add `schedule` subcommand

main.go

@@ -10,19 +10,40 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"strconv"
 )
 
 func main() {
-	if len(os.Args) != 2 {
+	if len(os.Args) < 2 {
 		usage(1)
 	}
-	switch os.Args[1] {
+	subcommand, args := os.Args[1], os.Args[2:]
+
+	switch subcommand {
 	case "upload":
+		if len(args) != 0 {
+			usage(1)
+		}
 		Upload(Scan())
 	case "generate":
+		if len(args) != 0 {
+			usage(1)
+		}
 		Generate(Scan())
+	case "schedule":
+		if len(args) != 1 {
+			usage(1)
+		}
+		count, err := strconv.ParseUint(args[0], 10, 32)
+		must(err)
+		PrintSchedule(count)
 	case "help", "--help":
+		if len(args) != 0 {
+			usage(1)
+		}
 		usage(0)
+	default:
+		usage(1)
 	}
 }
 
@@ -43,9 +64,10 @@ func fail(msg string, args ...interface{}) {
 func usage(exitCode int) {
 	fmt.Fprintf(os.Stderr,
 		"Usage:\n\n"+
-			"  %[1]s upload   - Upload all relevant files for one episode to <sftp://ftp.c3d2.de>.\n"+
-			"  %[1]s generate - Generate the c3d2-web news entry XML file for one episode.\n\n"+
-			"All relevant files (audios, chapter marks file, shownotes Markdown file) must be in the working directory.\n",
+			"  %[1]s upload       - Upload all relevant files for one episode to <sftp://ftp.c3d2.de>.\n"+
+			"  %[1]s generate     - Generate the c3d2-web news entry XML file for one episode.\n"+
+			"  %[1]s schedule <N> - Print the next N airdates.\n\n"+
+			"For `upload` and `generate`, all relevant files (audios, chapter marks file, shownotes Markdown file) must be in the working directory.\n",
 		filepath.Base(os.Args[0]),
 	)
 	os.Exit(exitCode)

schedule.go

@@ -0,0 +1,43 @@
+/*******************************************************************************
+* Copyright 2023 Stefan Majewsky <majewsky@gmx.net>
+* SPDX-License-Identifier: GPL-3.0-only
+* Refer to the file "LICENSE" for details.
+*******************************************************************************/
+
+package main
+
+import (
+	"fmt"
+	"time"
+)
+
+func PrintSchedule(count uint64) {
+	now := time.Now().UTC()
+	date := time.Date(
+		now.Year(), now.Month(), now.Day(),
+		12, 0, 0, 0,
+		now.Location(),
+	)
+
+	for printed := uint64(0); printed < count; date = date.AddDate(0, 0, 1) {
+		if date.Weekday() == time.Tuesday && date.Day() > 21 && date.Day() <= 28 {
+			printDate(date)
+			printed++
+		}
+	}
+}
+
+var germanMonths = []string{
+	"Januar", "Februar", "März", "April", "Mai", "Juni",
+	"Juli", "August", "September", "Oktober", "November", "Dezember",
+}
+
+func printDate(t time.Time) {
+	fmt.Printf(
+		"%s = %d. %s %d\n",
+		t.Format(time.DateOnly),
+		t.Day(),
+		germanMonths[t.Month()-1],
+		t.Year(),
+	)
+}