poe2-bot/tools/OcrDaemon/Daemon.cs

namespace OcrDaemon;

using System.Text.Json;
using System.Text.Json.Serialization;
using Tesseract;

static class Daemon
{
    private static readonly JsonSerializerOptions JsonOptions = new()
    {
        PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
        DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull,
    };

    public static int Run()
    {
        ScreenCapture.InitDpiAwareness();

        // Pre-create the Tesseract OCR engine (reused across all requests)
        var tessdataPath = Path.Combine(AppContext.BaseDirectory, "tessdata");
        var tessLang = File.Exists(Path.Combine(tessdataPath, "poe2.traineddata")) ? "poe2" : "eng";
        TesseractEngine tessEngine;
        try
        {
            tessEngine = new TesseractEngine(tessdataPath, tessLang, EngineMode.LstmOnly);
            tessEngine.DefaultPageSegMode = PageSegMode.SingleBlock;
            tessEngine.SetVariable("preserve_interword_spaces", "1");
            Console.Error.WriteLine($"Tesseract engine loaded with language: {tessLang}");
        }
        catch (Exception ex)
        {
            WriteResponse(new ErrorResponse($"Failed to create Tesseract engine: {ex.Message}. Ensure tessdata/eng.traineddata exists."));
            return 1;
        }

        // Signal ready
        WriteResponse(new ReadyResponse());

        var ocrHandler = new OcrHandler(tessEngine);
        var gridHandler = new GridHandler();
        var detectGridHandler = new DetectGridHandler();

        // Main loop: read one JSON line, handle, write one JSON line
        string? line;
        while ((line = Console.In.ReadLine()) != null)
        {
            line = line.Trim();
            if (line.Length == 0) continue;

            try
            {
                var request = JsonSerializer.Deserialize<Request>(line, JsonOptions);
                if (request == null)
                {
                    WriteResponse(new ErrorResponse("Failed to parse request"));
                    continue;
                }

                object response = request.Cmd?.ToLowerInvariant() switch
                {
                    "ocr"         => ocrHandler.HandleOcr(request),
                    "screenshot"  => ocrHandler.HandleScreenshot(request),
                    "capture"     => ocrHandler.HandleCapture(request),
                    "snapshot"    => ocrHandler.HandleSnapshot(request),
                    "diff-ocr"    => ocrHandler.HandleDiffOcr(request),
                    "grid"        => gridHandler.HandleGrid(request),
                    "detect-grid" => detectGridHandler.HandleDetectGrid(request),
                    _             => new ErrorResponse($"Unknown command: {request.Cmd}"),
                };
                WriteResponse(response);
            }
            catch (Exception ex)
            {
                WriteResponse(new ErrorResponse(ex.Message));
            }
        }

        return 0;
    }

    private static void WriteResponse(object response)
    {
        var json = JsonSerializer.Serialize(response, JsonOptions);
        Console.Out.WriteLine(json);
        Console.Out.Flush();
    }
}