package sortcli

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

func Open(sources []string) io.Reader {
	rs := make([]io.Reader, 0, len(sources))

	for _, source := range sources {
		var r io.Reader

		if source == "-" {
			r = os.Stdin
		} else {
			if _, err := os.Stat(source); err != nil {
				log.Fatalf("file not exists: %s", source)
			}

			f, err := os.Open(source)
			if err != nil {
				log.Fatalf("file open file: %s", err)
			}

			r = f
		}

		rs = append(rs, r)
	}

	return io.MultiReader(rs...)
}