diff --git a/.gitignore b/.gitignore
index a6fdc84..00b42c0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -10,6 +10,7 @@
 
 # Output of the go coverage tool, specifically when used with LiteIDE
 *.out
+ali-debug.log
 
 # IDE
 .idea
diff --git a/attacker/attacker.go b/attacker/attacker.go
index 046cefb..561d512 100644
--- a/attacker/attacker.go
+++ b/attacker/attacker.go
@@ -1,9 +1,12 @@
 package attacker
 
 import (
+	"context"
 	"net/http"
 	"time"
 
+	"github.com/k0kubun/pp"
+
 	vegeta "github.com/tsenart/vegeta/v12/lib"
 )
 
@@ -32,7 +35,8 @@ type Result struct {
 // Attack keeps the request running for the specified period of time.
 // Results are sent to the given channel as soon as they arrive.
 // When the attack is over, it gives back final statistics.
-func Attack(target string, resCh chan *Result, opts Options) *Metrics {
+func Attack(ctx context.Context, target string, resCh chan *Result, opts Options) *Metrics {
+	pp.Println("start attacking")
 	if opts.Rate == 0 {
 		opts.Rate = defaultRate
 	}
@@ -53,16 +57,23 @@ func Attack(target string, resCh chan *Result, opts Options) *Metrics {
 	attacker := vegeta.NewAttacker()
 
 	var metrics vegeta.Metrics
+
 	for res := range attacker.Attack(targeter, rate, opts.Duration, "main") {
+		// TODO: Stop if ctx is expired.
+		/*if <-ctx.Done() {
+			return newMetrics(&metrics)
+		}*/
 		resCh <- &Result{Latency: res.Latency}
 		metrics.Add(res)
 	}
 	metrics.Close()
+	pp.Println("vegeta metrics", metrics)
 
 	return newMetrics(&metrics)
 }
 
 type (
+	// Metrics wraps vegeta.Metrics to avoid dependency on it.
 	Metrics struct {
 		Latencies LatencyMetrics
 	}
diff --git a/go.mod b/go.mod
index d5ba24b..7f7e481 100644
--- a/go.mod
+++ b/go.mod
@@ -3,6 +3,9 @@ module github.com/nakabonne/ali
 go 1.15
 
