using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using System.Linq;
using System.Text;

namespace BoxPacker3D
{
    public static class PdfExporter
    {
        private const float PageW = 842f, PageH = 595f, Margin = 36f;

        public static void Export(string path,
            List<BoxSolution> solutions,
            List<Bitmap> overviews,
            List<Bitmap> layerBitmaps,
            List<(double YMin, double YMax)> layers,
            double wallPad, double itemPad,
            List<Item> unpackedItems = null)
        {
            var pages = new List<byte[]>();

            // Layer pages
            foreach (var bmp in layerBitmaps)
                pages.Add(BitmapToJpeg(bmp));

            // Overview pages
            foreach (var bmp in overviews)
                pages.Add(BitmapToJpeg(bmp));
            
            // Add unpacked items text page if needed
            bool hasUnpackedPage = unpackedItems != null && unpackedItems.Count > 0;

            using (var fs = new FileStream(path, FileMode.Create))
            {
                var w = new PdfWriter(fs);
                w.Raw("%PDF-1.4\n%\xe2\xe3\xcf\xd3\n");

                int n = pages.Count + (hasUnpackedPage ? 1 : 0);  // Total pages including text page
                int basePage    = 3;
                int baseContent = basePage + n;
                int baseImage   = baseContent + n;
                int objFont1    = baseImage + pages.Count;  // After image objects
                int objFont2    = objFont1 + 1;

                var offsets = new long[objFont2 + 1];

                // Object 1: Catalog
                offsets[1] = w.Pos;
                w.Obj(1); w.Raw("<< /Type /Catalog /Pages 2 0 R >>\n"); w.EndObj();

                // Object 2: Pages
                var kids = string.Join(" ", Enumerable.Range(basePage, n).Select(i => $"{i} 0 R"));
                offsets[2] = w.Pos;
                w.Obj(2);
                w.Raw($"<< /Type /Pages /Kids [{kids}] /Count {n} >>\n");
                w.EndObj();

                // Per-page objects (image pages)
                for (int i = 0; i < pages.Count; i++)
                {
                    bool isLayer = (i < layerBitmaps.Count);
                    string pageTitle;
                    if (isLayer)
                    {
                        int layIdx = i;
                        pageTitle = $"Vrstva {layIdx + 1} / {layerBitmaps.Count}" +
                            (layIdx < layers.Count ? $"  (Y: {layers[layIdx].YMin:F1} – {layers[layIdx].YMax:F1} mm)" : "");
                    }
                    else
                    {
                        int boxIdx = i - layerBitmaps.Count;
                        var sol = solutions[boxIdx];
                        pageTitle = $"Škatuľa {boxIdx + 1} / {solutions.Count}  " +
                                    $"({sol.Box.W}×{sol.Box.D}×{sol.Box.H} mm)";
                    }

                    int imgObj    = baseImage   + i;
                    int contentObj= baseContent + i;
                    int pageObj   = basePage    + i;

                    var imgBytes = pages[i];
                    int imgW, imgH;
                    using (var ms = new MemoryStream(imgBytes))
                    using (var bmp = new Bitmap(ms))
                    { imgW = bmp.Width; imgH = bmp.Height; }

                    float headerH = 52f, footerH = 22f;
                    float availW = PageW - 2 * Margin;
                    float availH = PageH - headerH - footerH - Margin;
                    float sc = Math.Min(availW / imgW, availH / imgH);
                    float scaledW = imgW * sc, scaledH = imgH * sc;
                    float imgX = Margin + (availW - scaledW) / 2;
                    float imgY = PageH - headerH - scaledH - 4;

                    var cs = new StringBuilder();
                    // White background
                    cs.AppendLine("1 1 1 rg");
                    cs.AppendLine($"0 0 {PageW:F2} {PageH:F2} re f");
                    // Header bar
                    cs.AppendLine("0.06 0.35 0.72 rg");
                    cs.AppendLine($"0 {PageH - 44:F2} {PageW:F2} 44 re f");
                    // Title
                    cs.AppendLine("1 1 1 rg BT /F1 14 Tf");
                    cs.AppendLine($"{Margin:F2} {PageH - 30:F2} Td");
                    cs.AppendLine($"({EscPdf(pageTitle)}) Tj ET");
                    // Date
                    cs.AppendLine("0.70 0.80 0.90 rg BT /F2 8 Tf");
                    cs.AppendLine($"{PageW - 200:F2} {PageH - 30:F2} Td");
                    cs.AppendLine($"(Strana {i + 1} / {n}   {DateTime.Now:dd.MM.yyyy}) Tj ET");
                    // Box info
                    if (isLayer && i < solutions.Count)
                    {
                        var sol = solutions[0]; // assume first box for layer pages
                        cs.AppendLine("0.40 0.40 0.50 rg BT /F2 8 Tf");
                        cs.AppendLine($"{Margin:F2} {PageH - 44:F2} Td");
                        string infoLine = $"Skatula: {sol.Box.W}×{sol.Box.H}×{sol.Box.D} mm  |  " +
                                          $"Stenova izolacia: {wallPad} mm  |  Medikusova: {itemPad} mm";
                        cs.AppendLine($"({EscPdf(infoLine)}) Tj ET");
                    }
                    // Image
                    cs.AppendLine("q");
                    cs.AppendLine($"{scaledW:F2} 0 0 {scaledH:F2} {imgX:F2} {imgY:F2} cm");
                    cs.AppendLine($"/Im{i} Do Q");
                    // Footer
                    cs.AppendLine("0.35 0.35 0.45 rg BT /F2 7 Tf");
                    cs.AppendLine($"{Margin:F2} 10 Td");
                    cs.AppendLine("(Generovane programom 3D Box Packer) Tj ET");

