joyful/internal/mappingrules/mapping_rule_button_combo.go

package mappingrules

import "github.com/holoplot/go-evdev"

// A Combo Mapping Rule can require multiple physical button presses for a single output button
type MappingRuleButtonCombo struct {
	MappingRuleBase
	Inputs []*RuleTargetButton
	Output *RuleTargetButton
	State  int
}

func NewMappingRuleButtonCombo(
	base MappingRuleBase,
	inputs []*RuleTargetButton,
	output *RuleTargetButton) *MappingRuleButtonCombo {

	return &MappingRuleButtonCombo{
		MappingRuleBase: base,
		Inputs:          inputs,
		Output:          output,
		State:           0,
	}
}

func (rule *MappingRuleButtonCombo) MatchEvent(device *evdev.InputDevice, event *evdev.InputEvent, mode *string) (*evdev.InputDevice, *evdev.InputEvent) {
	if !rule.MappingRuleBase.modeCheck(mode) {
		return nil, nil
	}

	// Check each of the inputs, and if we find a match, proceed
	var match *RuleTargetButton
	for _, input := range rule.Inputs {
		if input.MatchEvent(device, event) {
			match = input
			break
		}
	}

	if match == nil {
		return nil, 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.Device, rule.Output.CreateEvent(1, mode)
	}
	if oldState == targetState && rule.State == targetState-1 {
		return rule.Output.Device, rule.Output.CreateEvent(0, mode)
	}
	return nil, nil
}