package logstorage

import (
	"math"
	"testing"
)

func TestHistogramQuantile(t *testing.T) {
	f := func(a []float64, phi, qExpected float64) {
		t.Helper()

		var h histogram
		for _, f := range a {
			h.update(f)
		}
		q := h.quantile(phi)

		if math.IsNaN(qExpected) {
			if !math.IsNaN(q) {
				t.Fatalf("unexpected result for q=%v, phi=%v; got %v; want %v", a, phi, q, qExpected)
			}
		} else if q != qExpected {
			t.Fatalf("unexpected result for q=%v, phi=%v; got %v; want %v", a, phi, q, qExpected)
		}
	}

	f(nil, -1, nan)
	f(nil, 0, nan)
	f(nil, 0.5, nan)
	f(nil, 1, nan)
	f(nil, 10, nan)

	f([]float64{123}, -1, 123)
	f([]float64{123}, 0, 123)
	f([]float64{123}, 0.5, 123)
	f([]float64{123}, 1, 123)
	f([]float64{123}, 10, 123)

	f([]float64{5, 1}, -1, 1)
	f([]float64{5, 1}, 0, 1)
	f([]float64{5, 1}, 0.5-1e-5, 1)
	f([]float64{5, 1}, 0.5, 5)
	f([]float64{5, 1}, 1, 5)
	f([]float64{5, 1}, 10, 5)

	f([]float64{5, 1, 3}, -1, 1)
	f([]float64{5, 1, 3}, 0, 1)
	f([]float64{5, 1, 3}, 1.0/3-1e-5, 1)
	f([]float64{5, 1, 3}, 1.0/3, 3)
	f([]float64{5, 1, 3}, 2.0/3-1e-5, 3)
	f([]float64{5, 1, 3}, 2.0/3, 5)
	f([]float64{5, 1, 3}, 1-1e-5, 5)
	f([]float64{5, 1, 3}, 1, 5)
	f([]float64{5, 1, 3}, 10, 5)
}