address.go

// Copyright 2018 The uranus Authors
// This file is part of the uranus library.
//
// The uranus library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The uranus library 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 Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the uranus library. If not, see <http://www.gnu.org/licenses/>.

package utils

import (
	"bytes"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"math/big"
	"reflect"
	"strings"

	"golang.org/x/crypto/sha3"
)

const (
	addrPrefix  = "0x"
	addressSize = 20
)

// EmptyAddress presents an empty address
var EmptyAddress = Address{}

var addressT = reflect.TypeOf(Address{})

// Address represents the 20 byte address of an  account.
type Address [addressSize]byte

// BigToAddress returns Address with byte values of b.
func BigToAddress(b *big.Int) Address { return BytesToAddress(b.Bytes()) }

// HexToAddress returns Address with byte values of s.
func HexToAddress(s string) Address { return BytesToAddress(FromHex(s)) }

// BytesToAddress returns Address with value b.
func BytesToAddress(b []byte) Address {
	var a Address
	a.SetBytes(b)
	return a
}

// IsHexAddr verifies whether a string can represent a valid hex-encoded address or not.
func IsHexAddr(s string) bool {
	if hasHexPrefix(s) {
		s = s[2:]
	}
	return len(s) == 2*addressSize && isHex(s)
}

// Bytes gets the string representation of the underlying address.
func (a Address) Bytes() []byte { return a[:] }

// Big converts an address to a big integer.
func (a Address) Big() *big.Int { return new(big.Int).SetBytes(a[:]) }

// Hash converts an address to a hash by left-padding it with zeros.
func (a Address) Hash() Hash { return BytesToHash(a[:]) }

// Hex returns an EIP55-compliant hex string representation of the address.
func (a Address) Hex() string {
	unchecksummed := hex.EncodeToString(a[:])
	sha := sha3.NewLegacyKeccak256()
	sha.Write([]byte(unchecksummed))
	hash := sha.Sum(nil)
	result := []byte(unchecksummed)
	for i := 0; i < len(result); i++ {
		hashByte := hash[i/2]
		if i%2 == 0 {
			hashByte = hashByte >> 4
		} else {
			hashByte &= 0xf
		}
		if result[i] > '9' && hashByte > 7 {
			result[i] -= 32
		}
	}
	return addrPrefix + string(result)
}

// String implements fmt.Stringer.
func (a Address) String() string {
	return a.Hex()
}

// SetBytes sets the address to the value of b.
func (a *Address) SetBytes(b []byte) {
	if len(b) > len(a) {
		b = b[len(b)-addressSize:]
	}
	copy(a[addressSize-len(b):], b)
}

// MarshalText returns the hex representation of a.
func (a Address) MarshalText() ([]byte, error) {
	return Bytes(a[:]).MarshalText()
}

// UnmarshalText parses a hash in hex syntax.
func (a *Address) UnmarshalText(input []byte) error {
	return UnmarshalFixedText("Address", input, a[:])
}

// UnmarshalJSON parses a hash in hex syntax.
func (a *Address) UnmarshalJSON(input []byte) error {
	return UnmarshalFixedJSON(addressT, input, a[:])
}

// Equal checks if this address is the same with the specified address b.
func (a *Address) Equal(b Address) bool {
	return bytes.Equal(a[:], b[:])
}

// IsEmpty returns true if this address is empty. Otherwise, false.
func (a *Address) IsEmpty() bool {
	return a.Equal(EmptyAddress)
}

// NoprefixedAddress allows marshaling an Address without 0x prefix.
type NoprefixedAddress Address

// UnmarshalText decodes the address from hex. The 0x prefix is optional.
func (a *NoprefixedAddress) UnmarshalText(input []byte) error {
	return UnmarshalFixedUnprefixedText("NoprefixedAddress", input, a[:])
}

// MarshalText encodes the address as hex.
func (a NoprefixedAddress) MarshalText() ([]byte, error) {
	return []byte(hex.EncodeToString(a[:])), nil
}

// MixedcaseAddress retains the original string, which may or may not becorrectly checksummed.
type MixedcaseAddress struct {
	addr     Address
	original string
}

// NewMixedcaseAddress constructor (mainly for testing)
func NewMixedcaseAddress(addr Address) MixedcaseAddress {
	return MixedcaseAddress{addr: addr, original: addr.Hex()}
}

// NewMixedcaseAddressFromString is mainly meant for unit-testing
func NewMixedcaseAddressFromString(hexaddr string) (*MixedcaseAddress, error) {
	if !IsHexAddr(hexaddr) {
		return nil, fmt.Errorf("Invalid address")
	}
	a := FromHex(hexaddr)
	return &MixedcaseAddress{addr: BytesToAddress(a), original: hexaddr}, nil
}

// UnmarshalJSON parses MixedcaseAddress
func (ma *MixedcaseAddress) UnmarshalJSON(input []byte) error {
	if err := UnmarshalFixedJSON(addressT, input, ma.addr[:]); err != nil {
		return err
	}
	return json.Unmarshal(input, &ma.original)
}

// MarshalJSON marshals the original value
func (ma *MixedcaseAddress) MarshalJSON() ([]byte, error) {
	if strings.HasPrefix(ma.original, addrPrefix) || strings.HasPrefix(ma.original, strings.ToUpper(addrPrefix)) {
		return json.Marshal(fmt.Sprintf("0x%s", ma.original[2:]))
	}
	return json.Marshal(fmt.Sprintf("0x%s", ma.original))
}

// Address returns the address
func (ma *MixedcaseAddress) Address() Address {
	return ma.addr
}

// String implements fmt.Stringer
func (ma *MixedcaseAddress) String() string {
	if ma.ValidChecksum() {
		return fmt.Sprintf("%s [chksum ok]", ma.original)
	}
	return fmt.Sprintf("%s [chksum INVALID]", ma.original)
}

// ValidChecksum returns true if the address has valid checksum
func (ma *MixedcaseAddress) ValidChecksum() bool {
	return ma.original == ma.addr.Hex()
}

// Original returns the mixed-case input string
func (ma *MixedcaseAddress) Original() string {
	return ma.original
}