package metrics

import (
	"testing"
	"time"

	"github.com/ipfs/ipfs-cluster/api"
)

func makeMetric(value string) *api.Metric {
	metr := &api.Metric{
		Name:  "test",
		Peer:  "peer1",
		Value: value,
		Valid: true,
	}
	metr.SetTTL(5 * time.Second)
	return metr
}

func TestNewWindow(t *testing.T) {
	w := NewWindow(10)
	w.window.Next()
}

func BenchmarkWindow_Add(b *testing.B) {
	b.Run("window size 10", func(b *testing.B) {
		mw := NewWindow(10)

		b.ResetTimer()
		for i := 0; i < b.N; i++ {
			mw.Add(makeMetric("1"))
		}
	})

	b.Run("window size 25", func(b *testing.B) {
		mw := NewWindow(25)

		b.ResetTimer()
		for i := 0; i < b.N; i++ {
			mw.Add(makeMetric("1"))
		}
	})

	b.Run("window size 1000", func(b *testing.B) {
		mw := NewWindow(1000)

		b.ResetTimer()
		for i := 0; i < b.N; i++ {
			mw.Add(makeMetric("1"))
		}
	})
}

func TestWindow_Latest(t *testing.T) {
	t.Run("no metrics error", func(t *testing.T) {
		mw := NewWindow(4)
		_, err := mw.Latest()
		if err != ErrNoMetrics {
			t.Error("expected ErrNoMetrics")
		}
	})

	t.Run("single latest value", func(t *testing.T) {
		mw := NewWindow(4)
		mw.Add(makeMetric("1"))

		metr, err := mw.Latest()
		if err != nil {
			t.Fatal(err)
		}

		if metr.Value != "1" {
			t.Error("expected different value")
		}
	})
}

func BenchmarkWindow_Latest(b *testing.B) {
	b.Run("window size 10", func(b *testing.B) {
		mw := NewWindow(10)
		for i := 0; i < 10; i++ {
			mw.Add(makeMetric("1"))
		}

		b.ResetTimer()
		for i := 0; i < b.N; i++ {
			mw.Add(makeMetric("1"))
		}
	})

	b.Run("window size 25", func(b *testing.B) {
		mw := NewWindow(25)
		for i := 0; i < 25; i++ {
			mw.Add(makeMetric("1"))
		}

		b.ResetTimer()
		for i := 0; i < b.N; i++ {
			mw.Add(makeMetric("1"))
		}
	})

	b.Run("window size 1000", func(b *testing.B) {
		mw := NewWindow(1000)
		for i := 0; i < 1000; i++ {
			mw.Add(makeMetric("1"))
		}

		b.ResetTimer()
		for i := 0; i < b.N; i++ {
			mw.Add(makeMetric("1"))
		}
	})
}

func TestWindow_All(t *testing.T) {
	t.Run("empty window", func(t *testing.T) {
		mw := NewWindow(4)
		if len(mw.All()) != 0 {
			t.Error("expected 0 metrics")
		}
	})

	t.Run("half capacity", func(t *testing.T) {
		mw := NewWindow(4)
		mw.Add(makeMetric("1"))
		mw.Add(makeMetric("2"))

		all := mw.All()
		if len(all) != 2 {
			t.Fatalf("should only be storing 2 metrics: got: %d", len(all))
		}

		if all[0].Value != "2" {
			t.Error("newest metric should be first")
		}

		if all[1].Value != "1" {
			t.Error("older metric should be second")
		}
	})

	t.Run("full capacity", func(t *testing.T) {
		mw := NewWindow(4)
		mw.Add(makeMetric("1"))
		mw.Add(makeMetric("2"))
		mw.Add(makeMetric("3"))
		mw.Add(makeMetric("4"))

		all := mw.All()
		if len(all) != 4 {
			t.Fatalf("should only be storing 4 metrics: got: %d", len(all))
		}

		if all[len(all)-1].Value != "1" {
			t.Error("oldest metric should be 1")
		}
	})

	t.Run("over flow capacity", func(t *testing.T) {
		mw := NewWindow(4)
		mw.Add(makeMetric("1"))
		mw.Add(makeMetric("2"))
		mw.Add(makeMetric("3"))
		mw.Add(makeMetric("4"))
		mw.Add(makeMetric("5"))

