// Copyright 2023 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum 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 go-ethereum 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 go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

// Package utesting provides a standalone replacement for package testing.
//
// This package exists because package testing cannot easily be embedded into a
// standalone go program. It provides an API that mirrors the standard library
// testing API.

package blocktest

import (
	"bytes"
	"hash"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/crypto/keccak"
)

// testHasher is the helper tool for transaction/receipt list hashing.
// The original hasher is trie, in order to get rid of import cycle,
// use the testing hasher instead.
type testHasher struct {
	hasher hash.Hash
}

// NewHasher returns a new testHasher instance.
func NewHasher() *testHasher {
	return &testHasher{hasher: keccak.NewLegacyKeccak256()}
}

// Reset resets the hash state.
func (h *testHasher) Reset() {
	h.hasher.Reset()
}

// Update updates the hash state with the given key and value.
func (h *testHasher) Update(key, val []byte) error {
	h.hasher.Write(bytes.Clone(key))
	h.hasher.Write(bytes.Clone(val))
	return nil
}

// Hash returns the hash value.
func (h *testHasher) Hash() common.Hash {
	return common.BytesToHash(h.hasher.Sum(nil))
}
