using System;
using System.Collections.Generic;
using System.Linq;
using PdfSharp;
using PdfSharp.Drawing;
using PdfSharp.Pdf;

namespace Logof_Client;

public class PdfBuilder
{
    // Table layout
    private const int CellsPerRow = 3;
    private const int CellsPerPage = 21; // 3 columns × 7 rows
    private readonly XFont _boldFont = new("Arial", 9, XFontStyleEx.Bold);
    private readonly double _cellHeight = 42.43; // mm
    private readonly double _cellPaddingBottom = 5; // mm

    // Padding inside cells
    private readonly double _cellPaddingLeft = 5; // mm
    private readonly double _cellPaddingTop = 5; // mm

    // Cell dimensions (in mm)
    private readonly double _cellWidth = 70; // mm

    // Font settings
    private readonly double _fontSize = 9;

    private readonly double _marginBottom = 1; // mm

    // Paper and layout settings
    private readonly double _marginLeft = 0; // mm
    private readonly double _marginRight = 0; // mm
    private readonly double _marginTop = 0; // mm
    private readonly XFont _regularFont = new("Arial", 9, XFontStyleEx.Regular);
    private readonly XFont _smallFont = new("Arial", 6, XFontStyleEx.Regular);

    /// <summary>
    ///     Creates a PDF document with address stickers from an AddressSet in a 3×7 grid layout on A4 pages.
    /// </summary>
    /// <param name="addressSetId">The ID of the AddressSet to use</param>
    /// <param name="outputPath">Path where the PDF should be saved</param>
    public void CreateAddressLabelPdfFromAddressSet(int addressSetId, string outputPath)
    {
        // Find the AddressSet by ID
        var addressSet = Settings._instance.addressSets.GetAddressSetByID(addressSetId);
        if (addressSet == null)
            throw new ArgumentException($"AddressSet with ID {addressSetId} not found");

        if (addressSet.KasPersons == null || addressSet.KasPersons.Count == 0)
            throw new ArgumentException($"AddressSet with ID {addressSetId} contains no addresses");

        // Generate markdown addresses from all KasPersons in the set
        //var addresses = new string?[addressSet.KasPersons.Count];
        var addresses = new List<string>();

        // find customer (owner) to include sender_address
        string senderLine = null;
        try
        {
            var owner = Settings._instance.customers.customers.FirstOrDefault(c => c.ID == addressSet.owner_id);
            if (owner != null && !string.IsNullOrWhiteSpace(owner.sender_address))
                // ensure single line and wrap in a small-font tag
                senderLine = "<font6>" + owner.sender_address.Replace("\n", " ").Trim() + "</font6>\n";
        }
        catch
        {
            senderLine = null;
        }

        for (var i = 0; i < addressSet.KasPersons.Count; i++)
        {
            var addr = AddressCreator.CreateFinalMarkdownString(addressSet.KasPersons[i].refsid);
            if (string.IsNullOrWhiteSpace(addr.Trim())) continue;
            if (!string.IsNullOrEmpty(senderLine))
                addresses.Add(senderLine + addr);
            else
                addresses.Add(addr);
        }

        CreateAddressLabelPdf(addresses, outputPath);
    }

    /// <summary>
    ///     Creates a PDF document with address stickers from an AddressSet with a placeholder in the first cell.
    /// </summary>
    /// <param name="addressSetId">The ID of the AddressSet to use</param>
    /// <param name="placeholderText">Text for the first cell (top-left)</param>
    /// <param name="outputPath">Path where the PDF should be saved</param>
    public void CreateAddressLabelPdfFromAddressSetWithPlaceholder(int addressSetId, string placeholderText,
        string outputPath)
    {
        // Find the AddressSet by ID
        var addressSet = Settings._instance.addressSets.GetAddressSetByID(addressSetId);
        if (addressSet == null)
            throw new ArgumentException($"AddressSet with ID {addressSetId} not found");

        if (addressSet.KasPersons == null || addressSet.KasPersons.Count == 0)
            throw new ArgumentException($"AddressSet with ID {addressSetId} contains no addresses");

        // Generate markdown addresses from all KasPersons in the set
        //var addresses = new string?[addressSet.KasPersons.Count];
        var addresses = new List<string>();

        // find customer (owner) to include sender_address
        string senderLine = null;
        try
        {
            var owner = Settings._instance.customers.customers.FirstOrDefault(c => c.ID == addressSet.owner_id);
            if (owner != null && !string.IsNullOrWhiteSpace(owner.sender_address))
                senderLine = "<font6>" + owner.sender_address.Replace("\n", " ").Trim() + "</font6>\n";
        }
        catch
        {
            senderLine = null;
        }

        for (var i = 0; i < addressSet.KasPersons.Count; i++)
        {
            var addr = AddressCreator.CreateFinalMarkdownString(addressSet.KasPersons[i].refsid);
            if (string.IsNullOrWhiteSpace(addr.Trim())) continue;
            if (!string.IsNullOrEmpty(senderLine))
                addresses.Add(senderLine + (addr ?? ""));
            else
                addresses.Add(addr);
        }

