package telemetry

import (
	"strings"
	"testing"
	"time"

	"github.com/armon/go-metrics"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/sdk/instrumentation"
	"go.opentelemetry.io/otel/sdk/metric/metricdata"
	"go.opentelemetry.io/otel/sdk/resource"
	semconv "go.opentelemetry.io/otel/semconv/v1.17.0"
	cpb "go.opentelemetry.io/proto/otlp/common/v1"
	mpb "go.opentelemetry.io/proto/otlp/metrics/v1"
	rpb "go.opentelemetry.io/proto/otlp/resource/v1"
)

var (
	// Common attributes for test cases.
	start = time.Date(2000, time.January, 01, 0, 0, 0, 0, time.FixedZone("GMT", 0))
	end   = start.Add(30 * time.Second)

	alice = attribute.NewSet(attribute.String("user", "alice"))
	bob   = attribute.NewSet(attribute.String("user", "bob"))

	pbAlice = &cpb.KeyValue{Key: "user", Value: &cpb.AnyValue{
		Value: &cpb.AnyValue_StringValue{StringValue: "alice"},
	}}
	pbBob = &cpb.KeyValue{Key: "user", Value: &cpb.AnyValue{
		Value: &cpb.AnyValue_StringValue{StringValue: "bob"},
	}}

	// DataPoint test case : Histogram Datapoints (Histogram)
	minA, maxA, sumA = 2.0, 4.0, 90.0
	minB, maxB, sumB = 4.0, 150.0, 234.0
	inputHDP         = []metricdata.HistogramDataPoint[float64]{{
		Attributes:   alice,
		StartTime:    start,
		Time:         end,
		Count:        30,
		Bounds:       []float64{1, 5},
		BucketCounts: []uint64{0, 30, 0},
		Min:          metricdata.NewExtrema(minA),
		Max:          metricdata.NewExtrema(maxA),
		Sum:          sumA,
	}, {
		Attributes:   bob,
		StartTime:    start,
		Time:         end,
		Count:        3,
		Bounds:       []float64{1, 5},
		BucketCounts: []uint64{0, 1, 2},
		Min:          metricdata.NewExtrema(minB),
		Max:          metricdata.NewExtrema(maxB),
		Sum:          sumB,
	}}

	expectedHDP = []*mpb.HistogramDataPoint{{
		Attributes:        []*cpb.KeyValue{pbAlice},
		StartTimeUnixNano: uint64(start.UnixNano()),
		TimeUnixNano:      uint64(end.UnixNano()),
		Count:             30,
		Sum:               &sumA,
		ExplicitBounds:    []float64{1, 5},
		BucketCounts:      []uint64{0, 30, 0},
		Min:               &minA,
		Max:               &maxA,
	}, {
		Attributes:        []*cpb.KeyValue{pbBob},
		StartTimeUnixNano: uint64(start.UnixNano()),
		TimeUnixNano:      uint64(end.UnixNano()),
		Count:             3,
		Sum:               &sumB,
		ExplicitBounds:    []float64{1, 5},
		BucketCounts:      []uint64{0, 1, 2},
		Min:               &minB,
		Max:               &maxB,
	}}
	// DataPoint test case : Number Datapoints (Gauge / Counter)
	inputDP = []metricdata.DataPoint[float64]{
		{Attributes: alice, StartTime: start, Time: end, Value: 1.0},
		{Attributes: bob, StartTime: start, Time: end, Value: 2.0},
	}

	expectedDP = []*mpb.NumberDataPoint{
		{
			Attributes:        []*cpb.KeyValue{pbAlice},
			StartTimeUnixNano: uint64(start.UnixNano()),
			TimeUnixNano:      uint64(end.UnixNano()),
			Value:             &mpb.NumberDataPoint_AsDouble{AsDouble: 1.0},
		},
		{
			Attributes:        []*cpb.KeyValue{pbBob},
			StartTimeUnixNano: uint64(start.UnixNano()),
			TimeUnixNano:      uint64(end.UnixNano()),
			Value:             &mpb.NumberDataPoint_AsDouble{AsDouble: 2.0},
		},
	}

