// Copyright 2016 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 state

import (
	"fmt"
	"maps"
	"slices"
	"sort"
	"sync"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/crypto"
	"github.com/holiman/uint256"
)

type revision struct {
	id           int
	journalIndex int
}

// journalEntry is a modification entry in the state change journal that can be
// reverted on demand.
type journalEntry interface {
	// revert undoes the changes introduced by this journal entry.
	revert(*StateDB)

	// dirtied returns the Ethereum address modified by this journal entry.
	dirtied() *common.Address

	// copy returns a deep-copied journal entry.
	copy() journalEntry
}

// journal contains the list of state modifications applied since the last state
// commit. These are tracked to be able to be reverted in the case of an execution
// exception or request for reversal.
type journal struct {
	entries []journalEntry         // Current changes tracked by the journal
	dirties map[common.Address]int // Dirty accounts and the number of changes

	validRevisions []revision
	nextRevisionId int

	// Track storage entries separately for faster cleanup
	storageEntries []*storageChange
}

var storageChangePool = sync.Pool{
	New: func() interface{} {
		return &storageChange{}
	},
}

// newJournal creates a new initialized journal.
func newJournal() *journal {
	return &journal{
		dirties:        make(map[common.Address]int, defaultNumOfSlots),
		entries:        make([]journalEntry, 0, defaultNumOfSlots),
		storageEntries: make([]*storageChange, 0, defaultNumOfSlots),
	}
}

// reset clears the journal, after this operation the journal can be used anew.
// It is semantically similar to calling 'newJournal', but the underlying slices
// can be reused.
func (j *journal) reset() {
	// Return all storage entries to the pool
	for _, entry := range j.storageEntries {
		storageChangePool.Put(entry)
	}
	j.storageEntries = j.storageEntries[:0]
	j.entries = j.entries[:0]
	j.validRevisions = j.validRevisions[:0]
	clear(j.dirties)
	j.nextRevisionId = 0
}

// snapshot returns an identifier for the current revision of the state.
func (j *journal) snapshot() int {
	id := j.nextRevisionId
	j.nextRevisionId++
	j.validRevisions = append(j.validRevisions, revision{id, j.length()})
	return id
}

// revertToSnapshot reverts all state changes made since the given revision.
func (j *journal) revertToSnapshot(revid int, s *StateDB) {
	// Find the snapshot in the stack of valid snapshots.
	idx := sort.Search(len(j.validRevisions), func(i int) bool {
		return j.validRevisions[i].id >= revid
	})
	if idx == len(j.validRevisions) || j.validRevisions[idx].id != revid {
		panic(fmt.Errorf("revision id %v cannot be reverted", revid))
	}
	snapshot := j.validRevisions[idx].journalIndex

	// Replay the journal to undo changes and remove invalidated snapshots
	j.revert(s, snapshot)
	j.validRevisions = j.validRevisions[:idx]
}

// append inserts a new modification entry to the end of the change journal.
func (j *journal) append(entry journalEntry) {
	j.entries = append(j.entries, entry)
	if addr := entry.dirtied(); addr != nil {
		j.dirties[*addr]++
	}
	// Track storage entries separately
	if sc, ok := entry.(*storageChange); ok {
		j.storageEntries = append(j.storageEntries, sc)
	}
}

// revert undoes a batch of journalled modifications along with any reverted
// dirty handling too.
func (j *journal) revert(statedb *StateDB, snapshot int) {
	for i := len(j.entries) - 1; i >= snapshot; i-- {
		// Undo the changes made by the operation
		j.entries[i].revert(statedb)

		// Drop any dirty tracking induced by the change
		if addr := j.entries[i].dirtied(); addr != nil {
			if j.dirties[*addr]--; j.dirties[*addr] == 0 {
				delete(j.dirties, *addr)
			}
		}
	}
	j.entries = j.entries[:snapshot]
}

// dirty explicitly sets an address to dirty, even if the change entries would
// otherwise suggest it as clean. This method is an ugly hack to handle the RIPEMD
// precompile consensus exception.
func (j *journal) dirty(addr common.Address) {
	j.dirties[addr]++
}

// length returns the current number of entries in the journal.
func (j *journal) length() int {
	return len(j.entries)
}

