package prometheusremotewrite

import (
	"bytes"
	"fmt"
	"strings"
	"testing"
	"time"

	"github.com/golang/snappy"
	"github.com/prometheus/common/model"
	"github.com/prometheus/prometheus/prompb"
	"github.com/stretchr/testify/require"

	"github.com/influxdata/telegraf"
	"github.com/influxdata/telegraf/metric"
	"github.com/influxdata/telegraf/plugins/serializers"
	"github.com/influxdata/telegraf/testutil"
)

func BenchmarkRemoteWrite(b *testing.B) {
	batch := make([]telegraf.Metric, 1000)
	for i := range batch {
		batch[i] = metric.New(
			"cpu",
			map[string]string{
				"host": "example.org",
				"C":    "D",
				"A":    "B",
			},
			map[string]interface{}{
				"time_idle": 42.0,
			},
			time.Unix(0, 0),
		)
	}
	s := &Serializer{Log: &testutil.CaptureLogger{}}
	for n := 0; n < b.N; n++ {
		//nolint:errcheck // Benchmarking so skip the error check to avoid the unnecessary operations
		s.SerializeBatch(batch)
	}
}

func TestRemoteWriteSerialize(t *testing.T) {
	tests := []struct {
		name     string
		metric   telegraf.Metric
		expected []byte
	}{
		// the only way that we can produce an empty metric name is if the
		// metric is called "prometheus" and has no fields.
		{
			name: "empty name is skipped",
			metric: metric.New(
				"prometheus",
				map[string]string{
					"host": "example.org",
				},
				map[string]interface{}{},
				time.Unix(0, 0),
			),
			expected: []byte(``),
		},
		{
			name: "empty labels are skipped",
			metric: metric.New(
				"cpu",
				map[string]string{
					"": "example.org",
				},
				map[string]interface{}{
					"time_idle": 42.0,
				},
				time.Unix(0, 0),
			),
			expected: []byte(`
cpu_time_idle 42
`),
		},
		{
			name: "simple",
			metric: metric.New(
				"cpu",
				map[string]string{
					"host": "example.org",
				},
				map[string]interface{}{
					"time_idle": 42.0,
				},
				time.Unix(0, 0),
			),
			expected: []byte(`
cpu_time_idle{host="example.org"} 42
`),
		},
		{
			name: "prometheus input untyped",
			metric: metric.New(
				"prometheus",
				map[string]string{
					"code":   "400",
					"method": "post",
				},
				map[string]interface{}{
					"http_requests_total": 3.0,
				},
				time.Unix(0, 0),
				telegraf.Untyped,
			),
			expected: []byte(`
http_requests_total{code="400", method="post"} 3
`),
		},
		{
			name: "prometheus input counter",
			metric: metric.New(
				"prometheus",
				map[string]string{
					"code":   "400",
					"method": "post",
				},
				map[string]interface{}{
					"http_requests_total": 3.0,
				},
				time.Unix(0, 0),
				telegraf.Counter,
			),
			expected: []byte(`
http_requests_total{code="400", method="post"} 3
`),
		},
		{
			name: "prometheus input gauge",
			metric: metric.New(
				"prometheus",
				map[string]string{
					"code":   "400",
					"method": "post",
				},
				map[string]interface{}{
					"http_requests_total": 3.0,
				},
				time.Unix(0, 0),
				telegraf.Gauge,
			),
			expected: []byte(`
http_requests_total{code="400", method="post"} 3
`),
		},
		{
			name: "prometheus input histogram no buckets",
			metric: metric.New(
				"prometheus",
				map[string]string{},
				map[string]interface{}{
					"http_request_duration_seconds_sum":   53423,
					"http_request_duration_seconds_count": 144320,
				},
				time.Unix(0, 0),
				telegraf.Histogram,
			),
			expected: []byte(`
http_request_duration_seconds_count 144320
http_request_duration_seconds_sum 53423
http_request_duration_seconds_bucket{le="+Inf"} 144320
`),
		},
		{
			name: "prometheus input histogram only bucket",
			metric: metric.New(
				"prometheus",
				map[string]string{
					"le": "0.5",
				},
				map[string]interface{}{
					"http_request_duration_seconds_bucket": 129389.0,
				},
				time.Unix(0, 0),
				telegraf.Histogram,
			),
			expected: []byte(`
http_request_duration_seconds_count 0
http_request_duration_seconds_sum 0
http_request_duration_seconds_bucket{le="+Inf"} 0
http_request_duration_seconds_bucket{le="0.5"} 129389
`),
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			s := &Serializer{
				Log:         &testutil.CaptureLogger{},
				SortMetrics: true,
			}
			data, err := s.Serialize(tt.metric)
			require.NoError(t, err)
			actual, err := prompbToText(data)
			require.NoError(t, err)