	invalidSumTemporality = metricdata.Metrics{
		Name:        "invalid-sum",
		Description: "Sum with invalid temporality",
		Unit:        "1",
		Data: metricdata.Sum[float64]{
			Temporality: metricdata.DeltaTemporality,
			IsMonotonic: false,
			DataPoints:  inputDP,
		},
	}

	invalidSumAgg = metricdata.Metrics{
		Name:        "unknown",
		Description: "Unknown aggregation",
		Unit:        "1",
		Data:        metricdata.Sum[int64]{},
	}

	invalidHistTemporality = metricdata.Metrics{
		Name:        "invalid-histogram",
		Description: "Invalid histogram",
		Unit:        "1",
		Data: metricdata.Histogram[float64]{
			Temporality: metricdata.DeltaTemporality,
			DataPoints:  inputHDP,
		},
	}

	validFloat64Gauge = metricdata.Metrics{
		Name:        "float64-gauge",
		Description: "Gauge with float64 values",
		Unit:        "1",
		Data:        metricdata.Gauge[float64]{DataPoints: inputDP},
	}

	validFloat64Sum = metricdata.Metrics{
		Name:        "float64-sum",
		Description: "Sum with float64 values",
		Unit:        "1",
		Data: metricdata.Sum[float64]{
			Temporality: metricdata.CumulativeTemporality,
			IsMonotonic: false,
			DataPoints:  inputDP,
		},
	}

	validFloat64Hist = metricdata.Metrics{
		Name:        "float64-histogram",
		Description: "Histogram",
		Unit:        "1",
		Data: metricdata.Histogram[float64]{
			Temporality: metricdata.CumulativeTemporality,
			DataPoints:  inputHDP,
		},
	}

	// Metrics Test Case
	// - 3 invalid metrics and 3 Valid to test filtering
	//      - 1 invalid metric type
	//      - 2 invalid cummulative temporalities (only cummulative supported)
	// - 3 types (Gauge, Counter, and Histogram) supported
	inputMetrics = []metricdata.Metrics{
		validFloat64Gauge,
		validFloat64Sum,
		validFloat64Hist,
		invalidSumTemporality,
		invalidHistTemporality,
		invalidSumAgg,
	}

	expectedMetrics = []*mpb.Metric{
		{
			Name:        "float64-gauge",
			Description: "Gauge with float64 values",
			Unit:        "1",
			Data:        &mpb.Metric_Gauge{Gauge: &mpb.Gauge{DataPoints: expectedDP}},
		},
		{
			Name:        "float64-sum",
			Description: "Sum with float64 values",
			Unit:        "1",
			Data: &mpb.Metric_Sum{Sum: &mpb.Sum{
				AggregationTemporality: mpb.AggregationTemporality_AGGREGATION_TEMPORALITY_CUMULATIVE,
				IsMonotonic:            false,
				DataPoints:             expectedDP,
			}},
		},
		{
			Name:        "float64-histogram",
			Description: "Histogram",
			Unit:        "1",
			Data: &mpb.Metric_Histogram{Histogram: &mpb.Histogram{
				AggregationTemporality: mpb.AggregationTemporality_AGGREGATION_TEMPORALITY_CUMULATIVE,
				DataPoints:             expectedHDP,
			}},
		},
	}

	// ScopeMetrics Test Cases
	inputScopeMetrics = []metricdata.ScopeMetrics{{
		Scope: instrumentation.Scope{
			Name:    "test/code/path",
			Version: "v0.1.0",
		},
		Metrics: inputMetrics,
	}}

	expectedScopeMetrics = []*mpb.ScopeMetrics{{
		Scope: &cpb.InstrumentationScope{
			Name:    "test/code/path",
			Version: "v0.1.0",
		},
		Metrics: expectedMetrics,
	}}

