package bridge

import (
	"fmt"
	"os/exec"
	"strconv"
)

type vlanMember struct {
	Device   string
	VID      int
	Untagged bool
	Self     bool
}

func members(v *BridgeVLAN) map[vlanMember]bool {
	result := map[vlanMember]bool{}
	if v == nil || v.Disabled {
		return result
	}
	for _, vid := range parseVLANRange(v.VlanIDs) {
		for _, dev := range v.Tagged {
			result[vlanMember{dev, vid, false, dev == v.Bridge}] = true
		}
		for _, dev := range v.Untagged {
			result[vlanMember{dev, vid, true, dev == v.Bridge}] = true
		}
	}
	return result
}
func changeMember(action string, m vlanMember) error {
	args := []string{"vlan", action, "dev", m.Device, "vid", strconv.Itoa(m.VID)}
	if m.Self {
		args = append(args, "self")
	}
	if action == "add" && m.Untagged {
		args = append(args, "untagged")
	}
	out, err := exec.Command("bridge", args...).CombinedOutput()
	if err != nil {
		return fmt.Errorf("bridge VLAN %v failed: %s: %w", args, out, err)
	}
	return nil
}
func syncMembers(old, next *BridgeVLAN) error {
	before, after := members(old), members(next)
	var removed, added []vlanMember
	rollback := func() {
		for _, m := range added {
			_ = changeMember("del", m)
		}
		for _, m := range removed {
			_ = changeMember("add", m)
		}
	}
	for m := range before {
		if !after[m] {
			if err := changeMember("del", m); err != nil {
				rollback()
				return err
			}
			removed = append(removed, m)
		}
	}
	for m := range after {
		if !before[m] {
			if err := changeMember("add", m); err != nil {
				rollback()
				return err
			}
			added = append(added, m)
		}
	}
	return nil
}