package helper

import (
	"math"
	"testing"
)

func TestEqFloat64Fuzzy(t *testing.T) {
	tests := []struct {
		name string
		a, b float64
		want bool
	}{
		{"exactly equal", 1, 1, true},
		{"nearly equal", 1, math.Nextafter(1, math.Inf(1)), true},
		{"zero equal to itself", +0., -0., true},
		{"zero not equal to non-zero", 0., 1e-9, false},
		{"definitely not equal", 1, 1 + 1e-9, false},
		{"infinity equal to itself", math.Inf(1), math.Inf(1), true},
		{"infinity not equal to a finite value", math.Inf(1), 1, false},
		{"NaN equal to itself", math.NaN(), math.NaN(), true},
		{"NaN not equal to a finite value", math.NaN(), 1, false},
		{"NaN not equal to infinity", math.NaN(), math.Inf(1), false},

		// these are actual numbers encountered that should be equal, but failed the test at some point.
		// keeping them around as test cases.
		{"testcase1", 0.0015172579307272023, 0.001517257930727202, true},
		{"testcase2", 0, -8.131516293641283e-20, true},
		{"testcase3", 0, -5.0186702124817295e-20, true},
		{"testcase4", 0, -6.776263578034403e-21, true},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			if got := EqFloat64Fuzzy(tt.a, tt.b); got != tt.want {
				t.Errorf("EqFloat64Fuzzy(%v, %v) = %v, want %v", tt.a, tt.b, got, tt.want)
			}

			// swapping the arguments shouldn't change the outcome.
			if got := EqFloat64Fuzzy(tt.b, tt.a); got != tt.want {
				t.Errorf("EqFloat64Fuzzy(%v, %v) = %v, want %v", tt.b, tt.a, got, tt.want)
			}

			// negating the arguments shouldn't change the outcome either
			if got := EqFloat64Fuzzy(-tt.a, -tt.b); got != tt.want {
				t.Errorf("EqFloat64Fuzzy(%v, %v) = %v, want %v", -tt.a, -tt.b, got, tt.want)
			}

			if got := EqFloat64Fuzzy(tt.b, tt.a); got != tt.want {
				t.Errorf("EqFloat64Fuzzy(%v, %v) = %v, want %v", -tt.b, -tt.a, got, tt.want)
			}
		})
	}
}

func TestEqFloat64SliceFuzzy(t *testing.T) {
	tests := []struct {
		name string
		a, b []float64
		want bool
	}{
		{
			"equivalent float slices",
			[]float64{1, 2, 3, math.NaN()},
			[]float64{1, 2, math.Nextafter(3, math.Inf(1)), math.NaN()},
			true,
		}, {
			"dissimilar float slices",
			[]float64{1, 2, 4},
			[]float64{1, 3, 4},
			false,
		}, {
			"different lengths",
			[]float64{1, 2},
			[]float64{1, 2, 3},
			false,
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			if got := EqFloat64SliceFuzzy(tt.a, tt.b); got != tt.want {
				t.Errorf("EqFloat64SliceFuzzy(%v, %v) = %v, want %v", tt.a, tt.b, got, tt.want)
			}
		})
	}
}