package cli

import (
	"context"
	"encoding/binary"
	"errors"
	"fmt"
	"io"
	"net"
	"net/http"
	"path"
	"time"

	"github.com/ledgerwatch/erigon-lib/gointerfaces"
	"github.com/ledgerwatch/erigon-lib/gointerfaces/grpcutil"
	"github.com/ledgerwatch/erigon-lib/gointerfaces/remote"
	"github.com/ledgerwatch/erigon-lib/kv"
	"github.com/ledgerwatch/erigon-lib/kv/kvcache"
	kv2 "github.com/ledgerwatch/erigon-lib/kv/mdbx"
	"github.com/ledgerwatch/erigon-lib/kv/remotedb"
	"github.com/ledgerwatch/erigon-lib/kv/remotedbserver"
	"github.com/ledgerwatch/erigon/cmd/rpcdaemon/health"
	"github.com/ledgerwatch/erigon/cmd/rpcdaemon/interfaces"
	"github.com/ledgerwatch/erigon/cmd/rpcdaemon/services"
	"github.com/ledgerwatch/erigon/cmd/utils"
	"github.com/ledgerwatch/erigon/common/paths"
	"github.com/ledgerwatch/erigon/core/rawdb"
	"github.com/ledgerwatch/erigon/eth/ethconfig"
	"github.com/ledgerwatch/erigon/internal/debug"
	"github.com/ledgerwatch/erigon/node"
	"github.com/ledgerwatch/erigon/params"
	"github.com/ledgerwatch/erigon/rpc"
	"github.com/ledgerwatch/erigon/turbo/snapshotsync"
	"github.com/ledgerwatch/log/v3"
	"github.com/spf13/cobra"
	"google.golang.org/grpc"
	"google.golang.org/grpc/codes"
	grpcHealth "google.golang.org/grpc/health"
	"google.golang.org/grpc/health/grpc_health_v1"
	"google.golang.org/grpc/status"
)

type Flags struct {
	PrivateApiAddr         string
	SingleNodeMode         bool // Erigon's database can be read by separated processes on same machine - in read-only mode - with full support of transactions. It will share same "OS PageCache" with Erigon process.
	Datadir                string
	Chaindata              string
	HttpListenAddress      string
	TLSCertfile            string
	TLSCACert              string
	TLSKeyFile             string
	HttpPort               int
	HttpCORSDomain         []string
	HttpVirtualHost        []string
	HttpCompression        bool
	API                    []string
	Gascap                 uint64
	MaxTraces              uint64
	WebsocketEnabled       bool
	WebsocketCompression   bool
	RpcAllowListFilePath   string
	RpcBatchConcurrency    uint
	TraceCompatibility     bool // Bug for bug compatibility for trace_ routines with OpenEthereum
	TxPoolApiAddr          string
	TevmEnabled            bool
	StateCache             kvcache.CoherentConfig
	Snapshot               ethconfig.Snapshot
	GRPCServerEnabled      bool
	GRPCListenAddress      string
	GRPCPort               int
	GRPCHealthCheckEnabled bool
	StarknetGRPCAddress    string
}

var rootCmd = &cobra.Command{
	Use:   "rpcdaemon",
	Short: "rpcdaemon is JSON RPC server that connects to Erigon node for remote DB access",
}

func RootCommand() (*cobra.Command, *Flags) {
	utils.CobraFlags(rootCmd, append(debug.Flags, utils.MetricFlags...))

