From d0219b3a33a485350e71fec886488604e3a053ad Mon Sep 17 00:00:00 2001
From: arnaucube <root@arnaucube.com>
Date: Sun, 29 Mar 2020 00:42:52 +0100
Subject: [PATCH] Add bn256.G1 parser

---
 parsers.go | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 parsers.go

diff --git a/parsers.go b/parsers.go
new file mode 100644
index 0000000..8b37cee
--- /dev/null
+++ b/parsers.go
@@ -0,0 +1,68 @@
+package gocircomprover
+
+import (
+	"encoding/hex"
+	"fmt"
+	"math/big"
+	"strings"
+
+	bn256 "github.com/ethereum/go-ethereum/crypto/bn256/cloudflare"
+)
+
+func stringToG1(h []string) (*bn256.G1, error) {
+	if len(h) <= 2 {
+		return nil, fmt.Errorf("not enought data for stringToG1")
+	}
+	h = h[:2]
+	hexa := false
+	if len(h[0]) > 1 {
+		if "0x" == h[0][:2] {
+			hexa = true
+		}
+	}
+	in := ""
+
+	var b []byte
+	var err error
+	if hexa {
+		for i := range h {
+			in += strings.TrimPrefix(h[i], "0x")
+		}
+		b, err = hex.DecodeString(in)
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		// TODO TMP
+		// TODO use stringToBytes()
+		if h[0] == "1" {
+			h[0] = "0"
+		}
+		if h[1] == "1" {
+			h[1] = "0"
+		}
+		bi0, ok := new(big.Int).SetString(h[0], 10)
+		if !ok {
+			return nil, fmt.Errorf("error parsing stringToG1")
+		}
+		bi1, ok := new(big.Int).SetString(h[1], 10)
+		if !ok {
+			return nil, fmt.Errorf("error parsing stringToG1")
+		}
+		b0 := bi0.Bytes()
+		b1 := bi1.Bytes()
+		if len(b0) != 32 {
+			b0 = addZPadding(b0)
+		}
+		if len(b1) != 32 {
+			b1 = addZPadding(b1)
+		}
+
+		b = append(b, b0...)
+		b = append(b, b1...)
+	}
+	p := new(bn256.G1)
+	_, err = p.Unmarshal(b)
+
+	return p, err
+}