[gen] Add gen alias command (#2009)

## Summary

Add a command that allows creating aliases to devbox scripts. This lets
users source aliases from any project they want. It's opt-in, works in
POSIX and fish. Aliases make it easy to call the scripts for other
projects or directories.

How it works:

```bash
eval "$(devbox gen alias)"
devbox-build
```

It builds the alias name using the project name in devbox.json.

Alternatively the user can specify a prefix

```bash
eval "$(devbox gen alias --prefix dx)"
dx-build
```

## How was it tested?

```bash
eval "$(devbox gen alias --prefix dx)"
dx-build
cd $HOME && dx-build
```

---------

Signed-off-by: Mike Landau <[email protected]>
Co-authored-by: Greg Curtis <[email protected]>

Author: mikeland73

internal/boxcli/generate.go

@@ -4,9 +4,14 @@
 package boxcli
 
 import (
+	"cmp"
+	"fmt"
+	"regexp"
+
 	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
 
+	"go.jetpack.io/devbox/internal/boxcli/usererr"
 	"go.jetpack.io/devbox/internal/cloud"
 	"go.jetpack.io/devbox/internal/devbox"
 	"go.jetpack.io/devbox/internal/devbox/devopt"
@@ -28,6 +33,11 @@ type GenerateReadmeCmdFlags struct {
 	template     string
 }
 
+type GenerateAliasCmdFlags struct {
+	config configFlags
+	prefix string
+}
+
 func generateCmd() *cobra.Command {
 	flags := &generateCmdFlags{}
 
@@ -38,6 +48,7 @@ func generateCmd() *cobra.Command {
 		Args:              cobra.MaximumNArgs(0),
 		PersistentPreRunE: ensureNixInstalled,
 	}
+	command.AddCommand(genAliasCmd())
 	command.AddCommand(devcontainerCmd())
 	command.AddCommand(dockerfileCmd())
 	command.AddCommand(debugCmd())
@@ -180,6 +191,51 @@ func genReadmeCmd() *cobra.Command {
 	return command
 }
 
+func genAliasCmd() *cobra.Command {
+	flags := &GenerateAliasCmdFlags{}
+
+	command := &cobra.Command{
+		Use:   "alias",
+		Short: "Generate shell script aliases for this project",
+		Long: "Generate shell script aliases for this project. " +
+			"Usage is typically `eval \"$(devbox gen alias)\"`.",
+		Args: cobra.ExactArgs(0),
+		RunE: func(cmd *cobra.Command, args []string) error {
+			box, err := devbox.Open(&devopt.Opts{
+				Dir:    flags.config.path,
+				Stderr: cmd.ErrOrStderr(),
+			})
+			if err != nil {
+				return errors.WithStack(err)
+			}
+			re := regexp.MustCompile("[^a-zA-Z0-9_-]+")
+			prefix := cmp.Or(flags.prefix, box.Config().Root.Name)
+			if prefix == "" {
+				return usererr.New(
+					"To generate aliases, you must specify a prefix or set a name " +
+						"in devbox.json")
+			}
+			prefix = re.ReplaceAllString(prefix, "-")
+			for _, script := range box.ListScripts() {
+				fmt.Fprintf(
+					cmd.OutOrStdout(),
+					"alias %s-%s='devbox -c \"%s\" run %s'\n",
+					prefix,
+					script,
+					box.ProjectDir(),
+					script,
+				)
+			}
+			return nil
+		},
+	}
+	flags.config.register(command)
+	command.Flags().StringVarP(
+		&flags.prefix, "prefix", "p", "", "Prefix for the generated aliases")
+
+	return command
+}
+
 func runGenerateCmd(cmd *cobra.Command, flags *generateCmdFlags) error {
 	// Check the directory exists.
 	box, err := devbox.Open(&devopt.Opts{