package network

import (
	"encoding/json"
	"fmt"
	"net/http"
	"path/filepath"
	"strings"
	"time"

	jsonrpc "github.com/ethereum/go-ethereum/rpc"
	"github.com/gorilla/mux"
	"github.com/improbable-eng/grpc-web/go/grpcweb"
	"github.com/rs/cors"

	tmos "github.com/tendermint/tendermint/libs/os"
	"github.com/tendermint/tendermint/node"
	"github.com/tendermint/tendermint/p2p"
	pvm "github.com/tendermint/tendermint/privval"
	"github.com/tendermint/tendermint/proxy"
	"github.com/tendermint/tendermint/rpc/client/local"
	"github.com/tendermint/tendermint/types"
	tmtime "github.com/tendermint/tendermint/types/time"

	"github.com/cosmos/cosmos-sdk/server/api"
	servergrpc "github.com/cosmos/cosmos-sdk/server/grpc"
	authtypes "github.com/cosmos/cosmos-sdk/x/auth/types"
	banktypes "github.com/cosmos/cosmos-sdk/x/bank/types"
	"github.com/cosmos/cosmos-sdk/x/genutil"
	genutiltypes "github.com/cosmos/cosmos-sdk/x/genutil/types"
	stakingtypes "github.com/cosmos/cosmos-sdk/x/staking/types"

	"github.com/tharsis/ethermint/ethereum/rpc"
	ethsrv "github.com/tharsis/ethermint/server"
	ethermint "github.com/tharsis/ethermint/types"
)

func startInProcess(cfg Config, val *Validator) error {
	logger := val.Ctx.Logger
	tmCfg := val.Ctx.Config
	tmCfg.Instrumentation.Prometheus = false

	nodeKey, err := p2p.LoadOrGenNodeKey(tmCfg.NodeKeyFile())
	if err != nil {
		return fmt.Errorf("failed to load or generate node key: %w", err)
	}

	app := cfg.AppConstructor(*val)

	genDocProvider := node.DefaultGenesisDocProviderFunc(tmCfg)
	tmNode, err := node.NewNode(
		tmCfg,
		pvm.LoadOrGenFilePV(tmCfg.PrivValidatorKeyFile(), tmCfg.PrivValidatorStateFile()),
		nodeKey,
		proxy.NewLocalClientCreator(app),
		genDocProvider,
		node.DefaultDBProvider,
		node.DefaultMetricsProvider(tmCfg.Instrumentation),
		logger.With("module", val.Moniker),
	)
	if err != nil {
		return fmt.Errorf("failed to create node: %w", err)
	}

	if err := tmNode.Start(); err != nil {
		return fmt.Errorf("failed to start node: %w", err)
	}

	val.tmNode = tmNode

	if val.RPCAddress != "" {
		val.RPCClient = local.New(tmNode)
	}

	// We'll need a RPC client if the validator exposes a gRPC or REST endpoint.
	if val.APIAddress != "" || val.AppConfig.GRPC.Enable {
		val.ClientCtx = val.ClientCtx.
			WithClient(val.RPCClient)

		// Add the tx service in the gRPC router.
		app.RegisterTxService(val.ClientCtx)

		// Add the tendermint queries service in the gRPC router.
		app.RegisterTendermintService(val.ClientCtx)
	}

	if val.APIAddress != "" {
		apiSrv := api.New(val.ClientCtx, logger.With("module", "api-server"))
		app.RegisterAPIRoutes(apiSrv, val.AppConfig.API)

		errCh := make(chan error)

		go func() {
			if err := apiSrv.Start(val.AppConfig.Config); err != nil {
				errCh <- err
			}
		}()

		select {
		case err := <-errCh:
			return fmt.Errorf("failed to start API server: %w", err)
		case <-time.After(5 * time.Second): // assume server started successfully
		}

		val.api = apiSrv
	}

	if val.AppConfig.GRPC.Enable {
		grpcSrv, err := servergrpc.StartGRPCServer(val.ClientCtx, app, val.AppConfig.GRPC.Address)
		if err != nil {
			return fmt.Errorf("failed to start gRPC server: %w", err)
		}

		val.grpc = grpcSrv
	}

	if val.AppConfig.EVMRPC.Enable {
		tmEndpoint := "/websocket"
		tmRPCAddr := val.Ctx.Config.RPC.ListenAddress
		tmWsClient := ethsrv.ConnectTmWS(tmRPCAddr, tmEndpoint)

		val.jsonRPC = jsonrpc.NewServer()

		apis := rpc.GetRPCAPIs(val.ClientCtx, tmWsClient)
		for _, api := range apis {
			if err := val.jsonRPC.RegisterName(api.Namespace, api.Service); err != nil {
				return fmt.Errorf("failed to register JSON-RPC namespace %s: %w", api.Namespace, err)
			}
		}

		r := mux.NewRouter()
		r.HandleFunc("/", val.jsonRPC.ServeHTTP).Methods("POST")
		if val.grpc != nil {
			grpcWeb := grpcweb.WrapServer(val.grpc)
			ethsrv.MountGRPCWebServices(r, grpcWeb, grpcweb.ListGRPCResources(val.grpc))
		}