 require (
+	github.com/k0kubun/colorstring v0.0.0-20150214042306-9440f1994b88 // indirect
+	github.com/k0kubun/pp v3.0.1+incompatible
+	github.com/mattn/go-colorable v0.1.7 // indirect
 	github.com/mum4k/termdash v0.12.2
 	github.com/spf13/pflag v1.0.5
 	github.com/tsenart/vegeta/v12 v12.8.3
diff --git a/go.sum b/go.sum
index 39d054e..288f42d 100644
--- a/go.sum
+++ b/go.sum
@@ -3,6 +3,8 @@ github.com/alecthomas/jsonschema v0.0.0-20180308105923-f2c93856175a/go.mod h1:qp
 github.com/bmizerany/perks v0.0.0-20141205001514-d9a9656a3a4b h1:AP/Y7sqYicnjGDfD5VcY4CIfh1hRXBUavxrvELjTiOE=
 github.com/bmizerany/perks v0.0.0-20141205001514-d9a9656a3a4b/go.mod h1:ac9efd0D1fsDb3EJvhqgXRbFx7bs2wqZ10HQPeU8U/Q=
 github.com/c2h5oh/datasize v0.0.0-20171227191756-4eba002a5eae/go.mod h1:S/7n9copUssQ56c7aAgHqftWO4LTf4xY6CGWt8Bc+3M=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/dgryski/go-gk v0.0.0-20140819190930-201884a44051 h1:ByJUvQYyTtNNCVfYNM48q6uYUT4fAlN0wNmd3th4BSo=
 github.com/dgryski/go-gk v0.0.0-20140819190930-201884a44051/go.mod h1:qm+vckxRlDt0aOla0RYJJVeqHZlWfOm2UIxHaqPB46E=
 github.com/dgryski/go-lttb v0.0.0-20180810165845-318fcdf10a77/go.mod h1:Va5MyIzkU0rAM92tn3hb3Anb7oz7KcnixF49+2wOMe4=
@@ -30,11 +32,21 @@ github.com/google/go-cmp v0.2.0 h1:+dTQ8DZQJz0Mb/HjFlkptS1FeQ4cWSnN941F8aEG4SQ=
 github.com/google/go-cmp v0.2.0/go.mod h1:oXzfMopK8JAjlY9xF4vHSVASa0yLyX7SntLO5aqRK0M=
 github.com/influxdata/tdigest v0.0.0-20180711151920-a7d76c6f093a h1:vMqgISSVkIqWxCIZs8m1L4096temR7IbYyNdMiBxSPA=
 github.com/influxdata/tdigest v0.0.0-20180711151920-a7d76c6f093a/go.mod h1:9GkyshztGufsdPQWjH+ifgnIr3xNUL5syI70g2dzU1o=
+github.com/k0kubun/colorstring v0.0.0-20150214042306-9440f1994b88 h1:uC1QfSlInpQF+M0ao65imhwqKnz3Q2z/d8PWZRMQvDM=
+github.com/k0kubun/colorstring v0.0.0-20150214042306-9440f1994b88/go.mod h1:3w7q1U84EfirKl04SVQ/s7nPm1ZPhiXd34z40TNz36k=
+github.com/k0kubun/pp v3.0.1+incompatible h1:3tqvf7QgUnZ5tXO6pNAZlrvHgl6DvifjDrd9g2S9Z40=
+github.com/k0kubun/pp v3.0.1+incompatible/go.mod h1:GWse8YhT0p8pT4ir3ZgBbfZild3tgzSScAn6HmfYukg=
+github.com/konsorten/go-windows-terminal-sequences v1.0.3 h1:CE8S1cTafDpPvMhIxNJKvHsGVBgn1xWYf1NbHQhywc8=
+github.com/konsorten/go-windows-terminal-sequences v1.0.3/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
 github.com/kylelemons/godebug v1.1.0 h1:RPNrshWIDI6G2gRW9EHilWtl7Z6Sb1BR0xunSBf0SNc=
 github.com/kylelemons/godebug v1.1.0/go.mod h1:9/0rRGxNHcop5bhtWyNeEfOS8JIWk580+fNqagV/RAw=
 github.com/lucasb-eyer/go-colorful v1.0.2/go.mod h1:0MS4r+7BZKSJ5mw4/S5MPN+qHFF1fYclkSPilDOKW0s=
 github.com/mailru/easyjson v0.7.0 h1:aizVhC/NAAcKWb+5QsU1iNOZb4Yws5UO2I+aIprQITM=
 github.com/mailru/easyjson v0.7.0/go.mod h1:KAzv3t3aY1NaHWoQz1+4F1ccyAH66Jk7yos7ldAVICs=
+github.com/mattn/go-colorable v0.1.7 h1:bQGKb3vps/j0E9GfJQ03JyhRuxsvdAanXlT9BTw3mdw=
+github.com/mattn/go-colorable v0.1.7/go.mod h1:u6P/XSegPjTcexA+o6vUJrdnUu04hMope9wVRipJSqc=
+github.com/mattn/go-isatty v0.0.12 h1:wuysRhFDzyxgEmMf5xjvJ2M9dZoWAXNNr5LSBS7uHXY=
+github.com/mattn/go-isatty v0.0.12/go.mod h1:cbi8OIDigv2wuxKPP5vlRcQ1OAZbq2CE4Kysco4FUpU=
