package main

import (
    "fmt"
    "os"
    "errors"
    "io"
    "strings"
    "regexp"


    "github.com/charmbracelet/log"
    "github.com/h2non/filetype"
)


func getExtension(filePath string) (extension string, err error) {
    buf, _ := os.ReadFile(filePath)

    kind, _ := filetype.Match(buf)
    if kind == filetype.Unknown {
        return "", errors.New(fmt.Sprintf("Unknown file type."))
    }

    return kind.Extension, nil
}

func copyFile(src, dst string) (error) {
    log.Debugf("Copying file \"%s\" to \"%s\"", src, dst)

    // Get source file stats (e.g. permissions).
    srcFileStat, err := os.Stat(src)
    if err != nil {
        return fmt.Errorf("failed to get file info for %s: %v", src, err)
    }

    // Check whether the source is a regular file.
    if !srcFileStat.Mode().IsRegular() {
        return fmt.Errorf("source file %s is not a regular file", src)
    }

    // Open the source file.
    srcFile, err := os.Open(src)
    if err != nil {
        return fmt.Errorf("failed to open source file %s: %v", src, err)
    }
    defer srcFile.Close()

    // Create the destination file, with the same permissions as the source.
    dstFile, err := os.OpenFile(dst, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, srcFileStat.Mode())
    if err != nil {
        return fmt.Errorf("failed to create destination file %s: %v", dst, err)
    }
    defer dstFile.Close()

    // Copy the file contents from source to destination.
    if _, err := io.Copy(dstFile, srcFile); err != nil {
        return fmt.Errorf("error copying file from %s to %s: %v", src, dst, err)
    }

    return nil
}

func replaceDelimiters(input string) string {
    replacer := strings.NewReplacer(
        "/", "／",
        "\\", "＼",
    )
    return replacer.Replace(input)
}

func sanitizeFilename(filename string) string {
    invalidFilenameChars := regexp.MustCompile(`[^a-zA-Z0-9._-／＼[[:blank:]]]+`)

    sanitized := invalidFilenameChars.ReplaceAllString(filename, "-")

    // Trim any leading or trailing spaces or underscores.
    sanitized = strings.Trim(sanitized, " _.")

    if sanitized == "" {
        sanitized = " "
    }

    return sanitized
}