Coding challenge: avatar me

src/main.go

@@ -0,0 +1,92 @@
+package main
+
+import (
+	"crypto/sha1"
+	"flag"
+	"fmt"
+	"image"
+	"image/color/palette"
+	"image/draw"
+	"image/png"
+	"log"
+	"os"
+)
+
+const hashLength = 40
+
+func getHash(s string) string {
+	return fmt.Sprintf("%x", sha1.Sum([]byte(s)))
+}
+
+func switchIndexDirection() func() int {
+	idx := 0
+	currentSign := "+"
+	positiveSign := "+"
+	negativeSign := "-"
+
+	return func() int {
+		if idx == 0 {
+			currentSign = positiveSign
+		} else if idx == hashLength-1 {
+			currentSign = negativeSign
+		}
+		if currentSign == positiveSign {
+			idx++
+			return idx
+		}
+		idx--
+		return idx
+	}
+}
+
+func generateImage(s string, size, sideBlocks int) *image.RGBA {
+	scale := size / sideBlocks
+	img := image.NewRGBA(image.Rect(0, 0, sideBlocks*scale, sideBlocks*scale))
+
+	idx := switchIndexDirection()
+	for x := 0; x < sideBlocks; x++ {
+		for y := 0; y < sideBlocks; y++ {
+			col := palette.Plan9[s[idx()]]
+			startPoint := image.Point{x * scale, y * scale}
+			endPoint := image.Point{x*scale + scale, y*scale + scale}
+			rectangle := image.Rectangle{startPoint, endPoint}
+			draw.Draw(img, rectangle, &image.Uniform{col}, image.Point{}, draw.Src)
+		}
+	}
+
+	return img
+}
+
+func saveImage(img *image.RGBA, filename string) {
+
+	f, err := os.Create(fmt.Sprintf("%s.png", filename))
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	if err := png.Encode(f, img); err != nil {
+		f.Close()
+		log.Fatal(err)
+	}
+
+	if err := f.Close(); err != nil {
+		log.Fatal(err)
+	}
+
+}
+
+// Run it as: go run ./main.go -input=Awesome -size 256 -output image -blocks 8
+func main() {
+	inputString := flag.String("input", "Cool", "value to be hashed and generate identicon with")
+	outputFile := flag.String("output", "image", "image file name")
+	imageSize := flag.Int("size", 256, "image size")
+	blocks := flag.Int("blocks", 8, "number of side blocks")
+
+	flag.Parse()
+
+	hash := getHash(*inputString)
+	fmt.Println(hash)
+
+	img := generateImage(hash, *imageSize, *blocks)
+	saveImage(img, *outputFile)
+}