// Copyright 2021 The Prometheus 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 tracing

import (
	"testing"

	"github.com/go-kit/log"
	config_util "github.com/prometheus/common/config"
	"github.com/stretchr/testify/require"
	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/trace"

	"github.com/prometheus/prometheus/config"
)

func TestInstallingNewTracerProvider(t *testing.T) {
	tpBefore := otel.GetTracerProvider()

	m := NewManager(log.NewNopLogger())
	cfg := config.Config{
		TracingConfig: config.TracingConfig{
			Endpoint:   "localhost:1234",
			ClientType: config.TracingClientGRPC,
		},
	}

	require.NoError(t, m.ApplyConfig(&cfg))
	require.NotEqual(t, tpBefore, otel.GetTracerProvider())
}

func TestReinstallingTracerProvider(t *testing.T) {
	m := NewManager(log.NewNopLogger())
	cfg := config.Config{
		TracingConfig: config.TracingConfig{
			Endpoint:   "localhost:1234",
			ClientType: config.TracingClientGRPC,
			TLSConfig: config_util.TLSConfig{
				CAFile:     "ca-file.pem",
				CertFile:   "cert.pem",
				ServerName: "test-server",
			},
		},
	}

	require.NoError(t, m.ApplyConfig(&cfg))
	tpFirstConfig := otel.GetTracerProvider()

	// Trying to apply the same config should not reinstall provider.
	require.NoError(t, m.ApplyConfig(&cfg))
	require.Equal(t, tpFirstConfig, otel.GetTracerProvider())

	cfg2 := config.Config{
		TracingConfig: config.TracingConfig{
			Endpoint:   "localhost:1234",
			ClientType: config.TracingClientHTTP,
			TLSConfig: config_util.TLSConfig{
				CAFile:     "ca-file.pem",
				CertFile:   "cert.pem",
				ServerName: "test-server",
			},
		},
	}

	require.NoError(t, m.ApplyConfig(&cfg2))
	require.NotEqual(t, tpFirstConfig, otel.GetTracerProvider())
}

func TestUninstallingTracerProvider(t *testing.T) {
	m := NewManager(log.NewNopLogger())
	cfg := config.Config{
		TracingConfig: config.TracingConfig{
			Endpoint:   "localhost:1234",
			ClientType: config.TracingClientGRPC,
		},
	}

	require.NoError(t, m.ApplyConfig(&cfg))
	require.NotEqual(t, trace.NewNoopTracerProvider(), otel.GetTracerProvider())

	// Uninstall by passing empty config.
	cfg2 := config.Config{
		TracingConfig: config.TracingConfig{},
	}

	require.NoError(t, m.ApplyConfig(&cfg2))
	// Make sure we get a no-op tracer provider after uninstallation.
	require.Equal(t, trace.NewNoopTracerProvider(), otel.GetTracerProvider())
}

func TestTracerProviderShutdown(t *testing.T) {
	m := NewManager(log.NewNopLogger())
	cfg := config.Config{
		TracingConfig: config.TracingConfig{
			Endpoint:   "localhost:1234",
			ClientType: config.TracingClientGRPC,
		},
	}

	require.NoError(t, m.ApplyConfig(&cfg))
	m.Stop()

	// Check if we closed the done channel.
	_, ok := <-m.done
	require.Equal(t, ok, false)
}