Dynamic per-backend configuration options

internal/backends/backends.go

@@ -63,7 +63,7 @@ func (l BackendList) Swap(i, j int) {
 type Capability = string
 
 func ResolveBackend[T interface{}](config *viper.Viper) (T, error) {
-	backendName, backend, err := resolveBackend(config)
+	backendName, backend, err := backendWithConfig(config)
 	var result T
 	if err != nil {
 		return result, err
@@ -78,6 +78,14 @@ func ResolveBackend[T interface{}](config *viper.Viper) (T, error) {
 	return result, err
 }
 
+func BackendByName(backendName string) (models.Backend, error) {
+	backendType := knownBackends[backendName]
+	if backendType == nil {
+		return nil, fmt.Errorf("unknown backend %s", backendName)
+	}
+	return backendType(), nil
+}
+
 func GetBackends() BackendList {
 	backends := make(BackendList, 0)
 	for name, backendFunc := range knownBackends {
@@ -107,13 +115,13 @@ var knownBackends = map[string]func() models.Backend{
 	"subsonic":      func() models.Backend { return &subsonic.SubsonicApiBackend{} },
 }
 
-func resolveBackend(config *viper.Viper) (string, models.Backend, error) {
+func backendWithConfig(config *viper.Viper) (string, models.Backend, error) {
 	backendName := config.GetString("backend")
-	backendType := knownBackends[backendName]
-	if backendType == nil {
-		return backendName, nil, fmt.Errorf("unknown backend %s", backendName)
+	backend, err := BackendByName(backendName)
+	if err != nil {
+		return backendName, nil, err
 	}
-	return backendName, backendType().FromConfig(config), nil
+	return backendName, backend.FromConfig(config), nil
 }
 
 func ImplementsInterface[T interface{}](backend *models.Backend) (bool, string) {

internal/backends/deezer/deezer.go

@@ -36,6 +36,18 @@ type DeezerApiBackend struct {
 
 func (b *DeezerApiBackend) Name() string { return "deezer" }
 
+func (b *DeezerApiBackend) Options() *[]models.BackendOption {
+	return &[]models.BackendOption{{
+		Name:  "client-id",
+		Label: "Client ID",
+		Type:  models.String,
+	}, {
+		Name:  "client-secret",
+		Label: "Client secret",
+		Type:  models.Secret,
+	}}
+}
+
 func (b *DeezerApiBackend) FromConfig(config *viper.Viper) models.Backend {
 	b.clientId = config.GetString("client-id")
 	b.clientSecret = config.GetString("client-secret")

internal/backends/dump/dump.go

@@ -25,6 +25,8 @@ type DumpBackend struct{}
 
 func (b *DumpBackend) Name() string { return "dump" }
 
+func (b *DumpBackend) Options() *[]models.BackendOption { return nil }
+
 func (b *DumpBackend) FromConfig(config *viper.Viper) models.Backend {
 	return b
 }

internal/backends/funkwhale/funkwhale.go

@@ -33,6 +33,22 @@ type FunkwhaleApiBackend struct {
 
 func (b *FunkwhaleApiBackend) Name() string { return "funkwhale" }
 
+func (b *FunkwhaleApiBackend) Options() *[]models.BackendOption {
+	return &[]models.BackendOption{{
+		Name:  "server-url",
+		Label: "Server URL",
+		Type:  models.String,
+	}, {
+		Name:  "username",
+		Label: "User name",
+		Type:  models.String,
+	}, {
+		Name:  "token",
+		Label: "Access token",
+		Type:  models.Secret,
+	}}
+}
+
 func (b *FunkwhaleApiBackend) FromConfig(config *viper.Viper) models.Backend {
 	b.client = NewClient(
 		config.GetString("server-url"),

internal/backends/jspf/jspf.go

@@ -36,6 +36,26 @@ type JSPFBackend struct {
 
 func (b *JSPFBackend) Name() string { return "jspf" }
 
+func (b *JSPFBackend) Options() *[]models.BackendOption {
+	return &[]models.BackendOption{{
+		Name:  "file-path",
+		Label: "File path",
+		Type:  models.String,
+	}, {
+		Name:  "title",
+		Label: "Playlist title",
+		Type:  models.String,
+	}, {
+		Name:  "username",
+		Label: "User name",
+		Type:  models.String,
+	}, {
+		Name:  "identifier",
+		Label: "Unique playlist identifier",
+		Type:  models.String,
+	}}
+}
+
 func (b *JSPFBackend) FromConfig(config *viper.Viper) models.Backend {
 	b.filePath = config.GetString("file-path")
 	b.title = config.GetString("title")

internal/backends/lastfm/lastfm.go

@@ -43,6 +43,22 @@ type LastfmApiBackend struct {
 
 func (b *LastfmApiBackend) Name() string { return "lastfm" }
 
+func (b *LastfmApiBackend) Options() *[]models.BackendOption {
+	return &[]models.BackendOption{{
+		Name:  "username",
+		Label: "User name",
+		Type:  models.String,
+	}, {
+		Name:  "client-id",
+		Label: "Client ID",
+		Type:  models.String,
+	}, {
+		Name:  "client-secret",
+		Label: "Client secret",
+		Type:  models.Secret,
+	}}
+}
+
 func (b *LastfmApiBackend) FromConfig(config *viper.Viper) models.Backend {
 	clientId := config.GetString("client-id")
 	clientSecret := config.GetString("client-secret")

