package config

import (
	"fmt"
	"strings"
)

type Interface struct {
	Zone      string           `yaml:"zone,omitempty"`
	Interface string           `yaml:"interface"`
	Options   InterfaceOptions `yaml:"options,omitempty"`
}

type InterfaceOptions struct {
	// Rule generation options
	DHCP      bool  `yaml:"dhcp,omitempty"`
	TCPFlags  *bool `yaml:"tcpflags,omitempty"`
	NoSmurfs  bool  `yaml:"nosmurfs,omitempty"`
	RouteBack *bool `yaml:"routeback,omitempty"`
	Bridge    bool  `yaml:"bridge,omitempty"`
	DestOnly  bool  `yaml:"destonly,omitempty"`
	Unmanaged bool  `yaml:"unmanaged,omitempty"`
	Upnp      bool  `yaml:"upnp,omitempty"`

	// Startup behavior
	Optional bool `yaml:"optional,omitempty"`
	Required bool `yaml:"required,omitempty"`
	Wait     int  `yaml:"wait,omitempty"`

	// Logical-to-physical mapping
	Physical string `yaml:"physical,omitempty"`

	// TCP MSS clamping for forwarded SYN packets
	MSS int `yaml:"mss,omitempty"`

	// Limit zone to specific networks
	Nets []string `yaml:"nets,omitempty"`

	// Sysctl adjustments (applied on startup)
	RouteFilter *int  `yaml:"routefilter,omitempty"`
	LogMartians *bool `yaml:"logmartians,omitempty"`
	ArpFilter   *bool `yaml:"arp_filter,omitempty"`
	ArpIgnore   *int  `yaml:"arp_ignore,omitempty"`
	ProxyArp    *bool `yaml:"proxyarp,omitempty"`
	SourceRoute *bool `yaml:"sourceroute,omitempty"`

	// IPv6: controls acceptance of Router Advertisements (0/1/2)
	AcceptRA *int `yaml:"accept_ra,omitempty"`
}

// PhysicalName returns the actual interface name (physical if set, else logical).
func (iface *Interface) PhysicalName() string {
	if iface.Options.Physical != "" {
		return iface.Options.Physical
	}
	return iface.Interface
}

// IsWildcard returns true if the interface matches multiple devices (e.g. "ppp+").
func (iface *Interface) IsWildcard() bool {
	return strings.HasSuffix(iface.PhysicalName(), "+")
}

func (c *Config) validateInterfaces() error {
	seen := make(map[string]bool)
	fwZone := c.FirewallZone()

	for i, iface := range c.Interfaces {
		if iface.Interface == "" {
			return fmt.Errorf("interface[%d]: interface name required", i)
		}
		if strings.Contains(iface.Interface, ":") {
			return fmt.Errorf("interface[%d] %q: virtual interfaces (e.g. eth0:0) not supported; use the physical option instead", i, iface.Interface)
		}

		if iface.Zone != "" {
			if iface.Zone == fwZone {
				return fmt.Errorf("interface[%d] %q: firewall zone must not be listed in interfaces", i, iface.Interface)
			}
			if _, ok := c.Zones[iface.Zone]; !ok {
				return fmt.Errorf("interface[%d] %q: zone %q not defined", i, iface.Interface, iface.Zone)
			}
		}

		if iface.Options.Unmanaged && iface.Zone != "" {
			return fmt.Errorf("interface[%d] %q: unmanaged interfaces must have an empty zone", i, iface.Interface)
		}
		if iface.Options.Optional && iface.Options.Required {
			return fmt.Errorf("interface[%d] %q: optional and required are mutually exclusive", i, iface.Interface)
		}

		if seen[iface.Interface] {
			return fmt.Errorf("interface[%d]: duplicate interface %q", i, iface.Interface)
		}
		seen[iface.Interface] = true
	}
	return nil
}