package oplcli

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

func scanGameFileForID(filename string) (string, error) {
	file, err := os.Open(filename)
	if err != nil {
		return "", fmt.Errorf("failed to open file: %w", err)
	}
	defer file.Close()

	const bufferSize = 1024 * 1024 // 1MB
	buffer := make([]byte, bufferSize)

	n, err := file.Read(buffer)
	if err != nil && n == 0 {
		return "", fmt.Errorf("failed to read file: %w", err)
	}

	pattern := regexp.MustCompile(`(SLUS|SLES|SLPS|SCUS|SCES|SCPS)[_-]?\d{3}[\._]\d{2}`)

	match := pattern.Find(buffer[:n])
	if match != nil {
		gameID := string(match)
		return normalizeGameID(gameID), nil
	}

	return "", fmt.Errorf("no PS2 game ID found in file")
}

func normalizeGameID(id string) string {
	s := strings.ReplaceAll(id, "_", "-")
	s = strings.ReplaceAll(s, ".", "")
	s = strings.ToUpper(s)

	return s
}

func renameGameFile(filePath, gameName string) (string, error) {
	ext := filepath.Ext(filePath)
	dir := filepath.Dir(filePath)

	newPath := filepath.Join(dir, gameName+ext)

	if filePath == newPath {
		return filePath, nil
	}

	// Do not overwrite existing files
	if _, err := os.Stat(newPath); err == nil {
		return "", fmt.Errorf("file already exists: %s", newPath)
	} else if !os.IsNotExist(err) {
		return "", fmt.Errorf("failed to check destination: %w", err)
	}

	// rename file
	err := os.Rename(filePath, newPath)
	if err != nil {
		return "", fmt.Errorf("failed to rename file: %w", err)
	}

	return newPath, nil
}