/*
Copyright 2019 The Kubernetes 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 metrics

import (
	"bytes"
	"context"
	"sync"
	"testing"

	dto "github.com/prometheus/client_model/go"
	"github.com/prometheus/common/expfmt"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"go.opentelemetry.io/otel/trace"
	tracenoop "go.opentelemetry.io/otel/trace/noop"

	apimachineryversion "k8s.io/apimachinery/pkg/version"
)

func TestCounter(t *testing.T) {
	version1_15Alpha1 := apimachineryversion.Info{
		Major:      "1",
		Minor:      "15",
		GitVersion: "v1.15.0-alpha-1.12345",
	}

	var tests = []struct {
		desc string
		*CounterOpts
		currentVersion      apimachineryversion.Info
		expectedMetricCount int
		expectedHelp        string
	}{
		// Non-deprecated metrics
		{
			desc: "ALPHA metric non deprecated",
			CounterOpts: &CounterOpts{
				Namespace:      "namespace",
				Name:           "metric_test_name",
				Subsystem:      "subsystem",
				StabilityLevel: ALPHA,
				Help:           "counter help",
			},
			expectedMetricCount: 1,
			expectedHelp:        "[ALPHA] counter help",
		},
		{
			desc: "BETA metric non deprecated",
			CounterOpts: &CounterOpts{
				Namespace:      "namespace",
				Name:           "metric_test_name",
				Subsystem:      "subsystem",
				StabilityLevel: BETA,
				Help:           "counter help",
			},
			expectedMetricCount: 1,
			expectedHelp:        "[BETA] counter help",
		},
		{
			desc: "STABLE metric non deprecated",
			CounterOpts: &CounterOpts{
				Namespace:      "namespace",
				Name:           "metric_test_name",
				Subsystem:      "subsystem",
				StabilityLevel: STABLE,
				Help:           "counter help",
			},
			expectedMetricCount: 1,
			expectedHelp:        "[STABLE] counter help",
		},
		// Deprecated metrics
		{
			desc: "ALPHA metric deprecated",
			CounterOpts: &CounterOpts{
				Namespace:         "namespace",
				Name:              "metric_test_name",
				Subsystem:         "subsystem",
				Help:              "counter help",
				StabilityLevel:    ALPHA,
				DeprecatedVersion: "1.15.0",
			},
			expectedMetricCount: 0,
			expectedHelp:        "counter help",
		},
		{
			desc: "BETA metric deprecated",
			CounterOpts: &CounterOpts{
				Namespace:         "namespace",
				Name:              "metric_test_name",
				Subsystem:         "subsystem",
				Help:              "counter help",
				StabilityLevel:    BETA,
				DeprecatedVersion: "1.15.0",
			},
			expectedMetricCount: 1,
			expectedHelp:        "[BETA] (Deprecated since 1.15.0) counter help",
		},
		{
			desc: "STABLE metric deprecated",
			CounterOpts: &CounterOpts{
				Namespace:         "namespace",
				Name:              "metric_test_name",
				Subsystem:         "subsystem",
				Help:              "counter help",
				StabilityLevel:    STABLE,
				DeprecatedVersion: "1.14.0",
			},
			expectedMetricCount: 1,
			expectedHelp:        "[STABLE] (Deprecated since 1.14.0) counter help",
		},
		// Hidden metrics
		{
			desc: "ALPHA metric hidden",
			CounterOpts: &CounterOpts{
				Namespace:         "namespace",
				Name:              "metric_test_name",
				Subsystem:         "subsystem",
				Help:              "counter help",
				StabilityLevel:    ALPHA,
				DeprecatedVersion: "1.15.0",
			},
			expectedMetricCount: 0,
			expectedHelp:        "counter help",
		},
		{
			desc: "BETA metric hidden",
			CounterOpts: &CounterOpts{
				Namespace:         "namespace",
				Name:              "metric_test_name",
				Subsystem:         "subsystem",
				Help:              "counter help",
				StabilityLevel:    BETA,
				DeprecatedVersion: "1.14.0",
			},
			expectedMetricCount: 0},
		{
			desc: "STABLE metric hidden",
			CounterOpts: &CounterOpts{
				Namespace:         "namespace",
				Name:              "metric_test_name",
				Subsystem:         "subsystem",
				Help:              "counter help",
				StabilityLevel:    STABLE,
				DeprecatedVersion: "1.12.0",
			},
			expectedMetricCount: 0,
			expectedHelp:        "counter help",
		},
	}

