Test case for `tmux list-sessions | ./simplebox`

simplebox

package main

import (
	"bufio"
	"io"
	"log"
	"os"

	"github.com/nsf/termbox-go"
)

func writeLine(row int, text string, background termbox.Attribute) {
	col := 0
	for _, r := range text {
		termbox.SetCell(col, row, r, termbox.ColorDefault, background)
		col += 1
	}
}

func draw(items []string, selected int) {
	termbox.Clear(termbox.ColorDefault, termbox.ColorDefault)

	for i, item := range items {
		// write all lines
		writeLine(i, item, termbox.ColorDefault)
	}
	// rewrite the selected candidate line with Reverse attribute
	writeLine(selected, items[selected], termbox.AttrReverse)

	termbox.Flush()
}

func readStrings(r io.Reader) []string {
	scanner := bufio.NewScanner(r)
	var strings []string
	for scanner.Scan() {
		strings = append(strings, scanner.Text())
	}
	return strings
}

func main() {
	err := termbox.Init()
	if err != nil {
		log.Fatal(err)
	}
	defer termbox.Close()

	selected := 0
	items := readStrings(os.Stdin)

	draw(items, selected)

Loop:
	for {
		switch evt := termbox.PollEvent(); evt.Type {
		case termbox.EventKey:
			switch evt.Key {
			case termbox.KeyEsc:
				break Loop
			case termbox.KeyCtrlN, termbox.KeyArrowDown:
				if selected < len(items)-1 {
					selected += 1
				}
			case termbox.KeyCtrlP, termbox.KeyArrowUp:
				if selected > 0 {
					selected -= 1
				}
			}
		case termbox.EventError:
			panic(evt.Err)
		default:
			panic(evt)
		}
		draw(items, selected)
	}
}