package nebula

import (
	"testing"
	"time"

	"github.com/slackhq/nebula/firewall"
	"github.com/stretchr/testify/assert"
)

func TestNewTimerWheel(t *testing.T) {
	// Make sure we get an object we expect
	tw := NewTimerWheel(time.Second, time.Second*10)
	assert.Equal(t, 11, tw.wheelLen)
	assert.Equal(t, 0, tw.current)
	assert.Nil(t, tw.lastTick)
	assert.Equal(t, time.Second*1, tw.tickDuration)
	assert.Equal(t, time.Second*10, tw.wheelDuration)
	assert.Len(t, tw.wheel, 11)

	// Assert the math is correct
	tw = NewTimerWheel(time.Second*3, time.Second*10)
	assert.Equal(t, 4, tw.wheelLen)

	tw = NewTimerWheel(time.Second*120, time.Minute*10)
	assert.Equal(t, 6, tw.wheelLen)
}

func TestTimerWheel_findWheel(t *testing.T) {
	tw := NewTimerWheel(time.Second, time.Second*10)
	assert.Len(t, tw.wheel, 11)

	// Current + tick + 1 since we don't know how far into current we are
	assert.Equal(t, 2, tw.findWheel(time.Second*1))

	// Scale up to min duration
	assert.Equal(t, 2, tw.findWheel(time.Millisecond*1))

	// Make sure we hit that last index
	assert.Equal(t, 0, tw.findWheel(time.Second*10))

	// Scale down to max duration
	assert.Equal(t, 0, tw.findWheel(time.Second*11))

	tw.current = 1
	// Make sure we account for the current position properly
	assert.Equal(t, 3, tw.findWheel(time.Second*1))
	assert.Equal(t, 1, tw.findWheel(time.Second*10))
}

func TestTimerWheel_Add(t *testing.T) {
	tw := NewTimerWheel(time.Second, time.Second*10)

	fp1 := firewall.Packet{}
	tw.Add(fp1, time.Second*1)

	// Make sure we set head and tail properly
	assert.NotNil(t, tw.wheel[2])
	assert.Equal(t, fp1, tw.wheel[2].Head.Packet)
	assert.Nil(t, tw.wheel[2].Head.Next)
	assert.Equal(t, fp1, tw.wheel[2].Tail.Packet)
	assert.Nil(t, tw.wheel[2].Tail.Next)

	// Make sure we only modify head
	fp2 := firewall.Packet{}
	tw.Add(fp2, time.Second*1)
	assert.Equal(t, fp2, tw.wheel[2].Head.Packet)
	assert.Equal(t, fp1, tw.wheel[2].Head.Next.Packet)
	assert.Equal(t, fp1, tw.wheel[2].Tail.Packet)
	assert.Nil(t, tw.wheel[2].Tail.Next)

	// Make sure we use free'd items first
	tw.itemCache = &TimeoutItem{}
	tw.itemsCached = 1
	tw.Add(fp2, time.Second*1)
	assert.Nil(t, tw.itemCache)
	assert.Equal(t, 0, tw.itemsCached)
}

func TestTimerWheel_Purge(t *testing.T) {
	// First advance should set the lastTick and do nothing else
	tw := NewTimerWheel(time.Second, time.Second*10)
	assert.Nil(t, tw.lastTick)
	tw.advance(time.Now())
	assert.NotNil(t, tw.lastTick)
	assert.Equal(t, 0, tw.current)

	fps := []firewall.Packet{
		{LocalIP: 1},
		{LocalIP: 2},
		{LocalIP: 3},
		{LocalIP: 4},
	}

	tw.Add(fps[0], time.Second*1)
	tw.Add(fps[1], time.Second*1)
	tw.Add(fps[2], time.Second*2)
	tw.Add(fps[3], time.Second*2)

	ta := time.Now().Add(time.Second * 3)
	lastTick := *tw.lastTick
	tw.advance(ta)
	assert.Equal(t, 3, tw.current)
	assert.True(t, tw.lastTick.After(lastTick))

	// Make sure we get all 4 packets back
	for i := 0; i < 4; i++ {
		p, has := tw.Purge()
		assert.True(t, has)
		assert.Equal(t, fps[i], p)
	}

	// Make sure there aren't any leftover
	_, ok := tw.Purge()
	assert.False(t, ok)
	assert.Nil(t, tw.expired.Head)
	assert.Nil(t, tw.expired.Tail)

	// Make sure we cached the free'd items
	assert.Equal(t, 4, tw.itemsCached)
	ci := tw.itemCache
	for i := 0; i < 4; i++ {
		assert.NotNil(t, ci)
		ci = ci.Next
	}
	assert.Nil(t, ci)

	// Lets make sure we roll over properly
	ta = ta.Add(time.Second * 5)
	tw.advance(ta)
	assert.Equal(t, 8, tw.current)

	ta = ta.Add(time.Second * 2)
	tw.advance(ta)
	assert.Equal(t, 10, tw.current)

	ta = ta.Add(time.Second * 1)
	tw.advance(ta)
	assert.Equal(t, 0, tw.current)
}