		all := mw.All()
		if len(all) != 4 {
			t.Fatalf("should only be storing 4 metrics: got: %d", len(all))
		}

		if all[len(all)-1].Value != "2" {
			t.Error("oldest metric should be 2")
		}

	})
}

func TestWindow_AddParallel(t *testing.T) {
	t.Parallel()

	mw := NewWindow(10)

	t.Run("parallel adder 1", func(t *testing.T) {
		for i := 0; i < 100; i++ {
			mw.Add(makeMetric("adder 1"))
		}
	})

	t.Run("parallel adder 2", func(t *testing.T) {
		for i := 0; i < 100; i++ {
			mw.Add(makeMetric("adder 2"))
		}
	})
}

func BenchmarkWindow_All(b *testing.B) {
	b.Run("window size 10", func(b *testing.B) {
		mw := NewWindow(10)
		for i := 0; i < 10; i++ {
			mw.Add(makeMetric("1"))
		}

		b.ResetTimer()
		for i := 0; i < b.N; i++ {
			mw.All()
		}
	})

	b.Run("window size 25", func(b *testing.B) {
		mw := NewWindow(25)
		for i := 0; i < 25; i++ {
			mw.Add(makeMetric("1"))
		}

		b.ResetTimer()
		for i := 0; i < b.N; i++ {
			mw.All()
		}
	})

	b.Run("window size 1000", func(b *testing.B) {
		mw := NewWindow(1000)
		for i := 0; i < 1000; i++ {
			mw.Add(makeMetric("1"))
		}

		b.ResetTimer()
		for i := 0; i < b.N; i++ {
			mw.All()
		}
	})
}

func TestWindow_Distribution(t *testing.T) {
	var tests = []struct {
		name       string
		heartbeats []int64
		want       []int64
	}{
		{
			"even 1 sec distribution",
			[]int64{1, 1, 1, 1},
			[]int64{1, 1, 1, 1},
		},
		{
			"increasing latency distribution",
			[]int64{1, 1, 2, 2, 3, 3, 4},
			[]int64{4, 3, 3, 2, 2, 1, 1},
		},
		{
			"random latency distribution",
			[]int64{4, 1, 3, 9, 7, 8, 11, 18},
			[]int64{18, 11, 8, 7, 9, 3, 1, 4},
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			mw := NewWindow(len(tt.heartbeats) + 1)
			for i, v := range tt.heartbeats {
				mw.Add(makeMetric(string(v)))
				time.Sleep(time.Duration(v) * time.Millisecond)
				if i == len(tt.heartbeats)-1 {
					mw.Add(makeMetric("last"))
				}
			}

			got := mw.Distribution()

			if len(got) != len(tt.want) {
				t.Errorf("want len: %v, got len: %v", len(tt.want), len(got))
			}

			var gotseconds []int64
			for _, v := range got {
				// truncate nanoseconds to seconds for testing purposes
				gotseconds = append(gotseconds, v/1000000)
			}

			for i, s := range gotseconds {
				if s != tt.want[i] {
					t.Fatalf("want: %v, got: %v", tt.want, gotseconds)
					break
				}
			}
		})
	}
}

func BenchmarkWindow_Distribution(b *testing.B) {
	b.Run("window size 10", func(b *testing.B) {
		mw := NewWindow(10)
		for i := 0; i < 10; i++ {
			mw.Add(makeMetric("1"))
		}

		b.ResetTimer()
		for i := 0; i < b.N; i++ {
			mw.Distribution()
		}
	})

	b.Run("window size 25", func(b *testing.B) {
		mw := NewWindow(25)
		for i := 0; i < 25; i++ {
			mw.Add(makeMetric("1"))
		}

		b.ResetTimer()
		for i := 0; i < b.N; i++ {
			mw.Distribution()
		}
	})

	b.Run("window size 1000", func(b *testing.B) {
		mw := NewWindow(1000)
		for i := 0; i < 1000; i++ {
			mw.Add(makeMetric("1"))
		}

		b.ResetTimer()
		for i := 0; i < b.N; i++ {
			mw.Distribution()
		}
	})
}