using Elwig.Documents;
using iText.IO.Font.Constants;
using iText.Kernel.Font;
using iText.Kernel.Geom;
using iText.Kernel.Pdf;
using iText.Kernel.Pdf.Action;
using iText.Kernel.Pdf.Canvas;
using iText.Kernel.Pdf.Event;
using iText.Kernel.Pdf.Xobject;
using iText.Layout;
using iText.Layout.Borders;
using iText.Layout.Element;
using iText.Layout.Properties;
using System;
using System.Collections.Generic;

namespace Elwig.Helpers.Printing {
    public class FooterEventHandler : AbstractPdfDocumentEventHandler {

        private const float _fontSize = 10;
        private const float _ptInMm = 2.8346456693f;
        private const float _placeholderWidth = 50 * _ptInMm;

        private readonly string _date;
        private readonly string? _center;
        private readonly bool _doublePaged;
        private readonly bool _isPreview;
        private readonly bool _isBusiness;
        private readonly bool _showFoldMarks;
        private readonly PdfFont _font;
        private readonly PdfFont _fontBold;
        private readonly PdfFont _fontItalic;

        private readonly List<PdfFormXObject> _pageNumPlaceholders;

        public int NumberOfPages { get; private set; }

        public FooterEventHandler(Documents.Document? doc = null) {
            _date = $"{doc?.Date ?? DateOnly.FromDateTime(Utils.Today):dddd, d. MMMM yyyy}";
            _center = doc?.DocumentId;
            _doublePaged = doc?.IsDoublePaged ?? false;
            _isPreview = doc?.IsPreview ?? false;
            _isBusiness = doc is BusinessDocument;
            _showFoldMarks = doc?.ShowFoldMarks ?? false;
            _font = PdfFontFactory.CreateFont(StandardFonts.TIMES_ROMAN);
            _fontBold = PdfFontFactory.CreateFont(StandardFonts.TIMES_BOLD);
            _fontItalic = PdfFontFactory.CreateFont(StandardFonts.TIMES_ITALIC);
            _pageNumPlaceholders = [];
        }

        protected override void OnAcceptedEvent(AbstractPdfDocumentEvent evt) {
            if (evt.GetType() == PdfDocumentEvent.END_PAGE) {
                OnPageEnd((PdfDocumentEvent)evt);
            } else if (evt.GetType() == PdfDocumentEvent.START_DOCUMENT_CLOSING) {
                OnDocumentClose((PdfDocumentEvent)evt);
            }
        }

        private void OnPageEnd(PdfDocumentEvent evt) {
            var pdf = evt.GetDocument();
            var page = evt.GetPage();
            var pageNum = pdf.GetPageNumber(page);

            var pageSize = page.GetPageSize();
            float leftX1 = pageSize.GetLeft() + 25 * _ptInMm;
            float leftX2 = pageSize.GetLeft() + 20 * _ptInMm;
            float rightX1 = pageSize.GetRight() - 20 * _ptInMm;
            float rightX2 = pageSize.GetRight() - 25 * _ptInMm;
            float footerY = pageSize.GetBottom() + 25 * _ptInMm;
            float y = footerY + _fontSize;
            float footerWidth = 165 * _ptInMm;
            float footerHeight = 25 * _ptInMm;

            var pdfCanvas = new PdfCanvas(page.NewContentStreamAfter(), page.GetResources(), pdf);
            using var canvas = new Canvas(pdfCanvas, pageSize);

            var placeholder = new PdfFormXObject(new Rectangle(0, 0, _placeholderWidth, _fontSize));
            _pageNumPlaceholders.Add(placeholder);

            var c = App.Client;
            var dateP = new Paragraph(_date).SetFont(_font).SetFontSize(_fontSize);
            var centerP = new Paragraph(_center ?? "").SetFont(_fontItalic).SetFontSize(_fontSize);
            var pageNumP = new Paragraph().Add(new Image(placeholder)).SetFont(_font).SetFontSize(_fontSize);

            if (pageNum == 1) {
                // First page
                canvas.ShowTextAligned(dateP, leftX1, y, TextAlignment.LEFT);
                canvas.ShowTextAligned(centerP, (leftX1 + rightX1) / 2, y, TextAlignment.CENTER);
                canvas.ShowTextAligned(pageNumP, rightX1, y, TextAlignment.RIGHT);

