package utils

import (
	"errors"
	"io"
	"log"
	"os"
)

var MissingTarget = errors.New("Missing write target")

func NewWriter(paths ...string) (io.Writer, error) {
	if len(paths) == 0 {
		return nil, MissingTarget
	} else if len(paths) == 1 {
		return stringToWriter(paths[0])
	}
	var writers []io.Writer
	for _, path := range paths {
		writer, err := stringToWriter(path)
		if err != nil {
			return nil, err
		}
		writers = append(writers, writer)
	}
	ioWriter := io.MultiWriter(writers...)
	return ioWriter, nil
}

func MustWriter(paths ...string) io.Writer {
	writer, err := NewWriter(paths...)
	if err != nil {
		log.Fatalln(err)
	}
	return writer
}

var stringWriter = map[string]io.Writer{
	"stdout":  os.Stdout,
	"stderr":  os.Stderr,
	"stdin":   os.Stdin,
	"discard": io.Discard,
}

func stringToWriter(path string) (io.Writer, error) {
	if writer, ok := stringWriter[path]; ok {
		return writer, nil
	}
	f, err := os.OpenFile(path, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0666)
	return f, err
}