Add device list command (#21)

This PR introduces the device list command, useful to retrieve devices of arduino iot cloud.
To list devices, no flags or arguments are needed, the command is simply:
$ iot-cloud-cli device list

maybe worth doing in the future:

    list command could accept a list of IDs that should be retrieved from the cloud
    edit: a new show command might be better

commits log:
* Add device list command

* Add comments

* Update readme

Author: polldo

README.md

@@ -32,3 +32,8 @@ When provisioning a device, you can optionally specify the port to which the dev
 Use this command to provision a device:
 
 `$ iot-cloud-cli device create --name <deviceName> --port <port> --fqbn <deviceFqbn>`
+
+## Device commands
+
+Devices currently present on Arduino IoT Cloud can be retrieved by using this command:
+`$ iot-cloud-cli device list`

cli/device/device.go

@@ -12,6 +12,7 @@ func NewCommand() *cobra.Command {
 	}
 
 	deviceCommand.AddCommand(initCreateCommand())
+	deviceCommand.AddCommand(initListCommand())
 
 	return deviceCommand
 }

cli/device/list.go

@@ -0,0 +1,59 @@
+package device
+
+import (
+	"fmt"
+
+	"github.com/arduino/arduino-cli/cli/feedback"
+	"github.com/arduino/arduino-cli/table"
+	"github.com/arduino/iot-cloud-cli/command/device"
+	"github.com/spf13/cobra"
+)
+
+func initListCommand() *cobra.Command {
+	listCommand := &cobra.Command{
+		Use:   "list",
+		Short: "List devices",
+		Long:  "List devices on Arduino IoT Cloud",
+		RunE:  runListCommand,
+	}
+	return listCommand
+}
+
+func runListCommand(cmd *cobra.Command, args []string) error {
+	fmt.Println("Listing devices")
+
+	devs, err := device.List()
+	if err != nil {
+		return err
+	}
+
+	feedback.PrintResult(result{devs})
+
+	return nil
+}
+
+type result struct {
+	devices []device.DeviceInfo
+}
+
+func (r result) Data() interface{} {
+	return r.devices
+}
+
+func (r result) String() string {
+	if len(r.devices) == 0 {
+		return "No devices found."
+	}
+	t := table.New()
+	t.SetHeader("Name", "ID", "Board", "FQBN", "SerialNumber")
+	for _, device := range r.devices {
+		t.AddRow(
+			device.Name,
+			device.ID,
+			device.Board,
+			device.FQBN,
+			device.Serial,
+		)
+	}
+	return t.Render()
+}

command/device/list.go

@@ -0,0 +1,48 @@
+package device
+
+import (
+	"github.com/arduino/iot-cloud-cli/internal/config"
+	"github.com/arduino/iot-cloud-cli/internal/iot"
+)
+
+// DeviceInfo contains the most interesting
+// parameters of an Arduino IoT Cloud device.
+type DeviceInfo struct {
+	Name   string
+	ID     string
+	Board  string
+	Serial string
+	FQBN   string
+}
+
+// List command is used to list
+// the devices of Arduino IoT Cloud.
+func List() ([]DeviceInfo, error) {
+	conf, err := config.Retrieve()
+	if err != nil {
+		return nil, err
+	}
+	iotClient, err := iot.NewClient(conf.Client, conf.Secret)
+	if err != nil {
+		return nil, err
+	}
+
+	foundDevices, err := iotClient.ListDevices()
+	if err != nil {
+		return nil, err
+	}
+
+	var devices []DeviceInfo
+	for _, foundDev := range foundDevices {
+		dev := DeviceInfo{
+			Name:   foundDev.Name,
+			ID:     foundDev.Id,
+			Board:  foundDev.Type,
+			Serial: foundDev.Serial,
+			FQBN:   foundDev.Fqbn,
+		}
+		devices = append(devices, dev)
+	}
+
+	return devices, nil
+}

internal/iot/client.go

@@ -10,6 +10,7 @@ import (
 // Client can be used to perform actions on the arduino iot cloud.
 type Client interface {
 	AddDevice(fqbn, name, serial, devType string) (string, error)
+	ListDevices() ([]iotclient.ArduinoDevicev2, error)
 	AddCertificate(id, csr string) (*iotclient.ArduinoCompressedv2, error)
 }
 
@@ -47,6 +48,17 @@ func (cl *client) AddDevice(fqbn, name, serial, dType string) (string, error) {
 	return dev.Id, nil
 }
 
+// ListDevices retrieves and returns a list of all Arduino IoT Cloud devices
+// belonging to the user performing the request.
+func (cl *client) ListDevices() ([]iotclient.ArduinoDevicev2, error) {
+	devices, _, err := cl.api.DevicesV2Api.DevicesV2List(cl.ctx, nil)
+	if err != nil {
+		err = fmt.Errorf("listing devices: %w", err)
+		return nil, err
+	}
+	return devices, nil
+}
+
 // AddCertifcate allows to upload a certificate on arduino iot cloud.
 // It returns the certificate parameters populated by the cloud.
 func (cl *client) AddCertificate(id, csr string) (*iotclient.ArduinoCompressedv2, error) {