package main

import (
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"os"
	"strings"
)

func main() {
	files, err := ioutil.ReadDir("./")
	if err != nil {
		log.Fatal(err)
	}

	for _, f := range files {
		currentName := f.Name()
		if strings.HasSuffix(currentName, ".png") {
			if strings.Contains(currentName, "_") {
				tmpSplit := strings.Split(currentName, "_")
				newName := fmt.Sprintf("combined/%s", tmpSplit[len(tmpSplit)-1])
				if _, err := os.Stat(newName); os.IsNotExist(err) {
					err := copyFile(currentName, newName)
					if err != nil {
						log.Printf("failed to rename '%s' to '%s': %v", currentName, newName, err)
					}
				}

			}
		}
	}
}

func copyFile(src, dst string) error {
	in, err := os.Open(src)
	if err != nil {
		return err
	}
	defer in.Close()

	out, err := os.Create(dst)
	if err != nil {
		return err
	}
	defer out.Close()

	_, err = io.Copy(out, in)
	if err != nil {
		return err
	}
	return out.Close()
}