	// ResourceMetrics Test Cases
	inputResourceMetrics = &metricdata.ResourceMetrics{
		Resource: resource.NewSchemaless(
			semconv.ServiceName("test server"),
			semconv.ServiceVersion("v0.1.0"),
		),
		ScopeMetrics: inputScopeMetrics,
	}

	expectedResourceMetrics = &mpb.ResourceMetrics{
		Resource: &rpb.Resource{
			Attributes: []*cpb.KeyValue{
				{
					Key: "service.name",
					Value: &cpb.AnyValue{
						Value: &cpb.AnyValue_StringValue{StringValue: "test server"},
					},
				},
				{
					Key: "service.version",
					Value: &cpb.AnyValue{
						Value: &cpb.AnyValue_StringValue{StringValue: "v0.1.0"},
					},
				},
			},
		},
		ScopeMetrics: expectedScopeMetrics,
	}
)

// TestTransformOTLP runs tests from the "bottom-up" of the metricdata data types.
func TestTransformOTLP(t *testing.T) {
	t.Parallel()
	// Histogram DataPoint Test Case (Histograms)
	assert.Equal(t, expectedHDP, histogramDataPointsToPB(inputHDP))

	// Number DataPoint Test Case (Counters / Gauges)
	require.Equal(t, expectedDP, dataPointsToPB(inputDP))

	// MetricType Error Test Cases
	_, err := metricTypeToPB(invalidHistTemporality)
	require.Error(t, err)
	require.ErrorIs(t, err, temporalityErr)

	_, err = metricTypeToPB(invalidSumTemporality)
	require.Error(t, err)
	require.ErrorIs(t, err, temporalityErr)

	_, err = metricTypeToPB(invalidSumAgg)
	require.Error(t, err)
	require.ErrorIs(t, err, aggregationErr)

	// Metrics Test Case
	m := metricsToPB(inputMetrics)
	require.Equal(t, expectedMetrics, m)
	require.Equal(t, len(expectedMetrics), 3)

	// Scope Metrics Test Case
	sm := scopeMetricsToPB(inputScopeMetrics)
	require.Equal(t, expectedScopeMetrics, sm)

	// // Resource Metrics Test Case
	rm := transformOTLP(inputResourceMetrics)
	require.Equal(t, expectedResourceMetrics, rm)
}

// TestTransformOTLP_CustomMetrics tests that a custom metric (hcp.otel.transform.failure) is emitted
// when transform fails. This test cannot be run in parallel as the metrics.NewGlobal()
// sets a shared global sink.
func TestTransformOTLP_CustomMetrics(t *testing.T) {
	for name, tc := range map[string]struct {
		inputRM             *metricdata.ResourceMetrics
		expectedMetricCount int
	}{
		"successNoMetric": {
			inputRM: &metricdata.ResourceMetrics{
				// 3 valid metrics.
				ScopeMetrics: []metricdata.ScopeMetrics{
					{
						Metrics: []metricdata.Metrics{
							validFloat64Gauge,
							validFloat64Hist,
							validFloat64Sum,
						},
					},
				},
			},
		},
		"failureEmitsMetric": {
			// inputScopeMetrics contains 3 bad metrics.
			inputRM:             inputResourceMetrics,
			expectedMetricCount: 3,
		},
	} {
		tc := tc
		t.Run(name, func(t *testing.T) {
			// Init global sink.
			serviceName := "test.transform"
			cfg := metrics.DefaultConfig(serviceName)
			cfg.EnableHostname = false

			sink := metrics.NewInmemSink(10*time.Second, 10*time.Second)
			metrics.NewGlobal(cfg, sink)

			// Perform operation that emits metric.
			transformOTLP(tc.inputRM)

			// Collect sink metrics.
			intervals := sink.Data()
			require.Len(t, intervals, 1)
			key := serviceName + "." + strings.Join(internalMetricTransformFailure, ".")
			sv := intervals[0].Counters[key]

			if tc.expectedMetricCount == 0 {
				require.Empty(t, sv)
				return
			}

			// Verify count for transform failure metric.
			require.NotNil(t, sv)
			require.NotNil(t, sv.AggregateSample)
			require.Equal(t, 3, sv.AggregateSample.Count)
		})
	}
}