Use testify, write a couple more tests, and start a major refactor.

internal/mappingrules/rule_target_axis.go

@@ -0,0 +1,61 @@
+package mappingrules
+
+import (
+	"github.com/holoplot/go-evdev"
+)
+
+type RuleTargetAxis struct {
+	RuleTargetBase
+	AxisStart   int32
+	AxisEnd     int32
+	Sensitivity float64
+}
+
+func NewRuleTargetAxis(device_name string,
+	device *evdev.InputDevice,
+	code evdev.EvCode,
+	inverted bool,
+	axis_start int32,
+	axis_end int32,
+	sensitivity float64) *RuleTargetAxis {
+
+	return &RuleTargetAxis{
+		RuleTargetBase: NewRuleTargetBase(device_name, device, code, inverted),
+		AxisStart:      axis_start,
+		AxisEnd:        axis_end,
+		Sensitivity:    sensitivity,
+	}
+}
+
+func (target *RuleTargetAxis) NormalizeValue(value int32) int32 {
+	if !target.Inverted {
+		return value
+	}
+
+	axisRange := target.AxisEnd - target.AxisStart
+	axisMid := target.AxisEnd - axisRange/2
+	delta := value - axisMid
+	if delta < 0 {
+		delta = -delta
+	}
+
+	if value < axisMid {
+		return axisMid + delta
+	} else if value > axisMid {
+		return axisMid - delta
+	}
+
+	// If we reach here, we're either exactly at the midpoint or something
+	// strange has happened. Either way, just return the value.
+	return value
+}
+
+func (target *RuleTargetAxis) CreateEvent(value int32, mode *string) *evdev.InputEvent {
+	// TODO: we can use the axis begin/end to decide whether to emit the event
+	// TODO: oh no we need center deadzones actually...
+	return &evdev.InputEvent{
+		Type:  evdev.EV_ABS,
+		Code:  target.Code,
+		Value: value,
+	}
+}