feat: Interactive 'uc ctx connection` command to select preferred cluster connection (#170)

* feat: Interactive uc command to select preferred cluster connection

https://github.com/psviderski/uncloud/issues/125

* Simplify connection selection and reordering by using the index instead of a pointer

* Move connection reordering logic to a new SetDefaultConnection on context

cmd/uncloud/context/connection.go

@@ -0,0 +1,78 @@
+package context
+
+import (
+	"fmt"
+
+	"github.com/charmbracelet/huh"
+	"github.com/psviderski/uncloud/internal/cli"
+	"github.com/psviderski/uncloud/internal/cli/config"
+	"github.com/spf13/cobra"
+)
+
+func NewConnectionCommand() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "connection",
+		Short: "Choose a new default connection for the current context.",
+		RunE: func(cmd *cobra.Command, args []string) error {
+			uncli := cmd.Context().Value("cli").(*cli.CLI)
+			return selectConnection(uncli)
+		},
+	}
+	return cmd
+}
+
+func selectConnection(uncli *cli.CLI) error {
+	if uncli.Config == nil {
+		return fmt.Errorf("connection management is not available: Uncloud configuration file is not being used")
+	}
+	if len(uncli.Config.Contexts) == 0 {
+		return fmt.Errorf("no contexts found in Uncloud config (%s)", uncli.Config.Path())
+	}
+
+	currentCtxName := uncli.Config.CurrentContext
+	currentCtx, ok := uncli.Config.Contexts[currentCtxName]
+	if !ok {
+		return fmt.Errorf("current context '%s' not found", currentCtxName)
+	}
+
+	if len(currentCtx.Connections) == 0 {
+		return fmt.Errorf("no connections found in context '%s'", currentCtxName)
+	}
+
+	var selectedConnection int
+	form := huh.NewForm(
+		huh.NewGroup(
+			huh.NewSelect[int]().
+				Title("Select a default connection").
+				Options(buildConnectionOptions(currentCtx.Connections)...).
+				Value(&selectedConnection),
+		),
+	)
+	if err := form.Run(); err != nil {
+		return fmt.Errorf("select connection: %w", err)
+	}
+
+	currentCtx.SetDefaultConnection(selectedConnection)
+	selected := currentCtx.Connections[0]
+
+	if err := uncli.Config.Save(); err != nil {
+		return fmt.Errorf("save config: %w", err)
+	}
+
+	fmt.Printf("Default connection for context '%s' is now '%s'.\n", currentCtxName, selected)
+	return nil
+}
+
+func buildConnectionOptions(connections []config.MachineConnection) []huh.Option[int] {
+	options := make([]huh.Option[int], len(connections))
+	for i, conn := range connections {
+		key := conn.String()
+		opt := huh.NewOption(key, i)
+		if i == 0 {
+			opt.Key += " (default)"
+			opt = opt.Selected(true)
+		}
+		options[i] = opt
+	}
+	return options
+}

cmd/uncloud/context/root.go

@@ -19,6 +19,7 @@ func NewRootCommand() *cobra.Command {
 	cmd.AddCommand(
 		NewListCommand(),
 		NewUseCommand(),
+		NewConnectionCommand(),
 	)
 
 	return cmd

internal/cli/config/context.go

@@ -4,3 +4,21 @@ type Context struct {
 	Name        string              `yaml:"-"`
 	Connections []MachineConnection `yaml:"connections"`
 }
+
+func (c *Context) SetDefaultConnection(index int) {
+	// Do nothing if the index is out of range.
+	if index < 0 || index >= len(c.Connections) {
+		return
+	}
+
+	selected := c.Connections[index]
+	newConnections := make([]MachineConnection, 0, len(c.Connections))
+	newConnections = append(newConnections, selected)
+
+	for i, conn := range c.Connections {
+		if i != index {
+			newConnections = append(newConnections, conn)
+		}
+	}
+	c.Connections = newConnections
+}