			require.Equal(t, strings.TrimSpace(string(tt.expected)),
				strings.TrimSpace(string(actual)))
		})
	}
}

func TestRemoteWriteSerializeNegative(t *testing.T) {
	clog := &testutil.CaptureLogger{}
	s := &Serializer{Log: clog}

	assert := func(msg string, err error) {
		t.Helper()
		require.NoError(t, err)

		warnings := clog.Warnings()
		require.NotEmpty(t, warnings, "expected non-empty last message")
		lastMsg := warnings[len(warnings)-1]
		require.Contains(t, lastMsg, msg, "unexpected log message")

		// reset logger so it can be reused again
		clog.Clear()
	}

	m := metric.New("@@!!", nil, map[string]interface{}{"!!": "@@"}, time.Unix(0, 0))
	_, err := s.Serialize(m)
	assert("failed to parse metric name \"@@!!_!!\"", err)

	m = metric.New("prometheus", nil,
		map[string]interface{}{
			"http_requests_total": "asd",
		},
		time.Unix(0, 0),
	)
	_, err = s.Serialize(m)
	assert("bad sample", err)

	m = metric.New(
		"prometheus",
		map[string]string{
			"le": "0.5",
		},
		map[string]interface{}{
			"http_request_duration_seconds_bucket": "asd",
		},
		time.Unix(0, 0),
		telegraf.Histogram,
	)
	_, err = s.Serialize(m)
	assert("bad sample", err)

	m = metric.New(
		"prometheus",
		map[string]string{
			"code":   "400",
			"method": "post",
		},
		map[string]interface{}{
			"http_requests_total":        3.0,
			"http_requests_errors_total": "3.0",
		},
		time.Unix(0, 0),
		telegraf.Gauge,
	)
	_, err = s.Serialize(m)
	assert("bad sample", err)

	m = metric.New(
		"prometheus",
		map[string]string{"quantile": "0.01a"},
		map[string]interface{}{
			"rpc_duration_seconds": 3102.0,
		},
		time.Unix(0, 0),
		telegraf.Summary,
	)
	_, err = s.Serialize(m)
	assert("failed to parse", err)
}

