Build rules from config.

internal/config/rules.go

@@ -0,0 +1,93 @@
+package config
+
+import (
+	"fmt"
+
+	"git.annabunches.net/annabunches/joyful/internal/mappingrules"
+	"github.com/holoplot/go-evdev"
+)
+
+func makeSimpleRule(ruleConfig RuleConfig, pDevs map[string]*evdev.InputDevice, vDevs map[string]*evdev.InputDevice) (mappingrules.MappingRule, error) {
+	input, err := makeRuleTarget(ruleConfig.Input, pDevs)
+	if err != nil {
+		return nil, err
+	}
+
+	output, err := makeRuleTarget(ruleConfig.Output, vDevs)
+	if err != nil {
+		return nil, err
+	}
+
+	return &mappingrules.SimpleMappingRule{
+		Input:  input,
+		Output: output,
+	}, nil
+}
+
+func makeComboRule(ruleConfig RuleConfig, pDevs map[string]*evdev.InputDevice, vDevs map[string]*evdev.InputDevice) (mappingrules.MappingRule, error) {
+	inputs := make([]mappingrules.RuleTarget, 0)
+	for _, inputConfig := range ruleConfig.Inputs {
+		input, err := makeRuleTarget(inputConfig, pDevs)
+		if err != nil {
+			return nil, err
+		}
+		inputs = append(inputs, input)
+	}
+
+	output, err := makeRuleTarget(ruleConfig.Output, vDevs)
+	if err != nil {
+		return nil, err
+	}
+
+	return &mappingrules.ComboMappingRule{
+		Inputs: inputs,
+		Output: output,
+	}, nil
+}
+
+// makeInputRuleTarget takes an Input declaration from the YAML and returns a fully formed RuleTarget.
+func makeRuleTarget(targetConfig RuleTargetConfig, devs map[string]*evdev.InputDevice) (mappingrules.RuleTarget, error) {
+	ruleTarget := mappingrules.RuleTarget{}
+
+	device, ok := devs[targetConfig.Device]
+	if !ok {
+		return mappingrules.RuleTarget{}, fmt.Errorf("couldn't build rule due to non-existent device '%s'", targetConfig.Device)
+	}
+	ruleTarget.Device = device
+
+	eventType, eventCode, err := decodeRuleTargetValues(targetConfig)
+	if err != nil {
+		return ruleTarget, err
+	}
+	ruleTarget.Type = eventType
+	ruleTarget.Code = eventCode
+
+	return ruleTarget, nil
+}
+
+// decodeRuleTargetValues returns the appropriate evdev.EvType and evdev.EvCode values
+// for a given RuleTargetConfig, converting the config file strings into appropriate constants
+//
+// Todo: support different formats for key specification
+func decodeRuleTargetValues(target RuleTargetConfig) (evdev.EvType, evdev.EvCode, error) {
+	var eventType evdev.EvType
+	var eventCode evdev.EvCode
+	var ok bool
+
+	if target.Button != "" {
+		eventType = evdev.EV_KEY
+		eventCode, ok = evdev.KEYFromString[target.Button]
+		if !ok {
+			return 0, 0, fmt.Errorf("skipping rule due to invalid button code '%s'", target.Button)
+		}
+	}
+	if target.Axis != "" {
+		eventType = evdev.EV_ABS
+		eventCode, ok = evdev.ABSFromString[target.Axis]
+		if !ok {
+			return 0, 0, fmt.Errorf("skipping rule due to invalid axis code '%s'", target.Button)
+		}
+	}
+
+	return eventType, eventCode, nil
+}