commit f5e71f5a15167e185c5e8f14187a0b92f2872993
Author: Matt Baer <matt@baer.works>
Date:   Tue Feb 25 20:54:12 2020 -0500

    Add basic file renaming utility

diff --git a/cmd/cdr/main.go b/cmd/cdr/main.go
new file mode 100644
index 0000000..d9de0e6
--- /dev/null
+++ b/cmd/cdr/main.go
@@ -0,0 +1,28 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+
+	"github.com/thebaer/cdr"
+)
+
+var printUsage = func() {
+	fmt.Fprintf(os.Stderr, "usage: %s [optional flags] filename\n", os.Args[0])
+	flag.PrintDefaults()
+}
+
+func main() {
+	flag.Usage = printUsage
+	flag.Parse()
+	if flag.NArg() != 1 {
+		printUsage()
+		return
+	}
+
+	file := flag.Arg(0)
+	oldFilename, trackName := cdr.RenameTrack(file)
+	fmt.Println("Renaming", oldFilename, "to", trackName)
+	os.Rename(oldFilename, trackName)
+}
diff --git a/sanitize.go b/sanitize.go
new file mode 100644
index 0000000..15284ba
--- /dev/null
+++ b/sanitize.go
@@ -0,0 +1,52 @@
+package cdr
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"regexp"
+	"strings"
+	"unicode"
+
+	"github.com/dhowden/tag"
+)
+
+var trackNameReg = regexp.MustCompile("^([0-9]{2}).+")
+
+// RenameTrack takes a filename, opens it, reads the metadata, and returns both
+// the old and new filename.
+func RenameTrack(file string) (string, string) {
+	f, err := os.Open(file)
+	if err != nil {
+		fmt.Printf("error loading file: %v", err)
+		return "", ""
+	}
+	defer f.Close()
+
+	fMatch := trackNameReg.FindStringSubmatch(f.Name())
+	if len(fMatch) < 2 {
+		log.Fatal("Unexpect filename format")
+	}
+	trackNum := fMatch[1]
+	ext := ".mp3"
+
+	m, err := tag.ReadFrom(f)
+	if err != nil {
+		log.Fatal(err)
+	}
+	return f.Name(), fmt.Sprintf("%s-%s-%s%s", trackNum, Sanitize(m.Artist()), Sanitize(m.Title()), ext)
+}
+
+// Sanitize takes a string and removes problematic characters from it.
+func Sanitize(s string) string {
+	s = strings.Map(func(r rune) rune {
+		if r == '(' || r == ')' || r == '[' || r == ']' || r == '.' {
+			return -1
+		}
+		if unicode.IsSpace(r) {
+			return '_'
+		}
+		return r
+	}, s)
+	return s
+}