Implement rule matching for a couple of basic rule types.

internal/config/schema.go

@@ -22,7 +22,8 @@ type DeviceConfig struct {
 type RuleConfig struct {
 	Name   string            `yaml:"name,omitempty"`
 	Type   string            `yaml:"type"`
-	Input  []RuleInputConfig `yaml:"input"`
+	Input  RuleInputConfig   `yaml:"input,omitempty"`
+	Inputs []RuleInputConfig `yaml:"inputs,omitempty"`
 	Output RuleOutputConfig  `yaml:"output"`
 }
 

internal/logger/logger.go

@@ -9,6 +9,10 @@ func Log(msg string) {
 	fmt.Println(msg)
 }
 
+func Logf(msg string, params ...interface{}) {
+	fmt.Printf(msg, params...)
+}
+
 func LogError(err error, msg string) {
 	if msg == "" {
 		fmt.Printf("%s\n", err.Error())

internal/rules/keymapping.go

@@ -9,42 +9,86 @@ type KeyMappingRule interface {
 	MatchEvent(*evdev.InputDevice, *evdev.InputEvent)
 }
 
+// A Simple Mapping Rule can map a button to a button or an axis to an axis.
 type SimpleMappingRule struct {
 	Input  RuleTarget
 	Output RuleTarget
 }
 
+// A Combo Mapping Rule can require multiple physical button presses for a single output button
 type ComboMappingRule struct {
 	Input  []RuleTarget
 	Output RuleTarget
+	State  int
 }
 
-func (rule *SimpleMappingRule) MatchEvent(device *evdev.InputDevice, event *evdev.InputEvent) *evdev.InputEvent {
-	if event.Type != evdev.EV_KEY ||
-		device != rule.Input.Device ||
-		event.Code != rule.Input.Code {
-		return nil
+func eventFromTarget(output RuleTarget, value int32) *evdev.InputEvent {
+	return &evdev.InputEvent{
+		Type:  output.Type,
+		Code:  output.Code,
+		Value: value,
 	}
+}
 
+func valueFromTarget(rule RuleTarget, event *evdev.InputEvent) int32 {
 	// how we process inverted rules depends on the event type
 	value := event.Value
-	if rule.Input.Inverted {
-		switch rule.Input.Type {
+	if rule.Inverted {
+		switch rule.Type {
 		case evdev.EV_KEY:
 			if value == 0 {
 				value = 1
 			} else {
 				value = 0
 			}
+		case evdev.EV_ABS:
+			// TODO: how would we invert axes?
 		default:
-			logger.Log("Tried to handle inverted rule for unknown event type. Skipping rule.")
-			return nil
+			logger.Logf("Inverted rule for unknown event type '%d'. Not inverting value\n", event.Type)
 		}
 	}
 
-	return &evdev.InputEvent{
-		Type:  rule.Output.Type,
-		Code:  rule.Output.Code,
-		Value: value,
-	}
+	return value
+}
+
+func (rule *SimpleMappingRule) MatchEvent(device *evdev.InputDevice, event *evdev.InputEvent) *evdev.InputEvent {
+	if device != rule.Input.Device ||
+		event.Code != rule.Input.Code {
+		return nil
+	}
+
+	return eventFromTarget(rule.Output, valueFromTarget(rule.Input, event))
+}
+
+func (rule *ComboMappingRule) MatchEvent(device *evdev.InputDevice, event *evdev.InputEvent) *evdev.InputEvent {
+	// Check each of the inputs, and if we find a match, proceed
+	var match *RuleTarget
+	for _, input := range rule.Input {
+		if device == input.Device &&
+			event.Code == input.Code {
+			match = &input
+		}
+	}
+
+	if match == nil {
+		return nil
+	}
+
+	// Get the value and add/subtract it from State
+	inputValue := valueFromTarget(*match, event)
+	oldState := rule.State
+	if inputValue == 0 {
+		rule.State--
+	}
+	if inputValue == 1 {
+		rule.State++
+	}
+	targetState := len(rule.Input)
+	if oldState == targetState-1 && rule.State == targetState {
+		return eventFromTarget(rule.Output, 1)
+	}
+	if oldState == targetState && rule.State == targetState-1 {
+		return eventFromTarget(rule.Output, 0)
+	}
+	return nil
 }