using System.Diagnostics;
using MrGameEng.Atlases;

if (args.Length < 2 || args.Contains("--help") || args.Contains("-h"))
{
    Console.WriteLine(
        """
        MrGameEng.AtlasTool — packs a directory tree of images into texture atlases.

        Usage: MrGameEng.AtlasTool <source-dir> <output-dir> [options]

        Options:
          --group-depth <n>   directories forming one atlas (0 = single atlas; default 1)
          --page-size <n>     maximum page size in pixels (default 2048)
          --padding <n>       gap between images in pixels (default 2)
          --root-name <name>  atlas name for files above group depth (default "Atlas")
          --force             rebuild even when sources are unchanged
        """
    );
    return args.Length < 2 && !args.Contains("--help") && !args.Contains("-h") ? 1 : 0;
}

int Option(string name, int fallback)
{
    var index = Array.IndexOf(args, name);
    if (index < 0)
    {
        return fallback;
    }

    if (index + 1 < args.Length && int.TryParse(args[index + 1], out var value) && value >= 0)
    {
        return value;
    }

    Console.Error.WriteLine($"Option {name} requires a non-negative integer value.");
    Environment.Exit(1);
    return fallback; // недостижимо
}

var rootNameIndex = Array.IndexOf(args, "--root-name");
var options = new AtlasBuildOptions
{
    SourceDirectory = args[0],
    OutputDirectory = args[1],
    GroupDepth = Option("--group-depth", 1),
    MaxPageSize = Option("--page-size", 2048),
    Padding = Option("--padding", 2),
    RootAtlasName =
        rootNameIndex >= 0 && rootNameIndex + 1 < args.Length ? args[rootNameIndex + 1] : "Atlas",
    Force = args.Contains("--force"),
};

var stopwatch = Stopwatch.StartNew();
var result = AtlasBuilder.Build(options);
stopwatch.Stop();

foreach (var group in result.Groups)
{
    Console.WriteLine(
        group.Skipped
            ? $"  {group.Name}: up to date ({group.RegionCount} regions, {group.PageCount} pages)"
            : $"  {group.Name}: {group.RegionCount} regions -> {group.PageCount} pages"
    );
}

foreach (var orphan in result.DeletedOrphans)
{
    Console.WriteLine($"  deleted orphan {orphan}");
}

var built = result.Groups.Count(g => !g.Skipped);
Console.WriteLine(
    $"Done: {built} atlases built, {result.Groups.Count - built} up to date, {stopwatch.Elapsed.TotalSeconds:F1}s."
);
return 0;