feat(mnemonic): js doesnt handle List and swift doesnt handle Array t…

…his is the solution

base-asymmetric-encryption/src/commonMain/kotlin/io/iohk/atala/prism/apollo/derivation/MnemonicCode.kt

@@ -1,21 +1,51 @@
 package io.iohk.atala.prism.apollo.derivation
 
-import kotlin.js.ExperimentalJsExport
-import kotlin.js.JsExport
+import io.iohk.atala.prism.apollo.hashing.SHA256
 
 /**
  * A model representing the Mnemonic Code
  *
  * @exception MnemonicLengthException in case it is not 24 words
  */
-@OptIn(ExperimentalJsExport::class)
-@JsExport
-data class MnemonicCode
-@Throws(MnemonicLengthException::class)
-constructor(val words: List<String>) {
-    init {
-        if (words.size % 3 != 0) {
-            throw MnemonicLengthException("Can't create a DID from mnemonic that is not dividable by 3")
+
+data class MnemonicCode constructor(val words: List<String>) {
+    fun toMnemonic(entropy: ByteArray): List<String> {
+        if (entropy.size % 4 > 0) {
+            throw Exception("Entropy length not multiple of 32 bits.")
+        }
+        if (entropy.isEmpty()) {
+            throw Exception("Entropy is empty.")
+        }
+
+        val sha = SHA256()
+        sha.update(entropy)
+        val hash = sha.digest()
+        val checksumLengthBits = entropy.size / 4
+        val checksum = hash[0].toInt() ushr (8 - checksumLengthBits)
+
+        val concatBits = BooleanArray(entropy.size * 8 + checksumLengthBits)
+        for (i in entropy.indices) {
+            for (j in 0 until 8) {
+                concatBits[i * 8 + j] = entropy[i].toInt() and (1 shl (7 - j)) != 0
+            }
         }
+        for (i in 0 until checksumLengthBits) {
+            concatBits[entropy.size * 8 + i] = checksum and (1 shl (checksumLengthBits - i - 1)) != 0
+        }
+
+        val words = ArrayList<String>()
+        val nwords = concatBits.size / 11
+        for (i in 0 until nwords) {
+            var index = 0
+            for (j in 0 until 11) {
+                index = index shl 1
+                if (concatBits[i * 11 + j]) {
+                    index = index or 0x1
+                }
+            }
+            words.add(this.words[index]) // Assuming wordList is a list of words according to BIP-39
+        }
+
+        return words
     }
 }