namespace OcrDaemon;

using System.Drawing;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;
using Tesseract;
using SdImageFormat = System.Drawing.Imaging.ImageFormat;

static class ImageUtils
{
    public static Pix BitmapToPix(Bitmap bitmap)
    {
        using var ms = new MemoryStream();
        bitmap.Save(ms, SdImageFormat.Png);
        return Pix.LoadFromMemory(ms.ToArray());
    }

    public static List<OcrLineResult> ExtractLinesFromPage(Page page, int offsetX, int offsetY)
    {
        var lines = new List<OcrLineResult>();
        using var iter = page.GetIterator();
        if (iter == null) return lines;

        iter.Begin();

        do
        {
            var words = new List<OcrWordResult>();
            do
            {
                var wordText = iter.GetText(PageIteratorLevel.Word);
                if (string.IsNullOrWhiteSpace(wordText)) continue;

                float conf = iter.GetConfidence(PageIteratorLevel.Word);
                if (conf < 50) continue; // reject low-confidence garbage from background bleed

                if (iter.TryGetBoundingBox(PageIteratorLevel.Word, out var bounds))
                {
                    words.Add(new OcrWordResult
                    {
                        Text = wordText.Trim(),
                        X = bounds.X1 + offsetX,
                        Y = bounds.Y1 + offsetY,
                        Width = bounds.Width,
                        Height = bounds.Height,
                    });
                }
            } while (iter.Next(PageIteratorLevel.TextLine, PageIteratorLevel.Word));

            if (words.Count > 0)
            {
                var lineText = string.Join(" ", words.Select(w => w.Text));
                lines.Add(new OcrLineResult { Text = lineText, Words = words });
            }
        } while (iter.Next(PageIteratorLevel.Block, PageIteratorLevel.TextLine));

        return lines;
    }

    public static (byte[] gray, byte[] argb, int stride) BitmapToGrayAndArgb(Bitmap bmp)
    {
        int w = bmp.Width, h = bmp.Height;
        var data = bmp.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb);
        byte[] argb = new byte[data.Stride * h];
        Marshal.Copy(data.Scan0, argb, 0, argb.Length);
        bmp.UnlockBits(data);
        int stride = data.Stride;

        byte[] gray = new byte[w * h];
        for (int y = 0; y < h; y++)
            for (int x = 0; x < w; x++)
            {
                int i = y * stride + x * 4;
                gray[y * w + x] = (byte)((argb[i] + argb[i + 1] + argb[i + 2]) / 3);
            }
        return (gray, argb, stride);
    }

    public static SdImageFormat GetImageFormat(string path)
    {
        var ext = Path.GetExtension(path).ToLowerInvariant();
        return ext switch
        {
            ".jpg" or ".jpeg" => SdImageFormat.Jpeg,
            ".bmp" => SdImageFormat.Bmp,
            _ => SdImageFormat.Png,
        };
    }
}