+	return (secondsInRadians(t) / 60) + math.Pi/(30/float64(t.Minute()))
+}
+
+func minuteHandPoint(t time.Time) Point {
+	angle := minutesInRadians(t)
+	x := math.Sin(angle)
+	y := math.Cos(angle)
+
+	return Point{x, y}
+}
+
 func secondsInRadians(t time.Time) float64 {
 	// XXX:Wanted 3.141592653589793 radians, but got 3.1415926535897936
 	// return float64(t.Second()) * (math.Pi / 30)

clockface/clockface_test.go

@@ -6,6 +6,26 @@ import (
 	"time"
 )
 
+func TestMinutesInRadians(t *testing.T) {
+	cases := []struct {
+		time  time.Time
+		angle float64
+	}{
+		{simpleTime(0, 30, 0), math.Pi},
+		{simpleTime(0, 0, 7), 7 * (math.Pi / (30 * 60))},
+	}
+
+	for _, c := range cases {
+		t.Run(testName(c.time), func(t *testing.T) {
+			got := minutesInRadians(c.time)
+
+			if c.angle != got {
+				t.Fatalf("Wanted %v radians, but got %v", c.angle, got)
+			}
+		})
+	}
+}
+
 func TestSecondsInRadians(t *testing.T) {
 	cases := []struct {
 		time  time.Time
@@ -28,6 +48,25 @@ func TestSecondsInRadians(t *testing.T) {
 	}
 }
 
+func TestMinuteHandPoint(t *testing.T) {
+	cases := []struct {
+		time  time.Time
+		point Point
+	}{
+		{simpleTime(0, 30, 0), Point{0, -1}},
+		{simpleTime(0, 45, 0), Point{-1, 0}},
+	}
+
+	for _, c := range cases {
+		t.Run(testName(c.time), func(t *testing.T) {
+			got := minuteHandPoint(c.time)
+			if !roughlyEqualPoint(got, c.point) {
+				t.Fatalf("Wanted %v Point, but got %v", c.point, got)
+			}
+		})
+	}
+}
+
 func TestSecondHandPoint(t *testing.T) {
 	cases := []struct {
 		time  time.Time