package main

import (
	"fmt"
	"os"
	"path/filepath"
	"regexp"
	"slices"
	"strconv"
	"strings"
)

type Pair struct {
	originFull string
	newName    string
	newFull    string
	skip       bool
}

var (
	exts = []string{
		".jpg", ".jpeg", ".jfif",
		".png", ".gif", ".webp",
		".mp4", ".MP4", ".webm",
	}

	renameSlice []Pair

	pattern, _ = regexp.Compile("^\\d+(-\\d)?$") // 123456789, 123456789-1
)

func generateName(baseName string) string {
	counter := 1
	name := baseName

loop:
	for {
		for _, pair := range renameSlice {
			if pair.newName == name {
				name = fmt.Sprintf("%s-%d", baseName, counter)
				counter++
				continue loop
			}
		}
		break
	}

	return name
}

func main() {
	entries, err := os.ReadDir(".")
	if err != nil {
		panic(err)
	}

	renameSlice = make([]Pair, 0)

	for _, entry := range entries {
		if entry.IsDir() {
			continue
		}

		ext := filepath.Ext(entry.Name())
		extL := strings.ToLower(ext)
		if !slices.Contains(exts, extL) {
			continue
		}

		if pattern.MatchString(strings.TrimSuffix(entry.Name(), ext)) {
			renameSlice = append(renameSlice, Pair{
				originFull: entry.Name(),
				skip:       true})
			continue
		}

		info, err := entry.Info()
		if err != nil {
			panic(err)
		}

		newName := generateName(strconv.FormatInt(info.ModTime().Unix(), 10))

		renameSlice = append(renameSlice, Pair{
			originFull: entry.Name(),
			newName:    newName,
			newFull:    newName + extL})
	}

	counter := 0
	for i, pair := range renameSlice {
		if pair.skip || pair.originFull == pair.newFull {
			continue
		}

		fmt.Printf("%d. %s --> %s\n", i+1, pair.originFull, pair.newFull)
		err := os.Rename(pair.originFull, pair.newFull)
		if err != nil {
			panic(err)
		}
		counter++
	}

	fmt.Printf("Total: %d\n", len(renameSlice))
	fmt.Printf("Renamed: %d\n", counter)
}