package config

import "fmt"

type ArpAction string

const (
	ArpAccept ArpAction = "accept"
	ArpDrop   ArpAction = "drop"
	ArpSNAT   ArpAction = "snat"
	ArpDNAT   ArpAction = "dnat"
	ArpSMAT   ArpAction = "smat"
	ArpDMAT   ArpAction = "dmat"
)

type ArpRule struct {
	// Action to take on matching ARP packets.
	Action ArpAction `yaml:"action"`

	// ActionAddress is the IP address to rewrite to (required for snat/dnat).
	ActionAddress string `yaml:"action_address,omitempty"`

	// ActionMAC is the MAC address to rewrite to (required for smat/dmat).
	ActionMAC string `yaml:"action_mac,omitempty"`

	// Source zone/address spec.
	Source string `yaml:"source,omitempty"`

	// Dest zone/address spec.
	Dest string `yaml:"dest,omitempty"`

	// Opcode is the ARP operation code to match (e.g. 1=request, 2=reply).
	Opcode int `yaml:"opcode,omitempty"`

	Comment string `yaml:"comment,omitempty"`
}

var validArpActions = map[ArpAction]bool{
	ArpAccept: true, ArpDrop: true,
	ArpSNAT: true, ArpDNAT: true,
	ArpSMAT: true, ArpDMAT: true,
}

func (c *Config) validateArpRules() error {
	for i, a := range c.ArpRules {
		if !validArpActions[a.Action] {
			return fmt.Errorf("arprules[%d]: unknown action %q", i, a.Action)
		}

		if (a.Action == ArpSNAT || a.Action == ArpDNAT) && a.ActionAddress == "" {
			return fmt.Errorf("arprules[%d]: action_address required for %s action", i, a.Action)
		}

		if (a.Action == ArpSMAT || a.Action == ArpDMAT) && a.ActionMAC == "" {
			return fmt.Errorf("arprules[%d]: action_mac required for %s action", i, a.Action)
		}

		if a.Source == "" && a.Dest == "" {
			return fmt.Errorf("arprules[%d]: source or dest required", i)
		}
	}
	return nil
}