using System.Globalization;
using MigraDoc.DocumentObjectModel;
using MigraDoc.DocumentObjectModel.Tables;
using MigraDoc.Rendering;
using SQLInsight.Core.Findings;
using SQLInsight.Core.Instances;
using SQLInsight.Repository;

namespace SQLInsight.Reports;

/// <summary>
/// The management and compliance report as PDF: key figures, a plain-language summary, controls, instances and the
/// critical and high findings. Written for readers who are not DBAs.
/// </summary>
public static class ManagementReport
{
    public const int MaxFindingRows = 100;

    private static readonly CultureInfo Danish = CultureInfo.GetCultureInfo("da-DK");
    private static readonly TimeSpan UnreachableAfter = TimeSpan.FromMinutes(30);

    private static readonly Color Text = new(0x10, 0x18, 0x28);
    private static readonly Color Muted = new(0x66, 0x70, 0x85);
    private static readonly Color Border = new(0xE4, 0xE7, 0xEC);
    private static readonly Color Surface = new(0xF5, 0xF7, 0xFA);
    private static readonly Color Brand = new(0x0E, 0x74, 0x90);
    private static readonly Color Critical = new(0xD9, 0x2D, 0x20);
    private static readonly Color High = new(0xE6, 0x6A, 0x0A);
    private static readonly Color Medium = new(0xB5, 0x8B, 0x00);
    private static readonly Color Good = new(0x06, 0x76, 0x47);

    public static byte[] Render(ReportData data)
    {
        ArgumentNullException.ThrowIfNull(data);
        InterFontResolver.Install();

        var document = new Document();
        document.Info.Title = $"Driftsrapport for SQL Server: {data.Organization}";
        document.Info.Author = "SQLInsight Pro";
        Styles(document);

        var section = document.AddSection();
        section.PageSetup = document.DefaultPageSetup.Clone();
        section.PageSetup.PageFormat = PageFormat.A4;
        section.PageSetup.TopMargin = Unit.FromCentimeter(2.2);
        section.PageSetup.BottomMargin = Unit.FromCentimeter(2);
        section.PageSetup.LeftMargin = Unit.FromCentimeter(2);
        section.PageSetup.RightMargin = Unit.FromCentimeter(2);
        HeaderAndFooter(section, data);

        Title(section, data);
        KeyFigures(section, data);
        Summary(section, data);
        Controls(section, data);
        Instances(section, data);
        Findings(section, data);
        ConfigurationChanges(section, data);
        About(section, data);

        var renderer = new PdfDocumentRenderer { Document = document };
        renderer.RenderDocument();
        using var output = new MemoryStream();
        renderer.PdfDocument.Save(output, false);
        return output.ToArray();
    }

    private static void Styles(Document document)
    {
        var normal = document.Styles[StyleNames.Normal]!;
        normal.Font.Name = InterFontResolver.Family;
        normal.Font.Size = 9.5;
        normal.Font.Color = Text;
        normal.ParagraphFormat.SpaceAfter = Unit.FromPoint(4);

        var heading = document.Styles[StyleNames.Heading1]!;
        heading.Font.Size = 14;
        heading.Font.Bold = true;
        heading.ParagraphFormat.SpaceBefore = Unit.FromPoint(16);
        heading.ParagraphFormat.SpaceAfter = Unit.FromPoint(6);
        heading.ParagraphFormat.KeepWithNext = true;

        var muted = document.Styles.AddStyle("Muted", StyleNames.Normal);
        muted.Font.Color = Muted;
        muted.Font.Size = 8.5;
    }

    private static void HeaderAndFooter(Section section, ReportData data)
    {
        var header = section.Headers.Primary.AddParagraph();
        header.Style = "Muted";
        header.AddText($"SQLInsight Pro · {data.Organization}");
        header.Format.Borders.Bottom = new Border { Width = 0.5, Color = Border };

        var footer = section.Footers.Primary.AddParagraph();
        footer.Style = "Muted";
        footer.AddText($"Driftsrapport {Date(data, data.From)} – {Date(data, data.To)}    Side ");
        footer.AddPageField();
        footer.AddText(" af ");
        footer.AddNumPagesField();
    }

