1 files changed, 90 insertions, 0 deletions
diff --git a/pkg/util/util.go b/pkg/util/util.go
new file mode 100644
index 0000000..3c5e724
--- /dev/null
+++ b/pkg/util/util.go
@@ -0,0 +1,90 @@
+/*******************************************************************************
+*
+* Copyright 2017 Stefan Majewsky <majewsky@gmx.net>
+*
+* This program is free software: you can redistribute it and/or modify it under
+* the terms of the GNU General Public License as published by the Free Software
+* Foundation, either version 3 of the License, or (at your option) any later
+* version.
+*
+* This program is distributed in the hope that it will be useful, but WITHOUT ANY
+* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+* A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+*
+* You should have received a copy of the GNU General Public License along with
+* this program. If not, see <http://www.gnu.org/licenses/>.
+*
+*******************************************************************************/
+
+package util
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"sort"
+	"strings"
+)
+
+//ShowSorted sorts the given lines and prints them on stdout.
+func ShowSorted(lines []string) {
+	sort.Strings(lines)
+	fmt.Println(strings.Join(lines, "\n"))
+}
+
+//ShowError prints the given error on stderr if it is non-nil, or returns false otherwise.
+func ShowError(err error) bool {
+	if err == nil {
+		return false
+	}
+	fmt.Fprintf(os.Stderr, "ERROR: %s\n", err.Error())
+	return true
+}
+
+//FatalIfError prints the given error on stderr and exits with an error code.
+func FatalIfError(err error) {
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "FATAL: %s\n", 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(": "))
+	}
+}