// Copyright (C) 2018 Storj Labs, Inc.
// See LICENSE for copying information.

package kademlia

import (
	"context"
	"flag"

	"github.com/zeebo/errs"
	"go.uber.org/zap"
	monkit "gopkg.in/spacemonkeygo/monkit.v2"

	"storj.io/storj/pkg/node"
	"storj.io/storj/pkg/pb"
	"storj.io/storj/pkg/provider"
	"storj.io/storj/pkg/utils"
)

var (
	// Error defines a Kademlia error
	Error = errs.Class("kademlia error")
	mon   = monkit.Package()
)

const (
	defaultAlpha = 5
)

var (
	// TODO: replace these with constants after tuning
	flagBucketSize           = flag.Int("kademlia-bucket-size", 20, "Size of each Kademlia bucket")
	flagReplacementCacheSize = flag.Int("kademlia-replacement-cache-size", 5, "Size of Kademlia replacement cache")
)

//CtxKey Used as kademlia key
type CtxKey int

const (
	ctxKeyKad CtxKey = iota
)

// Config defines all of the things that are needed to start up Kademlia
// server endpoints (and not necessarily client code).
type Config struct {
	BootstrapAddr string `help:"the kademlia node to bootstrap against" default:"bootstrap-dev.storj.io:8080"`
	DBPath        string `help:"the path for our db services to be created on" default:"$CONFDIR/kademlia"`
	Alpha         int    `help:"alpha is a system wide concurrency parameter." default:"5"`
}

// Run implements provider.Responsibility
func (c Config) Run(ctx context.Context, server *provider.Provider) (
	err error) {

	defer mon.Task()(&ctx)(&err)

	// TODO(coyle): I'm thinking we just remove  this function and grab from the config.
	in, err := GetIntroNode(c.BootstrapAddr)
	if err != nil {
		return err
	}

	kad, err := NewKademlia(server.Identity().ID, []pb.Node{*in}, server.Addr().String(), server.Identity(), c.DBPath, c.Alpha)
	if err != nil {
		return err
	}
	defer func() { err = utils.CombineErrors(err, kad.Disconnect()) }()

	pb.RegisterNodesServer(server.GRPC(), node.NewServer(kad))

	go func() {
		if err = kad.Bootstrap(ctx); err != nil {
			zap.L().Error("Failed to bootstrap Kademlia", zap.String("ID", server.Identity().ID.String()))
		}
	}()

	return server.Run(context.WithValue(ctx, ctxKeyKad, kad))
}

// LoadFromContext loads an existing Kademlia from the Provider context
// stack if one exists.
func LoadFromContext(ctx context.Context) *Kademlia {
	if v, ok := ctx.Value(ctxKeyKad).(*Kademlia); ok {
		return v
	}
	return nil
}