package nmlite

import (
	"context"
	"fmt"
	"net"
	"sync"
	"time"

	"github.com/jetkvm/kvm/internal/confparser"
	"github.com/jetkvm/kvm/internal/logging"
	"github.com/jetkvm/kvm/internal/network/types"
	"github.com/jetkvm/kvm/pkg/nmlite/link"
	"github.com/rs/zerolog"
	"github.com/vishvananda/netlink"
)

// InterfaceManager manages a single network interface
type InterfaceManager struct {
	ctx       context.Context
	ifaceName string
	config    *types.NetworkConfig
	logger    *zerolog.Logger
	state     *types.InterfaceState
	stateMu   sync.RWMutex

	// Network components
	staticConfig *StaticConfigManager
	dhcpClient   *DHCPClient
	resolvConf   *ResolvConfManager
	hostname     *HostnameManager

	// Callbacks
	onStateChange     func(state *types.InterfaceState)
	onConfigChange    func(config *types.NetworkConfig)
	onDHCPLeaseChange func(lease *types.DHCPLease)

	// Control
	stopCh chan struct{}
	wg     sync.WaitGroup
}

// NewInterfaceManager creates a new interface manager
func NewInterfaceManager(ctx context.Context, ifaceName string, config *types.NetworkConfig, logger *zerolog.Logger) (*InterfaceManager, error) {
	if config == nil {
		return nil, fmt.Errorf("config cannot be nil")
	}

	if logger == nil {
		logger = logging.GetSubsystemLogger("interface")
	}

	scopedLogger := logger.With().Str("interface", ifaceName).Logger()

	// Validate and set defaults
	if err := confparser.SetDefaultsAndValidate(config); err != nil {
		return nil, fmt.Errorf("invalid config: %w", err)
	}

	im := &InterfaceManager{
		ctx:       ctx,
		ifaceName: ifaceName,
		config:    config,
		logger:    &scopedLogger,
		state: &types.InterfaceState{
			InterfaceName: ifaceName,
			// LastUpdated:   time.Now(),
		},
		stopCh: make(chan struct{}),
	}

	// Initialize components
	var err error
	im.staticConfig, err = NewStaticConfigManager(ifaceName, &scopedLogger)
	if err != nil {
		return nil, fmt.Errorf("failed to create static config manager: %w", err)
	}

	// create the dhcp client
	im.dhcpClient, err = NewDHCPClient(ctx, ifaceName, &scopedLogger)
	if err != nil {
		return nil, fmt.Errorf("failed to create DHCP client: %w", err)
	}

	im.resolvConf = NewResolvConfManager(&scopedLogger)
	im.hostname = NewHostnameManager(&scopedLogger)

	// Set up DHCP client callbacks
	im.dhcpClient.SetOnLeaseChange(func(lease *types.DHCPLease) {
		im.updateStateFromDHCPLease(lease)
		if im.onDHCPLeaseChange != nil {
			im.onDHCPLeaseChange(lease)
		}
	})

	return im, nil
}

// Start starts managing the interface
func (im *InterfaceManager) Start() error {
	im.logger.Info().Msg("starting interface manager")

	// Start monitoring interface state
	im.wg.Add(1)
	go im.monitorInterfaceState()

	// Apply initial configuration
	if err := im.applyConfiguration(); err != nil {
		im.logger.Error().Err(err).Msg("failed to apply initial configuration")
		return err
	}

	im.logger.Info().Msg("interface manager started")
	return nil
}

// Stop stops managing the interface
func (im *InterfaceManager) Stop() error {
	im.logger.Info().Msg("stopping interface manager")

	close(im.stopCh)
	im.wg.Wait()

	// Stop DHCP client
	if im.dhcpClient != nil {
		im.dhcpClient.Stop()
	}

	im.logger.Info().Msg("interface manager stopped")
	return nil
}

func (im *InterfaceManager) link() (*link.Link, error) {
	nl := getNetlinkManager()
	if nl == nil {
		return nil, fmt.Errorf("netlink manager not initialized")
	}
	return nl.GetLinkByName(im.ifaceName)
}

// IsUp returns true if the interface is up
func (im *InterfaceManager) IsUp() bool {
	return im.state.Up
}

func (im *InterfaceManager) IsOnline() bool {
	return im.IsUp()
}

func (im *InterfaceManager) GetIPv4Addresses() []string {
	return im.state.IPv4Addresses
}

func (im *InterfaceManager) GetIPv6Addresses() []string {
	addresses := []string{}
	for _, addr := range im.state.IPv6Addresses {
		addresses = append(addresses, addr.Address.String())
	}
	return []string{}
}

func (im *InterfaceManager) GetMACAddress() string {
	return im.state.MACAddress
}