	cfg := &Flags{StateCache: kvcache.DefaultCoherentConfig}
	rootCmd.PersistentFlags().StringVar(&cfg.PrivateApiAddr, "private.api.addr", "127.0.0.1:9090", "private api network address, for example: 127.0.0.1:9090")
	rootCmd.PersistentFlags().StringVar(&cfg.Datadir, "datadir", "", "path to Erigon working directory")
	rootCmd.PersistentFlags().StringVar(&cfg.Chaindata, "chaindata", "", "path to the database")
	rootCmd.PersistentFlags().StringVar(&cfg.HttpListenAddress, "http.addr", node.DefaultHTTPHost, "HTTP-RPC server listening interface")
	rootCmd.PersistentFlags().StringVar(&cfg.TLSCertfile, "tls.cert", "", "certificate for client side TLS handshake")
	rootCmd.PersistentFlags().StringVar(&cfg.TLSKeyFile, "tls.key", "", "key file for client side TLS handshake")
	rootCmd.PersistentFlags().StringVar(&cfg.TLSCACert, "tls.cacert", "", "CA certificate for client side TLS handshake")
	rootCmd.PersistentFlags().IntVar(&cfg.HttpPort, "http.port", node.DefaultHTTPPort, "HTTP-RPC server listening port")
	rootCmd.PersistentFlags().StringSliceVar(&cfg.HttpCORSDomain, "http.corsdomain", []string{}, "Comma separated list of domains from which to accept cross origin requests (browser enforced)")
	rootCmd.PersistentFlags().StringSliceVar(&cfg.HttpVirtualHost, "http.vhosts", node.DefaultConfig.HTTPVirtualHosts, "Comma separated list of virtual hostnames from which to accept requests (server enforced). Accepts '*' wildcard.")
	rootCmd.PersistentFlags().BoolVar(&cfg.HttpCompression, "http.compression", true, "Disable http compression")
	rootCmd.PersistentFlags().StringSliceVar(&cfg.API, "http.api", []string{"eth", "erigon"}, "API's offered over the HTTP-RPC interface: eth,erigon,web3,net,debug,trace,txpool,db,starknet. Supported methods: https://github.com/ledgerwatch/erigon/tree/devel/cmd/rpcdaemon")
	rootCmd.PersistentFlags().Uint64Var(&cfg.Gascap, "rpc.gascap", 50000000, "Sets a cap on gas that can be used in eth_call/estimateGas")
	rootCmd.PersistentFlags().Uint64Var(&cfg.MaxTraces, "trace.maxtraces", 200, "Sets a limit on traces that can be returned in trace_filter")
	rootCmd.PersistentFlags().BoolVar(&cfg.WebsocketEnabled, "ws", false, "Enable Websockets")
	rootCmd.PersistentFlags().BoolVar(&cfg.WebsocketCompression, "ws.compression", false, "Enable Websocket compression (RFC 7692)")
	rootCmd.PersistentFlags().StringVar(&cfg.RpcAllowListFilePath, "rpc.accessList", "", "Specify granular (method-by-method) API allowlist")
	rootCmd.PersistentFlags().UintVar(&cfg.RpcBatchConcurrency, "rpc.batch.concurrency", 2, "Does limit amount of goroutines to process 1 batch request. Means 1 bach request can't overload server. 1 batch still can have unlimited amount of request")
	rootCmd.PersistentFlags().BoolVar(&cfg.TraceCompatibility, "trace.compat", false, "Bug for bug compatibility with OE for trace_ routines")
	rootCmd.PersistentFlags().StringVar(&cfg.TxPoolApiAddr, "txpool.api.addr", "127.0.0.1:9090", "txpool api network address, for example: 127.0.0.1:9090")
	rootCmd.PersistentFlags().BoolVar(&cfg.TevmEnabled, "tevm", false, "Enables Transpiled EVM experiment")
	rootCmd.PersistentFlags().BoolVar(&cfg.Snapshot.Enabled, ethconfig.FlagSnapshot, false, "Enables Snapshot Sync")
	rootCmd.PersistentFlags().IntVar(&cfg.StateCache.KeysLimit, "state.cache", kvcache.DefaultCoherentConfig.KeysLimit, "Amount of keys to store in StateCache (enabled if no --datadir set). Set 0 to disable StateCache. 1_000_000 keys ~ equal to 2Gb RAM (maybe we will add RAM accounting in future versions).")
	rootCmd.PersistentFlags().BoolVar(&cfg.GRPCServerEnabled, "grpc", false, "Enable GRPC server")
	rootCmd.PersistentFlags().StringVar(&cfg.GRPCListenAddress, "grpc.addr", node.DefaultGRPCHost, "GRPC server listening interface")
	rootCmd.PersistentFlags().IntVar(&cfg.GRPCPort, "grpc.port", node.DefaultGRPCPort, "GRPC server listening port")
	rootCmd.PersistentFlags().BoolVar(&cfg.GRPCHealthCheckEnabled, "grpc.healthcheck", false, "Enable GRPC health check")
	rootCmd.PersistentFlags().StringVar(&cfg.StarknetGRPCAddress, "starknet.grpc.address", "127.0.0.1:6066", "Starknet GRPC address")

	if err := rootCmd.MarkPersistentFlagFilename("rpc.accessList", "json"); err != nil {
		panic(err)
	}
	if err := rootCmd.MarkPersistentFlagDirname("datadir"); err != nil {
		panic(err)
	}
	if err := rootCmd.MarkPersistentFlagDirname("chaindata"); err != nil {
		panic(err)
	}