                var footerP = new Paragraph().SetFont(_font).SetFontSize(_fontSize)
                    .SetTextAlignment(TextAlignment.CENTER).SetVerticalAlignment(VerticalAlignment.TOP)
                    .SetMargin(0).SetMultipliedLeading(1)
                    .SetWidth(footerWidth).SetHeight(footerHeight).SetPaddingTop(1 * _ptInMm).SetBorderTop(new SolidBorder(0.5f))
                    .Add(c.NameFull);
                if (_isBusiness) {
                    footerP.Add("\n");
                    footerP.AddAll(Utils.GenerateFooter("\n", " \u00b7 ")
                        .Item(c.Address).Item($"{c.Plz} {c.Ort}").Item("Österreich").Item("Tel.", c.PhoneNr).Item("Fax", c.FaxNr).NextLine()
                        .Item(c.EmailAddress != null ? new Link(c.EmailAddress, PdfAction.CreateURI($"mailto:{Uri.EscapeDataString(c.Name)}%20<{c.EmailAddress}>")) : null)
                            .Item(c.Website != null ? new Link(c.Website, PdfAction.CreateURI($"http://{c.Website}/")) : null)
                            .Item("Betriebs-Nr.", c.LfbisNr).Item("Bio-KSt.", c.OrganicAuthority).NextLine()
                        .Item("UID", c.UstIdNr).Item("BIC", c.Bic).Item("IBAN", c.Iban)
                        .ToLeafElements());
                }
                // FIXME links are drawn on next page - move footer into "normal" document creation
                canvas.ShowTextAligned(footerP, (leftX1 + rightX1) / 2, footerY, TextAlignment.CENTER, VerticalAlignment.TOP);
            } else if (_doublePaged && (pageNum % 2 == 0)) {
                // Swap side
                canvas.ShowTextAligned(pageNumP, leftX2, footerY, TextAlignment.LEFT, VerticalAlignment.TOP);
                canvas.ShowTextAligned(centerP, (leftX2 + rightX2) / 2, footerY, TextAlignment.CENTER, VerticalAlignment.TOP);
                canvas.ShowTextAligned(dateP, rightX2, footerY, TextAlignment.RIGHT, VerticalAlignment.TOP);
            } else {
                canvas.ShowTextAligned(dateP, leftX1, footerY, TextAlignment.LEFT, VerticalAlignment.TOP);
                canvas.ShowTextAligned(centerP, (leftX1 + rightX1) / 2, footerY, TextAlignment.CENTER, VerticalAlignment.TOP);
                canvas.ShowTextAligned(pageNumP, rightX1, footerY, TextAlignment.RIGHT, VerticalAlignment.TOP);
            }

            if (_showFoldMarks) {
                var m1 = pageSize.GetTop() - 105 * _ptInMm;
                var m2 = pageSize.GetTop() - 148.5 * _ptInMm;
                var m3 = pageSize.GetTop() - 210 * _ptInMm;
                pdfCanvas.SetLineWidth(0.5f);

                pdfCanvas.MoveTo(0, m1);
                pdfCanvas.LineTo(10 * _ptInMm, m1);
                pdfCanvas.MoveTo(pageSize.GetRight(), m1);
                pdfCanvas.LineTo(pageSize.GetRight() - 10 * _ptInMm, m1);

                pdfCanvas.MoveTo(0, m2);
                pdfCanvas.LineTo(7 * _ptInMm, m2);
                pdfCanvas.MoveTo(pageSize.GetRight(), m2);
                pdfCanvas.LineTo(pageSize.GetRight() - 7 * _ptInMm, m2);

                pdfCanvas.MoveTo(0, m3);
                pdfCanvas.LineTo(10 * _ptInMm, m3);
                pdfCanvas.MoveTo(pageSize.GetRight(), m3);
                pdfCanvas.LineTo(pageSize.GetRight() - 10 * _ptInMm, m3);

                pdfCanvas.ClosePathStroke();
            }

            if (NumberOfPages > 0) {
                // FillPlaceholders() was already called
                FillPlaceholder(pdf, pageNum);
            }
        }

        private void OnDocumentClose(PdfDocumentEvent evt) {
            FillPlaceholders(evt.GetDocument());
        }

        private void FillPlaceholders(PdfDocument pdf) {
            NumberOfPages = pdf.GetNumberOfPages();
            for (int i = 0; i < _pageNumPlaceholders.Count; i++)
                FillPlaceholder(pdf, i + 1);
        }

        private void FillPlaceholder(PdfDocument pdf, int pageNum) {
            var placeholder = _pageNumPlaceholders[pageNum - 1];
            using var canvas = new Canvas(placeholder, pdf);
            if (_doublePaged && (pageNum % 2 == 0)) {
                // swap
                var p = new Paragraph().SetFont(_font).SetFontSize(_fontSize);
                if (_isPreview) p.Add(new Text("(vorläufig) ").SetFont(_fontBold));
                p.Add($"Seite {pageNum:N0} von {NumberOfPages:N0} ");
                canvas.ShowTextAligned(p, 0, 0, TextAlignment.LEFT);
            } else {
                var p = new Paragraph().SetFont(_font).SetFontSize(_fontSize)
                    .Add($"Seite {pageNum:N0} von {NumberOfPages:N0}");
                if (_isPreview) p.Add(new Text(" (vorläufig)").SetFont(_fontBold));
                canvas.ShowTextAligned(p, _placeholderWidth, 0, TextAlignment.RIGHT);
            }
        }
    }
}