refactor: extract core logic to a plain Go package

commands/use.go

@@ -0,0 +1,53 @@
+package commands
+
+import (
+	"strings"
+
+	"github.com/jimeh/evm/manager"
+	"github.com/spf13/cobra"
+)
+
+func NewUse(mgr *manager.Manager) (*cobra.Command, error) {
+	cmd := &cobra.Command{
+		Use:               "use <version>",
+		Short:             "Switch to a specific version",
+		Aliases:           []string{"activate", "switch"},
+		Args:              cobra.ExactArgs(1),
+		ValidArgsFunction: useValidArgs(mgr),
+		RunE:              useRunE(mgr),
+	}
+
+	return cmd, nil
+}
+
+func useRunE(mgr *manager.Manager) runEFunc {
+	return func(cmd *cobra.Command, args []string) error {
+		return mgr.Use(cmd.Context(), args[0])
+	}
+}
+
+func useValidArgs(mgr *manager.Manager) validArgsFunc {
+	return func(
+		cmd *cobra.Command,
+		args []string,
+		toComplete string,
+	) ([]string, cobra.ShellCompDirective) {
+		if len(args) > 0 {
+			return nil, cobra.ShellCompDirectiveNoFileComp
+		}
+
+		versions, err := mgr.List(cmd.Context())
+		if err != nil {
+			return nil, cobra.ShellCompDirectiveNoFileComp
+		}
+
+		var r []string
+		for _, ver := range versions {
+			if toComplete == "" || strings.HasPrefix(ver.Version, toComplete) {
+				r = append(r, ver.Version)
+			}
+		}
+
+		return r, cobra.ShellCompDirectiveNoFileComp
+	}
+}