func TestRemoteWriteSerializeBatch(t *testing.T) {
	tests := []struct {
		name          string
		metrics       []telegraf.Metric
		stringAsLabel bool
		expected      []byte
	}{
		{
			name: "simple",
			metrics: []telegraf.Metric{
				metric.New(
					"cpu",
					map[string]string{
						"host": "one.example.org",
					},
					map[string]interface{}{
						"time_idle": 42.0,
					},
					time.Unix(0, 0),
				),
				metric.New(
					"cpu",
					map[string]string{
						"host": "two.example.org",
					},
					map[string]interface{}{
						"time_idle": 42.0,
					},
					time.Unix(0, 0),
				),
			},
			expected: []byte(`
cpu_time_idle{host="one.example.org"} 42
cpu_time_idle{host="two.example.org"} 42
`),
		},
		{
			name: "multiple metric families",
			metrics: []telegraf.Metric{
				metric.New(
					"cpu",
					map[string]string{
						"host": "one.example.org",
					},
					map[string]interface{}{
						"time_idle":  42.0,
						"time_guest": 42.0,
					},
					time.Unix(0, 0),
				),
			},
			expected: []byte(`
cpu_time_guest{host="one.example.org"} 42
cpu_time_idle{host="one.example.org"} 42
`),
		},
		{
			name: "histogram",
			metrics: []telegraf.Metric{
				metric.New(
					"prometheus",
					map[string]string{},
					map[string]interface{}{
						"http_request_duration_seconds_sum":   53423,
						"http_request_duration_seconds_count": 144320,
					},
					time.Unix(0, 0),
					telegraf.Histogram,
				),
				metric.New(
					"prometheus",
					map[string]string{"le": "0.05"},
					map[string]interface{}{
						"http_request_duration_seconds_bucket": 24054.0,
					},
					time.Unix(0, 0),
					telegraf.Histogram,
				),
				metric.New(
					"prometheus",
					map[string]string{"le": "0.1"},
					map[string]interface{}{
						"http_request_duration_seconds_bucket": 33444.0,
					},
					time.Unix(0, 0),
					telegraf.Histogram,
				),
				metric.New(
					"prometheus",
					map[string]string{"le": "0.2"},
					map[string]interface{}{
						"http_request_duration_seconds_bucket": 100392.0,
					},
					time.Unix(0, 0),
					telegraf.Histogram,
				),
				metric.New(
					"prometheus",
					map[string]string{"le": "0.5"},
					map[string]interface{}{
						"http_request_duration_seconds_bucket": 129389.0,
					},
					time.Unix(0, 0),
					telegraf.Histogram,
				),
				metric.New(
					"prometheus",
					map[string]string{"le": "1.0"},
					map[string]interface{}{
						"http_request_duration_seconds_bucket": 133988.0,
					},
					time.Unix(0, 0),
					telegraf.Histogram,
				),
				metric.New(
					"prometheus",
					map[string]string{"le": "+Inf"},
					map[string]interface{}{
						"http_request_duration_seconds_bucket": 144320.0,
					},
					time.Unix(0, 0),
					telegraf.Histogram,
				),
			},
			expected: []byte(`
http_request_duration_seconds_count 144320
http_request_duration_seconds_sum 53423
http_request_duration_seconds_bucket{le="+Inf"} 144320
http_request_duration_seconds_bucket{le="0.05"} 24054
http_request_duration_seconds_bucket{le="0.1"} 33444
http_request_duration_seconds_bucket{le="0.2"} 100392
http_request_duration_seconds_bucket{le="0.5"} 129389
http_request_duration_seconds_bucket{le="1"} 133988
`),
		},
		{
			name: "summary with quantile",
			metrics: []telegraf.Metric{
				metric.New(
					"prometheus",
					map[string]string{},
					map[string]interface{}{
						"rpc_duration_seconds_sum":   1.7560473e+07,
						"rpc_duration_seconds_count": 2693,
					},
					time.Unix(0, 0),
					telegraf.Summary,
				),
				metric.New(
					"prometheus",
					map[string]string{"quantile": "0.01"},
					map[string]interface{}{
						"rpc_duration_seconds": 3102.0,
					},
					time.Unix(0, 0),
					telegraf.Summary,
				),
				metric.New(
					"prometheus",
					map[string]string{"quantile": "0.05"},
					map[string]interface{}{
						"rpc_duration_seconds": 3272.0,
					},
					time.Unix(0, 0),
					telegraf.Summary,
				),
				metric.New(
					"prometheus",
					map[string]string{"quantile": "0.5"},
					map[string]interface{}{
						"rpc_duration_seconds": 4773.0,
					},
					time.Unix(0, 0),
					telegraf.Summary,
				),
				metric.New(
					"prometheus",
					map[string]string{"quantile": "0.9"},
					map[string]interface{}{
						"rpc_duration_seconds": 9001.0,
					},
					time.Unix(0, 0),
					telegraf.Summary,
				),
				metric.New(
					"prometheus",
					map[string]string{"quantile": "0.99"},
					map[string]interface{}{
						"rpc_duration_seconds": 76656.0,
					},
					time.Unix(0, 0),
					telegraf.Summary,
				),
			},
			expected: []byte(`
rpc_duration_seconds_count 2693
rpc_duration_seconds_sum 17560473
rpc_duration_seconds{quantile="0.01"} 3102
rpc_duration_seconds{quantile="0.05"} 3272
rpc_duration_seconds{quantile="0.5"} 4773
rpc_duration_seconds{quantile="0.9"} 9001
rpc_duration_seconds{quantile="0.99"} 76656
`),
		},
		{
			name: "newer sample",
			metrics: []telegraf.Metric{
				metric.New(
					"cpu",
					map[string]string{},
					map[string]interface{}{
						"time_idle": 43.0,
					},
					time.Unix(1, 0),
				),
				metric.New(
					"cpu",
					map[string]string{},
					map[string]interface{}{
						"time_idle": 42.0,
					},
					time.Unix(0, 0),
				),
			},
			expected: []byte(`
cpu_time_idle 43
