using MigraDoc.DocumentObjectModel;
using MigraDoc.DocumentObjectModel.Tables;
using MigraDoc.Rendering;
using System;
using System.Collections.Generic;
using System.Linq;
using timetracker.Shared;

namespace timetracker.Server.Services
{
    public class PdfGeneratorService
    {
        public byte[] GenerateTimesheetPdf(
            User user, 
            Tenant? tenant, 
            AppSettings settings, 
            int year, 
            int month, 
            List<WorkDay> workDays, 
            List<VacationDay> vacationDays, 
            List<PublicHoliday> holidays)
        {
            if (PdfSharp.Fonts.GlobalFontSettings.FontResolver == null)
            {
                PdfSharp.Fonts.GlobalFontSettings.FontResolver = new PdfFontResolver();
            }

            var document = new Document();
            document.Info.Title = "Stundenzettel";
            document.Info.Author = tenant?.Name ?? "Timetracker";
            
            var section = document.AddSection();
            section.PageSetup.PageFormat = PageFormat.A4;
            section.PageSetup.TopMargin = "2cm";
            section.PageSetup.BottomMargin = "2cm";
            section.PageSetup.LeftMargin = "2cm";
            section.PageSetup.RightMargin = "2cm";

            var style = document.Styles["Normal"];
            if (style != null && style.Font != null)
            {
                style.Font.Name = "OpenSans";
                style.Font.Size = 10;
            }

            ComposeHeader(section, user, tenant, year, month);
            ComposeContent(section, document, user, settings, year, month, workDays, vacationDays, holidays);
            ComposeFooter(section);

            var pdfRenderer = new PdfDocumentRenderer()
            {
                Document = document
            };
            pdfRenderer.RenderDocument();

            using var stream = new System.IO.MemoryStream();
            pdfRenderer.PdfDocument.Save(stream, false);
            return stream.ToArray();
        }

        private void ComposeHeader(Section section, User user, Tenant? tenant, int year, int month)
        {
            var monthName = new DateTime(year, month, 1).ToString("MMMM yyyy", new System.Globalization.CultureInfo("de-DE"));
            var companyName = tenant?.Name ?? "Hauptdomain";

            var paragraph = section.AddParagraph($"Stundenzettel - {monthName}");
            paragraph.Format.Font.Size = 20;
            paragraph.Format.Font.Bold = true;
            paragraph.Format.Font.Color = Colors.DarkBlue;
            paragraph.Format.SpaceAfter = "0.2cm";

            paragraph = section.AddParagraph($"Mitarbeiter: {user.Username}");
            paragraph.Format.Font.Size = 14;
            paragraph.Format.Font.Bold = true;
            paragraph.Format.SpaceAfter = "0.1cm";

            paragraph = section.AddParagraph($"Firma: {companyName}");
            paragraph.Format.Font.Size = 11;
            paragraph.Format.Font.Color = Colors.DarkGray;
            paragraph.Format.SpaceAfter = "1cm";
        }

        private void ComposeContent(Section section, Document document, User user, AppSettings settings, int year, int month, List<WorkDay> workDays, List<VacationDay> vacationDays, List<PublicHoliday> holidays)
        {
            ComposeTable(section, document, settings, year, month, workDays, vacationDays, holidays, out var totalNet, out var totalTarget, out var totalOvertime);
            
            ComposeSummary(section, totalNet, totalTarget, totalOvertime);

            ComposeSignatures(section);
        }

        private void ComposeTable(Section section, Document document, AppSettings settings, int year, int month, List<WorkDay> workDays, List<VacationDay> vacationDays, List<PublicHoliday> holidays, out TimeSpan totalNetOut, out TimeSpan totalTargetOut, out TimeSpan totalOvertimeOut)
        {
            var holidayMap = holidays.ToDictionary(h => h.Date, h => h.Name);
            var vacationSet = vacationDays.Select(v => v.Date).ToHashSet();
            var daysInMonth = DateTime.DaysInMonth(year, month);
            
            var totalNet = TimeSpan.Zero;
            var totalTarget = TimeSpan.Zero;
            var totalOvertime = TimeSpan.Zero;

            var table = section.AddTable();
            table.Borders.Width = 0.5;
            table.Borders.Color = Colors.LightGray;