 github.com/mattn/go-runewidth v0.0.4/go.mod h1:LwmH8dsx7+W8Uxz3IHJYH5QSwggIsqBzpuz5H//U1FU=
 github.com/mattn/go-runewidth v0.0.9 h1:Lm995f3rfxdpd6TSmuVCHVb/QhupuXlYr8sCI/QdE+0=
 github.com/mattn/go-runewidth v0.0.9/go.mod h1:H031xJmbD/WCDINGzjvQ9THkh0rPKHF+m2gUSrubnMI=
@@ -43,13 +55,22 @@ github.com/mum4k/termdash v0.12.2 h1:S2frz71OrXUKIVVZ3snYBEzyYlUNRTu0ElV6d5Pf6gI
 github.com/mum4k/termdash v0.12.2/go.mod h1:haerPCSO0U8pehROAecmuOHDF+2UXw2KaCTxdWooDFE=
 github.com/nsf/termbox-go v0.0.0-20200204031403-4d2b513ad8be h1:yzmWtPyxEUIKdZg4RcPq64MfS8NA6A5fNOJgYhpR9EQ=
 github.com/nsf/termbox-go v0.0.0-20200204031403-4d2b513ad8be/go.mod h1:IuKpRQcYE1Tfu+oAQqaLisqDeXgjyyltCfsaoYN18NQ=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/sirupsen/logrus v1.6.0 h1:UBcNElsrwanuuMsnGSlYmtmgbb23qDR5dG+6X6Oo89I=
+github.com/sirupsen/logrus v1.6.0/go.mod h1:7uNnSEd1DgxDLC74fIahvMZmmYsHGZGEOFrfsX/uA88=
 github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
 github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
 github.com/streadway/quantile v0.0.0-20150917103942-b0c588724d25 h1:7z3LSn867ex6VSaahyKadf4WtSsJIgne6A1WLOAGM8A=
 github.com/streadway/quantile v0.0.0-20150917103942-b0c588724d25/go.mod h1:lbP8tGiBjZ5YWIc2fzuRpTaz0b/53vT6PEs3QuAWzuU=
+github.com/stretchr/testify v1.2.2 h1:bSDNvY7ZPG5RlJ8otE/7V6gMiyenm9RtJ7IUVIAoJ1w=
+github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
 github.com/tsenart/go-tsz v0.0.0-20180814232043-cdeb9e1e981e/go.mod h1:SWZznP1z5Ki7hDT2ioqiFKEse8K9tU2OUvaRI0NeGQo=
 github.com/tsenart/vegeta/v12 v12.8.3 h1:UEsDkSrEJojMKW/xr7KUv4H/bYykX+V48KCsPZPqEfk=
 github.com/tsenart/vegeta/v12 v12.8.3/go.mod h1:ZiJtwLn/9M4fTPdMY7bdbIeyNeFVE8/AHbWFqCsUuho=
+github.com/yudai/pp v1.3.0 h1:8qxHWJnYPF9HC9nq1U4N/8toJNBWO4DxaMpDlzrcE6I=
+github.com/yudai/pp v2.0.1+incompatible h1:Q4//iY4pNF6yPLZIigmvcl7k/bPgrcTPIFIcmawg5bI=
+github.com/yudai/pp v2.0.1+incompatible/go.mod h1:PuxR/8QJ7cyCkFp/aUDS+JY727OFEZkTdatxwunjIkc=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20190829043050-9756ffdc2472/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
@@ -59,8 +80,13 @@ golang.org/x/net v0.0.0-20190827160401-ba9fcec4b297/go.mod h1:z5CRVTTTmAJ677TzLL
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20190422165155-953cdadca894/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190626150813-e07cf5db2756/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20190904154756-749cb33beabd h1:DBH9mDw0zluJT/R+nGuV3jWFWLFaHyYZWD4tOT+cjn0=
 golang.org/x/sys v0.0.0-20190904154756-749cb33beabd/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200116001909-b77594299b42/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200223170610-d5e6a3e2c0ae h1:/WDfKMnPU+m5M4xB+6x4kaepxRw6jWvR5iDRdvjHgy8=
+golang.org/x/sys v0.0.0-20200223170610-d5e6a3e2c0ae/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.2 h1:tW2bmiBqwgJj/UpqtC8EpXEZVYOwU0yG4iWbprSVAcs=
 golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
diff --git a/gui/widgets.go b/gui/widgets.go
index 378bf4f..6112d36 100644
--- a/gui/widgets.go
+++ b/gui/widgets.go
@@ -2,14 +2,16 @@ package gui
 