	for _, test := range tests {
		t.Run(test.desc, func(t *testing.T) {
			registry := newKubeRegistry(version1_15Alpha1)
			// c is a pointer to a Counter
			c := NewCounter(test.CounterOpts)
			registry.MustRegister(c)
			// mfs is a pointer to a dto.MetricFamily slice
			mfs, err := registry.Gather()
			var buf bytes.Buffer
			enc := expfmt.NewEncoder(&buf, "text/plain; version=0.0.4; charset=utf-8")
			assert.Lenf(t, mfs, test.expectedMetricCount, "Got %v metrics, Want: %v metrics", len(mfs), test.expectedMetricCount)
			require.NoError(t, err, "Gather failed %v", err)
			for _, metric := range mfs {
				err := enc.Encode(metric)
				require.NoError(t, err, "Unexpected err %v in encoding the metric", err)
				assert.Equalf(t, test.expectedHelp, metric.GetHelp(), "Got %s as help message, want %s", metric.GetHelp(), test.expectedHelp)
			}

			// increment the counter N number of times and verify that the metric retains the count correctly
			numberOfTimesToIncrement := 3
			for i := 0; i < numberOfTimesToIncrement; i++ {
				c.Inc()
			}
			mfs, err = registry.Gather()
			require.NoError(t, err, "Gather failed %v", err)

			for _, mf := range mfs {
				mfMetric := mf.GetMetric()
				for _, m := range mfMetric {
					assert.Equalf(t, numberOfTimesToIncrement, int(m.GetCounter().GetValue()), "Got %v, wanted %v as the count", m.GetCounter().GetValue(), numberOfTimesToIncrement)
				}
			}
		})
	}
}

func TestCounterVec(t *testing.T) {
	version1_15Alpha1 := apimachineryversion.Info{
		Major:      "1",
		Minor:      "15",
		GitVersion: "v1.15.0-alpha-1.12345",
	}

	var tests = []struct {
		desc string
		*CounterOpts
		labels                    []string
		expectedMetricFamilyCount int
		expectedHelp              string
	}{
		// Non-deprecated metrics
		{
			desc: "ALPHA metric non deprecated",
			CounterOpts: &CounterOpts{
				Namespace:      "namespace",
				Name:           "metric_test_name",
				Subsystem:      "subsystem",
				StabilityLevel: ALPHA,
				Help:           "counter help",
			},
			labels:                    []string{"label_a", "label_b"},
			expectedMetricFamilyCount: 1,
			expectedHelp:              "[ALPHA] counter help",
		},
		{
			desc: "BETA metric non deprecated",
			CounterOpts: &CounterOpts{
				Namespace:      "namespace",
				Name:           "metric_test_name",
				Subsystem:      "subsystem",
				StabilityLevel: BETA,
				Help:           "counter help",
			},
			labels:                    []string{"label_a", "label_b"},
			expectedMetricFamilyCount: 1,
			expectedHelp:              "[BETA] counter help",
		},
		{
			desc: "STABLE metric non deprecated",
			CounterOpts: &CounterOpts{
				Namespace:      "namespace",
				Name:           "metric_test_name",
				Subsystem:      "subsystem",
				StabilityLevel: STABLE,
				Help:           "counter help",
			},
			labels:                    []string{"label_a", "label_b"},
			expectedMetricFamilyCount: 1,
			expectedHelp:              "[STABLE] counter help",
		},
		// Deprecated metrics
		{
			desc: "ALPHA metric deprecated",
			CounterOpts: &CounterOpts{
				Namespace:         "namespace",
				Name:              "metric_test_name",
				Subsystem:         "subsystem",
				StabilityLevel:    ALPHA,
				Help:              "counter help",
				DeprecatedVersion: "1.15.0",
			},
			labels:                    []string{"label_a", "label_b"},
			expectedMetricFamilyCount: 0,
			expectedHelp:              "counter help",
		},
		{
			desc: "BETA metric deprecated",
			CounterOpts: &CounterOpts{
				Namespace:         "namespace",
				Name:              "metric_test_name",
				Subsystem:         "subsystem",
				StabilityLevel:    BETA,
				Help:              "counter help",
				DeprecatedVersion: "1.15.0",
			},
			labels:                    []string{"label_a", "label_b"},
			expectedMetricFamilyCount: 1,
			expectedHelp:              "[BETA] (Deprecated since 1.15.0) counter help",
		},
		{
			desc: "STABLE metric deprecated",
			CounterOpts: &CounterOpts{
				Namespace:         "namespace",
				Name:              "metric_test_name",
				Subsystem:         "subsystem",
				StabilityLevel:    STABLE,
				Help:              "counter help",
				DeprecatedVersion: "1.15.0",
			},
			labels:                    []string{"label_a", "label_b"},
			expectedMetricFamilyCount: 1,
			expectedHelp:              "[STABLE] (Deprecated since 1.15.0) counter help",
		},
		// Hidden metrics
		{
			desc: "ALPHA metric hidden",
			CounterOpts: &CounterOpts{
				Namespace:         "namespace",
				Name:              "metric_test_name",
				Subsystem:         "subsystem",
				StabilityLevel:    ALPHA,
				Help:              "counter help",
				DeprecatedVersion: "1.14.0",
			},
			labels:                    []string{"label_a", "label_b"},
			expectedMetricFamilyCount: 0,
			expectedHelp:              "counter help",
		},
		{
			desc: "BETA metric hidden",
			CounterOpts: &CounterOpts{
				Namespace:         "namespace",
				Name:              "metric_test_name",
				Subsystem:         "subsystem",
				StabilityLevel:    BETA,
				Help:              "counter help",
				DeprecatedVersion: "1.14.0",
			},
			labels:                    []string{"label_a", "label_b"},
			expectedMetricFamilyCount: 0,
			expectedHelp:              "counter help",
		},
		{
			desc: "STABLE metric hidden",
			CounterOpts: &CounterOpts{
				Namespace:         "namespace",
				Name:              "metric_test_name",
				Subsystem:         "subsystem",
				StabilityLevel:    STABLE,
				Help:              "counter help",
				DeprecatedVersion: "1.12.0",
			},
			labels:                    []string{"label_a", "label_b"},
			expectedMetricFamilyCount: 0,
			expectedHelp:              "counter help",
		},
	}

