Update RetroArch playlist files with missing roms

update_retroarch_playlists.groovy

import java.util.zip.*
  
// Update these two lines to match the location of your playlists and what extensions to skip
playlistDir = "C:\\Users\\brobert\\AppData\\Roaming\\RetroArch\\playlists" as File
ignoreExtensions="cht|clt|sav|dtc|txt|html"

def appendPlaylist(playlistFile, path) {
    println("Appending ${path}")
    // Mac | Linux users change this to forward slash, I could have used the path separator property but I was lazy.
    name = path.substring(path.lastIndexOf('\\')+1)
    playlistFile.append("""${path}
${name}
DETECT
DETECT
0|crc
${playlistFile.name}
""")
}

playlistDir.eachFile{playlistFile ->
    println "Playlist file ${playlistFile.name}"
    entries = [:]
    counter = 0
    entry = {}
    playlistFile.eachLine{line ->
        switch (counter) {
            case 0:
                entry = {}
                path = line.contains("#") ? line.substring(0, line.indexOf('#')) : line
                entry.path = path
                break
            case 1:
                entry.name = line
                break
            case 4:
                entry.crc = line
                entries[entry.path]=entry
                break
        }
        counter = (counter + 1) % 6
    }
    println "${entries.size()} entries found in file"
    
    firstEntry = entries.values().toArray()[0]
    romFile = firstEntry.path as File
    romDirectory = romFile.parentFile
    println "Detected folder is ${romDirectory.path}"
    
    missing = 0
    present = 0
    romDirectory.eachFile{rom ->
        if (rom.isDirectory()) return
        ext = rom.path.substring(rom.path.lastIndexOf('.')+1).toLowerCase()
        if (ignoreExtensions.contains(ext)) return
        if (entries[rom.path] == null) {
            missing++
            if (ext.equals("zip")) {
                // ZIP contents
                ZipFile file = new ZipFile(rom)
                file.entries().each { entry ->
                    name = entry.name.toLowerCase()
                    if (!name.endsWith("html") && !name.endsWith("txt") && !name.endsWith("me")) {
                        appendPlaylist(playlistFile, "${rom.path}#${entry.name}")
                    }
                }
            } else {
                // Basic rom path
                appendPlaylist(playlistFile, "${rom.path}")
            }
        } else {
            present++
        }
    }
    println "Directory scan found ${missing+present} files, ${present} are in playlist, ${missing} are missing from playlist"
}

Highly recommended: Backup your playlist files first and hand-edit them when this is done to ensure everything looks right