feat: add login command (#4)

Adds a login command that authenticates the user with the configured email and password.

README.md

@@ -59,3 +59,12 @@ $ litterrobot config show --show-secrets
 email: email@example.com
 password: changeIt
 ```
+
+### Login
+Use the `login` command to authenticate to Litter Robot.
+
+This command writes the `token` to the config file. Keep it secret!
+
+```console
+$ litterobot login
+```

internal/cmd/login.go

@@ -0,0 +1,27 @@
+package cmd
+
+import (
+	"context"
+
+	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
+	lrc "github.com/tlkamp/litter-api/v2/pkg/client"
+)
+
+func newLoginCmd(c *lrc.Client) *cobra.Command {
+	return &cobra.Command{
+		Use:          "login",
+		Short:        "log into the litter robot 3",
+		SilenceUsage: true,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			c = lrc.New(viper.GetString("email"), viper.GetString("password"))
+
+			if err := c.Login(context.Background()); err != nil {
+				return err
+			}
+
+			viper.Set("token", c.Token())
+			return viper.WriteConfig()
+		},
+	}
+}

internal/cmd/root.go

@@ -32,6 +32,7 @@ func newLitterRobotCmd(c *lrc.Client, version string) *cobra.Command {
 	cmd.AddCommand(
 		newVersionCmd(version),
 		newConfigCmd(),
+		newLoginCmd(c),
 	)
 
 	return cmd