// 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/api/global/internal"
	"go.opentelemetry.io/otel/api/metric"
)

// Meter creates an implementation of the Meter interface from the global
// MeterProvider. The instrumentationName 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
// instrumentationName is empty, then a implementation defined default name
// will be used instead.
//
// This is short for MeterProvider().Meter(name)
func Meter(instrumentationName string, opts ...metric.MeterOption) metric.Meter {
	return MeterProvider().Meter(instrumentationName, opts...)
}

// MeterProvider returns the registered global meter provider.  If
// none is registered then a default meter provider is returned that
// forwards the Meter interface to the first registered Meter.
//
// Use the meter provider to create a named meter. E.g.
//     meter := global.MeterProvider().Meter("example.com/foo")
// or
//     meter := global.Meter("example.com/foo")
func MeterProvider() metric.MeterProvider {
	return internal.MeterProvider()
}

// SetMeterProvider registers `mp` as the global meter provider.
func SetMeterProvider(mp metric.MeterProvider) {
	internal.SetMeterProvider(mp)
}