add lagrange interpolation js to wasm wrapper and parser of the data struct

shamirsecretsharing.go

@@ -73,7 +73,7 @@ func unpackSharesAndI(sharesPacked [][]*big.Int) ([]*big.Int, []*big.Int) {
 }
 
 // LagrangeInterpolation calculates the secret from given shares
-func LagrangeInterpolation(sharesGiven [][]*big.Int, p *big.Int) *big.Int {
+func LagrangeInterpolation(p *big.Int, sharesGiven [][]*big.Int) *big.Int {
 	resultN := big.NewInt(int64(0))
 	resultD := big.NewInt(int64(0))
 

shamirsecretsharing_test.go

@@ -30,7 +30,7 @@ func TestCreate(t *testing.T) {
 	sharesToUse = append(sharesToUse, shares[2])
 	sharesToUse = append(sharesToUse, shares[1])
 	sharesToUse = append(sharesToUse, shares[0])
-	secr := LagrangeInterpolation(sharesToUse, p)
+	secr := LagrangeInterpolation(p, sharesToUse)
 
 	// fmt.Print("original secret: ")
 	// fmt.Println(k)

wasm/shamirsecretsharing-wasm-wrapper.go

@@ -43,7 +43,42 @@ func createShares(i []js.Value) {
 		println("error generating the shares")
 	}
 	println(shares)
+	sharesStr := sharesToString(shares)
+	println(sharesStr)
+}
+
+func sharesToString(shares [][]*big.Int) []string {
+	var s []string
+	for i := 0; i < len(shares); i++ {
+		s = append(s, shares[i][0].String())
+		s = append(s, shares[i][1].String())
+	}
+	return s
 }
 
 func lagrangeInterpolation(i []js.Value) {
+	p, ok := new(big.Int).SetString(i[0].String(), 10)
+	if !ok {
+		println("error parsing parameter in position 0 (p)")
+	}
+
+	// parse the shares array
+	var shares [][]*big.Int
+	for n := 1; n < len(i); n = n + 2 {
+		a, ok := new(big.Int).SetString(i[n].String(), 10)
+		if !ok {
+			println("error parsing parameter in position ", n)
+		}
+		b, ok := new(big.Int).SetString(i[n+1].String(), 10)
+		if !ok {
+			println("error parsing parameter in position ", n+1)
+		}
+		var share []*big.Int
+		share = append(share, a)
+		share = append(share, b)
+		shares = append(shares, share)
+	}
+
+	secr := shamirsecretsharing.LagrangeInterpolation(p, shares)
+	println(secr.String())
 }