Add CSV button

cmd/txqr-tester/app/results_table.go

@@ -1,7 +1,10 @@
 package main
 
 import (
+	"encoding/csv"
 	"fmt"
+	"io"
+	"time"
 
 	"github.com/gopherjs/vecty"
 	"github.com/gopherjs/vecty/elem"
@@ -22,6 +25,14 @@ func NewResultsTable() *ResultsTable {
 // Render implements the vecty.Component interface for ResultsTable.
 func (r *ResultsTable) Render() vecty.ComponentOrHTML {
 	return elem.Div(
+		vecty.If(len(r.results) > 0,
+			elem.Span(
+				vecty.Markup(
+					vecty.Class("is-pulled-right"),
+				),
+				r.csvButton(),
+			),
+		),
 		elem.Heading1(
 			vecty.Markup(
 				vecty.Class("title", "has-text-weight-light"),
@@ -32,11 +43,45 @@ func (r *ResultsTable) Render() vecty.ComponentOrHTML {
 	)
 }
 
+// AddResult adds a new result and refreshes the table.
 func (r *ResultsTable) AddResult(res Result) {
 	r.results = append(r.results, res)
 	vecty.Rerender(r)
 }
 
+// csv returns two-dimensional slice of prepared strings,
+// to be used with encoding/csv package.
+func (r *ResultsTable) csv() [][]string {
+	ret := [][]string{}
+	row := []string{"QR Level", "FPS", "Chunk Size", "Duration (ms)"}
+	ret = append(ret, row)
+	for _, result := range r.results {
+		lvl := fmt.Sprintf("%s", result.lvl)
+		fps := fmt.Sprintf("%d", result.fps)
+		sz := fmt.Sprintf("%d", result.size)
+		dur := fmt.Sprintf("%d", result.Duration*time.Millisecond)
+		row := []string{lvl, fps, sz, dur}
+		ret = append(ret, row)
+	}
+	return ret
+}
+
+// WriteAsCSV writes results into io.Writer in CSV format.
+func (r *ResultsTable) WriteAsCSV(w io.Writer) error {
+	cw := csv.NewWriter(w)
+	for _, row := range r.csv() {
+		err := cw.Write(row)
+		if err != nil {
+			return fmt.Errorf("write csv: %v", err)
+		}
+	}
+	cw.Flush()
+	if err := cw.Error(); err != nil {
+		return fmt.Errorf("write csv: %v", err)
+	}
+	return nil
+}
+
 func (r *ResultsTable) table() vecty.ComponentOrHTML {
 	return elem.Table(
 		vecty.Markup(
@@ -74,3 +119,12 @@ func tableRow(r Result) *vecty.HTML {
 		elem.TableData(vecty.Text(fmt.Sprintf("%s", r.Duration))),
 	)
 }
+
+func (r *ResultsTable) csvButton() *vecty.HTML {
+	return elem.Button(
+		vecty.Markup(
+			vecty.Class("button", "is-success"),
+		),
+		vecty.Text("Download CSV"),
+	)
+}