gethwrappers

package main

import (
	"fmt"
	"strings"
)

// boxOutput formats its arguments as fmt.Printf, and encloses them in a box of
// arrows pointing at their content, in order to better highlight it. See
// ExampleBoxOutput
func boxOutput(errorMsgTemplate string, errorMsgValues ...interface{}) string {
	errorMsgTemplate = fmt.Sprintf(errorMsgTemplate, errorMsgValues...)
	lines := strings.Split(errorMsgTemplate, "\n")
	maxlen := 0
	for _, line := range lines {
		if len(line) > maxlen {
			maxlen = len(line)
		}
	}
	internalLength := maxlen + 4
	output := "↘" + strings.Repeat("↓", internalLength) + "↙\n"
	output += "→  " + strings.Repeat(" ", maxlen) + "  ←\n"
	readme := strings.Repeat("README ", maxlen/7)
	output += "→  " + readme + strings.Repeat(" ", maxlen-len(readme)) + "  ←\n"
	output += "→  " + strings.Repeat(" ", maxlen) + "  ←\n"
	for _, line := range lines {
		output += "→  " + line + strings.Repeat(" ", maxlen-len(line)) + "  ←\n"
	}
	output += "→  " + strings.Repeat(" ", maxlen) + "  ←\n"
	output += "→  " + readme + strings.Repeat(" ", maxlen-len(readme)) + "  ←\n"
	output += "→  " + strings.Repeat(" ", maxlen) + "  ←\n"
	return "\n" + output + "↗" + strings.Repeat("↑", internalLength) + "↖" +
		"\n\n"
}

func main() {
	fmt.Println()
	fmt.Print(boxOutput("%s is %d", "foo", 17))
}

Output:

↘↓↓↓↓↓↓↓↓↓↓↓↓↓↙
→             ←
→  README     ←
→             ←
→  foo is 17  ←
→             ←
→  README     ←
→             ←
↗↑↑↑↑↑↑↑↑↑↑↑↑↑↖