Add config listproviders, listoptions, jsonconfig for automated config

Addition of a method listing the providers, a method listing the
options of a provider and method of manual configuration.

cmd/config/config.go

@@ -26,14 +26,15 @@ Additional functions:
   * ` + "`rclone config edit`" + ` – same as above
   * ` + "`rclone config file`" + ` – show path of configuration file in use
   * ` + "`rclone config show`" + ` – print (decrypted) config file
+  * ` + "`rclone config listproviders`" + ` – List, in json format, the protocols supported by sync
+  * ` + "`rclone config listoptions type`" + ` – Lists all the options needed to connect to a protocol
+  * ` + "`rclone config jsonconfig`name type jsonoptions" + ` – Created a new remote type X with parameters Y
 `,
 	Run: func(command *cobra.Command, args []string) {
-		cmd.CheckArgs(0, 1, command, args)
+		cmd.CheckArgs(0, 4, command, args)
 		if len(args) == 0 {
 			fs.EditConfig()
-			return
+		} else if (len(args) == 1) {
-		}
-
 			switch args[0] {
 			case "edit":
 				fs.EditConfig()
@@ -41,8 +42,24 @@ Additional functions:
 				fs.ShowConfig()
 			case "file":
 				fs.ShowConfigLocation()
+			case "listproviders":
+				fs.ListProviders()
 			default:
 				fmt.Fprintf(os.Stderr, "Unknown subcommand %q, %s only supports edit, show and file.\n", args[0], command.Name())
 			}
+		} else if (len(args) == 2) {
+			if ((args[0] == "listoptions") && (args[1] != "")) {
+				fs.ListOptions(args[1])
+			} else {
+				fmt.Fprintf(os.Stderr, "Unknown subcommand %q %q, %s only supports optionsprovider <type>.\n", args[0], args[1], command.Name())
+			}
+		} else if (len(args) == 4) {
+			if ((args[0] == "jsonconfig") && (args[1] != "") && (args[2] != "") && (args[3]!= "")) {
+				fs.JsonConfig(args[1], args[2], args[3])
+			} else {
+				fmt.Fprintf(os.Stderr, "Unknown subcommand %q %q %q %q, %s only supports jsonconfig <name> <type> <json:options>.\n", args[0], args[1], args[2], args[3], command.Name())
+		    }
+		}
+		return
 	},
 }

fs/config.go

@@ -10,6 +10,7 @@ import (
 	"crypto/rand"
 	"crypto/sha256"
 	"encoding/base64"
+	"encoding/json"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -991,6 +992,58 @@ func ChooseOption(o *Option) string {
 	return ReadLine()
 }
 
+// JsonConfig Created a new remote type X with parameters Y
+func JsonConfig(name string, provider string, jsonstr string) {
+	bytes := []byte(jsonstr)
+
+	// Unmarshal string into structs.
+	var options []Option
+	json.Unmarshal(bytes, &options)
+
+	configData.SetValue(name, "type", provider)
+	// Loop over structs and display them.
+	for op := range options {
+		configData.SetValue(name, options[op].Name, options[op].Value)
+	}
+	configData.SetValue(name, ConfigAutomatic, "yes")
+	RemoteConfig(name)
+	ShowRemote(name)
+	SaveConfig()
+}
+
+// ListOptions Lists all the options needed to connect to a protocol
+func ListOptions(provider string) {
+	fs := MustFind(provider)
+	b, err := json.Marshal(fs.Options)
+	if err != nil {
+		fmt.Println("error:", err)
+	}
+	os.Stdout.Write(b)
+}
+
+// ListProviders print all providersList, in json format, the protocols supported by sync
+func ListProviders() {
+	o := &Option{
+		Name: "Storage",
+		Help: "Type of storage to configure.",
+	}
+	for _, item := range fsRegistry {
+		example := OptionExample{
+			Value: item.Name,
+			Help:  item.Description,
+		}
+		o.Examples = append(o.Examples, example)
+	}
+	if len(o.Examples) > 0 {
+		o.Examples.Sort()
+		b, err := json.Marshal(o.Examples)
+		if err != nil {
+			fmt.Println("error:", err)
+		}
+		os.Stdout.Write(b)
+	}
+}
+
 // fsOption returns an Option describing the possible remotes
 func fsOption() *Option {
 	o := &Option{

fs/fs.go

@@ -76,6 +76,7 @@ type Option struct {
 	Optional   bool
 	IsPassword bool
 	Examples   OptionExamples
+	Value      string
 }
 
 // OptionExamples is a slice of examples