    private static void Title(Section section, ReportData data)
    {
        var title = section.AddParagraph("Driftsrapport for SQL Server");
        title.Format.Font.Size = 22;
        title.Format.Font.Bold = true;
        title.Format.SpaceAfter = Unit.FromPoint(2);

        var subtitle = section.AddParagraph(data.Organization);
        subtitle.Format.Font.Size = 13;
        subtitle.Format.Font.Color = Brand;

        var period = section.AddParagraph($"Periode {Date(data, data.From)} – {Date(data, data.To)} · dannet {DateTime(data, data.GeneratedAt)}");
        period.Style = "Muted";
        period.Format.SpaceAfter = Unit.FromPoint(14);
    }

    private static void KeyFigures(Section section, ReportData data)
    {
        var unreachable = data.Unreachable(UnreachableAfter).Count();
        var figures = new (string Value, string Label, Color Color)[]
        {
            (data.Instances.Count.ToString(Danish), unreachable > 0 ? $"instanser, {unreachable} kan ikke nås" : "instanser, alle svarer", unreachable > 0 ? Critical : Text),
            (data.Count(Severity.Critical).ToString(Danish), "kritiske fund", data.Count(Severity.Critical) > 0 ? Critical : Good),
            (data.Count(Severity.High).ToString(Danish), "fund med høj alvor", data.Count(Severity.High) > 0 ? High : Good),
            (data.Period.Resolved.ToString(Danish), $"løst i perioden ({data.Period.Opened} nye)", Good),
        };

        var table = section.AddTable();
        table.Borders.Visible = false;
        foreach (var _ in figures)
        {
            table.AddColumn(Unit.FromCentimeter(4.25));
        }

        var row = table.AddRow();
        for (var i = 0; i < figures.Length; i++)
        {
            var cell = row.Cells[i];
            cell.Shading.Color = Surface;
            cell.Borders.Left = new Border { Width = 3, Color = Colors.White };
            cell.Borders.Right = new Border { Width = 3, Color = Colors.White };
            var value = cell.AddParagraph(figures[i].Value);
            value.Format.Font.Size = 20;
            value.Format.Font.Bold = true;
            value.Format.Font.Color = figures[i].Color;
            value.Format.SpaceBefore = Unit.FromPoint(6);
            value.Format.LeftIndent = Unit.FromPoint(6);
            var label = cell.AddParagraph(figures[i].Label);
            label.Style = "Muted";
            label.Format.LeftIndent = Unit.FromPoint(6);
            label.Format.SpaceAfter = Unit.FromPoint(6);
        }
    }

    private static void Summary(Section section, ReportData data)
    {
        section.AddParagraph("Sammenfatning", StyleNames.Heading1);
        foreach (var sentence in SummarySentences(data))
        {
            var paragraph = section.AddParagraph("• " + sentence);
            paragraph.Format.LeftIndent = Unit.FromPoint(10);
            paragraph.Format.FirstLineIndent = Unit.FromPoint(-10);
        }
    }

    /// <summary>The summary in plain language; public so it can be tested without reading the PDF.</summary>
    public static IReadOnlyList<string> SummarySentences(ReportData data)
    {
        ArgumentNullException.ThrowIfNull(data);
        var sentences = new List<string>();
        var critical = data.Count(Severity.Critical);
        var high = data.Count(Severity.High);
        sentences.Add(critical > 0
            ? $"Der er {Count(critical, "kritisk fund", "kritiske fund")}, som bør håndteres straks, og {Count(high, "fund", "fund")} med høj alvor."
            : high > 0 ? $"Der er ingen kritiske fund, men {Count(high, "fund", "fund")} med høj alvor, som bør planlægges løst." : "Der er hverken kritiske fund eller fund med høj alvor.");

        var unreachable = data.Unreachable(UnreachableAfter).Select(i => i.Name).ToList();
        if (unreachable.Count > 0)
        {
            sentences.Add($"{Count(unreachable.Count, "instans", "instanser")} kan ikke nås lige nu ({string.Join(", ", unreachable.Take(5))}{(unreachable.Count > 5 ? " …" : "")}); de kan ikke vurderes.");
        }

        void Control(string name, Func<int, int, string> text)
        {
            var control = ComplianceControl.All.Single(c => c.Name == name);
            var failing = data.Instances.Count(i => control.StatusOn(i.Name, data.RuleStates) == ControlStatus.NotMet);
            if (failing > 0)
            {
                sentences.Add(text(failing, data.Instances.Count));
            }
        }