`),
		},
		{
			name: "colons are not replaced in metric name from measurement",
			metrics: []telegraf.Metric{
				metric.New(
					"cpu::xyzzy",
					map[string]string{},
					map[string]interface{}{
						"time_idle": 42.0,
					},
					time.Unix(0, 0),
				),
			},
			expected: []byte(`
cpu::xyzzy_time_idle 42
`),
		},
		{
			name: "colons are not replaced in metric name from field",
			metrics: []telegraf.Metric{
				metric.New(
					"cpu",
					map[string]string{},
					map[string]interface{}{
						"time:idle": 42.0,
					},
					time.Unix(0, 0),
				),
			},
			expected: []byte(`
cpu_time:idle 42
`),
		},
		{
			name: "invalid label",
			metrics: []telegraf.Metric{
				metric.New(
					"cpu",
					map[string]string{
						"host-name": "example.org",
					},
					map[string]interface{}{
						"time_idle": 42.0,
					},
					time.Unix(0, 0),
				),
			},
			expected: []byte(`
cpu_time_idle{host_name="example.org"} 42
`),
		},
		{
			name: "colons are replaced in label name",
			metrics: []telegraf.Metric{
				metric.New(
					"cpu",
					map[string]string{
						"host:name": "example.org",
					},
					map[string]interface{}{
						"time_idle": 42.0,
					},
					time.Unix(0, 0),
				),
			},
			expected: []byte(`
cpu_time_idle{host_name="example.org"} 42
`),
		},
		{
			name: "discard strings",
			metrics: []telegraf.Metric{
				metric.New(
					"cpu",
					map[string]string{},
					map[string]interface{}{
						"time_idle": 42.0,
						"cpu":       "cpu0",
					},
					time.Unix(0, 0),
				),
			},
			expected: []byte(`
cpu_time_idle 42
`),
		},
		{
			name:          "string as label",
			stringAsLabel: true,
			metrics: []telegraf.Metric{
				metric.New(
					"cpu",
					map[string]string{},
					map[string]interface{}{
						"time_idle": 42.0,
						"cpu":       "cpu0",
					},
					time.Unix(0, 0),
				),
			},
			expected: []byte(`
cpu_time_idle{cpu="cpu0"} 42
`),
		},
		{
			name:          "string as label duplicate tag",
			stringAsLabel: true,
			metrics: []telegraf.Metric{
				metric.New(
					"cpu",
					map[string]string{
						"cpu": "cpu0",
					},
					map[string]interface{}{
						"time_idle": 42.0,
						"cpu":       "cpu1",
					},
					time.Unix(0, 0),
				),
			},
			expected: []byte(`
cpu_time_idle{cpu="cpu0"} 42
`),
		},
		{
			name:          "replace characters when using string as label",
			stringAsLabel: true,
			metrics: []telegraf.Metric{
				metric.New(
					"cpu",
					map[string]string{},
					map[string]interface{}{
						"host:name": "example.org",
						"time_idle": 42.0,
					},
					time.Unix(1574279268, 0),
				),
			},
			expected: []byte(`
cpu_time_idle{host_name="example.org"} 42
`),
		},
		{
			name: "multiple fields grouping",
			metrics: []telegraf.Metric{
				metric.New(
					"cpu",
					map[string]string{
						"cpu": "cpu0",
					},
					map[string]interface{}{
						"time_guest":  8106.04,
						"time_system": 26271.4,
						"time_user":   92904.33,
					},
					time.Unix(0, 0),
				),
				metric.New(
					"cpu",
					map[string]string{
						"cpu": "cpu1",
					},
					map[string]interface{}{
						"time_guest":  8181.63,
						"time_system": 25351.49,
						"time_user":   96912.57,
					},
					time.Unix(0, 0),
				),
				metric.New(
					"cpu",
					map[string]string{
						"cpu": "cpu2",
					},
					map[string]interface{}{
						"time_guest":  7470.04,
						"time_system": 24998.43,
						"time_user":   96034.08,
					},
					time.Unix(0, 0),
				),
				metric.New(
					"cpu",
					map[string]string{
						"cpu": "cpu3",
					},
					map[string]interface{}{
						"time_guest":  7517.95,
						"time_system": 24970.82,
						"time_user":   94148,
					},
					time.Unix(0, 0),
				),
			},
			expected: []byte(`
cpu_time_guest{cpu="cpu0"} 8106.04
cpu_time_guest{cpu="cpu1"} 8181.63
cpu_time_guest{cpu="cpu2"} 7470.04
cpu_time_guest{cpu="cpu3"} 7517.95
cpu_time_system{cpu="cpu0"} 26271.4
cpu_time_system{cpu="cpu1"} 25351.49
cpu_time_system{cpu="cpu2"} 24998.43
cpu_time_system{cpu="cpu3"} 24970.82
cpu_time_user{cpu="cpu0"} 92904.33
cpu_time_user{cpu="cpu1"} 96912.57
cpu_time_user{cpu="cpu2"} 96034.08
cpu_time_user{cpu="cpu3"} 94148
`),
		},
		{
			name: "summary with no quantile",
			metrics: []telegraf.Metric{
				metric.New(
					"prometheus",
					map[string]string{},
					map[string]interface{}{
						"rpc_duration_seconds_sum":   1.7560473e+07,
						"rpc_duration_seconds_count": 2693,
					},
					time.Unix(0, 0),
					telegraf.Summary,
				),
			},
			expected: []byte(`
rpc_duration_seconds_count 2693
rpc_duration_seconds_sum 17560473
`),
		},
		{
			name:          "empty label string value",
			stringAsLabel: true,
			metrics: []telegraf.Metric{
				metric.New(
					"prometheus",
					map[string]string{
						"cpu": "",
					},
					map[string]interface{}{
						"time_idle": 42.0,
					},
					time.Unix(0, 0),
				),
			},
			expected: []byte(`
			time_idle 42
`),
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			s := &Serializer{
				Log:           &testutil.CaptureLogger{},
				SortMetrics:   true,
				StringAsLabel: tt.stringAsLabel,
			}
			data, err := s.SerializeBatch(tt.metrics)
			require.NoError(t, err)
			actual, err := prompbToText(data)
			require.NoError(t, err)

