// Copyright 2022 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 main

import (
	"context"
	"fmt"
	"io"
	"os"

	"github.com/ethereum/go-ethereum/beacon/blsync"
	"github.com/ethereum/go-ethereum/cmd/utils"
	"github.com/ethereum/go-ethereum/internal/flags"
	"github.com/ethereum/go-ethereum/log"
	"github.com/ethereum/go-ethereum/node"
	"github.com/ethereum/go-ethereum/rpc"
	"github.com/mattn/go-colorable"
	"github.com/mattn/go-isatty"
	"github.com/urfave/cli/v2"
)

var (
	verbosityFlag = &cli.IntFlag{
		Name:     "verbosity",
		Usage:    "Logging verbosity: 0=silent, 1=error, 2=warn, 3=info, 4=debug, 5=detail",
		Value:    3,
		Category: flags.LoggingCategory,
	}
	vmoduleFlag = &cli.StringFlag{
		Name:     "vmodule",
		Usage:    "Per-module verbosity: comma-separated list of <pattern>=<level> (e.g. eth/*=5,p2p=4)",
		Value:    "",
		Hidden:   true,
		Category: flags.LoggingCategory,
	}
)

func main() {
	app := flags.NewApp("beacon light syncer tool")
	app.Flags = []cli.Flag{
		utils.BeaconApiFlag,
		utils.BeaconApiHeaderFlag,
		utils.BeaconThresholdFlag,
		utils.BeaconNoFilterFlag,
		utils.BeaconConfigFlag,
		utils.BeaconGenesisRootFlag,
		utils.BeaconGenesisTimeFlag,
		utils.BeaconCheckpointFlag,
		//TODO datadir for optional permanent database
		utils.MainnetFlag,
		utils.SepoliaFlag,
		utils.GoerliFlag,
		utils.BlsyncApiFlag,
		utils.BlsyncJWTSecretFlag,
		verbosityFlag,
		vmoduleFlag,
	}
	app.Action = sync

	if err := app.Run(os.Args); err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
}

func sync(ctx *cli.Context) error {
	usecolor := (isatty.IsTerminal(os.Stderr.Fd()) || isatty.IsCygwinTerminal(os.Stderr.Fd())) && os.Getenv("TERM") != "dumb"
	output := io.Writer(os.Stderr)
	if usecolor {
		output = colorable.NewColorable(os.Stderr)
	}
	verbosity := log.FromLegacyLevel(ctx.Int(verbosityFlag.Name))
	log.SetDefault(log.NewLogger(log.NewTerminalHandlerWithLevel(output, verbosity, usecolor)))

	// set up blsync
	client := blsync.NewClient(ctx)
	client.SetEngineRPC(makeRPCClient(ctx))
	client.Start()

	// run until stopped
	<-ctx.Done()
	client.Stop()
	return nil
}

func makeRPCClient(ctx *cli.Context) *rpc.Client {
	if !ctx.IsSet(utils.BlsyncApiFlag.Name) {
		log.Warn("No engine API target specified, performing a dry run")
		return nil
	}
	if !ctx.IsSet(utils.BlsyncJWTSecretFlag.Name) {
		utils.Fatalf("JWT secret parameter missing") //TODO use default if datadir is specified
	}

	engineApiUrl, jwtFileName := ctx.String(utils.BlsyncApiFlag.Name), ctx.String(utils.BlsyncJWTSecretFlag.Name)
	var jwtSecret [32]byte
	if jwt, err := node.ObtainJWTSecret(jwtFileName); err == nil {
		copy(jwtSecret[:], jwt)
	} else {
		utils.Fatalf("Error loading or generating JWT secret: %v", err)
	}
	auth := node.NewJWTAuth(jwtSecret)
	cl, err := rpc.DialOptions(context.Background(), engineApiUrl, rpc.WithHTTPAuth(auth))
	if err != nil {
		utils.Fatalf("Could not create RPC client: %v", err)
	}
	return cl
}