package state

import (
	"bytes"
	"context"
	"encoding/binary"

	"github.com/holiman/uint256"
	"github.com/ledgerwatch/turbo-geth/common/changeset"

	"github.com/ledgerwatch/turbo-geth/common"
	"github.com/ledgerwatch/turbo-geth/common/dbutils"
	"github.com/ledgerwatch/turbo-geth/core/types/accounts"
	"github.com/ledgerwatch/turbo-geth/ethdb"
)

var _ WriterWithChangeSets = (*PlainStateWriter)(nil)

type PlainStateWriter struct {
	db           ethdb.Database
	changeSetsDB ethdb.Database
	csw          *ChangeSetWriter
	blockNumber  uint64
}

func NewPlainStateWriter(db ethdb.Database, changeSetsDB ethdb.Database, blockNumber uint64) *PlainStateWriter {
	return &PlainStateWriter{
		db:           db,
		changeSetsDB: changeSetsDB,
		csw:          NewChangeSetWriterPlain(changeSetsDB, blockNumber),
		blockNumber:  blockNumber,
	}
}

func (w *PlainStateWriter) UpdateAccountData(ctx context.Context, address common.Address, original, account *accounts.Account) error {
	if err := w.csw.UpdateAccountData(ctx, address, original, account); err != nil {
		return err
	}
	value := make([]byte, account.EncodingLengthForStorage())
	account.EncodeForStorage(value)
	return w.db.Put(dbutils.PlainStateBucket, address[:], value)
}

func (w *PlainStateWriter) UpdateAccountCode(address common.Address, incarnation uint64, codeHash common.Hash, code []byte) error {
	if err := w.csw.UpdateAccountCode(address, incarnation, codeHash, code); err != nil {
		return err
	}
	if err := w.db.Put(dbutils.CodeBucket, codeHash[:], code); err != nil {
		return err
	}
	return w.db.Put(dbutils.PlainContractCodeBucket, dbutils.PlainGenerateStoragePrefix(address[:], incarnation), codeHash[:])
}

func (w *PlainStateWriter) DeleteAccount(ctx context.Context, address common.Address, original *accounts.Account) error {
	if err := w.csw.DeleteAccount(ctx, address, original); err != nil {
		return err
	}
	if err := w.db.Delete(dbutils.PlainStateBucket, address[:], nil); err != nil {
		return err
	}
	if original.Incarnation > 0 {
		var b [8]byte
		binary.BigEndian.PutUint64(b[:], original.Incarnation)
		if err := w.db.Put(dbutils.IncarnationMapBucket, address[:], b[:]); err != nil {
			return err
		}
	}
	return nil
}

func (w *PlainStateWriter) WriteAccountStorage(ctx context.Context, address common.Address, incarnation uint64, key *common.Hash, original, value *uint256.Int) error {
	if err := w.csw.WriteAccountStorage(ctx, address, incarnation, key, original, value); err != nil {
		return err
	}
	if *original == *value {
		return nil
	}
	compositeKey := dbutils.PlainGenerateCompositeStorageKey(address.Bytes(), incarnation, key.Bytes())

	v := value.Bytes()
	if len(v) == 0 {
		return w.db.Delete(dbutils.PlainStateBucket, compositeKey, nil)
	}
	return w.db.Put(dbutils.PlainStateBucket, compositeKey, v)
}

func (w *PlainStateWriter) CreateContract(address common.Address) error {
	if err := w.csw.CreateContract(address); err != nil {
		return err
	}
	if err := w.db.Delete(dbutils.IncarnationMapBucket, address[:], nil); err != nil {
		return err
	}
	return nil
}

func (w *PlainStateWriter) WriteChangeSets() error {
	db := w.db
	if w.changeSetsDB != nil {
		db = w.changeSetsDB
	}
	accountChanges, err := w.csw.GetAccountChanges()
	if err != nil {
		return err
	}
	var prevK []byte
	if err = changeset.Mapper[dbutils.PlainAccountChangeSetBucket].Encode(w.blockNumber, accountChanges, func(k, v []byte) error {
		if bytes.Equal(k, prevK) {
			if err = db.AppendDup(dbutils.PlainAccountChangeSetBucket, k, v); err != nil {
				return err
			}
		} else {
			if err = db.Append(dbutils.PlainAccountChangeSetBucket, k, v); err != nil {
				return err
			}
		}
		prevK = k
		return nil
	}); err != nil {
		return err
	}
	prevK = nil

	storageChanges, err := w.csw.GetStorageChanges()
	if err != nil {
		return err
	}
	if storageChanges.Len() == 0 {
		return nil
	}
	if err = changeset.Mapper[dbutils.PlainStorageChangeSetBucket].Encode(w.blockNumber, storageChanges, func(k, v []byte) error {
		if bytes.Equal(k, prevK) {
			if err = db.AppendDup(dbutils.PlainStorageChangeSetBucket, k, v); err != nil {
				return err
			}
		} else {
			if err = db.Append(dbutils.PlainStorageChangeSetBucket, k, v); err != nil {
				return err
			}
		}
		prevK = k
		return nil
	}); err != nil {
		return err
	}
	return nil
}

func (w *PlainStateWriter) WriteHistory() error {
	db := w.db
	if w.changeSetsDB != nil {
		db = w.changeSetsDB
	}
	accountChanges, err := w.csw.GetAccountChanges()
	if err != nil {
		return err
	}
	err = writeIndex(w.blockNumber, accountChanges, dbutils.AccountsHistoryBucket, db)
	if err != nil {
		return err
	}

	storageChanges, err := w.csw.GetStorageChanges()
	if err != nil {
		return err
	}
	err = writeIndex(w.blockNumber, storageChanges, dbutils.StorageHistoryBucket, db)
	if err != nil {
		return err
	}

	return nil
}

func (w *PlainStateWriter) ChangeSetWriter() *ChangeSetWriter {
	return w.csw
}