Add “preview” command

cmd/preview.go

@@ -0,0 +1,63 @@
+package cmd
+
+import (
+	"github.com/spf13/cobra"
+
+	"fmt"
+	"net/url"
+	"os/exec"
+	"runtime"
+	"time"
+)
+
+const previewURL = "http://www.paperboy.email/preview/connect"
+
+var previewCmd = &cobra.Command{
+	Use:   "preview",
+	Short: "Preview campaign in browser",
+	Long:  `A longer description...`,
+	// Uncomment the following line if your bare application
+	// has an action associated with it:
+	RunE: func(cmd *cobra.Command, args []string) error {
+		if err := loadConfig(); err != nil {
+			return err
+		}
+
+		if len(args) != 2 {
+			return newUserError("Invalid arguments")
+		}
+
+		go func() {
+			runtime.Gosched()
+			time.Sleep(100 * time.Millisecond)
+			openPreview(args[0], args[1])
+		}()
+
+		return startAPIServer()
+	},
+}
+
+func openPreview(content, list string) {
+	q := url.Values{}
+	q.Set("uri", "http://localhost:8080/graphql")
+	q.Set("content", content)
+	q.Set("list", list)
+
+	url := previewURL + "?" + q.Encode()
+	var err error
+
+	switch runtime.GOOS {
+	case "darwin":
+		err = exec.Command("open", url).Start()
+	case "linux":
+		err = exec.Command("xdg-open", url).Start()
+	case "windows":
+		err = exec.Command("rundll32", "url.dll,FileProtocolHandler", url).Start()
+	default:
+		err = fmt.Errorf("Unsupported platform")
+	}
+
+	if err != nil {
+		fmt.Printf("\nPlease open the browser to the following URL:\n%s\n\n", url)
+	}
+}

cmd/root.go

@@ -30,6 +30,7 @@ func Execute() {
 	RootCmd.AddCommand(sendCmd)
 	RootCmd.AddCommand(serverCmd)
 	RootCmd.AddCommand(versionCmd)
+	RootCmd.AddCommand(previewCmd)
 
 	if err := RootCmd.Execute(); err != nil {
 		fmt.Println(err)

cmd/server.go

@@ -16,9 +16,12 @@ var serverCmd = &cobra.Command{
 		if err := loadConfig(); err != nil {
 			return err
 		}
-
-		fmt.Println("API server listening at :8080 ... ")
-		http.Handle("/graphql", server.GraphQLHandler())
-		return http.ListenAndServe(":8080", nil)
+		return startAPIServer()
 	},
 }
+
+func startAPIServer() error {
+	fmt.Println("API server listening at :8080 ... ")
+	http.Handle("/graphql", server.GraphQLHandler())
+	return http.ListenAndServe(":8080", nil)
+}