// Copyright 2018 Weald Technology Ltd
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package util

import (
	"crypto/ecdsa"
	"errors"
	"math/big"

	"github.com/ethereum/go-ethereum/accounts"
	"github.com/ethereum/go-ethereum/accounts/abi/bind"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/crypto"
)

// KeySigner generates a signer using a private key
func KeySigner(chainID *big.Int, key *ecdsa.PrivateKey) (signerfn bind.SignerFn) {
	signerfn = func(signer types.Signer, address common.Address, tx *types.Transaction) (*types.Transaction, error) {
		keyAddr := crypto.PubkeyToAddress(key.PublicKey)
		if address != keyAddr {
			return nil, errors.New("not authorized to sign this account")
		}
		return types.SignTx(tx, types.NewEIP155Signer(chainID), key)
	}

	return
}

// AccountSigner generates a signer using an account
func AccountSigner(chainID *big.Int, wallet *accounts.Wallet, account *accounts.Account, passphrase string) (signerfn bind.SignerFn) {
	signerfn = func(signer types.Signer, address common.Address, tx *types.Transaction) (*types.Transaction, error) {
		if address != account.Address {
			return nil, errors.New("not authorized to sign this account")
		}
		return (*wallet).SignTxWithPassphrase(*account, passphrase, tx, chainID)
	}
	return
}