// GetState returns the current interface state
func (im *InterfaceManager) GetState() *types.InterfaceState {
	im.stateMu.RLock()
	defer im.stateMu.RUnlock()

	// Return a copy to avoid race conditions
	state := *im.state
	return &state
}

func (im *InterfaceManager) NTPServers() []net.IP {
	return im.state.NTPServers
}

// GetConfig returns the current interface configuration
func (im *InterfaceManager) GetConfig() *types.NetworkConfig {
	// Return a copy to avoid race conditions
	config := *im.config
	return &config
}

// SetConfig updates the interface configuration
func (im *InterfaceManager) SetConfig(config *types.NetworkConfig) error {
	if config == nil {
		return fmt.Errorf("config cannot be nil")
	}

	// Validate and set defaults
	if err := confparser.SetDefaultsAndValidate(config); err != nil {
		return fmt.Errorf("invalid config: %w", err)
	}

	im.config = config

	// Apply the new configuration
	if err := im.applyConfiguration(); err != nil {
		im.logger.Error().Err(err).Msg("failed to apply new configuration")
		return err
	}

	// Notify callback
	if im.onConfigChange != nil {
		im.onConfigChange(config)
	}

	im.logger.Info().Msg("configuration updated")
	return nil
}

// RenewDHCPLease renews the DHCP lease
func (im *InterfaceManager) RenewDHCPLease() error {
	if im.dhcpClient == nil {
		return fmt.Errorf("DHCP client not available")
	}

	return im.dhcpClient.Renew()
}

// SetOnStateChange sets the callback for state changes
func (im *InterfaceManager) SetOnStateChange(callback func(state *types.InterfaceState)) {
	im.onStateChange = callback
}

// SetOnConfigChange sets the callback for configuration changes
func (im *InterfaceManager) SetOnConfigChange(callback func(config *types.NetworkConfig)) {
	im.onConfigChange = callback
}

// SetOnDHCPLeaseChange sets the callback for DHCP lease changes
func (im *InterfaceManager) SetOnDHCPLeaseChange(callback func(lease *types.DHCPLease)) {
	im.onDHCPLeaseChange = callback
}

// applyConfiguration applies the current configuration to the interface
func (im *InterfaceManager) applyConfiguration() error {
	im.logger.Info().Msg("applying configuration")

	// Apply IPv4 configuration
	if err := im.applyIPv4Config(); err != nil {
		return fmt.Errorf("failed to apply IPv4 config: %w", err)
	}

	// Apply IPv6 configuration
	if err := im.applyIPv6Config(); err != nil {
		return fmt.Errorf("failed to apply IPv6 config: %w", err)
	}

	// Update hostname
	if err := im.updateHostname(); err != nil {
		im.logger.Warn().Err(err).Msg("failed to update hostname")
	}

	return nil
}

// applyIPv4Config applies IPv4 configuration
func (im *InterfaceManager) applyIPv4Config() error {
	mode := im.config.IPv4Mode.String
	im.logger.Info().Str("mode", mode).Msg("applying IPv4 configuration")

	switch mode {
	case "static":
		return im.applyIPv4Static()
	case "dhcp":
		return im.applyIPv4DHCP()
	case "disabled":
		return im.disableIPv4()
	default:
		return fmt.Errorf("invalid IPv4 mode: %s", mode)
	}
}

// applyIPv6Config applies IPv6 configuration
func (im *InterfaceManager) applyIPv6Config() error {
	mode := im.config.IPv6Mode.String
	im.logger.Info().Str("mode", mode).Msg("applying IPv6 configuration")

	switch mode {
	case "static":
		return im.applyIPv6Static()
	case "dhcpv6":
		return im.applyIPv6DHCP()
	case "slaac":
		return im.applyIPv6SLAAC()
	case "slaac_and_dhcpv6":
		return im.applyIPv6SLAACAndDHCP()
	case "link_local":
		return im.applyIPv6LinkLocal()
	case "disabled":
		return im.disableIPv6()
	default:
		return fmt.Errorf("invalid IPv6 mode: %s", mode)
	}
}

// applyIPv4Static applies static IPv4 configuration
func (im *InterfaceManager) applyIPv4Static() error {
	if im.config.IPv4Static == nil {
		return fmt.Errorf("IPv4 static configuration is nil")
	}

	// Disable DHCP
	if im.dhcpClient != nil {
		im.dhcpClient.SetIPv4(false)
	}

	// Apply static configuration
	return im.staticConfig.ApplyIPv4Static(im.config.IPv4Static)
}

// applyIPv4DHCP applies DHCP IPv4 configuration
func (im *InterfaceManager) applyIPv4DHCP() error {
	if im.dhcpClient == nil {
		return fmt.Errorf("DHCP client not available")
	}