	for _, test := range tests {
		t.Run(test.desc, func(t *testing.T) {
			registry := newKubeRegistry(version1_15Alpha1)
			c := NewCounterVec(test.CounterOpts, test.labels)
			registry.MustRegister(c)
			c.WithLabelValues("1", "2").Inc()
			mfs, err := registry.Gather()
			assert.Lenf(t, mfs, test.expectedMetricFamilyCount, "Got %v metric families, Want: %v metric families", len(mfs), test.expectedMetricFamilyCount)
			require.NoError(t, err, "Gather failed %v", err)

			// this no-opts here when there are no metric families (i.e. when the metric is hidden)
			for _, mf := range mfs {
				assert.Lenf(t, mf.GetMetric(), 1, "Got %v metrics, wanted 1 as the count", len(mf.GetMetric()))
				assert.Equalf(t, test.expectedHelp, mf.GetHelp(), "Got %s as help message, want %s", mf.GetHelp(), test.expectedHelp)
			}

			// let's increment the counter and verify that the metric still works
			c.WithLabelValues("1", "3").Inc()
			c.WithLabelValues("2", "3").Inc()
			mfs, err = registry.Gather()
			require.NoError(t, err, "Gather failed %v", err)

			// this no-opts here when there are no metric families (i.e. when the metric is hidden)
			for _, mf := range mfs {
				assert.Lenf(t, mf.GetMetric(), 3, "Got %v metrics, wanted 3 as the count", len(mf.GetMetric()))
			}
		})
	}
}

func TestCounterWithLabelValueAllowList(t *testing.T) {
	labelAllowValues := map[string]string{
		"namespace_subsystem_metric_allowlist_test,label_a": "allowed",
	}
	labels := []string{"label_a", "label_b"}
	opts := &CounterOpts{
		Namespace: "namespace",
		Name:      "metric_allowlist_test",
		Subsystem: "subsystem",
	}
	var tests = []struct {
		desc               string
		labelValues        [][]string
		expectMetricValues map[string]int
	}{
		{
			desc:        "Test no unexpected input",
			labelValues: [][]string{{"allowed", "b1"}, {"allowed", "b2"}},
			expectMetricValues: map[string]int{
				"allowed b1": 1,
				"allowed b2": 1,
			},
		},
		{
			desc:        "Test unexpected input",
			labelValues: [][]string{{"allowed", "b1"}, {"not_allowed", "b1"}},
			expectMetricValues: map[string]int{
				"allowed b1":    1,
				"unexpected b1": 1,
			},
		},
	}

