Refactor mapping rules.

internal/mappingrules/mapping_rule_combo.go

@@ -0,0 +1,48 @@
+package mappingrules
+
+import "github.com/holoplot/go-evdev"
+
+// A Combo Mapping Rule can require multiple physical button presses for a single output button
+type MappingRuleCombo struct {
+	MappingRuleBase
+	Inputs []RuleTarget
+	State  int
+}
+
+func (rule *MappingRuleCombo) MatchEvent(device *evdev.InputDevice, event *evdev.InputEvent, mode *string) *evdev.InputEvent {
+	if !rule.MappingRuleBase.modeCheck(mode) {
+		return nil
+	}
+
+	// Check each of the inputs, and if we find a match, proceed
+	var match RuleTarget
+	for _, input := range rule.Inputs {
+		if device == input.GetDevice() &&
+			event.Code == input.GetCode() {
+			match = input
+		}
+	}
+
+	if match == nil {
+		return nil
+	}
+
+	// Get the value and add/subtract it from State
+	inputValue := match.NormalizeValue(event.Value)
+	oldState := rule.State
+	if inputValue == 0 {
+		rule.State = max(rule.State-1, 0)
+	}
+	if inputValue == 1 {
+		rule.State++
+	}
+	targetState := len(rule.Inputs)
+
+	if oldState == targetState-1 && rule.State == targetState {
+		return rule.Output.CreateEvent(1, mode)
+	}
+	if oldState == targetState && rule.State == targetState-1 {
+		return rule.Output.CreateEvent(0, mode)
+	}
+	return nil
+}