commit b7da87cc65041a6ffa03d83d2cf1cae9eb926015
Author: Knut Ahlers <knut@ahlers.me>
Date:   Sun Sep 8 12:47:49 2019 +0200

    Initial version

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..88bb961
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+id3patch
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..5065a39
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,12 @@
+module github.com/Luzifer/id3patch
+
+go 1.13
+
+require (
+	github.com/Luzifer/rconfig/v2 v2.2.1
+	github.com/bogem/id3v2 v1.1.1
+	github.com/pkg/errors v0.8.1
+	github.com/sirupsen/logrus v1.4.2
+	golang.org/x/text v0.3.2 // indirect
+	gopkg.in/validator.v2 v2.0.0-20190827175613-1a84e0480e5b // indirect
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..1d13aa7
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,29 @@
+github.com/Luzifer/rconfig v2.2.0+incompatible h1:Kle3+rshPM7LxciOheaR4EfHUzibkDDGws04sefQ5m8=
+github.com/Luzifer/rconfig v2.2.0+incompatible/go.mod h1:9pet6z2+mm/UAB0jF/rf0s62USfHNolzgR6Q4KpsJI0=
+github.com/Luzifer/rconfig/v2 v2.2.1 h1:zcDdLQlnlzwcBJ8E0WFzOkQE1pCMn3EbX0dFYkeTczg=
+github.com/Luzifer/rconfig/v2 v2.2.1/go.mod h1:OKIX0/JRZrPJ/ZXXWklQEFXA6tBfWaljZbW37w+sqBw=
+github.com/bogem/id3v2 v1.1.1 h1:FnjS2vytMeEb39tOMG09uz852MaEccA2A3asRM3XxbE=
+github.com/bogem/id3v2 v1.1.1/go.mod h1:D1rDm80qF/ocBU+Ik8U4RKnwMq/oNkkB8vGcnrlMJmM=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/konsorten/go-windows-terminal-sequences v1.0.1 h1:mweAR1A6xJ3oS2pRaGiHgQ4OO8tzTaLawm8vnODuwDk=
+github.com/konsorten/go-windows-terminal-sequences v1.0.1/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
+github.com/pkg/errors v0.8.1 h1:iURUrRGxPUNPdy5/HRSm+Yj6okJ6UtLINN0Q9M4+h3I=
+github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/sirupsen/logrus v1.4.2 h1:SPIRibHv4MatM3XXNO2BJeFLZwZ2LvZgfQ5+UNI2im4=
+github.com/sirupsen/logrus v1.4.2/go.mod h1:tLMulIdttU9McNUspp0xgXVQah82FyeX6MwdIuYE2rE=
+github.com/spf13/pflag v1.0.3 h1:zPAT6CGy6wXeQ7NtTnaTerfKOsV6V6F8agHXFiazDkg=
+github.com/spf13/pflag v1.0.3/go.mod h1:DYY7MBk1bdzusC3SYhjObp+wFpr4gzcvqqNjLnInEg4=
+github.com/stretchr/objx v0.1.1/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
+golang.org/x/sys v0.0.0-20190422165155-953cdadca894 h1:Cz4ceDQGXuKRnVBDTS23GTn/pU5OE2C0WrNTOYK1Uuc=
+golang.org/x/sys v0.0.0-20190422165155-953cdadca894/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.2 h1:tW2bmiBqwgJj/UpqtC8EpXEZVYOwU0yG4iWbprSVAcs=
+golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/validator.v2 v2.0.0-20180514200540-135c24b11c19/go.mod h1:o4V0GXN9/CAmCsvJ0oXYZvrZOe7syiDZSN1GWGZTGzc=
+gopkg.in/validator.v2 v2.0.0-20190827175613-1a84e0480e5b h1:b11tvJzEfkdoOQNdYxuvkRvD7VNo5/A0U2Dqiq+wKdw=
+gopkg.in/validator.v2 v2.0.0-20190827175613-1a84e0480e5b/go.mod h1:o4V0GXN9/CAmCsvJ0oXYZvrZOe7syiDZSN1GWGZTGzc=
+gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..c25051f
--- /dev/null
+++ b/main.go
@@ -0,0 +1,142 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+
+	"github.com/Luzifer/rconfig/v2"
+	"github.com/bogem/id3v2"
+	"github.com/pkg/errors"
+	log "github.com/sirupsen/logrus"
+)
+
+var (
+	cfg = struct {
+		Album          string `flag:"album" default:"" description:"Set album tag"`
+		Artist         string `flag:"artist" default:"" description:"Set artist tag"`
