package state

import (
	"bytes"
	"fmt"
	"time"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/crypto"
	"github.com/ethereum/go-ethereum/metrics"
	"github.com/ethereum/go-ethereum/rlp"
	"github.com/holiman/uint256"
)

type Code []byte

func (c Code) String() string {
	return string(c) //strings.Join(Disassemble(c), " ")
}

type Storage map[common.Hash]common.Hash

func (s Storage) String() (str string) {
	for key, value := range s {
		str += fmt.Sprintf("%X : %X\n", key, value)
	}

	return
}

func (s Storage) Copy() Storage {
	cpy := make(Storage, len(s))
	for key, value := range s {
		cpy[key] = value
	}

	return cpy
}

// stateObject represents an Ethereum account which is being modified.
//
// The usage pattern is as follows:
// First you need to obtain a state object.
// Account values can be accessed and modified through the object.
type stateObject struct {
	db        *StateDB
	address   common.Address
	addrHash  common.Hash         // hash of ethereum address of the account
	blockHash common.Hash         // hash of the block this state object exists at or is being applied on top of
	origin    *types.StateAccount // Account original data without any change applied, nil means it was not existent
	data      types.StateAccount

	// Write caches.
	code Code // contract bytecode, which gets set when code is loaded

	originStorage  Storage // Storage cache of original entries to dedup rewrites
	pendingStorage Storage // Storage entries that need to be flushed to disk, at the end of an entire block
	dirtyStorage   Storage // Storage entries that have been modified in the current transaction execution, reset for every transaction

	// Cache flags.
	dirtyCode bool // true if the code was updated

	// Flag whether the account was marked as self-destructed. The self-destructed account
	// is still accessible in the scope of same transaction.
	selfDestructed bool

	// Flag whether the account was marked as deleted. A self-destructed account
	// or an account that is considered as empty will be marked as deleted at
	// the end of transaction and no longer accessible anymore.
	deleted bool

	// Flag whether the object was created in the current transaction
	created bool
}

// empty returns whether the account is considered empty.
func (s *stateObject) empty() bool {
	return s.data.Nonce == 0 && s.data.Balance.IsZero() && bytes.Equal(s.data.CodeHash, types.EmptyCodeHash.Bytes())
}

// newObject creates a state object.
func newObject(db *StateDB, address common.Address, acct *types.StateAccount, blockHash common.Hash) *stateObject {
	var (
		origin  = acct
		created = acct == nil // true if the account was not existent
	)
	if acct == nil {
		acct = types.NewEmptyStateAccount()
	}
	return &stateObject{
		db:             db,
		address:        address,
		addrHash:       crypto.Keccak256Hash(address[:]),
		blockHash:      blockHash,
		origin:         origin,
		data:           *acct,
		originStorage:  make(Storage),
		pendingStorage: make(Storage),
		dirtyStorage:   make(Storage),
		created:        created,
	}
}

func (s *stateObject) markSelfdestructed() {
	s.selfDestructed = true
}

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

// GetState retrieves a value from the account storage trie.
func (s *stateObject) GetState(key common.Hash) common.Hash {
	// If we have a dirty value for this state entry, return it
	value, dirty := s.dirtyStorage[key]
	if dirty {
		return value
	}
	// Otherwise return the entry's original value
	return s.GetCommittedState(key)
}

// GetCommittedState retrieves a value from the committed account storage trie.
func (s *stateObject) GetCommittedState(key common.Hash) common.Hash {
	// If we have a pending write or clean cached, return that
	if value, pending := s.pendingStorage[key]; pending {
		return value
	}
	// If we have a pending write or clean cached, return that
	if value, cached := s.originStorage[key]; cached {
		return value
	}
	// If the object was destructed in *this* block (and potentially resurrected),
	// the storage has been cleared out, and we should *not* consult the previous
	// database about any storage values. The only possible alternatives are:
	//   1) resurrect happened, and new slot values were set -- those should
	//      have been handles via pendingStorage above.
	//   2) we don't have new values, and can deliver empty response back
	if _, destructed := s.db.stateObjectsDestruct[s.address]; destructed {
		return common.Hash{}
	}
	// If no live objects are available, load from database
	start := time.Now()
	keyHash := crypto.Keccak256Hash(key[:])
	enc, err := s.db.db.StorageValue(s.addrHash, keyHash, s.blockHash)
	if metrics.EnabledExpensive {
		s.db.StorageReads += time.Since(start)
	}
	if err != nil {
		s.db.setError(err)
		return common.Hash{}
	}
	var value common.Hash
	if len(enc) > 0 {
		_, content, _, err := rlp.Split(enc)
		if err != nil {
			s.db.setError(err)
		}
		value.SetBytes(content)
	}
	s.originStorage[key] = value
	return value
}