	// Enable DHCP
	im.dhcpClient.SetIPv4(true)
	return im.dhcpClient.Start()
}

// disableIPv4 disables IPv4
func (im *InterfaceManager) disableIPv4() error {
	// Disable DHCP
	if im.dhcpClient != nil {
		im.dhcpClient.SetIPv4(false)
	}

	// Remove all IPv4 addresses
	return im.staticConfig.DisableIPv4()
}

// applyIPv6Static applies static IPv6 configuration
func (im *InterfaceManager) applyIPv6Static() error {
	if im.config.IPv6Static == nil {
		return fmt.Errorf("IPv6 static configuration is nil")
	}

	// Disable DHCPv6
	if im.dhcpClient != nil {
		im.dhcpClient.SetIPv6(false)
	}

	// Apply static configuration
	return im.staticConfig.ApplyIPv6Static(im.config.IPv6Static)
}

// applyIPv6DHCP applies DHCPv6 configuration
func (im *InterfaceManager) applyIPv6DHCP() error {
	if im.dhcpClient == nil {
		return fmt.Errorf("DHCP client not available")
	}

	// Enable DHCPv6
	im.dhcpClient.SetIPv6(true)
	return im.dhcpClient.Start()
}

// applyIPv6SLAAC applies SLAAC configuration
func (im *InterfaceManager) applyIPv6SLAAC() error {
	// Disable DHCPv6
	if im.dhcpClient != nil {
		im.dhcpClient.SetIPv6(false)
	}

	// Remove static IPv6 configuration
	l, err := im.link()
	if err != nil {
		return fmt.Errorf("failed to get interface: %w", err)
	}

	netlinkMgr := getNetlinkManager()
	if err := netlinkMgr.RemoveNonLinkLocalIPv6Addresses(l); err != nil {
		return fmt.Errorf("failed to remove non-link-local IPv6 addresses: %w", err)
	}

	// Enable SLAAC
	return im.staticConfig.EnableIPv6SLAAC()
}

// applyIPv6SLAACAndDHCP applies SLAAC + DHCPv6 configuration
func (im *InterfaceManager) applyIPv6SLAACAndDHCP() error {
	// Enable both SLAAC and DHCPv6
	if im.dhcpClient != nil {
		im.dhcpClient.SetIPv6(true)
		im.dhcpClient.Start()
	}

	return im.staticConfig.EnableIPv6SLAAC()
}

// applyIPv6LinkLocal applies link-local only IPv6 configuration
func (im *InterfaceManager) applyIPv6LinkLocal() error {
	// Disable DHCPv6
	if im.dhcpClient != nil {
		im.dhcpClient.SetIPv6(false)
	}

	// Enable link-local only
	return im.staticConfig.EnableIPv6LinkLocal()
}

// disableIPv6 disables IPv6
func (im *InterfaceManager) disableIPv6() error {
	// Disable DHCPv6
	if im.dhcpClient != nil {
		im.dhcpClient.SetIPv6(false)
	}

	// Disable IPv6
	return im.staticConfig.DisableIPv6()
}

// updateHostname updates the system hostname
func (im *InterfaceManager) updateHostname() error {
	hostname := im.getHostname()
	domain := im.getDomain()
	fqdn := fmt.Sprintf("%s.%s", hostname, domain)

	return im.hostname.SetHostname(hostname, fqdn)
}

// getHostname returns the configured hostname or default
func (im *InterfaceManager) getHostname() string {
	if im.config.Hostname.String != "" {
		return im.config.Hostname.String
	}
	return "jetkvm"
}

// getDomain returns the configured domain or default
func (im *InterfaceManager) getDomain() string {
	if im.config.Domain.String != "" {
		return im.config.Domain.String
	}

	// Try to get domain from DHCP lease
	if im.dhcpClient != nil {
		if lease := im.dhcpClient.GetLease4(); lease != nil && lease.Domain != "" {
			return lease.Domain
		}
	}

	return "local"
}

// monitorInterfaceState monitors the interface state and updates accordingly
func (im *InterfaceManager) monitorInterfaceState() {
	defer im.wg.Done()

	// TODO: use netlink subscription instead of polling
	ticker := time.NewTicker(5 * time.Second)
	defer ticker.Stop()

	for {
		select {
		case <-im.ctx.Done():
			return
		case <-im.stopCh:
			return
		case <-ticker.C:
			if err := im.updateInterfaceState(); err != nil {
				im.logger.Error().Err(err).Msg("failed to update interface state")
			}
		}
	}
}

