// SPDX-License-Identifier: 0BSD
// Copyright (c) 2024-2026 Sudo-Ivan / Quad4.io
package common

import (
	"encoding/binary"
	"net"
	"sync"
	"time"
)

// NetworkInterface defines the interface for all network communication methods
type NetworkInterface interface {
	// Core interface operations
	Start() error
	Stop() error
	Enable()
	Disable()
	Detach()

	// Network operations
	Send(data []byte, address string) error
	GetConn() net.Conn
	GetMTU() int
	GetName() string

	// Interface properties
	GetType() InterfaceType
	GetMode() InterfaceMode
	IsEnabled() bool
	IsOnline() bool
	IsDetached() bool
	GetBandwidthAvailable() bool

	// Packet handling
	ProcessIncoming([]byte)
	ProcessOutgoing([]byte) error
	SendPathRequest([]byte) error
	SendLinkPacket([]byte, []byte, time.Time) error
	SetPacketCallback(PacketCallback)
	GetPacketCallback() PacketCallback
	GetTxBytes() uint64
	GetRxBytes() uint64
	GetTxPackets() uint64
	GetRxPackets() uint64
}

// BaseInterface provides common implementation for network interfaces
type BaseInterface struct {
	Name     string
	Mode     InterfaceMode
	Type     InterfaceType
	Online   bool
	Enabled  bool
	Detached bool

	IN  bool
	OUT bool

	MTU     int
	Bitrate int64

	TxBytes   uint64
	RxBytes   uint64
	TxPackets uint64
	RxPackets uint64
	lastTx    time.Time

	Mutex          sync.RWMutex
	Owner          interface{}
	PacketCallback PacketCallback
}

// NewBaseInterface creates a new BaseInterface instance
func NewBaseInterface(name string, ifaceType InterfaceType, enabled bool) BaseInterface {
	return BaseInterface{
		Name:    name,
		Type:    ifaceType,
		Mode:    IF_MODE_FULL,
		Enabled: enabled,
		MTU:     DEFAULT_MTU,
		Bitrate: BITRATE_MINIMUM,
		lastTx:  time.Now(),
	}
}

// Default implementations for BaseInterface
func (i *BaseInterface) GetType() InterfaceType {
	return i.Type
}

func (i *BaseInterface) GetMode() InterfaceMode {
	return i.Mode
}

func (i *BaseInterface) GetMTU() int {
	return i.MTU
}

func (i *BaseInterface) GetName() string {
	return i.Name
}

func (i *BaseInterface) IsEnabled() bool {
	i.Mutex.RLock()
	defer i.Mutex.RUnlock()
	return i.Enabled && i.Online && !i.Detached
}

func (i *BaseInterface) IsOnline() bool {
	i.Mutex.RLock()
	defer i.Mutex.RUnlock()
	return i.Online
}

func (i *BaseInterface) IsDetached() bool {
	i.Mutex.RLock()
	defer i.Mutex.RUnlock()
	return i.Detached
}

func (i *BaseInterface) SetPacketCallback(callback PacketCallback) {
	i.Mutex.Lock()
	defer i.Mutex.Unlock()
	i.PacketCallback = callback
}

func (i *BaseInterface) GetPacketCallback() PacketCallback {
	i.Mutex.RLock()
	defer i.Mutex.RUnlock()
	return i.PacketCallback
}

func (i *BaseInterface) GetTxBytes() uint64 {
	i.Mutex.RLock()
	defer i.Mutex.RUnlock()
	return i.TxBytes
}

func (i *BaseInterface) GetRxBytes() uint64 {
	i.Mutex.RLock()
	defer i.Mutex.RUnlock()
	return i.RxBytes
}

func (i *BaseInterface) GetTxPackets() uint64 {
	i.Mutex.RLock()
	defer i.Mutex.RUnlock()
	return i.TxPackets
}

func (i *BaseInterface) GetRxPackets() uint64 {
	i.Mutex.RLock()
	defer i.Mutex.RUnlock()
	return i.RxPackets
}

func (i *BaseInterface) Detach() {
	i.Mutex.Lock()
	defer i.Mutex.Unlock()
	i.Detached = true
	i.Online = false
}

func (i *BaseInterface) Enable() {
	i.Mutex.Lock()
	defer i.Mutex.Unlock()
	i.Enabled = true
	i.Online = true
}

func (i *BaseInterface) Disable() {
	i.Mutex.Lock()
	defer i.Mutex.Unlock()
	i.Enabled = false
	i.Online = false
}

// Default implementations that should be overridden by specific interfaces
func (i *BaseInterface) Start() error {
	return nil
}

func (i *BaseInterface) Stop() error {
	return nil
}

func (i *BaseInterface) GetConn() net.Conn {
	return nil
}

func (i *BaseInterface) Send(data []byte, address string) error {
	i.Mutex.Lock()
	i.TxBytes += uint64(len(data))
	i.TxPackets++
	i.lastTx = time.Now()
	i.Mutex.Unlock()
	return i.ProcessOutgoing(data)
}

func (i *BaseInterface) ProcessIncoming(data []byte) {
	i.Mutex.Lock()
	i.RxBytes += uint64(len(data))
	i.RxPackets++
	i.Mutex.Unlock()

	if i.PacketCallback != nil {
		i.PacketCallback(data, i)
	}
}

func (i *BaseInterface) ProcessOutgoing(data []byte) error {
	return nil
}

func (i *BaseInterface) SendPathRequest(data []byte) error {
	return i.Send(data, "")
}

func (i *BaseInterface) SendLinkPacket(dest []byte, data []byte, timestamp time.Time) error {
	// Create link packet
	packet := make([]byte, 0, len(dest)+len(data)+9) // 1 byte type + dest + 8 byte timestamp
	packet = append(packet, 0x02)                    // Link packet type
	packet = append(packet, dest...)

	ts := make([]byte, 8)
	binary.BigEndian.PutUint64(ts, uint64(timestamp.Unix())) // #nosec G115
	packet = append(packet, ts...)

	packet = append(packet, data...)

	return i.Send(packet, "")
}

func (i *BaseInterface) GetBandwidthAvailable() bool {
	i.Mutex.RLock()
	defer i.Mutex.RUnlock()

	// If no transmission in last second, bandwidth is available
	if time.Since(i.lastTx) > time.Second {
		return true
	}

	// Calculate current bandwidth usage
	bytesPerSec := float64(i.TxBytes) / time.Since(i.lastTx).Seconds()
	currentUsage := bytesPerSec * 8 // Convert to bits/sec

	// Check if usage is below threshold (2% of total bitrate)
	maxUsage := float64(i.Bitrate) * 0.02 // 2% propagation rate
	return currentUsage < maxUsage
}