                    byte[] csBytes = Encoding.Latin1.GetBytes(cs.ToString());

                    // Page
                    offsets[pageObj] = w.Pos;
                    w.Obj(pageObj);
                    w.Raw($"<< /Type /Page /Parent 2 0 R\n");
                    w.Raw($"   /MediaBox [0 0 {PageW:F2} {PageH:F2}]\n");
                    w.Raw($"   /Contents {contentObj} 0 R\n");
                    w.Raw($"   /Resources << /Font << /F1 {objFont1} 0 R /F2 {objFont2} 0 R >>");
                    w.Raw($" /XObject << /Im{i} {imgObj} 0 R >> >>\n>>\n");
                    w.EndObj();

                    // Content
                    offsets[contentObj] = w.Pos;
                    w.Obj(contentObj);
                    w.Raw($"<< /Length {csBytes.Length} >>\nstream\n");
                    w.Bytes(csBytes);
                    w.Raw("\nendstream\n");
                    w.EndObj();

                    // Image
                    offsets[imgObj] = w.Pos;
                    w.Obj(imgObj);
                    w.Raw($"<< /Type /XObject /Subtype /Image /Width {imgW} /Height {imgH}");
                    w.Raw($" /ColorSpace /DeviceRGB /BitsPerComponent 8 /Filter /DCTDecode");
                    w.Raw($" /Length {imgBytes.Length} >>\nstream\n");
                    w.Bytes(imgBytes);
                    w.Raw("\nendstream\n");
                    w.EndObj();
                }

                // Unpacked items text page (if any)
                if (hasUnpackedPage)
                {
                    int pageIdx = pages.Count;
                    int pageObj = basePage + pageIdx;
                    int contentObj = baseContent + pageIdx;
                    
                    // Group unpacked items by name
                    var grouped = unpackedItems
                        .GroupBy(it => it.Name)
                        .Select(g => new { 
                            Name = g.Key, 
                            Count = g.Count(), 
                            W = g.First().W, 
                            H = g.First().H, 
                            D = g.First().D 
                        })
                        .OrderBy(x => x.Name)
                        .ToList();

                    var cs = new StringBuilder();
                    // White background
                    cs.AppendLine("1 1 1 rg");
                    cs.AppendLine($"0 0 {PageW:F2} {PageH:F2} re f");
                    
                    // Header bar (red for warning)
                    cs.AppendLine("0.83 0.18 0.18 rg");
                    cs.AppendLine($"0 {PageH - 44:F2} {PageW:F2} 44 re f");
                    
                    // Title
                    cs.AppendLine("1 1 1 rg BT /F1 14 Tf");
                    cs.AppendLine($"{Margin:F2} {PageH - 30:F2} Td");
                    cs.AppendLine($"(NEZABALENE KUSY) Tj ET");
                    
                    // Date
                    cs.AppendLine("1 1 1 rg BT /F2 8 Tf");
                    cs.AppendLine($"{PageW - 200:F2} {PageH - 30:F2} Td");
                    cs.AppendLine($"(Strana {n} / {n}   {DateTime.Now:dd.MM.yyyy}) Tj ET");
                    
                    // Summary
                    cs.AppendLine("0.20 0.20 0.30 rg BT /F1 11 Tf");
                    cs.AppendLine($"{Margin:F2} {PageH - 80:F2} Td");
                    cs.AppendLine($"(Nasledujuce kusy sa nezmestili do skatul:) Tj ET");
                    
                    // Table header
                    float y = PageH - 120;
                    cs.AppendLine("0.85 0.85 0.90 rg");
                    cs.AppendLine($"{Margin:F2} {y:F2} {PageW - 2*Margin:F2} 20 re f");
                    
                    cs.AppendLine("0.25 0.25 0.35 rg BT /F1 9 Tf");
                    cs.AppendLine($"{Margin + 10:F2} {y + 6:F2} Td");
                    cs.AppendLine("(Nazov) Tj");
                    cs.AppendLine($"{250:F2} {0:F2} Td (Rozmery \\(mm\\)) Tj");
                    cs.AppendLine($"{160:F2} {0:F2} Td (Pocet) Tj ET");
                    
                    y -= 25;
                    
