package udp

import (
	"testing"
	"time"
)

// WSJT-X stamps a decode with a time of DAY and no date, so the date has to come
// from our own clock — and around midnight the two disagree. A decode stamped
// 23:59:58 that reaches us at 00:00:01 would be dated the NEW day, putting it
// almost 24 hours in the future: it would sort to the top of the decodes panel
// and stay there for the rest of the session, and its period would never line up
// with the ones around it.
func TestDecodeTimeCrossesMidnight(t *testing.T) {
	const ms = 1000
	sec := func(h, m, s int) uint32 { return uint32((h*3600 + m*60 + s) * ms) }

	got := decodeTime(sec(23, 59, 58))
	now := time.Now().UTC()
	// Whatever the clock says, a decode must never land in the future beyond the
	// slack of a single period, nor more than a day in the past.
	if d := got.Sub(now); d > time.Minute {
		t.Errorf("decode at 23:59:58 resolved to %s, %s in the FUTURE", got.Format(time.RFC3339), d)
	}
	if d := now.Sub(got); d > 24*time.Hour {
		t.Errorf("decode at 23:59:58 resolved to %s, %s in the past", got.Format(time.RFC3339), d)
	}

	// And the ordinary case: a stamp close to now stays on today.
	near := decodeTime(sec(now.Hour(), now.Minute(), now.Second()))
	if diff := near.Sub(now); diff > 2*time.Second || diff < -2*time.Second {
		t.Errorf("a decode stamped at the current time resolved to %s (%s off)", near.Format(time.RFC3339), diff)
	}
}

// The whole point of the timestamp is grouping, so two decodes from the same
// fifteen-second slot must floor to the same period however far apart in the
// slot they were heard.
func TestDecodesInOneSlotShareAPeriod(t *testing.T) {
	const ms = 1000
	at := func(h, m, s int) time.Time { return decodeTime(uint32((h*3600 + m*60 + s) * ms)) }
	floor := func(x time.Time) int64 { return x.Unix() / 15 * 15 }

	a, b := at(12, 30, 0), at(12, 30, 14)
	if floor(a) != floor(b) {
		t.Errorf("12:30:00 and 12:30:14 fell in different periods (%d vs %d)", floor(a), floor(b))
	}
	c := at(12, 30, 15)
	if floor(a) == floor(c) {
		t.Error("12:30:00 and 12:30:15 shared a period — the slot boundary was not honoured")
	}
}