package econetmetrics

import "go.opentelemetry.io/otel/metric"

// gaugeBuilder creates observable gauges, accumulating them for a single
// RegisterCallback and short-circuiting on the first creation error.
//
// Units are intentionally baked into the metric names (Prometheus idiom)
// rather than set via metric.WithUnit — the OTEL→Prometheus exporter would
// otherwise append a second unit suffix (e.g. econet_setpoint_fahrenheit_F).
type gaugeBuilder struct {
	m   metric.Meter
	obs []metric.Observable
	err error
}

func (b *gaugeBuilder) i64(name, desc string) metric.Int64ObservableGauge {
	if b.err != nil {
		return nil
	}
	g, err := b.m.Int64ObservableGauge(name, metric.WithDescription(desc))
	if err != nil {
		b.err = err
		return nil
	}
	b.obs = append(b.obs, g)
	return g
}

func (b *gaugeBuilder) f64(name, desc string) metric.Float64ObservableGauge {
	if b.err != nil {
		return nil
	}
	g, err := b.m.Float64ObservableGauge(name, metric.WithDescription(desc))
	if err != nil {
		b.err = err
		return nil
	}
	b.obs = append(b.obs, g)
	return g
}