                    // Table rows
                    int rowNum = 0;
                    foreach (var item in grouped)
                    {
                        if (y < 60) break; // Don't overflow page
                        
                        // Alternating row background
                        if (rowNum % 2 == 0)
                        {
                            cs.AppendLine("0.96 0.96 0.98 rg");
                            cs.AppendLine($"{Margin:F2} {y:F2} {PageW - 2*Margin:F2} 18 re f");
                        }
                        
                        cs.AppendLine("0.20 0.20 0.30 rg BT /F2 8 Tf");
                        cs.AppendLine($"{Margin + 10:F2} {y + 5:F2} Td");
                        cs.AppendLine($"({EscPdf(item.Name)}) Tj");
                        cs.AppendLine($"{250:F2} {0:F2} Td ({item.W:F0} x {item.H:F0} x {item.D:F0}) Tj");
                        cs.AppendLine($"{160:F2} {0:F2} Td ({item.Count}) Tj ET");
                        
                        y -= 18;
                        rowNum++;
                    }
                    
                    if (grouped.Count > rowNum)
                    {
                        cs.AppendLine("0.50 0.50 0.60 rg BT /F2 7 Tf");
                        cs.AppendLine($"{Margin + 10:F2} {y:F2} Td");
                        cs.AppendLine($"(... a dalsich {grouped.Count - rowNum} typov kusov) Tj ET");
                    }
                    
                    // Footer
                    cs.AppendLine("0.35 0.35 0.45 rg BT /F2 7 Tf");
                    cs.AppendLine($"{Margin:F2} 10 Td");
                    cs.AppendLine("(Generovane programom 3D Box Packer) Tj ET");

                    byte[] csBytes = Encoding.Latin1.GetBytes(cs.ToString());

                    // Page
                    offsets[pageObj] = w.Pos;
                    w.Obj(pageObj);
                    w.Raw($"<< /Type /Page /Parent 2 0 R\n");
                    w.Raw($"   /MediaBox [0 0 {PageW:F2} {PageH:F2}]\n");
                    w.Raw($"   /Contents {contentObj} 0 R\n");
                    w.Raw($"   /Resources << /Font << /F1 {objFont1} 0 R /F2 {objFont2} 0 R >> >>\n>>\n");
                    w.EndObj();

                    // Content
                    offsets[contentObj] = w.Pos;
                    w.Obj(contentObj);
                    w.Raw($"<< /Length {csBytes.Length} >>\nstream\n");
                    w.Bytes(csBytes);
                    w.Raw("\nendstream\n");
                    w.EndObj();
                }

                // Fonts
                offsets[objFont1] = w.Pos;
                w.Obj(objFont1);
                w.Raw("<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica-Bold /Encoding /WinAnsiEncoding >>\n");
                w.EndObj();

                offsets[objFont2] = w.Pos;
                w.Obj(objFont2);
                w.Raw("<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica /Encoding /WinAnsiEncoding >>\n");
                w.EndObj();

                // xref
                long xrefPos = w.Pos;
                w.Raw($"xref\n0 {offsets.Length}\n");
                w.Raw("0000000000 65535 f \n");
                for (int i = 1; i < offsets.Length; i++)
                    w.Raw($"{offsets[i]:D10} 00000 n \n");

                w.Raw($"trailer\n<< /Size {offsets.Length} /Root 1 0 R >>\n");
                w.Raw($"startxref\n{xrefPos}\n%%EOF\n");
            }
        }

        private static byte[] BitmapToJpeg(Bitmap bmp)
        {
            using (var ms = new MemoryStream())
            {
                var enc = GetJpegEncoder();
                var prms = new EncoderParameters(1);
                prms.Param[0] = new EncoderParameter(
                    System.Drawing.Imaging.Encoder.Quality, (long)88);
                bmp.Save(ms, enc, prms);
                return ms.ToArray();
            }
        }

        private static ImageCodecInfo GetJpegEncoder() =>
            ImageCodecInfo.GetImageEncoders().First(c => c.MimeType == "image/jpeg");

        private static string EscPdf(string s) =>
            s.Replace("\\", "\\\\").Replace("(", "\\(").Replace(")", "\\)");

        private class PdfWriter
        {
            private readonly FileStream _fs;
            public long Pos => _fs.Position;

            public PdfWriter(FileStream fs) { _fs = fs; }

            public void Raw(string s) { var b = Encoding.Latin1.GetBytes(s); _fs.Write(b, 0, b.Length); }
            public void Bytes(byte[] b) { _fs.Write(b, 0, b.Length); }
            public void Obj(int n) { Raw($"{n} 0 obj\n"); }
            public void EndObj() { Raw("endobj\n"); }
        }
    }
}