        CreateAddressLabelPdfWithPlaceholder(addresses, placeholderText, outputPath);
    }

    /// <summary>
    ///     Creates a PDF document with address stickers in a 3×7 grid layout on A4 pages.
    /// </summary>
    /// <param name="addresses">Array of addresses (from CreateFinalMarkdownString)</param>
    /// <param name="outputPath">Path where the PDF should be saved</param>
    public void CreateAddressLabelPdf(List<string> addresses, string outputPath)
    {
        if (addresses == null || addresses.Count == 0)
            throw new ArgumentException("Addresses array cannot be null or empty");

        var document = new PdfDocument();

        var addressIndex = 0;
        while (addressIndex < addresses.Count)
        {
            var page = document.AddPage();
            page.Size = PageSize.A4;

            using (var gfx = XGraphics.FromPdfPage(page))
            {
                // Draw the grid and fill cells
                DrawPage(gfx, addresses, ref addressIndex);
            }
        }

        // Save the document
        document.Save(outputPath);
    }

    /// <summary>
    ///     Creates a PDF document with a single placeholder cell for other information.
    /// </summary>
    /// <param name="addresses">Array of addresses</param>
    /// <param name="placeholderText">Text for the first cell (top-left)</param>
    /// <param name="outputPath">Path where the PDF should be saved</param>
    public void CreateAddressLabelPdfWithPlaceholder(List<string> addresses, string placeholderText, string outputPath)
    {
        if (addresses == null || addresses.Count == 0)
            throw new ArgumentException("Addresses array cannot be null or empty");

        var document = new PdfDocument();

        var addressIndex = 0;
        var isFirstCell = true;

        while (addressIndex < addresses.Count || isFirstCell)
        {
            var page = document.AddPage();
            page.Size = PageSize.A4;

            using (var gfx = XGraphics.FromPdfPage(page))
            {
                DrawPageWithPlaceholder(gfx, addresses, ref addressIndex, ref isFirstCell, placeholderText);
            }
        }

        document.Save(outputPath);
    }

    private void DrawPage(XGraphics gfx, List<string> addresses, ref int addressIndex)
    {
        var cellCount = 0;

        for (var row = 0; row < 7; row++)
        {
            for (var col = 0; col < 3; col++)
            {
                if (addressIndex >= addresses.Count) break;

                var x = MmToPoints(_marginLeft + col * _cellWidth);
                var y = MmToPoints(_marginTop + row * _cellHeight);

                DrawCell(gfx, x, y, addresses[addressIndex]);
                addressIndex++;
                cellCount++;
            }

            if (addressIndex >= addresses.Count) break;
        }
    }

    private void DrawPageWithPlaceholder(XGraphics gfx, List<string> addresses, ref int addressIndex,
        ref bool isFirstCell, string placeholderText)
    {
        var cellCount = 0;

        for (var row = 0; row < 7; row++)
        for (var col = 0; col < 3; col++)
        {
            var x = MmToPoints(_marginLeft + col * _cellWidth);
            var y = MmToPoints(_marginTop + row * _cellHeight);

            // First cell: placeholder
            if (isFirstCell)
            {
                DrawCell(gfx, x, y, placeholderText);
                isFirstCell = false;
            }
            else if (addressIndex < addresses.Count)
            {
                DrawCell(gfx, x, y, addresses[addressIndex]);
                addressIndex++;
            }
            else
            {
                DrawEmptyCell(gfx, x, y);
            }

            cellCount++;
        }
    }

    private void DrawCell(XGraphics gfx, double x, double y, string? address)
    {
        var cellWidthPoints = MmToPoints(_cellWidth);
        var cellHeightPoints = MmToPoints(_cellHeight);

        // Draw cell border
        var rect = new XRect(x, y, cellWidthPoints, cellHeightPoints);
        gfx.DrawRectangle(XPens.Black, rect);