 import (
 	"context"
-	"math"
 	"time"
 
+	"github.com/k0kubun/pp"
 	"github.com/mum4k/termdash/cell"
 	"github.com/mum4k/termdash/container"
 	"github.com/mum4k/termdash/widgets/button"
 	"github.com/mum4k/termdash/widgets/linechart"
 	"github.com/mum4k/termdash/widgets/textinput"
+
+	"github.com/nakabonne/ali/attacker"
 )
 
 // redrawInterval is how often termdash redraws the screen.
@@ -38,12 +40,6 @@ func newWidgets(ctx context.Context, c *container.Container) (*widgets, error) {
 
 // newLineChart returns a line plotChart that displays a heartbeat-like progression.
 func newLineChart(ctx context.Context) (*linechart.LineChart, error) {
-	var inputs []float64
-	for i := 0; i < 100; i++ {
-		v := math.Pow(math.Sin(float64(i)), 63) * math.Sin(float64(i)+1.5) * 8
-		inputs = append(inputs, v)
-	}
-
 	lc, err := linechart.New(
 		linechart.AxesCellOpts(cell.FgColor(cell.ColorRed)),
 		linechart.YLabelCellOpts(cell.FgColor(cell.ColorGreen)),
@@ -52,41 +48,33 @@ func newLineChart(ctx context.Context) (*linechart.LineChart, error) {
 	if err != nil {
 		return nil, err
 	}
-	step := 0
-	go periodic(ctx, redrawInterval/3, func() error {
-		step = (step + 1) % len(inputs)
-		return lc.Series("heartbeat", rotateFloats(inputs, step),
-			linechart.SeriesCellOpts(cell.FgColor(cell.ColorNumber(87))),
-			linechart.SeriesXLabels(map[int]string{
-				0: "zero",
-			}),
-		)
-	})
+
+	resultCh := make(chan *attacker.Result)
+	go func() {
+		// TODO: Enalble to poplulate from input
+		metrics := attacker.Attack(ctx, "http://34.84.111.163:9898", resultCh, attacker.Options{Rate: 50, Duration: 10 * time.Second})
+		pp.Println(metrics)
+	}()
+	go redrawChart(ctx, lc, resultCh)
+
 	return lc, nil
 }
 
-// periodic executes the provided closure periodically every interval.
-// Exits when the context expires.
-func periodic(ctx context.Context, interval time.Duration, fn func() error) {
-	ticker := time.NewTicker(interval)
-	defer ticker.Stop()
+func redrawChart(ctx context.Context, lineChart *linechart.LineChart, resultCh chan *attacker.Result) {
+	values := []float64{}
 	for {
 		select {
-		case <-ticker.C:
-			if err := fn(); err != nil {
-				panic(err)
-			}
 		case <-ctx.Done():
 			return
+		case res := <-resultCh:
+			pp.Println("latency", res.Latency/time.Millisecond)
+			values = append(values, float64(res.Latency/time.Millisecond))
+			lineChart.Series("plot", values,
+				linechart.SeriesCellOpts(cell.FgColor(cell.ColorNumber(87))),
+				linechart.SeriesXLabels(map[int]string{
+					0: "zero",
+				}),
+			)
 		}
 	}
 }
-
-// rotateFloats returns a new slice with inputs rotated by step.
-// I.e. for a step of one:
-//   inputs[0] -> inputs[len(inputs)-1]
-//   inputs[1] -> inputs[0]
-// And so on.
-func rotateFloats(inputs []float64, step int) []float64 {
-	return append(inputs[step:], inputs[:step]...)
-}
diff --git a/main.go b/main.go
index 1e469bb..3c555f2 100644
--- a/main.go
+++ b/main.go
@@ -4,9 +4,12 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"os"
+	"path/filepath"
 	"runtime"
 
+	"github.com/k0kubun/pp"
 	flag "github.com/spf13/pflag"
 
 	"github.com/nakabonne/ali/gui"
@@ -55,6 +58,7 @@ func (c *cli) run() int {
 		fmt.Fprintf(c.stderr, "version=%s, commit=%s, buildDate=%s, os=%s, arch=%s\n", version, commit, date, runtime.GOOS, runtime.GOARCH)
 		return 0
 	}
+	setDebug(nil, c.debug)
 
 	if err := gui.Run(); err != nil {
 		fmt.Fprintf(c.stderr, "failed to start application: %s", err.Error())
@@ -63,3 +67,18 @@ func (c *cli) run() int {
 
 	return 0
 }
+
+// Makes a new file under the working directory only when debug use.
+func setDebug(w io.Writer, debug bool) {
+	if !debug {
+		pp.SetDefaultOutput(ioutil.Discard)
+	}
+	if w == nil {
+		var err error
+		w, err = os.OpenFile(filepath.Join(".", "ali-debug.log"), os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0666)
+		if err != nil {
+			panic(err)
+		}
+	}
+	pp.SetDefaultOutput(w)
+}