Re-order GoPro files in alphabetical order (renaming)

gopro-file-reordered.kt

// Re-order GoPro files in alphabetical order (fine rename)
// Probably does not cover all use cases.
// more info about GoPro naming can be found here https://community.gopro.com/s/article/GoPro-Camera-File-Naming-Convention?language=en_US

import java.io.File

fun main(args: Array<String>) {

    val dir = File("PATH_TO_DIR_CONTAINS_MP4_FILES")
    dir.listFiles { dir, name ->

        val part1 = name.substring(0, 4)
        val part2 = name.substring(4, name.lastIndexOf("."))

        if (part1.startsWith("GX") || part1.startsWith("GH")) {
            val index = part1.substring(2, 4)
            val newName = "VIDEO_${part2}_$index.MP4"
            println("$dir/$newName")
            File(dir, name).renameTo(File(dir, newName))
        }

        true
    }
}