internal/backends/listenbrainz/listenbrainz.go

@@ -34,6 +34,18 @@ type ListenBrainzApiBackend struct {
 
 func (b *ListenBrainzApiBackend) Name() string { return "listenbrainz" }
 
+func (b *ListenBrainzApiBackend) Options() *[]models.BackendOption {
+	return &[]models.BackendOption{{
+		Name:  "username",
+		Label: "User name",
+		Type:  models.String,
+	}, {
+		Name:  "token",
+		Label: "Access token",
+		Type:  models.Secret,
+	}}
+}
+
 func (b *ListenBrainzApiBackend) FromConfig(config *viper.Viper) models.Backend {
 	b.client = NewClient(config.GetString("token"))
 	b.client.MaxResults = MaxItemsPerGet

internal/backends/maloja/maloja.go

@@ -33,6 +33,22 @@ type MalojaApiBackend struct {
 
 func (b *MalojaApiBackend) Name() string { return "maloja" }
 
+func (b *MalojaApiBackend) Options() *[]models.BackendOption {
+	return &[]models.BackendOption{{
+		Name:  "server-url",
+		Label: "Server URL",
+		Type:  models.String,
+	}, {
+		Name:  "token",
+		Label: "Access token",
+		Type:  models.Secret,
+	}, {
+		Name:  "nofix",
+		Label: "Disable auto correction of submitted listens",
+		Type:  models.Bool,
+	}}
+}
+
 func (b *MalojaApiBackend) FromConfig(config *viper.Viper) models.Backend {
 	b.client = NewClient(
 		config.GetString("server-url"),

internal/backends/scrobblerlog/scrobblerlog.go

@@ -36,6 +36,22 @@ type ScrobblerLogBackend struct {
 
 func (b *ScrobblerLogBackend) Name() string { return "scrobbler-log" }
 
+func (b *ScrobblerLogBackend) Options() *[]models.BackendOption {
+	return &[]models.BackendOption{{
+		Name:  "file-path",
+		Label: "File path",
+		Type:  models.String,
+	}, {
+		Name:  "include-skipped",
+		Label: "Include skipped listens",
+		Type:  models.Bool,
+	}, {
+		Name:  "append",
+		Label: "Append to file",
+		Type:  models.Bool,
+	}}
+}
+
 func (b *ScrobblerLogBackend) FromConfig(config *viper.Viper) models.Backend {
 	b.filePath = config.GetString("file-path")
 	b.includeSkipped = config.GetBool("include-skipped")

internal/backends/spotify/spotify.go

@@ -39,6 +39,18 @@ type SpotifyApiBackend struct {
 
 func (b *SpotifyApiBackend) Name() string { return "spotify" }
 
+func (b *SpotifyApiBackend) Options() *[]models.BackendOption {
+	return &[]models.BackendOption{{
+		Name:  "client-id",
+		Label: "Client ID",
+		Type:  models.String,
+	}, {
+		Name:  "client-secret",
+		Label: "Client secret",
+		Type:  models.Secret,
+	}}
+}
+
 func (b *SpotifyApiBackend) FromConfig(config *viper.Viper) models.Backend {
 	b.clientId = config.GetString("client-id")
 	b.clientSecret = config.GetString("client-secret")

internal/backends/subsonic/subsonic.go

@@ -34,6 +34,22 @@ type SubsonicApiBackend struct {
 
 func (b *SubsonicApiBackend) Name() string { return "subsonic" }
 
+func (b *SubsonicApiBackend) Options() *[]models.BackendOption {
+	return &[]models.BackendOption{{
+		Name:  "server-url",
+		Label: "Server URL",
+		Type:  models.String,
+	}, {
+		Name:  "username",
+		Label: "User name",
+		Type:  models.String,
+	}, {
+		Name:  "token",
+		Label: "Access token",
+		Type:  models.Secret,
+	}}
+}
+
 func (b *SubsonicApiBackend) FromConfig(config *viper.Viper) models.Backend {
 	b.client = subsonic.Client{
 		Client:     &http.Client{},

internal/models/interfaces.go

@@ -33,6 +33,9 @@ type Backend interface {
 
 	// Initialize the backend from a config.
 	FromConfig(config *viper.Viper) Backend
+
+	// Return configuration options
+	Options() *[]BackendOption
 }
 
 type ImportBackend interface {

internal/models/options.go

@@ -0,0 +1,32 @@
+/*
+Copyright © 2023 Philipp Wolfer <phw@uploadedlobster.com>
+
+Scotty 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.
+
+Scotty 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
+Scotty. If not, see <https://www.gnu.org/licenses/>.
+*/
+
+package models
+
+type OptionType string
+
+const (
+	Bool   OptionType = "bool"
+	Secret OptionType = "secret"
+	String OptionType = "string"
+)
+
+type BackendOption struct {
+	Name     string
+	Label    string
+	Type     OptionType
+	Default  string
+	Validate func(string) error
+}