// Copyright 2014 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 (
	"bytes"
	"fmt"
	"io"
	"math/big"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/crypto"
	"github.com/ethereum/go-ethereum/logger"
	"github.com/ethereum/go-ethereum/logger/glog"
	"github.com/ethereum/go-ethereum/rlp"
	"github.com/ethereum/go-ethereum/trie"
)

var emptyCodeHash = crypto.Keccak256(nil)

type Code []byte

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

type Storage map[common.Hash]common.Hash

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

	return
}

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

	return cpy
}

type StateObject struct {
	db   trie.Database // State database for storing state changes
	trie *trie.SecureTrie

	// Address belonging to this account
	address common.Address
	// The balance of the account
	balance *big.Int
	// The nonce of the account
	nonce uint64
	// The code hash if code is present (i.e. a contract)
	codeHash []byte
	// The code for this account
	code Code
	// Temporarily initialisation code
	initCode Code
	// Cached storage (flushed when updated)
	storage Storage

	// Mark for deletion
	// When an object is marked for deletion it will be delete from the trie
	// during the "update" phase of the state transition
	remove  bool
	deleted bool
	dirty   bool
}

func NewStateObject(address common.Address, db trie.Database) *StateObject {
	object := &StateObject{
		db:       db,
		address:  address,
		balance:  new(big.Int),
		dirty:    true,
		codeHash: emptyCodeHash,
		storage:  make(Storage),
	}
	object.trie, _ = trie.NewSecure(common.Hash{}, db)
	return object
}

func (self *StateObject) MarkForDeletion() {
	self.remove = true
	self.dirty = true

	if glog.V(logger.Core) {
		glog.Infof("%x: #%d %v X\n", self.Address(), self.nonce, self.balance)
	}
}

func (c *StateObject) getAddr(addr common.Hash) common.Hash {
	var ret []byte
	rlp.DecodeBytes(c.trie.Get(addr[:]), &ret)
	return common.BytesToHash(ret)
}

func (c *StateObject) setAddr(addr, value common.Hash) {
	v, err := rlp.EncodeToBytes(bytes.TrimLeft(value[:], "\x00"))
	if err != nil {
		// if RLPing failed we better panic and not fail silently. This would be considered a consensus issue
		panic(err)
	}
	c.trie.Update(addr[:], v)
}

func (self *StateObject) Storage() Storage {
	return self.storage
}

func (self *StateObject) GetState(key common.Hash) common.Hash {
	value, exists := self.storage[key]
	if !exists {
		value = self.getAddr(key)
		if (value != common.Hash{}) {
			self.storage[key] = value
		}
	}

	return value
}

func (self *StateObject) SetState(key, value common.Hash) {
	self.storage[key] = value
	self.dirty = true
}

// Update updates the current cached storage to the trie
func (self *StateObject) Update() {
	for key, value := range self.storage {
		if (value == common.Hash{}) {
			self.trie.Delete(key[:])
			continue
		}
		self.setAddr(key, value)
	}
}

func (c *StateObject) AddBalance(amount *big.Int) {
	c.SetBalance(new(big.Int).Add(c.balance, amount))

	if glog.V(logger.Core) {
		glog.Infof("%x: #%d %v (+ %v)\n", c.Address(), c.nonce, c.balance, amount)
	}
}

func (c *StateObject) SubBalance(amount *big.Int) {
	c.SetBalance(new(big.Int).Sub(c.balance, amount))

	if glog.V(logger.Core) {
		glog.Infof("%x: #%d %v (- %v)\n", c.Address(), c.nonce, c.balance, amount)
	}
}

func (c *StateObject) SetBalance(amount *big.Int) {
	c.balance = amount
	c.dirty = true
}

func (c *StateObject) St() Storage {
	return c.storage
}

// Return the gas back to the origin. Used by the Virtual machine or Closures
func (c *StateObject) ReturnGas(gas, price *big.Int) {}

func (self *StateObject) Copy() *StateObject {
	stateObject := NewStateObject(self.Address(), self.db)
	stateObject.balance.Set(self.balance)
	stateObject.codeHash = common.CopyBytes(self.codeHash)
	stateObject.nonce = self.nonce
	stateObject.trie = self.trie
	stateObject.code = self.code
	stateObject.initCode = common.CopyBytes(self.initCode)
	stateObject.storage = self.storage.Copy()
	stateObject.remove = self.remove
	stateObject.dirty = self.dirty
	stateObject.deleted = self.deleted

	return stateObject
}

//
// Attribute accessors
//

func (self *StateObject) Balance() *big.Int {
	return self.balance
}

// Returns the address of the contract/account
func (c *StateObject) Address() common.Address {
	return c.address
}

func (self *StateObject) Trie() *trie.SecureTrie {
	return self.trie
}

func (self *StateObject) Root() []byte {
	return self.trie.Root()
}

func (self *StateObject) Code() []byte {
	return self.code
}

func (self *StateObject) SetCode(code []byte) {
	self.code = code
	self.codeHash = crypto.Keccak256(code)
	self.dirty = true
}

func (self *StateObject) SetNonce(nonce uint64) {
	self.nonce = nonce
	self.dirty = true
}

func (self *StateObject) Nonce() uint64 {
	return self.nonce
}

// Never called, but must be present to allow StateObject to be used
// as a vm.Account interface that also satisfies the vm.ContractRef
// interface. Interfaces are awesome.
func (self *StateObject) Value() *big.Int {
	panic("Value on StateObject should never be called")
}

func (self *StateObject) ForEachStorage(cb func(key, value common.Hash) bool) {
	// When iterating over the storage check the cache first
	for h, value := range self.storage {
		cb(h, value)
	}

	it := self.trie.Iterator()
	for it.Next() {
		// ignore cached values
		key := common.BytesToHash(self.trie.GetKey(it.Key))
		if _, ok := self.storage[key]; !ok {
			cb(key, common.BytesToHash(it.Value))
		}
	}
}

type extStateObject struct {
	Nonce    uint64
	Balance  *big.Int
	Root     common.Hash
	CodeHash []byte
}

// EncodeRLP implements rlp.Encoder.
func (c *StateObject) EncodeRLP(w io.Writer) error {
	return rlp.Encode(w, []interface{}{c.nonce, c.balance, c.Root(), c.codeHash})
}

// DecodeObject decodes an RLP-encoded state object.
func DecodeObject(address common.Address, db trie.Database, data []byte) (*StateObject, error) {
	var (
		obj = &StateObject{address: address, db: db, storage: make(Storage)}
		ext extStateObject
		err error
	)
	if err = rlp.DecodeBytes(data, &ext); err != nil {
		return nil, err
	}
	if obj.trie, err = trie.NewSecure(ext.Root, db); err != nil {
		return nil, err
	}
	if !bytes.Equal(ext.CodeHash, emptyCodeHash) {
		if obj.code, err = db.Get(ext.CodeHash); err != nil {
			return nil, fmt.Errorf("can't get code for hash %x: %v", ext.CodeHash, err)
		}
	}
	obj.nonce = ext.Nonce
	obj.balance = ext.Balance
	obj.codeHash = ext.CodeHash
	return obj, nil
}