initial commit

3 files changed, 88 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..8b9c5c3
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+hashimg
+out.png
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..6291d63
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module github.com/benburwell/hashimg
+
+go 1.12
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..28a859d
--- /dev/null
+++ b/main.go
@@ -0,0 +1,83 @@
+package main
+
+import (
+	"bytes"
+	"crypto/sha256"
+	"encoding/base64"
+	"flag"
+	"fmt"
+	"image"
+	"image/color"
+	"image/png"
+	"regexp"
+	"strings"
+)
+
+var usernamePattern = regexp.MustCompile("[a-zA-Z][a-zA-Z0-9]+")
+
+func main() {
+	username := flag.String("username", "", "username to encode as image")
+	flag.Parse()
+	if strings.TrimSpace(*username) == "" {
+		fmt.Println("no username")
+		return
+	}
+	if !usernamePattern.MatchString(*username) {
+		fmt.Println("no match")
+		return
+	}
+
+	seed := hash(*username)
+	err, img := generateImage(seed)
+	if err != nil {
+		fmt.Printf("%v\n", err)
+		return
+	}
+	err, str := encodeImage(img)
+	if err != nil {
+		fmt.Printf("%v\n", err)
+		return
+	}
+	fmt.Println(str)
+}
+
+func hash(username string) [32]byte {
+	return sha256.Sum256([]byte(username))
+}
+
+func generateImage(hash [32]byte) (error, image.Image) {
+	img := image.NewNRGBA(image.Rect(0, 0, 5, 5))
+	colorA := color.NRGBA{
+		R: hash[0],
+		G: hash[1],
+		B: hash[2],
+		A: 255,
+	}
+	colorB := color.NRGBA{
+		R: hash[3],
+		G: hash[4],
+		B: hash[5],
+		A: 255,
+	}
+	offset := 6
+	for x := 0; x < 5; x++ {
+		for y := 0; y < 5; y++ {
+			on := hash[offset]&0xf0 > 0
+			color := colorA
+			if on {
+				color = colorB
+			}
+			img.Set(x, y, color)
+			offset++
+		}
+	}
+	return nil, img
+}
+
+func encodeImage(img image.Image) (error, string) {
+	var b bytes.Buffer
+	if err := png.Encode(&b, img); err != nil {
+		return err, ""
+	}
+	return nil, base64.StdEncoding.EncodeToString(b.Bytes())
+}