package lp2p

import (
	"crypto/rand"
	"time"

	"github.com/filecoin-project/lotus/build"
	"github.com/filecoin-project/lotus/chain/types"
	"golang.org/x/xerrors"

	logging "github.com/ipfs/go-log"
	"github.com/libp2p/go-libp2p"
	connmgr "github.com/libp2p/go-libp2p-connmgr"
	"github.com/libp2p/go-libp2p-core/crypto"
	"github.com/libp2p/go-libp2p-core/peer"
	"github.com/libp2p/go-libp2p-core/peerstore"
	"go.uber.org/fx"
)

var log = logging.Logger("p2pnode")

const kstorePrivkey = "libp2p-host"

type Libp2pOpts struct {
	fx.Out

	Opts []libp2p.Option `group:"libp2p"`
}

func PrivKey(ks types.KeyStore) (crypto.PrivKey, error) {
	k, err := ks.Get(kstorePrivkey)
	if err == nil {
		return crypto.UnmarshalPrivateKey(k.PrivateKey)
	}
	if !xerrors.Is(err, types.ErrKeyInfoNotFound) {
		return nil, err
	}
	pk, err := genLibp2pKey()
	if err != nil {
		return nil, err
	}
	kbytes, err := pk.Bytes()
	if err != nil {
		return nil, err
	}

	if err := ks.Put(kstorePrivkey, types.KeyInfo{
		Type:       kstorePrivkey,
		PrivateKey: kbytes,
	}); err != nil {
		return nil, err
	}

	return pk, nil
}

func genLibp2pKey() (crypto.PrivKey, error) {
	pk, _, err := crypto.GenerateEd25519Key(rand.Reader)
	if err != nil {
		return nil, err
	}
	return pk, nil
}

// Misc options

func ConnectionManager(low, high uint, grace time.Duration, protected []string) func() (opts Libp2pOpts, err error) {
	return func() (Libp2pOpts, error) {
		cm := connmgr.NewConnManager(int(low), int(high), grace)
		for _, p := range protected {
			pid, err := peer.IDFromString(p)
			if err != nil {
				return Libp2pOpts{}, xerrors.Errorf("failed to parse peer ID in protected peers array: %w", err)
			}

			cm.Protect(pid, "config-prot")
		}

		infos, err := build.BuiltinBootstrap()
		if err != nil {
			return Libp2pOpts{}, xerrors.Errorf("failed to get bootstrap peers: %w", err)
		}

		for _, inf := range infos {
			cm.Protect(inf.ID, "bootstrap")
		}

		return Libp2pOpts{
			Opts: []libp2p.Option{libp2p.ConnectionManager(cm)},
		}, nil
	}
}

func PstoreAddSelfKeys(id peer.ID, sk crypto.PrivKey, ps peerstore.Peerstore) error {
	if err := ps.AddPubKey(id, sk.GetPublic()); err != nil {
		return err
	}

	return ps.AddPrivKey(id, sk)
}

func simpleOpt(opt libp2p.Option) func() (opts Libp2pOpts, err error) {
	return func() (opts Libp2pOpts, err error) {
		opts.Opts = append(opts.Opts, opt)
		return
	}
}