package tracing

import (
	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/trace"
)

// tracerName is the instrumentation scope for every span this module emits.
const tracerName = "gitea.home.hrajfrisbee.cz/kacerr/egress-proxies-operator"

type options struct {
	tp trace.TracerProvider
}

// Option configures the tracing decorators. The zero configuration uses the
// global TracerProvider installed by Setup; tests inject their own recorder
// via WithTracerProvider so they can run in parallel without touching
// process-global state.
type Option func(*options)

// WithTracerProvider overrides the global TracerProvider.
func WithTracerProvider(tp trace.TracerProvider) Option {
	return func(o *options) { o.tp = tp }
}

func newOptions(opts []Option) options {
	var o options
	for _, opt := range opts {
		opt(&o)
	}
	return o
}

// Tracer resolves a tracer from the given options, for decorators outside
// this package (provider.WithTracing).
func Tracer(opts ...Option) trace.Tracer {
	return newOptions(opts).tracer()
}

// tracer resolves the configured tracer. The global path goes through
// otel.Tracer, which delegates to whatever provider Setup installs later —
// construction order between decorators and Setup does not matter.
func (o options) tracer() trace.Tracer {
	if o.tp != nil {
		return o.tp.Tracer(tracerName)
	}
	return otel.Tracer(tracerName)
}