            // Define columns
            table.AddColumn("2.5cm"); // Datum
            table.AddColumn("1.5cm"); // Start
            table.AddColumn("1.5cm"); // Ende
            table.AddColumn("1.8cm"); // Pause
            table.AddColumn("1.8cm"); // Netto
            table.AddColumn("1.8cm"); // Gleitzeit
            table.AddColumn("6.1cm"); // Info

            // Header Row
            var row = table.AddRow();
            row.HeadingFormat = true;
            row.Format.Font.Bold = true;
            row.Shading.Color = Colors.White;
            row.Borders.Bottom.Width = 1;
            row.Borders.Bottom.Color = Colors.Black;

            row.Cells[0].AddParagraph("Datum");
            row.Cells[1].AddParagraph("Start").Format.Alignment = ParagraphAlignment.Right;
            row.Cells[2].AddParagraph("Ende").Format.Alignment = ParagraphAlignment.Right;
            row.Cells[3].AddParagraph("Pause").Format.Alignment = ParagraphAlignment.Right;
            row.Cells[4].AddParagraph("Netto").Format.Alignment = ParagraphAlignment.Right;
            row.Cells[5].AddParagraph("Gleitzeit").Format.Alignment = ParagraphAlignment.Right;
            row.Cells[6].AddParagraph("Info/Status");

            for (int day = 1; day <= daysInMonth; day++)
            {
                var date = new DateOnly(year, month, day);
                var wd = workDays.FirstOrDefault(w => w.Date == date);
                var isWorkDay = settings.IsWorkDay(date.DayOfWeek);
                var isVacation = vacationSet.Contains(date);
                var holidayName = holidayMap.GetValueOrDefault(date);

                TimeSpan? net = null;
                TimeSpan breakSum = TimeSpan.Zero;

                if (wd?.StartTime != null && wd.EndTime != null)
                {
                    var gross = wd.EndTime.Value.ToTimeSpan() - wd.StartTime.Value.ToTimeSpan();
                    breakSum = wd.Breaks
                        .Where(b => b.StartTime.HasValue && b.EndTime.HasValue && b.EndTime > b.StartTime)
                        .Aggregate(TimeSpan.Zero, (s, b) =>
                            s + (b.EndTime!.Value.ToTimeSpan() - b.StartTime!.Value.ToTimeSpan()));
                    var minMinutes = gross.TotalHours >= 9.0 ? 45 : 30;
                    var minBreak = TimeSpan.FromMinutes(Math.Max(minMinutes, settings.MinimumBreakMinutes));
                    var finalBreak = breakSum > minBreak ? breakSum : minBreak;
                    net = gross - finalBreak;
                    if (net < TimeSpan.Zero) net = null;
                }

                var target = isWorkDay ? TimeSpan.FromHours(settings.DailyTargetHours) : TimeSpan.Zero;
                var overtime = net.HasValue ? net.Value - target : TimeSpan.Zero;

                if (net.HasValue) totalNet += net.Value;
                if (isWorkDay) totalTarget += target;
                if (isWorkDay && net.HasValue) totalOvertime += overtime;

                string status = "";
                if (!string.IsNullOrEmpty(holidayName)) status = holidayName;
                else if (isVacation) status = "Urlaub";
                else if (!isWorkDay) status = "Wochenende";

                var bgColor = Colors.White;
                if (!isWorkDay || !string.IsNullOrEmpty(holidayName)) bgColor = new Color(245, 245, 245); // Light Gray
                if (isVacation) bgColor = new Color(255, 236, 179); // Light Orange

                row = table.AddRow();
                row.Shading.Color = bgColor;

