feat(brake): implement brake feature

pkg/brake/config.go

@@ -0,0 +1,54 @@
+package brake
+
+import (
+	"encoding/json"
+	"fmt"
+	"github.com/cyrilix/robocar-throttle/pkg/types"
+	"os"
+)
+
+var (
+	defaultBrakeConfig = Config{
+		DeltaSteps: []float32{0.05, 0.3, 0.5},
+		Data:       []types.Throttle{-0.1, -0.5, -1.},
+	}
+)
+
+func NewConfig() *Config {
+	return &defaultBrakeConfig
+}
+
+func NewConfigFromJson(fileName string) (*Config, error) {
+	content, err := os.ReadFile(fileName)
+	if err != nil {
+		return nil, fmt.Errorf("unable to read content from %s file: %w", fileName, err)
+	}
+	var ft Config
+	err = json.Unmarshal(content, &ft)
+	if err != nil {
+		return nil, fmt.Errorf("unable to unmarshal json content from %s file: %w", fileName, err)
+	}
+	return &ft, nil
+}
+
+type Config struct {
+	DeltaSteps []float32        `json:"delta_steps"`
+	Data       []types.Throttle `json:"data"`
+}
+
+func (tc *Config) ValueOf(currentThrottle, targetThrottle types.Throttle) types.Throttle {
+	delta := float32(currentThrottle - targetThrottle)
+
+	if delta < tc.DeltaSteps[0] {
+		return targetThrottle
+	}
+	if delta >= tc.DeltaSteps[len(tc.DeltaSteps)-1] {
+		return tc.Data[len(tc.Data)-1]
+	}
+	for idx, step := range tc.DeltaSteps {
+		if delta < step {
+			return tc.Data[idx-1]
+		}
+	}
+	return tc.Data[len(tc.Data)-1]
+}