// Copyright The OpenTelemetry Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

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

import (
	"go.opentelemetry.io/otel/metric"
	"go.opentelemetry.io/otel/metric/internal/global"
)

// Meter returns a Meter from the global MeterProvider. The name must be the
// name of the library providing instrumentation. This name may be the same as
// the instrumented code only if that code provides built-in instrumentation.
// If the name is empty, then a implementation defined default name will be
// used instead.
//
// If this is called before a global MeterProvider is registered the returned
// Meter will be a No-op implementation of a Meter. When a global MeterProvider
// is registered for the first time, the returned Meter, and all the
// instruments it has created or will create, are recreated automatically from
// the new MeterProvider.
//
// This is short for GetMeterProvider().Meter(name).
func Meter(instrumentationName string, opts ...metric.MeterOption) metric.Meter {
	return MeterProvider().Meter(instrumentationName, opts...)
}

// MeterProvider returns the registered global meter provider.
//
// If no global MeterProvider has been registered, a No-op MeterProvider implementation is returned. When a global MeterProvider is registered for the first time, the returned MeterProvider, and all the Meters it has created or will create, are recreated automatically from the new MeterProvider.
func MeterProvider() metric.MeterProvider {
	return global.MeterProvider()
}

// SetMeterProvider registers mp as the global MeterProvider.
func SetMeterProvider(mp metric.MeterProvider) {
	global.SetMeterProvider(mp)
}