package main

import (
	"testing"
	"time"
)

func TestRateWindowLatestNeedsTwoBuckets(t *testing.T) {
	w := newRateWindow(4)
	if got := w.latest(rxRatePPS); got != 0 {
		t.Errorf("empty ring gave %v, want 0", got)
	}
	w.push(counterSet{t: time.Now(), s: sample{rxFrames: 100}})
	if got := w.latest(rxRatePPS); got != 0 {
		t.Errorf("one bucket gave %v, want 0", got)
	}
}

// The newest pair alone, so a step in the rate shows at once instead of being
// averaged against everything still in the ring.
func TestRateWindowLatestUsesNewestPair(t *testing.T) {
	w := newRateWindow(4)
	t0 := time.Now()
	w.push(counterSet{t: t0, s: sample{rxFrames: 100}})
	w.push(counterSet{t: t0.Add(time.Second), s: sample{rxFrames: 300}})
	if got := w.latest(rxRatePPS); got != 200 {
		t.Errorf("rate = %v, want 200", got)
	}
	w.push(counterSet{t: t0.Add(2 * time.Second), s: sample{rxFrames: 400}})
	if got := w.latest(rxRatePPS); got != 100 {
		t.Errorf("rate = %v, want 100 rather than the mean of the ring", got)
	}
}

func TestRateWindowLatestIgnoresZeroSpan(t *testing.T) {
	w := newRateWindow(4)
	t0 := time.Now()
	w.push(counterSet{t: t0, s: sample{rxFrames: 100}})
	w.push(counterSet{t: t0, s: sample{rxFrames: 300}})
	if got := w.latest(rxRatePPS); got != 0 {
		t.Errorf("rate = %v, want 0", got)
	}
}

// Which counter feeds which bucket is the whole taxonomy the panel reports, so
// it is pinned here rather than left to whoever reads errsBetween next.
func TestErrsBetweenBuckets(t *testing.T) {
	n := counterSet{
		s: sample{
			lost: 1, late: 7,
			crcErr: 2, badMagic: 3, badLen: 4,
			txErrs: 6, rxErrs: 5,
		},
		drops: 9,
		nic:   8,
	}
	got := errsBetween(counterSet{}, n)
	want := errs{lost: 1, corrupt: 2 + 3 + 4, link: 8 + 5, internal: 9 + 7 + 6}
	if got != want {
		t.Errorf("errsBetween = %+v, want %+v", got, want)
	}
	if got.total() != 45 {
		t.Errorf("total = %d, want 45", got.total())
	}
}

// A reset re-bases from a fresh capture while the ring still holds buckets from
// just before it, so the newest bucket must not be left behind the new origin.
func TestResetDoesNotUnderflowTotals(t *testing.T) {
	d := &direction{
		win:     newRateWindow(8),
		cable:   newCableStats(),
		rxStats: []*rxStats{{}},
	}

	d.rxStats[0].frames.Store(100)
	d.rxStats[0].bytes.Store(6400)
	d.sample()

	d.rxStats[0].frames.Store(150)
	d.rxStats[0].bytes.Store(9600)
	d.reset()

	v := d.displayView()
	if v.rxFrames != 0 {
		t.Errorf("rxFrames = %d, want 0", v.rxFrames)
	}
	if v.rxBytes != 0 {
		t.Errorf("rxBytes = %d, want 0", v.rxBytes)
	}

	// The rolling window and the rates are about now rather than since the
	// reset, so the buckets from before it have to survive.
	if got := d.win.count(); got < 2 {
		t.Errorf("ring holds %d buckets after reset, want the pre-reset history kept", got)
	}
}