Program.cs

using GBX.NET;
using GBX.NET.Engines.Game;
using GBX.NET.LZO;
using System;
using Blocklist;
using Sharprompt;
using Microsoft.Extensions.Logging;

GBX.NET.Lzo.SetLzo(typeof(GBX.NET.LZO.MiniLZO)); //needed

if (args.Length < 1){
    Console.WriteLine("Please drag your TM2 map file on this executable.");
    return 0;
} 

//shamelessly stolen from https://github.com/BigBang1112/gbx-net/blob/master/Samples/SolidExtract/Program.cs
var logger = LoggerFactory.Create( builder => {
    builder.AddSimpleConsole(options => {
        options.IncludeScopes = true;
        options.SingleLine = true;
        options.TimestampFormat = "HH:mm:ss ";
    });
    builder.SetMinimumLevel(args.Contains("-v") ? LogLevel.Debug : LogLevel.Information);
}).CreateLogger<Program>();


int blockHeight(string name){
    //Special rules:
    //all blocks from TM2 are raised by 8 because some space got added under the stadium.
    //However, terrain blocks' origin has changed and as such those must get lowered by 9 instead
    //except for StadiumDirtHill whose origin has changed the other way and has to get lowered by 7.
    if (name == "StadiumPool" || name == "StadiumWater" || name == "StadiumDirtBorder" || name == "StadiumDirt") return 9; else if (name == "StadiumDirtHill") return 7; else return 8;
}

string getVersion(CGameCtnChallenge map){
    
    if (map.Chunks.TryGet(0x05F, out _)) return "TM2020";
    if (map.TitleID != null && (map.TitleID == "TMCE@nadeolabs" || map.TitleID == "TMTurbo@nadeolabs")) return "TMTurbo";
    if (map.TitleID != null) return "TM2";
    if (map.Thumbnail != null) return "TMForever";
    return "TM1";
}

void unMapTMForever(CGameCtnChallenge map, string mapName, string path = ""){
        var didiask = false;
        var minheight = 1;
        var defaultMap = GameBox.ParseNode<CGameCtnChallenge>("DefaultForever.Challenge.Gbx", logger:(args.Contains("-v")? logger:null));
        defaultMap.MapName = mapName;
        defaultMap.Blocks!.Clear();
        foreach(CGameCtnBlock block in map.Blocks!){
            //Special block rules
            block.Coord = new Int3(block.Coord.X, block.Coord.Y - blockHeight(block.Name) , block.Coord.Z);

            if (block.Name == "StadiumCircuitToRoadMain") block.Name = "StadiumPlatformToRoadMain"; //Nadeo has added a new block in TM2 that looks the same except it's Circuit (blocky platform). I doubt this is a big change to 99% of maps (remaining are prob kacky or trial using a trick with that block for some reason)

            block.WaypointSpecialProperty = null;   //Remove TM2-only things

            //just in case the user wants some additional blocks under their map
            if (block.Coord.Y == 0 && !didiask && TMNF.Blocks.Contains(block.Name) && !(blockHeight(block.Name) == 9)){
                didiask = true;
                if (Prompt.Confirm("Blocks at height 0 (right under the grass) have been detected. These Blocks will crash the game, except if TMUnlimiter is loaded. Do you wish to make the map TMUnlimiter-only?", false)){
                    minheight = 0;
                }
            }


            if ((block.Coord.Y >= minheight && block.Coord.Y <= 31) || blockHeight(block.Name) == 9){
                if (TMNF.Blocks.Contains(block.Name)){
                    //FIX FLAGS                                                                                     //Part of a bigger structure        //reference (only works for inflatables rn)
                    block.Flags = (block.Variant == null ? 0 : (int)block.Variant) + (block.IsGround ? 4096 : 0) + (block.Flags & 0b100000000000000) + (block.Name.Contains("Inflatable")? (block.Flags & 0b1000000000000000) : 0);
                    //fix filerefs
                    if (block.Skin!=null){
                        block.Skin.PackDesc = block.Skin.PackDesc! with {Version = 2};
                        block.Skin.ParentPackDesc = block.Skin.ParentPackDesc! with {Version = 2};
                        block.Skin.Text = "";
                    }
                    //Copy blocks over
                    defaultMap.Blocks.Add(block);
                    //copy other stuff
                    