        // Draw address content if available
        if (!string.IsNullOrEmpty(address)) DrawMarkdownText(gfx, address, x, y, cellWidthPoints, cellHeightPoints);
    }

    private void DrawEmptyCell(XGraphics gfx, double x, double y)
    {
        var cellWidthPoints = MmToPoints(_cellWidth);
        var cellHeightPoints = MmToPoints(_cellHeight);

        var rect = new XRect(x, y, cellWidthPoints, cellHeightPoints);
        gfx.DrawRectangle(XPens.Black, rect);
    }

    private void DrawMarkdownText(XGraphics gfx, string text, double x, double y, double cellWidth, double cellHeight)
    {
        var paddingLeftPoints = MmToPoints(_cellPaddingLeft);
        var paddingTopPoints = MmToPoints(_cellPaddingTop);
        var paddingBottomPoints = MmToPoints(_cellPaddingBottom);

        var maxWidth = cellWidth - paddingLeftPoints * 2;

        // Split text by newlines and remove empty trailing lines
        var rawLines = text.Split(new[] { "\n" }, StringSplitOptions.None);
        var lines = rawLines.Where(l => l != null).ToArray();

        // Use a conservative line height in points
        var lineHeight = _regularFont.Size * 1.2;

        // Calculate total height of the text block
        var totalHeight = lines.Length * lineHeight;

        // Start drawing from the top of the cell (align addresses to top)
        var startY = y + paddingTopPoints;

        var currentY = startY;

        foreach (var line in lines)
        {
            // Stop if we've reached the top boundary
            if (currentY + lineHeight > y + cellHeight - paddingBottomPoints + 0.001)
                break;

            // Parse and draw the line with markdown support
            DrawLineWithMarkdown(gfx, line, x + paddingLeftPoints, currentY, maxWidth);
            currentY += lineHeight;
        }
    }

    private void DrawLineWithMarkdown(XGraphics gfx, string line, double x, double y, double maxWidth)
    {
        var currentX = x;
        var i = 0;

        while (i < line.Length)
        {
            // Check for small-font tag <font6> ... </font6>
            if (i <= line.Length - 7 && line.Substring(i, 7) == "<font6>")
            {
                var endTag = line.IndexOf("</font6>", i + 7, StringComparison.Ordinal);
                if (endTag != -1)
                {
                    var inner = line.Substring(i + 7, endTag - (i + 7));
                    if (!string.IsNullOrEmpty(inner))
                    {
                        gfx.DrawString(inner, _smallFont, XBrushes.Black,
                            new XRect(currentX, y, maxWidth - (currentX - x), _smallFont.Size * 1.2),
                            XStringFormats.TopLeft);
                        var measuredSmall = gfx.MeasureString(inner, _smallFont);
                        currentX += measuredSmall.Width;
                    }

                    i = endTag + 8; // move past </font6>
                    continue;
                }
            }

            // Check for bold marker (**)
            if (i < line.Length - 1 && line[i] == '*' && line[i + 1] == '*')
            {
                // Find closing **
                var endIndex = line.IndexOf("**", i + 2, StringComparison.Ordinal);
                if (endIndex != -1)
                {
                    var boldText = line.Substring(i + 2, endIndex - (i + 2));
                    // Draw bold text and measure width accurately
                    gfx.DrawString(boldText, _boldFont, XBrushes.Black,
                        new XRect(currentX, y, maxWidth - (currentX - x), _boldFont.Size * 1.2),
                        XStringFormats.TopLeft);
                    var measured = gfx.MeasureString(boldText, _boldFont);
                    currentX += measured.Width;
                    i = endIndex + 2;
                    continue;
                }
            }

            // Regular text until next ** or end of line
            var nextBoldIndex = line.IndexOf("**", i, StringComparison.Ordinal);
            var textEnd = nextBoldIndex == -1 ? line.Length : nextBoldIndex;
            var regularText = line.Substring(i, textEnd - i);

            if (!string.IsNullOrEmpty(regularText))
            {
                gfx.DrawString(regularText, _regularFont, XBrushes.Black,
                    new XRect(currentX, y, maxWidth - (currentX - x), _regularFont.Size * 1.2), XStringFormats.TopLeft);
                var measured = gfx.MeasureString(regularText, _regularFont);
                currentX += measured.Width;
            }

            i = textEnd;
        }
    }

    /// <summary>
    ///     Converts millimeters to points (1 mm = 2.834645669 points)
    /// </summary>
    private double MmToPoints(double mm)
    {
        return mm * 2.834645669;
    }

    // Configuration methods to allow customization

    /// <summary>
    ///     Sets the cell dimensions in millimeters
    /// </summary>
    public void SetCellDimensions(double width, double height)
    {
        if (width <= 0 || height <= 0)
            throw new ArgumentException("Cell dimensions must be positive");
    }

    /// <summary>
    ///     Sets the page margins in millimeters
    /// </summary>
    public void SetMargins(double left, double top, double right, double bottom)
    {
        if (left < 0 || top < 0 || right < 0 || bottom < 0)
            throw new ArgumentException("Margins cannot be negative");
    }
}