// SetState updates a value in account storage.
func (s *stateObject) SetState(key, value common.Hash) {
	// If the new value is the same as old, don't set
	prev := s.GetState(key)
	if prev == value {
		return
	}
	// New value is different, update and journal the change
	s.db.journal.append(storageChange{
		account:  &s.address,
		key:      key,
		prevalue: prev,
	})
	s.setState(key, value)
}

func (s *stateObject) setState(key, value common.Hash) {
	s.dirtyStorage[key] = value
}

// finalise moves all dirty storage slots into the pending area to be hashed or
// committed later. It is invoked at the end of every transaction.
func (s *stateObject) finalise(prefetch bool) {
	slotsToPrefetch := make([][]byte, 0, len(s.dirtyStorage))
	for key, value := range s.dirtyStorage {
		s.pendingStorage[key] = value
		if value != s.originStorage[key] {
			slotsToPrefetch = append(slotsToPrefetch, common.CopyBytes(key[:])) // Copy needed for closure
		}
	}
	if len(s.dirtyStorage) > 0 {
		s.dirtyStorage = make(Storage)
	}
}

// AddBalance adds amount to s's balance.
// It is used to add funds to the destination account of a transfer.
func (s *stateObject) AddBalance(amount *uint256.Int) {
	// EIP161: We must check emptiness for the objects such that the account
	// clearing (0,0,0 objects) can take effect.
	if amount.IsZero() {
		if s.empty() {
			s.touch()
		}
		return
	}
	s.SetBalance(new(uint256.Int).Add(s.Balance(), amount))
}

// SubBalance removes amount from s's balance.
// It is used to remove funds from the origin account of a transfer.
func (s *stateObject) SubBalance(amount *uint256.Int) {
	if amount.IsZero() {
		return
	}
	s.SetBalance(new(uint256.Int).Sub(s.Balance(), amount))
}

func (s *stateObject) SetBalance(amount *uint256.Int) {
	s.db.journal.append(balanceChange{
		account: &s.address,
		prev:    new(uint256.Int).Set(s.data.Balance),
	})
	s.setBalance(amount)
}

func (s *stateObject) setBalance(amount *uint256.Int) {
	s.data.Balance = amount
}

func (s *stateObject) deepCopy(db *StateDB) *stateObject {
	obj := &stateObject{
		db:       db,
		address:  s.address,
		addrHash: s.addrHash,
		origin:   s.origin,
		data:     s.data,
	}
	obj.code = s.code
	obj.dirtyStorage = s.dirtyStorage.Copy()
	obj.originStorage = s.originStorage.Copy()
	obj.pendingStorage = s.pendingStorage.Copy()
	obj.selfDestructed = s.selfDestructed
	obj.dirtyCode = s.dirtyCode
	obj.deleted = s.deleted
	return obj
}

//
// Attribute accessors
//

// Address returns the address of the contract/account
func (s *stateObject) Address() common.Address {
	return s.address
}

// Code returns the contract code associated with this object, if any.
func (s *stateObject) Code() []byte {
	if s.code != nil {
		return s.code
	}
	if bytes.Equal(s.CodeHash(), types.EmptyCodeHash.Bytes()) {
		return nil
	}
	code, err := s.db.db.ContractCode(common.BytesToHash(s.CodeHash()))
	if err != nil {
		s.db.setError(fmt.Errorf("can't load code hash %x: %v", s.CodeHash(), err))
	}
	s.code = code
	return code
}

// CodeSize returns the size of the contract code associated with this object,
// or zero if none. This method is an almost mirror of Code, but uses a cache
// inside the database to avoid loading codes seen recently.
func (s *stateObject) CodeSize() int {
	if s.code != nil {
		return len(s.code)
	}
	if bytes.Equal(s.CodeHash(), types.EmptyCodeHash.Bytes()) {
		return 0
	}
	size, err := s.db.db.ContractCodeSize(common.BytesToHash(s.CodeHash()))
	if err != nil {
		s.db.setError(fmt.Errorf("can't load code size %x: %v", s.CodeHash(), err))
	}
	return size
}

func (s *stateObject) SetCode(codeHash common.Hash, code []byte) {
	prevcode := s.Code()
	s.db.journal.append(codeChange{
		account:  &s.address,
		prevhash: s.CodeHash(),
		prevcode: prevcode,
	})
	s.setCode(codeHash, code)
}

func (s *stateObject) setCode(codeHash common.Hash, code []byte) {
	s.code = code
	s.data.CodeHash = codeHash[:]
	s.dirtyCode = true
}

func (s *stateObject) SetNonce(nonce uint64) {
	s.db.journal.append(nonceChange{
		account: &s.address,
		prev:    s.data.Nonce,
	})
	s.setNonce(nonce)
}

func (s *stateObject) setNonce(nonce uint64) {
	s.data.Nonce = nonce
}

func (s *stateObject) CodeHash() []byte {
	return s.data.CodeHash
}

func (s *stateObject) Balance() *uint256.Int {
	return s.data.Balance
}

func (s *stateObject) Nonce() uint64 {
	return s.data.Nonce
}

func (s *stateObject) Root() common.Hash {
	return s.data.Root
}