                }
            }
        }
        defaultMap.Decoration = map.Decoration; //mood
        defaultMap.Thumbnail = map.Thumbnail; //thumbnail
        defaultMap.TMObjective_NbLaps = map.TMObjective_NbLaps; //number of laps
        defaultMap.Save(path + mapName + ".Challenge.Gbx");
        // do not copy the medal/author times. As physics change, this becomes irrelevant. just validate again lol
}

void unMapTMNESWC(CGameCtnChallenge map, string mapName, string version, string path = ""){
    var defaultMap = GameBox.ParseNode<CGameCtnChallenge>("DefaultESWC.Challenge.Gbx", logger:(args.Contains("-v")? logger:null));
        defaultMap.MapName = mapName;
        defaultMap.Blocks!.Clear();
        foreach(CGameCtnBlock block in map.Blocks!){
            if (version == "TM2"){
                block.Coord = new Int3(block.Coord.X, block.Coord.Y - 8, block.Coord.Z); //tmneswc has no terrain so SURELY i will not have any problem with that
                block.WaypointSpecialProperty = null;   //Remove TM2-only things
            }

            if (31 >= block.Coord.Y && block.Coord.Y >= 1 && TMNESWC.Blocks.Contains(block.Name)){
                block.Flags = (block.Variant == null ? 0 : (int)block.Variant) + (block.IsGround ? 4096 : 0) + (block.Flags & 0b100000000000000) + (block.Name.Contains("Inflatable")? (block.Flags & 0b1000000000000000) : 0);
                //fix filerefs
                if (block.Skin!=null){
                    block.Skin.PackDesc = block.Skin.PackDesc! with {Version = 1};
                    block.Skin.ParentPackDesc = block.Skin.ParentPackDesc! with {Version = 1};
                    block.Skin.Text = "";
                }
                defaultMap.Blocks.Add(block);
            }
        }
        defaultMap.Thumbnail = map.Thumbnail; //thumbnail
        defaultMap.TMObjective_NbLaps = map.TMObjective_NbLaps; //number of laps
        defaultMap.Save(path + mapName + ".Challenge.Gbx", IDRemap.TrackMania2006);
}

if (Directory.Exists(args[0])){
    //BATCH
    logger.LogInformation("Batch computing enabled. All files in the provided folder will be processed.");
    var game = Prompt.Select("What game will the converted maps be for? Use arrow keys to select.", new[] {"TrackMania Nations/United Forever", "TrackMania Nations ESWC"}, defaultValue:"TrackMania Nations/United Forever");
    DirectoryInfo sDir = new DirectoryInfo(args[0]);
    Directory.CreateDirectory(sDir.Name + "-exported");
    var eDir = sDir.FullName.TrimEnd('/', '\\') + "-exported/";
    logger.LogInformation("Maps will be saved in " +eDir);
    foreach (FileInfo file in sDir.GetFiles()){
        try{
            var node = GameBox.ParseNode(Path.Combine(sDir.FullName,file.Name) , logger:(args.Contains("-v")? logger:null));
            if (node is CGameCtnChallenge map){
                if (game == "TrackMania Nations/United Forever" && getVersion(map) == "TMForever"){
                    logger.LogWarning("File {0} is from the same game than the destination - skipping file.", file.Name);
                } else {
                    logger.LogInformation("Exporting " + file.Name + " to " + game + "...");
                    if (game == "TrackMania Nations/United Forever") unMapTMForever(map, map.MapName, eDir);
                    else unMapTMNESWC(map, map.MapName, getVersion(map), eDir);
                }
            } else {
                logger.LogWarning("File "+file.Name+" is not a challenge! Skipping.");
            }
        } catch (Exception e){
            logger.LogWarning("Error : " + e.Message + " Skipping file " + file.Name);
        }
    }

} else if (File.Exists(args[0])){
    Node? node;
    try{
        node = GameBox.ParseNode(args[0], logger:(args.Contains("-v")? logger:null));
    } catch (Exception e){
        logger.LogError("Error : " + e.Message + " Press any key to continue...");
        Console.ReadKey();
        return 0;
    }
    if (node is CGameCtnChallenge map){
        var version = getVersion(map);
        if (version != "TM2" && version != "TMForever"){
            logger.LogError("This is not a TM2 or TMForever map! Press any key to continue...");
            Console.ReadKey();
            return 0;
        }

        var game = version == "TM2" ? Prompt.Select("What game will this map be for? Use arrow keys to select.", new[] {"TrackMania Nations/United Forever", "TrackMania Nations ESWC"}) : "TrackMania Nations ESWC";
        var mapName = Prompt.Input<string>("What do you want your map to be named?", validators: new[] {Validators.Required()});
        logger.LogInformation("Exporting " + mapName + " to " + game + "...");
        //TMNF/UF
        if (game != "TrackMania Nations ESWC"){
            unMapTMForever(map, mapName);
        //TMNESWC
        } else {
            unMapTMNESWC(map, mapName, version);
        }
        logger.LogInformation("Done. Saved as " + mapName + ".Challenge.Gbx");
    } else {
        logger.LogError("File is not a challenge! Press any key to continue...");
        Console.ReadKey();
        return 0;
    }
} else {
    logger.LogError("File does not exist! Press any key to continue...");
    Console.ReadKey();
    return 0;
}


return 0;