// copy returns a deep-copied journal.
func (j *journal) copy() *journal {
	entries := make([]journalEntry, 0, j.length())
	for i := 0; i < j.length(); i++ {
		entries = append(entries, j.entries[i].copy())
	}

	return &journal{
		entries:        entries,
		dirties:        maps.Clone(j.dirties),
		validRevisions: slices.Clone(j.validRevisions),
		nextRevisionId: j.nextRevisionId,
		storageEntries: make([]*storageChange, 0, defaultNumOfSlots),
	}
}

func (j *journal) logChange(txHash common.Hash) {
	j.append(addLogChange{txhash: txHash})
}

func (j *journal) createObject(addr common.Address) {
	j.append(createObjectChange{account: addr})
}

func (j *journal) createContract(addr common.Address) {
	j.append(createContractChange{account: addr})
}

func (j *journal) destruct(addr common.Address) {
	j.append(selfDestructChange{account: addr})
}

func (j *journal) storageChange(addr common.Address, key, prev, origin common.Hash) {
	entry := storageChangePool.Get().(*storageChange)
	entry.account = addr
	entry.key = key
	entry.prevvalue = prev
	entry.origvalue = origin
	j.append(entry)
}

func (j *journal) transientStateChange(addr common.Address, key, prev common.Hash) {
	j.append(transientStorageChange{
		account:  addr,
		key:      key,
		prevalue: prev,
	})
}

func (j *journal) refundChange(previous uint64) {
	j.append(refundChange{prev: previous})
}

func (j *journal) balanceChange(addr common.Address, previous *uint256.Int) {
	j.append(balanceChange{
		account: addr,
		prev:    previous.Clone(),
	})
}

func (j *journal) setCode(address common.Address, prevCode []byte) {
	j.append(codeChange{
		account:  address,
		prevCode: prevCode,
	})
}

func (j *journal) nonceChange(address common.Address, prev uint64) {
	j.append(nonceChange{
		account: address,
		prev:    prev,
	})
}

func (j *journal) touchChange(address common.Address) {
	j.append(touchChange{
		account: address,
	})
	if address == ripemd {
		// Explicitly put it in the dirty-cache, which is otherwise generated from
		// flattened journals.
		j.dirty(address)
	}
}

func (j *journal) accessListAddAccount(addr common.Address) {
	j.append(accessListAddAccountChange{addr})
}

func (j *journal) accessListAddSlot(addr common.Address, slot common.Hash) {
	j.append(accessListAddSlotChange{
		address: addr,
		slot:    slot,
	})
}

type (
	// Changes to the account trie.
	createObjectChange struct {
		account common.Address
	}
	// createContractChange represents an account becoming a contract-account.
	// This event happens prior to executing initcode. The journal-event simply
	// manages the created-flag, in order to allow same-tx destruction.
	createContractChange struct {
		account common.Address
	}
	selfDestructChange struct {
		account common.Address
	}

	// Changes to individual accounts.
	balanceChange struct {
		account common.Address
		prev    *uint256.Int
	}
	nonceChange struct {
		account common.Address
		prev    uint64
	}
	storageChange struct {
		account   common.Address
		key       common.Hash
		prevvalue common.Hash
		origvalue common.Hash
	}
	codeChange struct {
		account  common.Address
		prevCode []byte
	}

	// Changes to other state values.
	refundChange struct {
		prev uint64
	}
	addLogChange struct {
		txhash common.Hash
	}
	touchChange struct {
		account common.Address
	}

	// Changes to the access list
	accessListAddAccountChange struct {
		address common.Address
	}
	accessListAddSlotChange struct {
		address common.Address
		slot    common.Hash
	}

	// Changes to transient storage
	transientStorageChange struct {
		account       common.Address
		key, prevalue common.Hash
	}
)

func (ch createObjectChange) revert(s *StateDB) {
	delete(s.stateObjects, ch.account)
}

func (ch createObjectChange) dirtied() *common.Address {
	return &ch.account
}

func (ch createObjectChange) copy() journalEntry {
	return createObjectChange{
		account: ch.account,
	}
}

func (ch createContractChange) revert(s *StateDB) {
	s.getStateObject(ch.account).newContract = false
}

func (ch createContractChange) dirtied() *common.Address {
	return nil
}

func (ch createContractChange) copy() journalEntry {
	return createContractChange{
		account: ch.account,
	}
}

func (ch selfDestructChange) revert(s *StateDB) {
	obj := s.getStateObject(ch.account)
	if obj != nil {
		obj.selfDestructed = false
	}
}

