From 5169b2d145b0086516491a35887bfc5eb07be2ae Mon Sep 17 00:00:00 2001
From: Stefan Majewsky <majewsky@gmx.net>
Date: Tue, 4 Apr 2017 22:00:22 +0200
Subject: implement "index" subcommand

---
 util.go | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

(limited to 'util.go')

diff --git a/util.go b/util.go
index 09f93be..a1cea5f 100644
--- a/util.go
+++ b/util.go
@@ -19,8 +19,10 @@
 package main
 
 import (
+	"bufio"
 	"fmt"
 	"os"
+	"strings"
 )
 
 //ShowError prints the given error on stderr if it is non-nil, or returns false otherwise.
@@ -39,3 +41,43 @@ func FatalIfError(err error) {
 		os.Exit(255)
 	}
 }
+
+var stdin = bufio.NewReader(os.Stdin)
+
+//Prompt prints the question, then waits for the user to press one of the
+//possible answer keys. Answer keys will automatically be converted to lower
+//case and returned as such.
+//
+//    choice := Prompt("(y)es or (n)o", []string{"y","n"})
+//    //choice is either "y" or "n"
+func Prompt(question string, answers []string) string {
+	for idx, answer := range answers {
+		answers[idx] = strings.ToLower(answer)
+	}
+
+	os.Stdout.Write([]byte(">> " + strings.TrimSpace(question) + " "))
+	for {
+		input, err := stdin.ReadString('\n')
+		FatalIfError(err)
+		input = strings.TrimSpace(input)
+		for _, answer := range answers {
+			if strings.ToLower(input) == answer {
+				return answer
+			}
+		}
+
+		//user typed gibberish - ask again
+		os.Stdout.Write([]byte("Please type "))
+		for idx, answer := range answers {
+			if idx > 0 {
+				if idx == len(answers)-1 {
+					os.Stdout.Write([]byte(" or "))
+				} else {
+					os.Stdout.Write([]byte(", "))
+				}
+			}
+			os.Stdout.Write([]byte("'" + answer + "'"))
+		}
+		os.Stdout.Write([]byte(": "))
+	}
+}
-- 
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