package unsub

import (
	"math"
	"testing"
	"time"
)

func TestCalculateRefundRatio(t *testing.T) {
	effective := time.Date(2026, 1, 1, 0, 0, 0, 0, time.UTC)
	cases := []struct {
		name   string
		cutoff time.Time
		want   float64
	}{
		{name: "before effective refunds all", cutoff: effective.Add(-time.Hour), want: 1},
		{name: "half paid period", cutoff: time.Date(2026, 7, 1, 0, 0, 0, 0, time.UTC), want: 184.0 / 365.0},
		{name: "during gift period refunds none", cutoff: time.Date(2027, 2, 1, 0, 0, 0, 0, time.UTC), want: 0},
		{name: "after paid period refunds none", cutoff: time.Date(2027, 1, 1, 0, 0, 0, 0, time.UTC), want: 0},
	}
	for _, testCase := range cases {
		t.Run(testCase.name, func(t *testing.T) {
			got := calculateRefundRatio(effective, testCase.cutoff, 12)
			if math.Abs(got-testCase.want) > 0.000001 {
				t.Fatalf("calculateRefundRatio() = %v, want %v", got, testCase.want)
			}
		})
	}
}

func TestAddRefundMonthsClampsMonthEnd(t *testing.T) {
	got := addRefundMonths(time.Date(2026, 1, 31, 12, 0, 0, 0, time.UTC), 1)
	want := time.Date(2026, 2, 28, 12, 0, 0, 0, time.UTC)
	if !got.Equal(want) {
		t.Fatalf("addRefundMonths() = %v, want %v", got, want)
	}
}