isle/go/cmd/entrypoint/flags.go

package main

import (
	"encoding"
	"errors"
	"fmt"
	"isle/nebula"
	"isle/toolkit"
	"net"
	"net/netip"
	"strconv"

	"dev.mediocregopher.com/mediocre-go-lib.git/mlog"
)

type textUnmarshaler[T any] interface {
	encoding.TextUnmarshaler
	*T
}

type textUnmarshalerFlag[T encoding.TextMarshaler, P textUnmarshaler[T]] struct {
	V T
}

func (f *textUnmarshalerFlag[T, P]) Set(v string) error {
	return P(&(f.V)).UnmarshalText([]byte(v))
}

func (f *textUnmarshalerFlag[T, P]) String() string {
	b, err := f.V.MarshalText()
	if err != nil {
		panic(fmt.Sprintf("calling MarshalText on %#v: %v", f.V, err))
	}
	return string(b)
}

func (f *textUnmarshalerFlag[T, P]) Type() string { return "string" }

type (
	hostNameFlag = textUnmarshalerFlag[nebula.HostName, *nebula.HostName]
	ipNetFlag    = textUnmarshalerFlag[nebula.IPNet, *nebula.IPNet]
	ipFlag       = textUnmarshalerFlag[netip.Addr, *netip.Addr]
)

////////////////////////////////////////////////////////////////////////////////

type (
	addrFlagStr string
	addrFlag    = textUnmarshalerFlag[addrFlagStr, *addrFlagStr]
)

func (f addrFlagStr) MarshalText() ([]byte, error) {
	return []byte(f), nil
}

func (f *addrFlagStr) UnmarshalText(b []byte) error {
	str := string(b)

	_, portStr, err := net.SplitHostPort(str)
	if err != nil {
		return err
	}

	if _, err := strconv.ParseUint(portStr, 10, 16); err != nil {
		return fmt.Errorf("invalid port %q", portStr)
	}

	*f = addrFlagStr(str)
	return nil
}

////////////////////////////////////////////////////////////////////////////////

type logLevelFlag struct {
	mlog.Level
}

func (f *logLevelFlag) Set(v string) error {
	f.Level = toolkit.LogLevelFromString(v)
	if f.Level == nil {
		return errors.New("not a valid log level")
	}
	return nil
}

func (f *logLevelFlag) String() string {
	if f.Level == nil {
		return "UNKNOWN"
	}
	return f.Level.String()
}

func (f *logLevelFlag) Type() string { return "string" }