	rootCmd.PersistentPreRunE = func(cmd *cobra.Command, args []string) error {
		if err := utils.SetupCobra(cmd); err != nil {
			return err
		}
		cfg.SingleNodeMode = cfg.Datadir != "" || cfg.Chaindata != ""
		if cfg.SingleNodeMode {
			if cfg.Datadir == "" {
				cfg.Datadir = paths.DefaultDataDir()
			}
			if cfg.Chaindata == "" {
				cfg.Chaindata = path.Join(cfg.Datadir, "chaindata")
			}
			cfg.Snapshot = ethconfig.NewSnapshotCfg(cfg.Snapshot.Enabled, cfg.Snapshot.RetireEnabled)
		}
		return nil
	}
	rootCmd.PersistentPostRunE = func(cmd *cobra.Command, args []string) error {
		utils.StopDebug()
		return nil
	}

	cfg.StateCache.MetricsLabel = "rpc"

	return rootCmd, cfg
}

type StateChangesClient interface {
	StateChanges(ctx context.Context, in *remote.StateChangeRequest, opts ...grpc.CallOption) (remote.KV_StateChangesClient, error)
}

func subscribeToStateChangesLoop(ctx context.Context, client StateChangesClient, cache kvcache.Cache) {
	go func() {
		for {
			select {
			case <-ctx.Done():
				return
			default:
			}
			if err := subscribeToStateChanges(ctx, client, cache); err != nil {
				if s, ok := status.FromError(err); ok && retryLater(s.Code()) {
					time.Sleep(time.Second)
					continue
				}
				if errors.Is(err, io.EOF) || errors.Is(err, context.Canceled) {
					continue
				}
				log.Warn("[txpool.handleStateChanges]", "err", err)
			}
		}
	}()
}

func retryLater(code codes.Code) bool {
	return code == codes.Unavailable || code == codes.Canceled || code == codes.ResourceExhausted
}

func subscribeToStateChanges(ctx context.Context, client StateChangesClient, cache kvcache.Cache) error {
	streamCtx, cancel := context.WithCancel(ctx)
	defer cancel()
	stream, err := client.StateChanges(streamCtx, &remote.StateChangeRequest{WithStorage: true, WithTransactions: false}, grpc.WaitForReady(true))
	if err != nil {
		return err
	}
	for req, err := stream.Recv(); ; req, err = stream.Recv() {
		if err != nil {
			return err
		}
		if req == nil {
			return nil
		}

		cache.OnNewBlock(req)
	}
}

func checkDbCompatibility(ctx context.Context, db kv.RoDB) error {
	// DB schema version compatibility check
	var version []byte
	var compatErr error
	var compatTx kv.Tx
	if compatTx, compatErr = db.BeginRo(ctx); compatErr != nil {
		return fmt.Errorf("open Ro Tx for DB schema compability check: %w", compatErr)
	}
	defer compatTx.Rollback()
	if version, compatErr = compatTx.GetOne(kv.DatabaseInfo, kv.DBSchemaVersionKey); compatErr != nil {
		return fmt.Errorf("read version for DB schema compability check: %w", compatErr)
	}
	if len(version) != 12 {
		return fmt.Errorf("database does not have major schema version. upgrade and restart Erigon core")
	}
	major := binary.BigEndian.Uint32(version)
	minor := binary.BigEndian.Uint32(version[4:])
	patch := binary.BigEndian.Uint32(version[8:])
	var compatible bool
	dbSchemaVersion := &kv.DBSchemaVersion
	if major != dbSchemaVersion.Major {
		compatible = false
	} else if minor != dbSchemaVersion.Minor {
		compatible = false
	} else {
		compatible = true
	}
	if !compatible {
		return fmt.Errorf("incompatible DB Schema versions: reader %d.%d.%d, database %d.%d.%d",
			dbSchemaVersion.Major, dbSchemaVersion.Minor, dbSchemaVersion.Patch,
			major, minor, patch)
	}
	log.Info("DB schemas compatible", "reader", fmt.Sprintf("%d.%d.%d", dbSchemaVersion.Major, dbSchemaVersion.Minor, dbSchemaVersion.Patch),
		"database", fmt.Sprintf("%d.%d.%d", major, minor, patch))
	return nil
}

func RemoteServices(ctx context.Context, cfg Flags, logger log.Logger, rootCancel context.CancelFunc) (db kv.RoDB, eth services.ApiBackend, txPool *services.TxPoolService, mining *services.MiningService, starknet *services.StarknetService, stateCache kvcache.Cache, blockReader interfaces.BlockAndTxnReader, err error) {
	if !cfg.SingleNodeMode && cfg.PrivateApiAddr == "" {
		return nil, nil, nil, nil, nil, nil, nil, fmt.Errorf("either remote db or local db must be specified")
	}