			require.Equal(t,
				strings.TrimSpace(string(tt.expected)),
				strings.TrimSpace(string(actual)))
		})
	}
}

func TestRemoteWriteSerializeNativeHistogram(t *testing.T) {
	tests := []struct {
		name     string
		metric   telegraf.Metric
		expected []byte
	}{
		{
			name: "native histogram",
			metric: metric.New(
				"rpc_duration_seconds",
				map[string]string{
					"host": "example.org",
					"node": "node1",
				},
				map[string]interface{}{
					"count":                  float64(20),
					"sum":                    float64(10),
					"schema":                 int64(0),
					"counter_reset_hint":     uint64(1),
					"zero_threshold":         float64(0.001),
					"zero_count":             float64(2),
					"positive_span_0_offset": int64(0),
					"positive_span_0_length": uint64(2),
					"positive_bucket_0":      float64(3),
					"positive_bucket_1":      float64(5),
					"negative_span_0_offset": int64(0),
					"negative_span_0_length": uint64(2),
					"negative_bucket_0":      float64(4),
					"negative_bucket_1":      float64(6),
				},
				time.Unix(0, 0),
				telegraf.Histogram,
			),
			expected: []byte(`
rpc_duration_seconds{host="example.org", node="node1"} {count:20, sum:10, [-2,-1):6, [-1,-0.5):4, [-0.001,0.001]:2, (0.5,1]:3, (1,2]:5}
`),
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			s := &Serializer{
				Log:         &testutil.CaptureLogger{},
				SortMetrics: true,
			}

