cmd/list: Decode image/container JSON to struct

Every time Podman changes their JSON API Toolbox breaks horribly. That
is caused by the combination of decoding the JSON purely by hand and by
the complete lack of type assertions to make the process stable.

I previously didn't know that unmarshalling with Go works on the 'do the
best job it can' logic (thank you Owen!). This makes the need to check
for subtle changes in the names of fields go away and type checking a
bit more bareable (marking the questioned field as interface{} and then
immediatelly type asserting).

If even now an existing field does not hold an expected value the field
will remain blank.

src/cmd/list.go

@@ -17,13 +17,16 @@
 package cmd
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
 	"os"
 	"text/tabwriter"
+	"time"
 
 	"github.com/containers/toolbox/pkg/podman"
 	"github.com/containers/toolbox/pkg/utils"
+	"github.com/docker/go-units"
 	"github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
 )
@@ -187,25 +190,36 @@ func listOutput(images, containers []map[string]interface{}) {
 		writer := tabwriter.NewWriter(os.Stdout, 0, 0, 2, ' ', 0)
 		fmt.Fprintf(writer, "%s\t%s\t%s\n", "IMAGE ID", "IMAGE NAME", "CREATED")
 
-		var idKey, nameKey, createdKey string
-		if podman.CheckVersion("2.0.0") {
-			idKey = "Id"
-			nameKey = "Names"
-			createdKey = "Created"
-		} else if podman.CheckVersion("1.8.3") {
-			idKey = "ID"
-			nameKey = "Names"
-			createdKey = "Created"
-		} else {
-			idKey = "id"
-			nameKey = "names"
-			createdKey = "created"
-		}
-
 		for _, image := range images {
-			id := utils.ShortID(image[idKey].(string))
-			name := image[nameKey].([]interface{})[0].(string)
-			created := image[createdKey].(string)
+			imageJSON, err := json.Marshal(image)
+			if err != nil {
+				logrus.Errorf("failed to marshal image: %v", err)
+				continue
+			}
+
+			var toolboxImage struct {
+				ID      string
+				Names   []string
+				Created interface{}
+			}
+			err = json.Unmarshal(imageJSON, &toolboxImage)
+			if err != nil {
+				logrus.Errorf("failed to unmarshal toolbox image: %v", err)
+				continue
+			}
+
+			var id, name, created string
+			id = utils.ShortID(toolboxImage.ID)
+
+			name = toolboxImage.Names[0]
+
+			switch value := toolboxImage.Created.(type) {
+			case string:
+				created = value
+			case float64:
+				created = units.HumanDuration(time.Since(time.Unix(int64(value), 0))) + " ago"
+			}
+
 			fmt.Fprintf(writer, "%s\t%s\t%s\n", id, name, created)
 		}
 
@@ -226,33 +240,53 @@ func listOutput(images, containers []map[string]interface{}) {
 			"STATUS",
 			"IMAGE NAME")
 
-		var idKey, createdKey, statusKey string
-		if podman.CheckVersion("2.0.0") {
-			idKey = "Id"
-			createdKey = "CreatedAt"
-			statusKey = "State"
-		} else {
-			idKey = "ID"
-			createdKey = "Created"
-			statusKey = "Status"
-		}
-
 		for _, container := range containers {
-			id := utils.ShortID(container[idKey].(string))
+			containerJSON, err := json.Marshal(container)
+			if err != nil {
+				logrus.Errorf("failed to marshal container: %v", err)
+				continue
+			}
+
+			var toolboxContainer struct {
+				ID      string
+				Name    string
+				Names   []string
+				Status  string
+				State   string
+				Created interface{}
+				Image   string
+			}
+			err = json.Unmarshal(containerJSON, &toolboxContainer)
+			if err != nil {
+				logrus.Errorf("failed to unmarshal toolbox container: %v", err)
+				continue
+			}
+
+			var id, name, created, status, imageName string
+			id = utils.ShortID(toolboxContainer.ID)
+
+			if toolboxContainer.Name != "" {
+				name = toolboxContainer.Name
+			} else {
+				name = toolboxContainer.Names[0]
+			}
+
+			if toolboxContainer.Status != "" {
+				status = toolboxContainer.Status
+			} else {
+				status = toolboxContainer.State
+			}
 
-			var nameString string
-			switch name := container["Names"].(type) {
+			switch value := toolboxContainer.Created.(type) {
 			case string:
-				nameString = name
-			case []interface{}:
-				nameString = name[0].(string)
+				created = value
+			case float64:
+				created = units.HumanDuration(time.Since(time.Unix(int64(value), 0))) + " ago"
 			}
 
-			created := container[createdKey].(string)
-			status := container[statusKey].(string)
-			imageName := container["Image"].(string)
+			imageName = toolboxContainer.Image
 
-			fmt.Fprintf(writer, "%s\t%s\t%s\t%s\t%s\n", id, nameString, created, status, imageName)
+			fmt.Fprintf(writer, "%s\t%s\t%s\t%s\t%s\n", id, name, created, status, imageName)
 		}
 
 		writer.Flush()