Add custom implementation for graphql scalar BigInt

pkg/graphql/types.go

@@ -0,0 +1,94 @@
+// VulcanizeDB
+// Copyright © 2022 Vulcanize
+
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package graphql
+
+import (
+	"fmt"
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/common/hexutil"
+)
+
+type BigInt big.Int
+
+// ToInt converts b to a big.Int.
+func (b *BigInt) ToInt() *big.Int {
+	return (*big.Int)(b)
+}
+
+// String returns value of b as a decimal string.
+func (b *BigInt) String() string {
+	return b.ToInt().String()
+}
+
+// SetUint64 sets b to x and returns x.
+func (b *BigInt) SetUint64(x uint64) *BigInt {
+	var val big.Int
+	val.SetUint64(x)
+	*b = (BigInt)(val)
+	return b
+}
+
+// MarshalText implements encoding.TextMarshaler
+func (b BigInt) MarshalText() ([]byte, error) {
+	return []byte(b.String()), nil
+}
+
+// UnmarshalText implements encoding.TextUnmarshaler
+func (b *BigInt) UnmarshalText(input []byte) error {
+	raw, err := checkNumberText(input)
+	if err != nil {
+		return err
+	}
+	if len(raw) > 64 {
+		return hexutil.ErrBig256Range
+	}
+
+	var val big.Int
+	val.SetString(string(input[:]), 10)
+	*b = (BigInt)(val)
+	return nil
+}
+
+// ImplementsGraphQLType returns true if BigInt implements the provided GraphQL type.
+func (b BigInt) ImplementsGraphQLType(name string) bool { return name == "BigInt" }
+
+// UnmarshalGraphQL unmarshals the provided GraphQL query data.
+func (b *BigInt) UnmarshalGraphQL(input interface{}) error {
+	var err error
+	switch input := input.(type) {
+	case string:
+		return b.UnmarshalText([]byte(input))
+	case int32:
+		var num big.Int
+		num.SetInt64(int64(input))
+		*b = BigInt(num)
+	default:
+		err = fmt.Errorf("unexpected type %T for BigInt", input)
+	}
+	return err
+}
+
+func checkNumberText(input []byte) (raw []byte, err error) {
+	if len(input) == 0 {
+		return nil, nil // empty strings are allowed
+	}
+	if len(input) > 1 && input[0] == '0' {
+		return nil, hexutil.ErrLeadingZero
+	}
+	return input, nil
+}