		handlerWithCors := cors.New(cors.Options{
			AllowedOrigins: []string{"*"},
			AllowedMethods: []string{
				http.MethodHead,
				http.MethodGet,
				http.MethodPost,
				http.MethodPut,
				http.MethodPatch,
				http.MethodDelete,
			},
			AllowedHeaders:     []string{"*"},
			AllowCredentials:   false,
			OptionsPassthrough: false,
		})

		httpSrv := &http.Server{
			Addr: strings.TrimPrefix(val.AppConfig.EVMRPC.RPCAddress, "tcp://"), // FIXME: timeouts
			// Addr:    val.AppConfig.EVMRPC.RPCAddress, // FIXME: address has too many colons
			Handler: handlerWithCors.Handler(r),
		}

		httpSrvDone := make(chan struct{}, 1)

		errCh := make(chan error)
		go func() {
			if err := httpSrv.ListenAndServe(); err != nil {
				if err == http.ErrServerClosed {
					close(httpSrvDone)
					return
				}

				errCh <- err
			}
		}()

		select {
		case err := <-errCh:
			return fmt.Errorf("JSON-RPC go routine failed to start: %w", err)
		case <-time.After(1 * time.Second): // assume EVM RPC server started successfully
		}
	}

	return nil
}

func collectGenFiles(cfg Config, vals []*Validator, outputDir string) error {
	genTime := tmtime.Now()

	for i := 0; i < cfg.NumValidators; i++ {
		tmCfg := vals[i].Ctx.Config

		nodeDir := filepath.Join(outputDir, vals[i].Moniker, "ethermintd")
		gentxsDir := filepath.Join(outputDir, "gentxs")

		tmCfg.Moniker = vals[i].Moniker
		tmCfg.SetRoot(nodeDir)

		initCfg := genutiltypes.NewInitConfig(cfg.ChainID, gentxsDir, vals[i].NodeID, vals[i].PubKey)

		genFile := tmCfg.GenesisFile()
		genDoc, err := types.GenesisDocFromFile(genFile)
		if err != nil {
			return fmt.Errorf("failed to create genesis doc: %w", err)
		}

		appState, err := genutil.GenAppStateFromConfig(cfg.Codec, cfg.TxConfig,
			tmCfg, initCfg, *genDoc, banktypes.GenesisBalancesIterator{})
		if err != nil {
			return fmt.Errorf("failed to create app state: %w", err)
		}

		// overwrite each validator's genesis file to have a canonical genesis time
		if err := genutil.ExportGenesisFileWithTime(genFile, cfg.ChainID, nil, appState, genTime); err != nil {
			return fmt.Errorf("failed to export genesis: %w", err)
		}
	}

	return nil
}

func initGenFiles(cfg Config, genAccounts []authtypes.GenesisAccount, genBalances []banktypes.Balance, genFiles []string) error {

	// set the accounts in the genesis state
	var authGenState authtypes.GenesisState
	cfg.Codec.MustUnmarshalJSON(cfg.GenesisState[authtypes.ModuleName], &authGenState)

	accounts, err := authtypes.PackAccounts(genAccounts)
	if err != nil {
		return err
	}

	authGenState.Accounts = accounts
	cfg.GenesisState[authtypes.ModuleName] = cfg.Codec.MustMarshalJSON(&authGenState)

	// set the balances in the genesis state
	var bankGenState banktypes.GenesisState
	cfg.Codec.MustUnmarshalJSON(cfg.GenesisState[banktypes.ModuleName], &bankGenState)

	bankGenState.Balances = genBalances
	cfg.GenesisState[banktypes.ModuleName] = cfg.Codec.MustMarshalJSON(&bankGenState)

	var stakingGenState stakingtypes.GenesisState
	cfg.Codec.MustUnmarshalJSON(cfg.GenesisState[stakingtypes.ModuleName], &stakingGenState)

	stakingGenState.Params.BondDenom = ethermint.AttoPhoton
	cfg.GenesisState[stakingtypes.ModuleName] = cfg.Codec.MustMarshalJSON(&stakingGenState)

	appGenStateJSON, err := json.MarshalIndent(cfg.GenesisState, "", "  ")
	if err != nil {
		return err
	}

	genDoc := types.GenesisDoc{
		ChainID:    cfg.ChainID,
		AppState:   appGenStateJSON,
		Validators: nil,
	}

	// generate empty genesis files for each validator and save
	for i := 0; i < cfg.NumValidators; i++ {
		if err := genDoc.SaveAs(genFiles[i]); err != nil {
			return err
		}
	}

	return nil
}

func writeFile(name string, dir string, contents []byte) error {
	writePath := filepath.Join(dir)
	file := filepath.Join(writePath, name)

	err := tmos.EnsureDir(writePath, 0755)
	if err != nil {
		return err
	}

	return tmos.WriteFile(file, contents, 0644)
}