1 files changed, 149 insertions, 0 deletions
diff --git a/shared/src/main/scala/Identicon.scala b/shared/src/main/scala/Identicon.scala
new file mode 100644
index 0000000..0242d92
--- /dev/null
+++ b/shared/src/main/scala/Identicon.scala
@@ -0,0 +1,149 @@
+package identicon
+
+import java.lang.Math
+import java.util.Base64
+
+trait Identicon {
+
+  private def lrot(x: Int, c: Int) = (x << c) | (x >>> (32 - c))
+
+  // NB: this implementation has a bug and does NOT correspond to the actual MD5
+  // specification. It does however produce a hash that appears to be good
+  // enough for generating identicons.
+  private def md5(in: IndexedSeq[Byte]): Array[Byte] = {
+    var s = Array[Int](
+      7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, 5, 9, 14, 20,
+      5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20, 4, 11, 16, 23, 4, 11, 16, 23, 4,
+      11, 16, 23, 4, 11, 16, 23, 6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21, 6,
+      10, 15, 21
+    )
+    var K = Array[Int](
+      0xd76aa478, 0xe8c7b756, 0x242070db, 0xc1bdceee, 0xf57c0faf, 0x4787c62a,
+      0xa8304613, 0xfd469501, 0x698098d8, 0x8b44f7af, 0xffff5bb1, 0x895cd7be,
+      0x6b901122, 0xfd987193, 0xa679438e, 0x49b40821, 0xf61e2562, 0xc040b340,
+      0x265e5a51, 0xe9b6c7aa, 0xd62f105d, 0x02441453, 0xd8a1e681, 0xe7d3fbc8,
+      0x21e1cde6, 0xc33707d6, 0xf4d50d87, 0x455a14ed, 0xa9e3e905, 0xfcefa3f8,
+      0x676f02d9, 0x8d2a4c8a, 0xfffa3942, 0x8771f681, 0x6d9d6122, 0xfde5380c,
+      0xa4beea44, 0x4bdecfa9, 0xf6bb4b60, 0xbebfbc70, 0x289b7ec6, 0xeaa127fa,
+      0xd4ef3085, 0x04881d05, 0xd9d4d039, 0xe6db99e5, 0x1fa27cf8, 0xc4ac5665,
+      0xf4292244, 0x432aff97, 0xab9423a7, 0xfc93a039, 0x655b59c3, 0x8f0ccc92,
+      0xffeff47d, 0x85845dd1, 0x6fa87e4f, 0xfe2ce6e0, 0xa3014314, 0x4e0811a1,
+      0xf7537e82, 0xbd3af235, 0x2ad7d2bb, 0xeb86d391
+    )
+
+    var a0 = 0x67452301
+    var b0 = 0xefcdab89
+    var c0 = 0x98badcfe
+    var d0 = 0x10325476
+
+    // 1 = extra "0b1000000" byte
+    val zeroBytes = Math.floorMod(61 - (in.size + 1), 64)
+    val data = new Array[Byte](in.size + 1 + zeroBytes + 4) // 4 = length
+    for ((byte, i) <- in.zipWithIndex) {
+      data(i) = byte
+    }
+    data(in.size) = (1 << 7).toByte
+    data(in.size + 1 + zeroBytes) = ((in.size >>> 24) & 0xff).toByte
+    data(in.size + 1 + zeroBytes + 1) = ((in.size >>> 16) & 0xff).toByte
+    data(in.size + 1 + zeroBytes + 2) = ((in.size >>> 8) & 0xff).toByte
+    data(in.size + 1 + zeroBytes + 3) = ((in.size) & 0xff).toByte
+
+    for (chunk <- 0 until data.size / 64) {
+      val M = for (i <- 0 until 16) yield {
+        (data(chunk * 64 + i * 4) << 24) |
+          (data(chunk * 64 + i * 4 + 1) << 16) |
+          (data(chunk * 64 + i * 4 + 2) << 8) |
+          data(chunk * 64 + i * 4 + 3)
+      }
+
+      var A = a0
+      var B = b0
+      var C = c0
+      var D = d0
+
+      for (i <- 0 until 64) {
+        var F = 0
+        var g = 0
+        if (0 <= i && i <= 15) {
+          F = (B & C) | ((~B) & D)
+          g = i
+        } else if (16 <= i && i <= 31) {
+          F = (D & B) | ((~D) & C)
+          g = (5 * i + 1) % 16
+        } else if (32 <= i && i <= 47) {
+          F = B ^ C ^ D
+          g = (3 * i + 5) % 16
+        } else if (48 <= i && i <= 63) {
+          F = C ^ (B | (~D))
+          g = (7 * i) % 16
+        }
+        F = F + A + K(i) + M(g)
+        A = D
+        D = C
+        C = B
+        B = B + lrot(F, s(i))
+      }
+      a0 = a0 + A
+      b0 = b0 + B
+      c0 = c0 + C
+      d0 = d0 + D
+    }
+
+    val digest = new Array[Byte](16)
+    digest(0) = ((a0 >>> 24) & 0xff).toByte
+    digest(1) = ((a0 >>> 16) & 0xff).toByte
+    digest(2) = ((a0 >>> 8) & 0xff).toByte
+    digest(3) = ((a0 & 0xff)).toByte
+    digest(4) = ((b0 >>> 24) & 0xff).toByte
+    digest(5) = ((b0 >>> 16) & 0xff).toByte
+    digest(6) = ((b0 >>> 8) & 0xff).toByte
+    digest(7) = ((b0 & 0xff)).toByte
+    digest(8) = ((c0 >>> 24) & 0xff).toByte
+    digest(9) = ((c0 >>> 16) & 0xff).toByte
+    digest(10) = ((c0 >>> 8) & 0xff).toByte
+    digest(11) = ((c0 & 0xff)).toByte
+    digest(12) = ((d0 >>> 24) & 0xff).toByte
+    digest(13) = ((d0 >>> 16) & 0xff).toByte
+    digest(14) = ((d0 >>> 8) & 0xff).toByte
+    digest(15) = ((d0 & 0xff)).toByte
+    digest
+  }
+
+  def svg(name: String): String = {
+    val hash = md5(name.getBytes("UTF-8"))
+    val builder = new StringBuilder
+    val color = {
+      val r = hash(0) & 0xff
+      val g = hash(1) & 0xff
+      val b = hash(2) & 0xff
+      f"#$r%02x$g%02x$b%02x"
+    }
+    val style = s"fill:$color;stroke:$color;stroke-width:0.05"
+    builder ++= s"""<svg xmlns="http://www.w3.org/2000/svg" width="5" height="5">"""
+    for (x <- 0 until 2) {
+      for (y <- 0 until 5) {
+        if (((hash(x) >>> y) & 0x01) != 0) {
+          builder ++= s"""<rect x="$x" y="$y" width="1" height="1" style="$style"/>"""
+          builder ++= s"""<rect x="${4 - x}" y="$y" width="1" height="1" style="$style"/>"""
+        }
+      }
+    }
+    for (y <- 0 until 5) {
+      if (((hash(2) >>> y) & 0x01) != 0) {
+        builder ++= s"""<rect x="2" y="$y" width="1" height="1" style="$style"/>"""
+      }
+    }
+    builder ++= "</svg>"
+    builder.result()
+  }
+
+  def url(name: String): String = {
+    val b64 = Base64.getEncoder().encodeToString(svg(name).getBytes("UTF-8"))
+    s"data:image/svg+xml;base64,$b64"
+  }
+
+  // def url(name: String): String = {
+  //   s"data:image/svg+xml;utf8,${svg(name)}"
+  // }
+
+}