func findFormat(name, path string, buffer *bytes.Buffer, filter func(*format.Format) bool) (*format.Format, error) {
formats := format.Formats{}
if name != "" {
f, ok := format.ByName(name)
if !ok {
return nil, fmt.Errorf("unable to find format %q", name)
}
formats = append(formats, f)
} else if path != "" {
ext := filepath.Ext(path)
if ext != "" {
formats = format.RegisteredFormats()
formats = formats.Filter(func(f *format.Format) bool {
for _, e := range f.Extensions {
if strings.ToLower(e) == ext {
return true
}
}
return false
})
}
}
formats = formats.Filter(filter)
if len(formats) > 0 {
return formats[0], nil
}
return nil, fmt.Errorf("unable to find format")
}
func (cmd *options) execute(args []string) error {
if len(args) > 1 {
return fmt.Errorf("too many positional arguments")
}
var err error
in := os.Stdin
file := ""
if len(args) == 1 {
file = args[0]
in, err = os.Open(file)
if err != nil {
return fmt.Errorf("unable to open %q: %v", file, err)
}
}
inBytes, err := ioutil.ReadAll(in)
if err != nil {
return fmt.Errorf("unable to read: %v", err)
}
input := bytes.NewBuffer(inBytes)
readFormat, err := findReadFormat(cmd.CurrentFormat, file, input)
if err != nil {
return fmt.Errorf("unable to find input format for %q: %v", file, err)
}
writeFormat := readFormat
if cmd.ToFormat != "" {
var ok bool
if writeFormat, ok = format.ByName(cmd.ToFormat); !ok {
return fmt.Errorf("unable to find output format %q", cmd.ToFormat)
}
}
if writeFormat.Writer == nil {
return fmt.Errorf("the input format %q is unable to be used for writing", readFormat.Name)
}
song, err := readFormat.Reader.Read(input)
if err != nil {
return fmt.Errorf("unable to parse %q: %v", file, err)
}
setSongTitleIfNecessary(file, song)
if cmd.ToKey != "" {
fromKey := songtools.Key(cmd.CurrentKey)
if fromKey == "" && song.Key == "" {
return fmt.Errorf("unable to get current key")
} else if fromKey == "" {
fromKey = song.Key
}
toKey := songtools.Key(cmd.ToKey)
noteNames, interval, err := songtools.NoteNamesAndIntervalFromKeyToKey(fromKey, toKey)
if err != nil {
return fmt.Errorf("unable to get note names and interval: %v", err)
}
song, err = songtools.TransposeSong(song, interval, noteNames)
if err != nil {
return fmt.Errorf("unable to transpose from %q to %q: %v", fromKey, toKey, err)
}
song.Key = toKey
}
out := os.Stdout
defer out.Close()
if cmd.Out == "<unset>" {
name := song.Title
if name == "" && file == "" {
return fmt.Errorf("'out' was specified, but the song does not have a title and the input was not a file")
} else if name == "" {
_, file := filepath.Split(file)
ext := filepath.Ext(file)
name = strings.TrimSuffix(file, ext)
}
if len(writeFormat.Extensions) > 0 {
name += writeFormat.Extensions[0]
}
cmd.Out = name
}
if cmd.Out != "" {
out, err = os.OpenFile(cmd.Out, os.O_CREATE, 0666)
if err != nil {
return fmt.Errorf("unable to open %q: %v", cmd.Out, err)
}
}
return writeFormat.Writer.Write(out, song)
}