	for _, test := range tests {
		t.Run(test.desc, func(t *testing.T) {
			labelValueAllowLists = map[string]*MetricLabelAllowList{}

			registry := newKubeRegistry(apimachineryversion.Info{
				Major:      "1",
				Minor:      "15",
				GitVersion: "v1.15.0-alpha-1.12345",
			})
			c := NewCounterVec(opts, labels)
			registry.MustRegister(c)
			SetLabelAllowList(labelAllowValues)
			for _, lv := range test.labelValues {
				c.WithLabelValues(lv...).Inc()
			}
			mfs, err := registry.Gather()
			require.NoError(t, err, "Gather failed %v", err)

			for _, mf := range mfs {
				if *mf.Name != BuildFQName(opts.Namespace, opts.Subsystem, opts.Name) {
					continue
				}
				mfMetric := mf.GetMetric()

				for _, m := range mfMetric {
					var aValue, bValue string
					for _, l := range m.Label {
						if *l.Name == "label_a" {
							aValue = *l.Value
						}
						if *l.Name == "label_b" {
							bValue = *l.Value
						}
					}
					labelValuePair := aValue + " " + bValue
					expectedValue, ok := test.expectMetricValues[labelValuePair]
					assert.True(t, ok, "Got unexpected label values, lable_a is %v, label_b is %v", aValue, bValue)
					actualValue := int(m.GetCounter().GetValue())
					assert.Equalf(t, expectedValue, actualValue, "Got %v, wanted %v as the count while setting label_a to %v and label b to %v", actualValue, expectedValue, aValue, bValue)
				}
			}
		})
	}
}

func TestCounterWithExemplar(t *testing.T) {
	// Set exemplar.
	fn := func(offset int) []byte {
		arr := make([]byte, 16)
		for i := 0; i < 16; i++ {
			arr[i] = byte(2<<7 - i - offset)
		}
		return arr
	}
	traceID := trace.TraceID(fn(1))
	spanID := trace.SpanID(fn(2))
	ctxForSpanCtx := trace.ContextWithSpanContext(context.Background(), trace.NewSpanContext(trace.SpanContextConfig{
		SpanID:     spanID,
		TraceID:    traceID,
		TraceFlags: trace.FlagsSampled,
	}))
	toAdd := float64(40)

	// Create contextual counter.
	counter := NewCounter(&CounterOpts{
		Name: "metric_exemplar_test",
		Help: "helpless",
	})

	// Register counter.
	registry := newKubeRegistry(apimachineryversion.Info{
		Major:      "1",
		Minor:      "15",
		GitVersion: "v1.15.0-alpha-1.12345",
	})
	registry.MustRegister(counter)

	// Call underlying exemplar methods.
	counter.WithContext(ctxForSpanCtx).Add(toAdd)
	counter.WithContext(ctxForSpanCtx).Inc()
	counter.WithContext(ctxForSpanCtx).Inc()

	// Gather.
	mfs, err := registry.Gather()
	if err != nil {
		t.Fatalf("Gather failed %v", err)
	}
	if len(mfs) != 1 {
		t.Fatalf("Got %v metric families, Want: 1 metric family", len(mfs))
	}

	// Verify metric type.
	mf := mfs[0]
	var m *dto.Metric
	switch mf.GetType() {
	case dto.MetricType_COUNTER:
		m = mfs[0].GetMetric()[0]
	default:
		t.Fatalf("Got %v metric type, Want: %v metric type", mf.GetType(), dto.MetricType_COUNTER)
	}

	// Verify value.
	want := toAdd + 2
	got := m.GetCounter().GetValue()
	if got != want {
		t.Fatalf("Got %f, wanted %f as the count", got, want)
	}

	// Verify exemplars.
	e := m.GetCounter().GetExemplar()
	if e == nil {
		t.Fatalf("Got nil exemplar, wanted an exemplar")
	}
	eLabels := e.GetLabel()
	if eLabels == nil {
		t.Fatalf("Got nil exemplar label, wanted an exemplar label")
	}
	if len(eLabels) != 2 {
		t.Fatalf("Got %v exemplar labels, wanted 2 exemplar labels", len(eLabels))
	}
	for _, l := range eLabels {
		switch *l.Name {
		case "trace_id":
			if *l.Value != traceID.String() {
				t.Fatalf("Got %s as traceID, wanted %s", *l.Value, traceID.String())
			}
		case "span_id":
			if *l.Value != spanID.String() {
				t.Fatalf("Got %s as spanID, wanted %s", *l.Value, spanID.String())
			}
		default:
			t.Fatalf("Got unexpected label %s", *l.Name)
		}
	}
}