// updateInterfaceState updates the current interface state
func (im *InterfaceManager) updateInterfaceState() error {
	nl, err := im.link()
	if err != nil {
		return fmt.Errorf("failed to get interface: %w", err)
	}

	attrs := nl.Attrs()
	isUp := attrs.OperState == netlink.OperUp

	hasAddrs := false
	addrs, err := nl.AddrList(link.AfInet)
	if err != nil {
		return fmt.Errorf("failed to get addresses: %w", err)
	}
	if len(addrs) > 0 {
		hasAddrs = true
	}

	im.stateMu.Lock()
	defer im.stateMu.Unlock()

	// Check if state changed
	stateChanged := false
	if im.state.Up != isUp {
		im.state.Up = isUp
		stateChanged = true
	}
	if im.state.Online != hasAddrs {
		im.state.Online = hasAddrs
		stateChanged = true
	}

	// if im.state.MACAddr != attrs.HardwareAddr {
	// 	im.state.MACAddr = attrs.HardwareAddr
	// 	stateChanged = true
	// }

	// Update IP addresses
	if err := im.updateIPAddresses(nl); err != nil {
		im.logger.Error().Err(err).Msg("failed to update IP addresses")
	}

	// im.state.LastUpdated = time.Now() // TODO: remove this

	// Notify callback if state changed
	if stateChanged && im.onStateChange != nil {
		state := *im.state
		im.onStateChange(&state)
	}

	return nil
}

// updateIPAddresses updates the IP addresses in the state
func (im *InterfaceManager) updateIPAddresses(nl *link.Link) error {
	addrs, err := nl.AddrList(link.AfUnspec)
	if err != nil {
		return fmt.Errorf("failed to get addresses: %w", err)
	}

	var ipv4Addresses []string
	var ipv6Addresses []types.IPv6Address
	var ipv4Addr, ipv6Addr string
	var ipv6LinkLocal string

	for _, addr := range addrs {
		if addr.IP.To4() != nil {
			// IPv4 address
			ipv4Addresses = append(ipv4Addresses, addr.IPNet.String())
			if ipv4Addr == "" {
				ipv4Addr = addr.IP.String()
			}
		} else if addr.IP.To16() != nil {
			// IPv6 address
			if addr.IP.IsLinkLocalUnicast() {
				ipv6LinkLocal = addr.IP.String()
			} else if addr.IP.IsGlobalUnicast() {
				ipv6Addresses = append(ipv6Addresses, types.IPv6Address{
					Address: addr.IP,
					Prefix:  *addr.IPNet,
					Scope:   addr.Scope,
				})
				if ipv6Addr == "" {
					ipv6Addr = addr.IP.String()
				}
			}
		}
	}

	im.state.IPv4Addresses = ipv4Addresses
	im.state.IPv6Addresses = ipv6Addresses
	im.state.IPv6LinkLocal = ipv6LinkLocal

	return nil
}

// updateStateFromDHCPLease updates the state from a DHCP lease
func (im *InterfaceManager) updateStateFromDHCPLease(lease *types.DHCPLease) {
	im.stateMu.Lock()
	defer im.stateMu.Unlock()

	im.state.DHCPLease4 = lease

	// Update resolv.conf with DNS information
	if im.resolvConf != nil {
		im.resolvConf.UpdateFromLease(lease)
	}
}

func (im *InterfaceManager) ReconcileLinkAddrs(ipv4Config *types.IPv4StaticConfig) error {
	// nl := getNetlinkManager()
	// return nl.ReconcileLinkAddrs(ipv4Config)
	return nil
}

// applyDHCPLease applies DHCP lease configuration using ReconcileLinkAddrs
func (im *InterfaceManager) applyDHCPLease(lease *types.DHCPLease) error {
	// Convert DHCP lease to IPv4Config
	// ipv4Config := im.convertDHCPLeaseToIPv4Config(lease)

	// Apply the configuration using ReconcileLinkAddrs
	// return im.ReconcileLinkAddrs(ipv4Config)
	return nil
}

// convertDHCPLeaseToIPv4Config converts a DHCP lease to IPv4Config
// func (im *InterfaceManager) convertDHCPLeaseToIPv4Config(lease *types.DHCPLease) *netif.IPv4Config {
// 	// Create IPNet from IP and netmask
// 	ipNet := &net.IPNet{
// 		IP:   lease.IPAddress,
// 		Mask: net.IPMask(lease.Netmask),
// 	}

// 	// Create IPv4Address
// 	ipv4Addr := netif.IPv4Address{
// 		Address:   *ipNet,
// 		Gateway:   lease.Gateway,
// 		Secondary: false,
// 		Permanent: false,
// 	}

// 	// Create IPv4Config
// 	return &netif.IPv4Config{
// 		Addresses:   []netif.IPv4Address{ipv4Addr},
// 		Nameservers: lease.DNS,
// 		SearchList:  lease.SearchList,
// 		Domain:      lease.Domain,
// 		Interface:   im.ifaceName,
// 	}
// }