	// Do not change the order of these checks. Chaindata needs to be checked first, because PrivateApiAddr has default value which is not ""
	// If PrivateApiAddr is checked first, the Chaindata option will never work
	if cfg.SingleNodeMode {
		var rwKv kv.RwDB
		rwKv, err = kv2.NewMDBX(logger).Path(cfg.Chaindata).Readonly().Open()
		if err != nil {
			return nil, nil, nil, nil, nil, nil, nil, err
		}
		if compatErr := checkDbCompatibility(ctx, rwKv); compatErr != nil {
			return nil, nil, nil, nil, nil, nil, nil, compatErr
		}
		db = rwKv
		stateCache = kvcache.NewDummy()
	} else {
		if cfg.StateCache.KeysLimit > 0 {
			stateCache = kvcache.New(cfg.StateCache)
		} else {
			stateCache = kvcache.NewDummy()
		}
		log.Info("if you run RPCDaemon on same machine with Erigon add --datadir option")
	}

	if cfg.SingleNodeMode {
		if cfg.Snapshot.Enabled {
			var cc *params.ChainConfig
			if err := db.View(context.Background(), func(tx kv.Tx) error {
				genesisBlock, err := rawdb.ReadBlockByNumber(tx, 0)
				if err != nil {
					return err
				}
				cc, err = rawdb.ReadChainConfig(tx, genesisBlock.Hash())
				if err != nil {
					return err
				}
				return nil
			}); err != nil {
				return nil, nil, nil, nil, nil, nil, nil, err
			}
			if cc == nil {
				return nil, nil, nil, nil, nil, nil, nil, fmt.Errorf("chain config not found in db. Need start erigon at least once on this db")
			}

			allSnapshots := snapshotsync.NewAllSnapshots(cfg.Snapshot, path.Join(cfg.Datadir, "snapshots"))
			if err := allSnapshots.ReopenSegments(); err != nil {
				return nil, nil, nil, nil, nil, nil, nil, err
			}
			if err := allSnapshots.ReopenIndices(); err != nil {
				return nil, nil, nil, nil, nil, nil, nil, err
			}
			blockReader = snapshotsync.NewBlockReaderWithSnapshots(allSnapshots)
		} else {
			blockReader = snapshotsync.NewBlockReader()
		}
	}
	if cfg.PrivateApiAddr == "" {
		return db, eth, txPool, mining, starknet, stateCache, blockReader, nil
	}

	creds, err := grpcutil.TLS(cfg.TLSCACert, cfg.TLSCertfile, cfg.TLSKeyFile)
	if err != nil {
		return nil, nil, nil, nil, nil, nil, nil, fmt.Errorf("open tls cert: %w", err)
	}
	conn, err := grpcutil.Connect(creds, cfg.PrivateApiAddr)
	if err != nil {
		return nil, nil, nil, nil, nil, nil, nil, fmt.Errorf("could not connect to execution service privateApi: %w", err)
	}

	kvClient := remote.NewKVClient(conn)
	remoteKv, err := remotedb.NewRemote(gointerfaces.VersionFromProto(remotedbserver.KvServiceAPIVersion), logger, kvClient).Open()
	if err != nil {
		return nil, nil, nil, nil, nil, nil, nil, fmt.Errorf("could not connect to remoteKv: %w", err)
	}

	subscribeToStateChangesLoop(ctx, kvClient, stateCache)

	if !cfg.SingleNodeMode {
		blockReader = snapshotsync.NewRemoteBlockReader(remote.NewETHBACKENDClient(conn))
	}
	remoteEth := services.NewRemoteBackend(conn, db, blockReader)
	blockReader = remoteEth

	txpoolConn := conn
	if cfg.TxPoolApiAddr != cfg.PrivateApiAddr {
		txpoolConn, err = grpcutil.Connect(creds, cfg.TxPoolApiAddr)
		if err != nil {
			return nil, nil, nil, nil, nil, nil, nil, fmt.Errorf("could not connect to txpool api: %w", err)
		}
	}

