feat: added exercises handler/service/repo

internal/domain/exercise_metric.go

@@ -0,0 +1,95 @@
+package domain
+
+import (
+	"database/sql/driver"
+	"fmt"
+)
+
+type Metric int
+
+const (
+	MetricUnknown Metric = iota
+	MetricReps
+	MetricSeconds
+)
+
+var metricNames = [...]string{
+	MetricUnknown: "",
+	MetricReps:    "reps",
+	MetricSeconds: "seconds",
+}
+
+var metricValues = func() map[string]Metric {
+	m := make(map[string]Metric, len(metricNames))
+	for i, name := range metricNames {
+		m[name] = Metric(i)
+	}
+	return m
+}()
+
+func (m Metric) String() string {
+	if m < 0 || int(m) > len(metricNames) {
+		return ""
+	}
+	return metricNames[m]
+}
+
+func ParseMetric(s string) (Metric, error) {
+	if m, ok := metricValues[s]; ok {
+		return m, nil
+	}
+	return MetricUnknown, fmt.Errorf("metric: unknown value %q", s)
+}
+
+//func (m Metric) MarshalJSON() ([]byte, error) {
+//	s := m.String()
+//	if s == "" {
+//		return nil, fmt.Errorf("metric: cannot marshal value %d", int(m))
+//	}
+//	return json.Marshal(s)
+//}
+//
+//func (m *Metric) UnmarshalJSON(data []byte) error {
+//	var s string
+//	if err := json.Unmarshal(data, &s); err != nil {
+//		return err
+//	}
+//
+//	v, err := ParseMetric(s)
+//	if err != nil {
+//		return err
+//	}
+//
+//	*m = v
+//	return nil
+//}
+
+func (m *Metric) Scan(src any) error {
+	var s string
+	switch v := src.(type) {
+	case nil:
+		return fmt.Errorf("metric: unexpected NULL")
+	case string:
+		s = v
+	case []byte:
+		s = string(v)
+	default:
+		return fmt.Errorf("metric: cannot scan %T", src)
+	}
+
+	parsed, err := ParseMetric(s)
+	if err != nil {
+		return err
+	}
+
+	*m = parsed
+	return nil
+}
+
+func (m Metric) Value() (driver.Value, error) {
+	s := m.String()
+	if s == "" {
+		return nil, fmt.Errorf("metric: cannot store value %d", int(m))
+	}
+	return s, nil
+}