func (ch selfDestructChange) dirtied() *common.Address {
	return &ch.account
}

func (ch selfDestructChange) copy() journalEntry {
	return selfDestructChange{
		account: ch.account,
	}
}

var ripemd = common.HexToAddress("0000000000000000000000000000000000000003")

func (ch touchChange) revert(s *StateDB) {
}

func (ch touchChange) dirtied() *common.Address {
	return &ch.account
}

func (ch touchChange) copy() journalEntry {
	return touchChange{
		account: ch.account,
	}
}

func (ch balanceChange) revert(s *StateDB) {
	s.getStateObject(ch.account).setBalance(ch.prev)
}

func (ch balanceChange) dirtied() *common.Address {
	return &ch.account
}

func (ch balanceChange) copy() journalEntry {
	return balanceChange{
		account: ch.account,
		prev:    new(uint256.Int).Set(ch.prev),
	}
}

func (ch nonceChange) revert(s *StateDB) {
	s.getStateObject(ch.account).setNonce(ch.prev)
}

func (ch nonceChange) dirtied() *common.Address {
	return &ch.account
}

func (ch nonceChange) copy() journalEntry {
	return nonceChange{
		account: ch.account,
		prev:    ch.prev,
	}
}

func (ch codeChange) revert(s *StateDB) {
	s.getStateObject(ch.account).setCode(crypto.Keccak256Hash(ch.prevCode), ch.prevCode)
}

func (ch codeChange) dirtied() *common.Address {
	return &ch.account
}

func (ch codeChange) copy() journalEntry {
	return codeChange{
		account:  ch.account,
		prevCode: ch.prevCode,
	}
}

func (ch *storageChange) revert(s *StateDB) {
	s.getStateObject(ch.account).setState(ch.key, ch.prevvalue, ch.origvalue)
}

func (ch *storageChange) dirtied() *common.Address {
	return &ch.account
}

func (ch *storageChange) copy() journalEntry {
	cpy := storageChangePool.Get().(*storageChange)
	cpy.account = ch.account
	cpy.key = ch.key
	cpy.prevvalue = ch.prevvalue
	cpy.origvalue = ch.origvalue
	return cpy
}

func (ch transientStorageChange) revert(s *StateDB) {
	s.setTransientState(ch.account, ch.key, ch.prevalue)
}

func (ch transientStorageChange) dirtied() *common.Address {
	return nil
}

func (ch transientStorageChange) copy() journalEntry {
	return transientStorageChange{
		account:  ch.account,
		key:      ch.key,
		prevalue: ch.prevalue,
	}
}

func (ch refundChange) revert(s *StateDB) {
	s.refund = ch.prev
}

func (ch refundChange) dirtied() *common.Address {
	return nil
}

func (ch refundChange) copy() journalEntry {
	return refundChange{
		prev: ch.prev,
	}
}

func (ch addLogChange) revert(s *StateDB) {
	logs := s.logs[ch.txhash]
	if len(logs) == 1 {
		delete(s.logs, ch.txhash)
	} else {
		s.logs[ch.txhash] = logs[:len(logs)-1]
	}
	s.logSize--
}

func (ch addLogChange) dirtied() *common.Address {
	return nil
}

func (ch addLogChange) copy() journalEntry {
	return addLogChange{
		txhash: ch.txhash,
	}
}

func (ch accessListAddAccountChange) revert(s *StateDB) {
	/*
		One important invariant here, is that whenever a (addr, slot) is added, if the
		addr is not already present, the add causes two journal entries:
		- one for the address,
		- one for the (address,slot)
		Therefore, when unrolling the change, we can always blindly delete the
		(addr) at this point, since no storage adds can remain when come upon
		a single (addr) change.
	*/
	s.accessList.DeleteAddress(ch.address)
}

func (ch accessListAddAccountChange) dirtied() *common.Address {
	return nil
}

func (ch accessListAddAccountChange) copy() journalEntry {
	return accessListAddAccountChange{
		address: ch.address,
	}
}

func (ch accessListAddSlotChange) revert(s *StateDB) {
	s.accessList.DeleteSlot(ch.address, ch.slot)
}

func (ch accessListAddSlotChange) dirtied() *common.Address {
	return nil
}

func (ch accessListAddSlotChange) copy() journalEntry {
	return accessListAddSlotChange{
		address: ch.address,
		slot:    ch.slot,
	}
}
