// Package lib contains functions useful for most programs.
package lib

import (
	"fmt"
	"os"
	"path/filepath"
)

var progname = filepath.Base(os.Args[0])

// Warnx displays a formatted error message to standard error, à la
// warnx(3).
func Warnx(format string, a ...interface{}) (int, error) {
	format = fmt.Sprintf("[%s] %s", progname, format)
	format += "\n"
	return fmt.Fprintf(os.Stderr, format, a...)
}

// Warn displays a formatted error message to standard output,
// appending the error string, à la warn(3).
func Warn(err error, format string, a ...interface{}) (int, error) {
	format = fmt.Sprintf("[%s] %s", progname, format)
	format += ": %v\n"
	a = append(a, err)
	return fmt.Fprintf(os.Stderr, format, a...)
}

// Errx displays a formatted error message to standard error and exits
// with the status code from `exit`, à la errx(3).
func Errx(exit int, format string, a ...interface{}) {
	format = fmt.Sprintf("[%s] %s", progname, format)
	format += "\n"
	fmt.Fprintf(os.Stderr, format, a...)
	os.Exit(exit)
}

// Err displays a formatting error message to standard error,
// appending the error string, and exits with the status code from
// `exit`, à la err(3).
func Err(exit int, err error, format string, a ...interface{}) {
	format = fmt.Sprintf("[%s] %s", progname, format)
	format += ": %v\n"
	a = append(a, err)
	fmt.Fprintf(os.Stderr, format, a...)
	os.Exit(exit)
}