// TestCounterConcurrentWithContextRace reproduces the race condition in Counter.WithContext
// where c.ctx is written concurrently with reads in withExemplar method.
// This test simulates the real authentication flow that triggers the race:
// x509.AuthenticateRequest -> union.AuthenticateRequest -> group.AuthenticateRequest
func TestCounterConcurrentWithContextRace(t *testing.T) {
	opts := &CounterOpts{
		Namespace: "apiserver",
		Subsystem: "authentication",
		Name:      "requests_total",
		Help:      "Authentication requests counter for race condition testing",
	}

	c := NewCounter(opts)

	// Force initialization by calling initializeMetric directly
	c.initializeMetric()

	// Create contexts with trace spans to trigger exemplar code path
	ctx1, span1 := createContextWithSpanCounter("x509-auth", "authenticate-request")
	defer span1.End()
	ctx2, span2 := createContextWithSpanCounter("union-auth", "union-authenticate")
	defer span2.End()

	var wg sync.WaitGroup
	iterations := 10000 // Increase iterations to make race more likely

	// Goroutine 1: Simulate x509 Authenticator calling WithContext
	// This matches: x509.(*Authenticator).AuthenticateRequest() calling WithContext
	wg.Add(1)
	go func() {
		defer wg.Done()
		for i := 0; i < iterations; i++ {
			// Simulate authentication request processing
			simulateX509AuthenticateRequestCounter(c, ctx1, i)
		}
	}()

	// Goroutine 2: Simulate concurrent Add/Inc calls (metrics collection)
	// This matches the withExemplar/Add path that reads c.ctx
	wg.Add(1)
	go func() {
		defer wg.Done()
		for i := 0; i < iterations; i++ {
			c.Add(float64(i % 10))
			if i%2 == 0 {
				c.Inc()
			}
		}
	}()

	// Goroutine 3: Simulate union AuthenticateRequest calling WithContext
	// This matches: union.(*unionAuthRequestHandler).AuthenticateRequest()
	wg.Add(1)
	go func() {
		defer wg.Done()
		for i := 0; i < iterations; i++ {
			// Simulate union authentication processing
			simulateUnionAuthenticateRequestCounter(c, ctx2, i)
		}
	}()

	// Goroutine 4: Simulate group AuthenticateRequest calling WithContext
	// This matches: group.(*AuthenticatedGroupAdder).AuthenticateRequest()
	wg.Add(1)
	go func() {
		defer wg.Done()
		for i := 0; i < iterations; i++ {
			// Simulate group authentication processing
			simulateGroupAuthenticateRequestCounter(c, ctx1, ctx2, i)
		}
	}()

	wg.Wait()
}

// simulateX509AuthenticateRequestCounter simulates the call path from x509 authenticator
func simulateX509AuthenticateRequestCounter(c CounterMetric, ctx context.Context, iteration int) {
	// Simulate the authentication request processing that calls WithContext
	if cWithCtx, ok := c.(*Counter); ok {
		cWithCtx.WithContext(ctx)
	}
}

// simulateUnionAuthenticateRequestCounter simulates the call path from union authenticator
func simulateUnionAuthenticateRequestCounter(c CounterMetric, ctx context.Context, iteration int) {
	// Simulate union authentication processing
	if cWithCtx, ok := c.(*Counter); ok {
		cWithCtx.WithContext(ctx)
	}
}

// simulateGroupAuthenticateRequestCounter simulates the call path from group authenticator
func simulateGroupAuthenticateRequestCounter(c CounterMetric, ctx1, ctx2 context.Context, iteration int) {
	// Alternate between contexts to simulate different authentication scenarios
	ctx := ctx1
	if iteration%3 == 0 {
		ctx = ctx2
	}

	if cWithCtx, ok := c.(*Counter); ok {
		cWithCtx.WithContext(ctx)
	}
}

// Helper function to create a context with a valid trace span
func createContextWithSpanCounter(traceID, spanID string) (context.Context, trace.Span) {
	ctx := context.Background()

	// Create a noop tracer and span for testing
	tracer := tracenoop.NewTracerProvider().Tracer("test")
	ctx, span := tracer.Start(ctx, "test-span")

	return ctx, span
}