config: add utility function for backend config with list and custom input

backend/jottacloud/jottacloud.go

@@ -127,7 +127,7 @@ func init() {
 func Config(ctx context.Context, name string, m configmap.Mapper, config fs.ConfigIn) (*fs.ConfigOut, error) {
 	switch config.State {
 	case "":
-		return fs.ConfigChooseFixed("auth_type_done", "config_type", `Authentication type.`, []fs.OptionExample{{
+		return fs.ConfigChooseExclusiveFixed("auth_type_done", "config_type", `Authentication type.`, []fs.OptionExample{{
 			Value: "standard",
 			Help:  "Standard authentication.\nUse this if you're a normal Jottacloud user.",
 		}, {
@@ -286,7 +286,7 @@ machines.`)
 		if err != nil {
 			return nil, err
 		}
-		return fs.ConfigChoose("choose_device_result", "config_device", `Please select the device to use. Normally this will be Jotta`, len(acc.Devices), func(i int) (string, string) {
+		return fs.ConfigChooseExclusive("choose_device_result", "config_device", `Please select the device to use. Normally this will be Jotta`, len(acc.Devices), func(i int) (string, string) {
 			return acc.Devices[i].Name, ""
 		})
 	case "choose_device_result":
@@ -304,7 +304,7 @@ machines.`)
 		if err != nil {
 			return nil, err
 		}
-		return fs.ConfigChoose("choose_device_mountpoint", "config_mountpoint", `Please select the mountpoint to use. Normally this will be Archive.`, len(dev.MountPoints), func(i int) (string, string) {
+		return fs.ConfigChooseExclusive("choose_device_mountpoint", "config_mountpoint", `Please select the mountpoint to use. Normally this will be Archive.`, len(dev.MountPoints), func(i int) (string, string) {
 			return dev.MountPoints[i].Name, ""
 		})
 	case "choose_device_mountpoint":

backend/onedrive/onedrive.go

@@ -424,7 +424,7 @@ func Config(ctx context.Context, name string, m configmap.Mapper, config fs.Conf
 
 	switch config.State {
 	case "choose_type":
-		return fs.ConfigChooseFixed("choose_type_done", "config_type", "Type of connection", []fs.OptionExample{{
+		return fs.ConfigChooseExclusiveFixed("choose_type_done", "config_type", "Type of connection", []fs.OptionExample{{
 			Value: "onedrive",
 			Help:  "OneDrive Personal or Business",
 		}, {

fs/backend_config.go

@@ -176,7 +176,13 @@ func ConfigConfirm(state string, Default bool, name string, help string) (*Confi
 	}, nil
 }
 
-// ConfigChooseFixed returns a ConfigOut structure which has a list of items to choose from.
+// ConfigChooseExclusiveFixed returns a ConfigOut structure which has a list of
+// items to choose from.
+//
+// Possible items must be supplied as a fixed list.
+//
+// User is required to supply a value, and is restricted to the specified list,
+// i.e. free text input is not allowed.
 //
 // state should be the next state required
 // name is the config name for this item
@@ -185,8 +191,8 @@ func ConfigConfirm(state string, Default bool, name string, help string) (*Confi
 //
 // It chooses the first item to be the default.
 // If there are no items then it will return an error.
-// If there is only one item it will short cut to the next state
-func ConfigChooseFixed(state string, name string, help string, items []OptionExample) (*ConfigOut, error) {
+// If there is only one item it will short cut to the next state.
+func ConfigChooseExclusiveFixed(state string, name string, help string, items []OptionExample) (*ConfigOut, error) {
 	if len(items) == 0 {
 		return nil, fmt.Errorf("no items found in: %s", help)
 	}
@@ -208,7 +214,13 @@ func ConfigChooseFixed(state string, name string, help string, items []OptionExa
 	return choose, nil
 }
 
-// ConfigChoose returns a ConfigOut structure which has a list of items to choose from.
+// ConfigChooseExclusive returns a ConfigOut structure which has a list of
+// items to choose from.
+//
+// Possible items are retrieved from a supplied function.
+//
+// User is required to supply a value, and is restricted to the specified list,
+// i.e. free text input is not allowed.
 //
 // state should be the next state required
 // name is the config name for this item
@@ -218,7 +230,60 @@ func ConfigChooseFixed(state string, name string, help string, items []OptionExa
 //
 // It chooses the first item to be the default.
 // If there are no items then it will return an error.
-// If there is only one item it will short cut to the next state
+// If there is only one item it will short cut to the next state.
+func ConfigChooseExclusive(state string, name string, help string, n int, getItem func(i int) (itemValue string, itemHelp string)) (*ConfigOut, error) {
+	items := make(OptionExamples, n)
+	for i := range items {
+		items[i].Value, items[i].Help = getItem(i)
+	}
+	return ConfigChooseExclusiveFixed(state, name, help, items)
+}
+
+// ConfigChooseFixed returns a ConfigOut structure which has a list of
+// suggested items.
+//
+// Suggested items must be supplied as a fixed list.
+//
+// User is required to supply a value, but is not restricted to the specified
+// list, i.e. free text input is accepted.
+//
+// state should be the next state required
+// name is the config name for this item
+// help should be the help shown to the user
+// items should be the items in the list
+//
+// It chooses the first item to be the default.
+func ConfigChooseFixed(state string, name string, help string, items []OptionExample) (*ConfigOut, error) {
+	choose := &ConfigOut{
+		State: state,
+		Option: &Option{
+			Name:     name,
+			Help:     help,
+			Examples: items,
+			Required: true,
+		},
+	}
+	if len(choose.Option.Examples) > 0 {
+		choose.Option.Default = choose.Option.Examples[0].Value
+	}
+	return choose, nil
+}
+
+// ConfigChoose returns a ConfigOut structure which has a list of suggested
+// items.
+//
+// Suggested items are retrieved from a supplied function.
+//
+// User is required to supply a value, but is not restricted to the specified
+// list, i.e. free text input is accepted.
+//
+// state should be the next state required
+// name is the config name for this item
+// help should be the help shown to the user
+// n should be the number of items in the list
+// getItem should return the items (value, help)
+//
+// It chooses the first item to be the default.
 func ConfigChoose(state string, name string, help string, n int, getItem func(i int) (itemValue string, itemHelp string)) (*ConfigOut, error) {
 	items := make(OptionExamples, n)
 	for i := range items {