	mining = services.NewMiningService(txpoolConn)
	txPool = services.NewTxPoolService(txpoolConn)
	if db == nil {
		db = remoteKv
	}
	eth = remoteEth
	go func() {
		if !remoteKv.EnsureVersionCompatibility() {
			rootCancel()
		}
		if !remoteEth.EnsureVersionCompatibility() {
			rootCancel()
		}
		if mining != nil && !mining.EnsureVersionCompatibility() {
			rootCancel()
		}
		if !txPool.EnsureVersionCompatibility() {
			rootCancel()
		}
	}()

	if cfg.StarknetGRPCAddress != "" {
		starknetConn, err := grpcutil.Connect(creds, cfg.StarknetGRPCAddress)
		if err != nil {
			return nil, nil, nil, nil, nil, nil, nil, fmt.Errorf("could not connect to starknet api: %w", err)
		}
		starknet = services.NewStarknetService(starknetConn)
	}

	return db, eth, txPool, mining, starknet, stateCache, blockReader, err
}

func StartRpcServer(ctx context.Context, cfg Flags, rpcAPI []rpc.API) error {
	// register apis and create handler stack
	httpEndpoint := fmt.Sprintf("%s:%d", cfg.HttpListenAddress, cfg.HttpPort)

	srv := rpc.NewServer(cfg.RpcBatchConcurrency)

	allowListForRPC, err := parseAllowListForRPC(cfg.RpcAllowListFilePath)
	if err != nil {
		return err
	}
	srv.SetAllowList(allowListForRPC)

	if err := node.RegisterApisFromWhitelist(rpcAPI, cfg.API, srv, false); err != nil {
		return fmt.Errorf("could not start register RPC apis: %w", err)
	}

	httpHandler := node.NewHTTPHandlerStack(srv, cfg.HttpCORSDomain, cfg.HttpVirtualHost, cfg.HttpCompression)
	var wsHandler http.Handler
	if cfg.WebsocketEnabled {
		wsHandler = srv.WebsocketHandler([]string{"*"}, cfg.WebsocketCompression)
	}

	var handler http.Handler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// adding a healthcheck here
		if health.ProcessHealthcheckIfNeeded(w, r, rpcAPI) {
			return
		}
		if cfg.WebsocketEnabled && r.Method == "GET" {
			wsHandler.ServeHTTP(w, r)
			return
		}
		httpHandler.ServeHTTP(w, r)
	})

	listener, _, err := node.StartHTTPEndpoint(httpEndpoint, rpc.DefaultHTTPTimeouts, handler)
	if err != nil {
		return fmt.Errorf("could not start RPC api: %w", err)
	}
	info := []interface{}{"url", httpEndpoint, "ws", cfg.WebsocketEnabled,
		"ws.compression", cfg.WebsocketCompression, "grpc", cfg.GRPCServerEnabled}
	var (
		healthServer *grpcHealth.Server
		grpcServer   *grpc.Server
		grpcListener net.Listener
		grpcEndpoint string
	)
	if cfg.GRPCServerEnabled {
		grpcEndpoint = fmt.Sprintf("%s:%d", cfg.GRPCListenAddress, cfg.GRPCPort)
		if grpcListener, err = net.Listen("tcp", grpcEndpoint); err != nil {
			return fmt.Errorf("could not start GRPC listener: %w", err)
		}
		grpcServer = grpc.NewServer()
		if cfg.GRPCHealthCheckEnabled {
			healthServer = grpcHealth.NewServer()
			grpc_health_v1.RegisterHealthServer(grpcServer, healthServer)
		}
		go grpcServer.Serve(grpcListener)
		info = append(info, "grpc.port", cfg.GRPCPort)
	}

	log.Info("HTTP endpoint opened", info...)

	defer func() {
		srv.Stop()
		shutdownCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
		defer cancel()
		_ = listener.Shutdown(shutdownCtx)
		log.Info("HTTP endpoint closed", "url", httpEndpoint)

		if cfg.GRPCServerEnabled {
			if cfg.GRPCHealthCheckEnabled {
				healthServer.Shutdown()
			}
			grpcServer.GracefulStop()
			_ = grpcListener.Close()
			log.Info("GRPC endpoint closed", "url", grpcEndpoint)
		}
	}()
	<-ctx.Done()
	log.Info("Exiting...")
	return nil
}