+		File           string `flag:"file,f" default:"" description:"File to read / write" validate:"nonzero"`
+		LogLevel       string `flag:"log-level" default:"info" description:"Log level (debug, info, warn, error, fatal)"`
+		Title          string `flag:"title" default:"" description:"Set title tag"`
+		VersionAndExit bool   `flag:"version" default:"false" description:"Prints current version and exits"`
+		Year           string `flag:"year" default:"" description:"Set year tag"`
+	}{}
+
+	version = "dev"
+)
+
+func init() {
+	rconfig.AutoEnv(true)
+	if err := rconfig.ParseAndValidate(&cfg); err != nil {
+		log.Fatalf("Unable to parse commandline options: %s", err)
+	}
+
+	if cfg.VersionAndExit {
+		fmt.Printf("id3patch %s\n", version)
+		os.Exit(0)
+	}
+
+	if l, err := log.ParseLevel(cfg.LogLevel); err != nil {
+		log.WithError(err).Fatal("Unable to parse log level")
+	} else {
+		log.SetLevel(l)
+	}
+}
+
+func main() {
+	var (
+		logger     = log.WithField("file", cfg.File)
+		needsWrite bool
+	)
+
+	tag, err := id3v2.Open(cfg.File, id3v2.Options{Parse: true})
+	switch err {
+
+	case nil:
+		// Everything fine
+
+	case id3v2.ErrUnsupportedVersion:
+		logger.Warn("No supported ID3v2 tags found")
+
+	default:
+		logger.WithError(err).Fatal("Unable to open file")
+
+	}
+	defer tag.Close()
+
+	logger.WithFields(log.Fields{
+		"album":       tag.Album(),
+		"artist":      tag.Artist(),
+		"title":       tag.Title(),
+		"tag_version": tag.Version(),
+		"year":        tag.Year(),
+	}).Info("File opened successfully")
+
+	needsWrite = modTag(cfg.Album, tag.Album, tag.SetAlbum, needsWrite)
+	needsWrite = modTag(cfg.Artist, tag.Artist, tag.SetArtist, needsWrite)
+	needsWrite = modTag(cfg.Title, tag.Title, tag.SetTitle, needsWrite)
+	needsWrite = modTag(cfg.Year, tag.Year, tag.SetYear, needsWrite)
+
+	if !needsWrite {
+		logger.Info("No tags changed, no write needed")
+		return
+	}
+
+	if err := save(tag); err != nil {
+		logger.WithError(err).Fatal("Unable to save tags")
+	}
+
+	logger.Info("Tags written successfully")
+}
+
+func modTag(content string, contentFunc func() string, setFunc func(string), needsWrite bool) bool {
+	if content == "" || content == contentFunc() {
+		return needsWrite
+	}
+
+	setFunc(content)
+	return true
+}
+
+func save(tag *id3v2.Tag) error {
+	var err = tag.Save()
+	switch err {
+
+	case id3v2.ErrNoFile:
+		// We need to do the save ourselves
+
+	default:
+		return err
+
+	}
+
+	// Library does not supporting initial tag addition, assemble the
+	// newly added tag ourselves...
+	var buf = new(bytes.Buffer)
+
+	oStat, err := os.Stat(cfg.File)
+	if err != nil {
+		return errors.Wrap(err, "Unable to determine original file stats")
+	}
+
+	oFile, err := os.Open(cfg.File)
+	if err != nil {
+		return errors.Wrap(err, "Unable to open original file")
+	}
+
+	if _, err = tag.WriteTo(buf); err != nil {
+		return errors.Wrap(err, "Unable to write tag header to buffer")
+	}
+
+	if _, err = io.Copy(buf, oFile); err != nil {
+		return errors.Wrap(err, "Unable to copy original file contents to buffer")
+	}
+
+	if err = oFile.Close(); err != nil {
+		return errors.Wrap(err, "Unable to close original file")
+	}
+
+	return errors.Wrap(ioutil.WriteFile(cfg.File, buf.Bytes(), oStat.Mode()), "Unable to write file contents")
+}