// Copyright 2025 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 p2p

import (
	"crypto/ecdsa"
	"encoding"
	"fmt"

	"github.com/ethereum/go-ethereum/common/mclock"
	"github.com/ethereum/go-ethereum/log"
	"github.com/ethereum/go-ethereum/p2p/enode"
	"github.com/ethereum/go-ethereum/p2p/nat"
	"github.com/ethereum/go-ethereum/p2p/netutil"
)

//go:generate go run github.com/fjl/gencodec -type Config -field-override configMarshaling -formats toml -out config_toml.go

// Config holds Server options.
type Config struct {
	// This field must be set to a valid secp256k1 private key.
	PrivateKey *ecdsa.PrivateKey `toml:"-"`

	// MaxPeers is the maximum number of peers that can be connected.
	MaxPeers int

	// MaxPendingPeers is the maximum number of peers that can be pending in the
	// handshake phase, counted separately for inbound and outbound connections.
	// Zero defaults to preset values.
	MaxPendingPeers int `toml:",omitempty"`

	// DialRatio controls the ratio of inbound to dialed connections.
	// Example: a DialRatio of 2 allows 1/2 of connections to be dialed.
	// Setting DialRatio to zero defaults it to 3.
	DialRatio int `toml:",omitempty"`

	// NoDiscovery can be used to disable the peer discovery mechanism.
	// Disabling is useful for protocol debugging (manual topology).
	NoDiscovery bool

	// DiscoveryV4 specifies whether V4 discovery should be started.
	DiscoveryV4 bool `toml:",omitempty"`

	// DiscoveryV5 specifies whether the new topic-discovery based V5 discovery
	// protocol should be started or not.
	DiscoveryV5 bool `toml:",omitempty"`

	// Name sets the node name of this server.
	Name string `toml:"-"`

	// BootstrapNodes are used to establish connectivity
	// with the rest of the network.
	BootstrapNodes []*enode.Node

	// BootstrapNodesV5 are used to establish connectivity
	// with the rest of the network using the V5 discovery
	// protocol.
	BootstrapNodesV5 []*enode.Node `toml:",omitempty"`

	// Static nodes are used as pre-configured connections which are always
	// maintained and re-connected on disconnects.
	StaticNodes []*enode.Node

	// Trusted nodes are used as pre-configured connections which are always
	// allowed to connect, even above the peer limit.
	TrustedNodes []*enode.Node

	// Connectivity can be restricted to certain IP networks.
	// If this option is set to a non-nil value, only hosts which match one of the
	// IP networks contained in the list are considered.
	NetRestrict *netutil.Netlist `toml:",omitempty"`

	// NodeDatabase is the path to the database containing the previously seen
	// live nodes in the network.
	NodeDatabase string `toml:",omitempty"`

	// Protocols should contain the protocols supported
	// by the server. Matching protocols are launched for
	// each peer.
	Protocols []Protocol `toml:"-" json:"-"`

	// If ListenAddr is set to a non-nil address, the server
	// will listen for incoming connections.
	//
	// If the port is zero, the operating system will pick a port. The
	// ListenAddr field will be updated with the actual address when
	// the server is started.
	ListenAddr string

	// If DiscAddr is set to a non-nil value, the server will use ListenAddr
	// for TCP and DiscAddr for the UDP discovery protocol.
	DiscAddr string

	// If set to a non-nil value, the given NAT port mapper
	// is used to make the listening port available to the
	// Internet.
	NAT nat.Interface `toml:",omitempty"`

	// If Dialer is set to a non-nil value, the given Dialer
	// is used to dial outbound peer connections.
	Dialer NodeDialer `toml:"-"`

	// If NoDial is true, the server will not dial any peers.
	NoDial bool `toml:",omitempty"`

	// If EnableMsgEvents is set then the server will emit PeerEvents
	// whenever a message is sent to or received from a peer
	EnableMsgEvents bool

	// Logger is a custom logger to use with the p2p.Server.
	Logger log.Logger `toml:"-"`

	clock mclock.Clock
}

type configMarshaling struct {
	NAT configNAT
}

type configNAT struct {
	nat.Interface
}

func (w *configNAT) MarshalText() ([]byte, error) {
	if tm, ok := w.Interface.(encoding.TextMarshaler); ok {
		return tm.MarshalText()
	}
	return nil, fmt.Errorf("NAT specification %#v cannot be marshaled", w.Interface)
}

func (w *configNAT) UnmarshalText(input []byte) error {
	n, err := nat.Parse(string(input))
	if err != nil {
		return fmt.Errorf("invalid NAT specification: %v", err)
	}
	w.Interface = n
	return nil
}