using Lagerbestand.Models;
using QuestPDF.Fluent;
using QuestPDF.Helpers;
using QuestPDF.Infrastructure;

namespace Lagerbestand.Services;

public interface IStorageRowPdfService
{
    /// <summary>
    /// Generates a printable A4 inventory sheet for one shelf row (Area + Row).
    /// </summary>
    byte[] GenerateRowPdf(AreaType area, int row, IReadOnlyList<StorageLocation> locations);
}

public class StorageRowPdfService : IStorageRowPdfService
{
    private static readonly string HeaderBackground = Colors.Grey.Lighten3;
    private static readonly string BorderColor = Colors.Grey.Medium;

    public byte[] GenerateRowPdf(AreaType area, int row, IReadOnlyList<StorageLocation> locations)
    {
        var rowLocations = locations
            .Where(l => l.Area == area && l.Row == row)
            .ToList();

        var occupied = rowLocations.Count(l => l.IsOccupied);
        var total = StorageLocation.PositionsPerSlot * StorageLocation.MaxSlot;
        var printedAt = DateTime.Now;

        var document = Document.Create(container =>
        {
            container.Page(page =>
            {
                page.Size(PageSizes.A4);
                page.Margin(1.5f, Unit.Centimetre);
                page.DefaultTextStyle(x => x.FontSize(9));

                page.Header()
                    .PaddingBottom(12)
                    .AlignCenter()
                    .Text($"{area.GetDisplayName()} – Regal {row}")
                    .Bold()
                    .FontSize(20);

                page.Content().Row(r =>
                {
                    r.RelativeItem().Column(col =>
                    {
                        col.Spacing(14);
                        col.Item().Element(c => RenderPositionTable(c, area, row, ShelfPosition.LinksOben, rowLocations));
                        col.Item().Element(c => RenderPositionTable(c, area, row, ShelfPosition.LinksUnten, rowLocations));
                    });

                    r.ConstantItem(14);

                    r.RelativeItem().Column(col =>
                    {
                        col.Spacing(14);
                        col.Item().Element(c => RenderPositionTable(c, area, row, ShelfPosition.RechtsOben, rowLocations));
                        col.Item().Element(c => RenderPositionTable(c, area, row, ShelfPosition.RechtsUnten, rowLocations));
                    });
                });

                page.Footer()
                    .PaddingTop(10)
                    .Row(f =>
                    {
                        f.RelativeItem().Text($"Gedruckt am {printedAt:dd.MM.yyyy HH:mm}").FontSize(8).FontColor(Colors.Grey.Darken1);
                        f.RelativeItem().AlignRight().Text($"{occupied} / {total} belegt").FontSize(8).FontColor(Colors.Grey.Darken1);
                    });
            });
        });

        return document.GeneratePdf();
    }

    private static void RenderPositionTable(IContainer container, AreaType area, int row, ShelfPosition position, List<StorageLocation> rowLocations)
    {
        var bySlot = rowLocations
            .Where(l => l.Position == position)
            .GroupBy(l => l.SlotNumber)
            .ToDictionary(g => g.Key, g => g.First());

        container.Column(col =>
        {
            col.Spacing(4);
            col.Item().Text(position.GetDisplayName()).Bold().FontSize(11);

            col.Item().Table(table =>
            {
                table.ColumnsDefinition(columns =>
                {
                    columns.ConstantColumn(28);
                    columns.ConstantColumn(34);
                    columns.RelativeColumn(3);
                    columns.RelativeColumn(2);
                    columns.ConstantColumn(44);
                });

                table.Header(header =>
                {
                    header.Cell().Element(HeaderCell).Text("Platz");
                    header.Cell().Element(HeaderCell).Text("Code");
                    header.Cell().Element(HeaderCell).Text("Kunde/Inhalt");
                    header.Cell().Element(HeaderCell).Text("Fahrzeug");
                    header.Cell().Element(HeaderCell).Text("Saison");
                });

                for (var slot = StorageLocation.MinSlot; slot <= StorageLocation.MaxSlot; slot++)
                {
                    bySlot.TryGetValue(slot, out var location);
                    var code = location?.Code ?? $"{(int)area}{row}{(int)position}{slot}";

                    string content, vehicle, season;
                    var muted = false;

                    if (location is { IsOccupied: true, OccupiedTireStack: not null })
                    {
                        var stack = location.OccupiedTireStack;
                        content = stack.Customer?.FullName ?? stack.CatalogItem?.Name ?? "Lager";
                        vehicle = stack.Vehicle?.ShortName ?? "–";
                        season = SeasonText(stack.Season);
                    }
                    else if (location is { IsOccupied: true })
                    {
                        content = "Belegt";
                        vehicle = "–";
                        season = "–";
                    }
                    else if (location is { IsAvailable: false })
                    {
                        content = "Gesperrt";
                        vehicle = "–";
                        season = "–";
                        muted = true;
                    }
                    else
                    {
                        content = "Frei";
                        vehicle = "–";
                        season = "–";
                        muted = true;
                    }

                    table.Cell().Element(BodyCell).Text(slot.ToString());
                    table.Cell().Element(BodyCell).Text(code);
                    table.Cell().Element(BodyCell).Text(t => Styled(t.Span(content), muted));
                    table.Cell().Element(BodyCell).Text(t => Styled(t.Span(vehicle), muted));
                    table.Cell().Element(BodyCell).Text(t => Styled(t.Span(season), muted));
                }
            });
        });
    }

    private static void Styled(TextSpanDescriptor span, bool muted)
    {
        if (muted)
            span.FontColor(Colors.Grey.Medium).Italic();
    }

    private static string SeasonText(TireSeason season) => season switch
    {
        TireSeason.Sommer => "Sommer",
        TireSeason.Winter => "Winter",
        TireSeason.Allrad => "Ganzjahr",
        _ => season.ToString()
    };

    private static IContainer HeaderCell(IContainer container) => container
        .Background(HeaderBackground)
        .Border(0.5f)
        .BorderColor(BorderColor)
        .PaddingVertical(3)
        .PaddingHorizontal(4)
        .DefaultTextStyle(x => x.Bold().FontSize(8));

    private static IContainer BodyCell(IContainer container) => container
        .Border(0.5f)
        .BorderColor(BorderColor)
        .PaddingVertical(3)
        .PaddingHorizontal(4)
        .DefaultTextStyle(x => x.FontSize(8));
}