docker-ex: something like `docker images` with emoji digest

Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>

docker-ex/main.go

@@ -0,0 +1,110 @@
+package main
+
+import (
+	"encoding/hex"
+	"encoding/json"
+	"flag"
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+	"strings"
+
+	esum "github.com/emojisum/emojisum/emoji"
+)
+
+var (
+	flJson       = flag.Bool("json", false, "output json (no emoji)")
+	formatOutput = `
+{
+	"repo": "{{.Repository}}",
+	"id": "{{.ID}}",
+	"digest": "{{.Digest}}",
+	"tag": "{{.Tag}}",
+	"createdSince": "{{.CreatedSince}}",
+	"createdAt": "{{.CreatedAt}}",
+	"size": "{{.Size}}"
+}
+`
+)
+
+func main() {
+	flag.Parse()
+	args := []string{"images", "--digests", fmt.Sprintf("--format=%s", formatOutput)}
+	args = append(args, flag.Args()...)
+	cmd := exec.Command("docker", args...)
+
+	if !*flJson {
+		pR, pW := io.Pipe()
+		cmd.Stdout = pW
+		jR := json.NewDecoder(pR)
+		go func() {
+			for {
+				it := ImageThing{}
+				err := jR.Decode(&it)
+				if err != nil {
+					fmt.Fprintln(os.Stderr, err)
+					os.Exit(1)
+				}
+				var digest, d, h string
+				var name string
+
+				if it.Tag == "" {
+					name = it.Repo
+				} else {
+					name = fmt.Sprintf("%s:%s", it.Repo, it.Tag)
+				}
+
+				if strings.Contains(it.Digest, ":") {
+					chunks := strings.SplitN(it.Digest, ":", 2)
+					h = chunks[0]
+					d, err = emojiFromHexString(chunks[1])
+					if err != nil {
+						fmt.Fprintln(os.Stderr, err)
+						os.Exit(1)
+					}
+					digest = fmt.Sprintf("%s:%s", h, d)
+				} else {
+					digest = "<none>"
+				}
+
+				fmt.Printf("%s (id %s) %s\n", name, it.ID, digest)
+			}
+		}()
+	} else {
+		cmd.Stdout = os.Stdout
+	}
+
+	cmd.Stdin = os.Stdin
+	cmd.Stderr = os.Stderr
+	cmd.Run()
+}
+
+func emojiFromHexString(s string) (string, error) {
+	d, err := hex.DecodeString(s)
+	if err != nil {
+		return "", err
+	}
+
+	var ret string
+	for _, b := range d {
+		for _, e := range esum.Map(b) {
+			// use the first colon notation word and continue
+			if esum.IsCodepoint(e) {
+				ret = ret + esum.CodepointToUnicode(e)
+				break
+			}
+		}
+	}
+	return ret, nil
+}
+
+type ImageThing struct {
+	Repo        string
+	ID          string
+	Digest      string
+	Tag         string
+	CreateSince string
+	CreateAt    string
+	Size        string
+}