                row.Cells[0].AddParagraph(date.ToString("dd.MM.yyyy"));
                row.Cells[1].AddParagraph(wd?.StartTime?.ToString(@"HH\:mm") ?? "-").Format.Alignment = ParagraphAlignment.Right;
                row.Cells[2].AddParagraph(wd?.EndTime?.ToString(@"HH\:mm") ?? "-").Format.Alignment = ParagraphAlignment.Right;
                row.Cells[3].AddParagraph(net.HasValue ? FormatTs(breakSum) : "-").Format.Alignment = ParagraphAlignment.Right;
                row.Cells[4].AddParagraph(net.HasValue ? FormatTs(net.Value) : "-").Format.Alignment = ParagraphAlignment.Right;
                
                var overtimePara = row.Cells[5].AddParagraph(net.HasValue ? FormatTs(overtime, true) : "-");
                overtimePara.Format.Alignment = ParagraphAlignment.Right;
                if (net.HasValue && overtime != TimeSpan.Zero)
                {
                    overtimePara.Format.Font.Color = overtime < TimeSpan.Zero ? Colors.DarkRed : Colors.DarkGreen;
                }

                var statusPara = row.Cells[6].AddParagraph(status);
                statusPara.Format.Font.Color = Colors.DarkGray;
            }

            totalNetOut = totalNet;
            totalTargetOut = totalTarget;
            totalOvertimeOut = totalOvertime;
        }

        private void ComposeSummary(Section section, TimeSpan totalNet, TimeSpan totalTarget, TimeSpan totalOvertime)
        {
            var paragraph = section.AddParagraph();
            paragraph.Format.SpaceBefore = "1cm";
            
            var table = section.AddTable();
            table.Shading.Color = new Color(245, 245, 245);
            table.AddColumn("4cm");
            table.AddColumn("4cm");

            var row = table.AddRow();
            row.Cells[0].AddParagraph("Zusammenfassung").Format.Font.Bold = true;
            row.Cells[0].MergeRight = 1;

            row = table.AddRow();
            row.Cells[0].AddParagraph("Soll-Stunden:");
            row.Cells[1].AddParagraph(FormatTs(totalTarget));

            row = table.AddRow();
            row.Cells[0].AddParagraph("Ist-Stunden:");
            row.Cells[1].AddParagraph(FormatTs(totalNet));

            row = table.AddRow();
            row.Cells[0].AddParagraph("Saldo:");
            var saldoPara = row.Cells[1].AddParagraph(FormatTs(totalOvertime, true));
            saldoPara.Format.Font.Bold = true;
            if (totalOvertime != TimeSpan.Zero)
            {
                saldoPara.Format.Font.Color = totalOvertime < TimeSpan.Zero ? Colors.DarkRed : Colors.DarkGreen;
            }
        }

        private void ComposeSignatures(Section section)
        {
            var table = section.AddTable();
            table.Format.SpaceBefore = "2cm";
            table.AddColumn("7cm");
            table.AddColumn("2cm");
            table.AddColumn("7cm");

            var row = table.AddRow();
            row.Cells[0].Borders.Bottom.Width = 1;
            row.Cells[2].Borders.Bottom.Width = 1;

            row = table.AddRow();
            row.Cells[0].AddParagraph("Datum, Unterschrift Mitarbeiter").Format.Font.Size = 8;
            row.Cells[2].AddParagraph("Datum, Unterschrift Arbeitgeber").Format.Font.Size = 8;
        }

        private void ComposeFooter(Section section)
        {
            var paragraph = section.Footers.Primary.AddParagraph();
            paragraph.AddText("Seite ");
            paragraph.AddPageField();
            paragraph.AddText(" von ");
            paragraph.AddNumPagesField();
            paragraph.Format.Alignment = ParagraphAlignment.Center;
        }

        private static string FormatTs(TimeSpan ts, bool sign = false)
        {
            var neg = ts < TimeSpan.Zero;
            var abs = neg ? ts.Negate() : ts;
            var h = (int)abs.TotalHours;
            var m = abs.Minutes;
            if (!sign) return $"{h}:{m:D2} h";
            return neg ? $"-{h}:{m:D2} h" : $"+{h}:{m:D2} h";
        }
    }
}