package interfaces

import (
	"context"
	"math/big"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/consensus"
	"github.com/ethereum/go-ethereum/core"
	"github.com/ethereum/go-ethereum/core/bloombits"
	"github.com/ethereum/go-ethereum/core/state"
	"github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/core/vm"
	"github.com/ethereum/go-ethereum/eth/downloader"
	"github.com/ethereum/go-ethereum/ethdb"
	"github.com/ethereum/go-ethereum/event"
	"github.com/ethereum/go-ethereum/params"
	"github.com/ethereum/go-ethereum/rpc"
)

// Backend interface provides the common API services (that are provided by
// both full and light clients) with access to necessary functions.
type Backend interface {
	// General Ethereum API
	Downloader() *downloader.Downloader
	SuggestGasTipCap(ctx context.Context) (*big.Int, error)
	ChainDb() ethdb.Database
	ExtRPCEnabled() bool
	RPCGasCap() uint64        // global gas cap for eth_call over rpc: DoS protection
	RPCTxFeeCap() float64     // global tx fee cap for all transaction related APIs
	UnprotectedAllowed() bool // allows only for EIP155 transactions.

	// Blockchain API
	SetHead(number uint64)
	HeaderByNumber(ctx context.Context, number rpc.BlockNumber) (*types.Header, error)
	HeaderByHash(ctx context.Context, hash common.Hash) (*types.Header, error)
	HeaderByNumberOrHash(ctx context.Context, blockNrOrHash rpc.BlockNumberOrHash) (*types.Header, error)
	CurrentHeader() *types.Header
	CurrentBlock() *types.Block
	BlockByNumber(ctx context.Context, number rpc.BlockNumber) (*types.Block, error)
	BlockByHash(ctx context.Context, hash common.Hash) (*types.Block, error)
	BlockByNumberOrHash(ctx context.Context, blockNrOrHash rpc.BlockNumberOrHash) (*types.Block, error)
	StateAndHeaderByNumber(ctx context.Context, number rpc.BlockNumber) (*state.StateDB, *types.Header, error)
	StateAndHeaderByNumberOrHash(ctx context.Context, blockNrOrHash rpc.BlockNumberOrHash) (*state.StateDB, *types.Header, error)
	GetReceipts(ctx context.Context, hash common.Hash) (types.Receipts, error)
	GetTd(ctx context.Context, hash common.Hash) *big.Int
	GetEVM(ctx context.Context, msg core.Message, state *state.StateDB, header *types.Header, cfg *vm.Config) (*vm.EVM, func() error, error)
	SubscribeChainEvent(ch chan<- core.ChainEvent) event.Subscription
	SubscribeChainHeadEvent(ch chan<- core.ChainHeadEvent) event.Subscription
	SubscribeChainSideEvent(ch chan<- core.ChainSideEvent) event.Subscription

	// Transaction pool API
	SendTx(ctx context.Context, signedTx *types.Transaction) error
	GetTransaction(ctx context.Context, txHash common.Hash) (*types.Transaction, common.Hash, uint64, uint64, error)
	GetPoolTransactions() (types.Transactions, error)
	GetPoolTransaction(txHash common.Hash) *types.Transaction
	GetPoolNonce(ctx context.Context, addr common.Address) (uint64, error)
	Stats() (pending int, queued int)
	TxPoolContent() (map[common.Address]types.Transactions, map[common.Address]types.Transactions)
	SubscribeNewTxsEvent(chan<- core.NewTxsEvent) event.Subscription

	// Filter API
	BloomStatus() (uint64, uint64)
	GetLogs(ctx context.Context, blockHash common.Hash) ([][]*types.Log, error)
	ServiceFilter(ctx context.Context, session *bloombits.MatcherSession)
	SubscribeLogsEvent(ch chan<- []*types.Log) event.Subscription
	SubscribePendingLogsEvent(ch chan<- []*types.Log) event.Subscription
	SubscribeRemovedLogsEvent(ch chan<- core.RemovedLogsEvent) event.Subscription

	ChainConfig() *params.ChainConfig
	Engine() consensus.Engine
}


type TracerResult interface {
	vm.Tracer
	GetResult() (interface{}, error)
}