			data, err := s.Serialize(tt.metric)
			require.NoError(t, err)
			actual, err := prompbToHistogramText(data)
			require.NoError(t, err)

			require.Equal(t, strings.TrimSpace(string(tt.expected)),
				strings.TrimSpace(string(actual)))
		})
	}
}

func prompbToText(data []byte) ([]byte, error) {
	var buf = bytes.Buffer{}
	protobuff, err := snappy.Decode(nil, data)
	if err != nil {
		return nil, err
	}
	var req prompb.WriteRequest
	err = req.Unmarshal(protobuff)
	if err != nil {
		return nil, err
	}
	samples := protoToSamples(&req)
	for _, sample := range samples {
		fmt.Fprintf(&buf, "%s %s\n", sample.Metric.String(), sample.Value.String())
	}

	return buf.Bytes(), nil
}

func protoToSamples(req *prompb.WriteRequest) model.Samples {
	var samples model.Samples
	for _, ts := range req.Timeseries {
		mt := make(model.Metric, len(ts.Labels))
		for _, l := range ts.Labels {
			mt[model.LabelName(l.Name)] = model.LabelValue(l.Value)
		}

		for _, s := range ts.Samples {
			samples = append(samples, &model.Sample{
				Metric:    mt,
				Value:     model.SampleValue(s.Value),
				Timestamp: model.Time(s.Timestamp),
			})
		}
	}
	return samples
}

func prompbToHistogramText(data []byte) ([]byte, error) {
	var buf = bytes.Buffer{}
	protobuff, err := snappy.Decode(nil, data)
	if err != nil {
		return nil, err
	}
	var req prompb.WriteRequest
	err = req.Unmarshal(protobuff)
	if err != nil {
		return nil, err
	}
	for _, ts := range req.Timeseries {
		// There is no text representation for native histogram and it has to be written out as proto exposition.
		// For test purpose we format a reasonable string for verification. Labels are sorted to make it deterministic.
		nameString := ""
		var lb strings.Builder
		lb.WriteByte('{')
		firstLabel := true
		for _, l := range ts.Labels {
			if l.Name == model.MetricNameLabel {
				nameString = l.Value
			} else {
				if !firstLabel {
					lb.WriteString(", ")
				}
				fmt.Fprintf(&lb, "%s=%q", l.Name, l.Value)
				firstLabel = false
			}
		}
		lb.WriteByte('}')
		labelString := lb.String()
		for _, h := range ts.Histograms {
			fh := *h.ToFloatHistogram()
			buf.WriteString(nameString)
			buf.WriteString(labelString)
			fmt.Fprintf(&buf, " %v\n", fh.String())
		}
	}
	return buf.Bytes(), nil
}

func BenchmarkSerialize(b *testing.B) {
	s := &Serializer{Log: &testutil.CaptureLogger{}}
	metrics := serializers.BenchmarkMetrics(b)
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		_, err := s.Serialize(metrics[i%len(metrics)])
		require.NoError(b, err)
	}
}

func BenchmarkSerializeBatch(b *testing.B) {
	s := &Serializer{Log: &testutil.CaptureLogger{}}
	m := serializers.BenchmarkMetrics(b)
	metrics := m[:]
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		_, err := s.SerializeBatch(metrics)
		require.NoError(b, err)
	}
}