        Control("Supporteret version", (n, total) => $"{n} af {total} instanser kører en SQL Server-version, som Microsoft ikke længere (fuldt) understøtter. Planlæg opgradering.");
        Control("Opdateret", (n, total) => $"{n} af {total} instanser mangler de seneste opdateringer fra Microsoft.");
        Control("Fuld backup", (n, _) => $"{Count(n, "instans", "instanser")} har databaser uden en nylig fuld backup. Det er en risiko for datatab.");
        Control("Integritetstjek", (n, _) => $"{Count(n, "instans", "instanser")} mangler integritetstjek eller har registreret korrupte sider.");

        var period = data.Period;
        sentences.Add($"I perioden er der kommet {(period.Opened == 0 ? "ingen" : period.Opened.ToString(Danish))} nye fund til"
            + (period.Opened > 0 ? $" ({period.OpenedCriticalOrHigh} kritiske eller høje)" : "")
            + (period.Resolved == 0 ? ", og ingen er løst." : $", og {period.Resolved} er løst"
                + (period.AverageDaysToResolve is { } days ? $" efter gennemsnitligt {days.ToString("0.#", Danish)} dage." : ".")));
        return sentences;
    }

    private static string Count(int n, string one, string many) => $"{n.ToString(Danish)} {(n == 1 ? one : many)}";

    private static void Controls(Section section, ReportData data)
    {
        section.AddParagraph("Kontroller", StyleNames.Heading1);
        var intro = section.AddParagraph("Opfyldt betyder, at kontrollen er målt og intet fund er registreret. Ikke målt betyder, at rettighederne eller en fejl forhindrede målingen; det er ikke det samme som opfyldt. Instanser, hvor kontrollen ikke er relevant for SQL Server-versionen, tælles ikke med.");
        intro.Style = "Muted";

        var table = Table(section, ("Kontrol", 5.2), ("Opfyldt", 1.8), ("Ikke opfyldt", 2.1), ("Ikke målt", 1.9), ("Instanser, der ikke opfylder", 6));
        foreach (var control in ComplianceControl.All)
        {
            var statuses = data.Instances.Select(i => (i.Name, Status: control.StatusOn(i.Name, data.RuleStates))).ToList();
            var failing = statuses.Where(s => s.Status == ControlStatus.NotMet).Select(s => s.Name).ToList();
            var row = table.AddRow();
            row.Cells[0].AddParagraph(control.Name).Format.Font.Bold = true;
            row.Cells[0].AddParagraph(control.Description).Style = "Muted";
            Number(row.Cells[1], statuses.Count(s => s.Status == ControlStatus.Met), Good);
            Number(row.Cells[2], failing.Count, failing.Count > 0 ? Critical : Muted);
            Number(row.Cells[3], statuses.Count(s => s.Status == ControlStatus.NotMeasured), Muted);
            row.Cells[4].AddParagraph(failing.Count == 0 ? "–" : string.Join(", ", failing.Take(12)) + (failing.Count > 12 ? $" og {failing.Count - 12} flere" : ""));
        }
    }

    private static void Instances(Section section, ReportData data)
    {
        section.AddParagraph("Instanser", StyleNames.Heading1);
        var table = Table(section, ("Instans", 4.2), ("Version", 5.4), ("Kontakt", 2.8), ("Kritisk", 1.8), ("Høj", 1.4), ("Middel", 1.4));
        foreach (var i in data.Instances)
        {
            var row = table.AddRow();
            row.Cells[0].AddParagraph(i.Name).Format.Font.Bold = true;
            row.Cells[1].AddParagraph(VersionText(i));
            var reachable = !data.Unreachable(UnreachableAfter).Contains(i);
            var contact = row.Cells[2].AddParagraph(reachable ? "Svarer" : "Kan ikke nås");
            contact.Format.Font.Color = reachable ? Good : Critical;
            Number(row.Cells[3], i.Critical, i.Critical > 0 ? Critical : Muted);
            Number(row.Cells[4], i.High, i.High > 0 ? High : Muted);
            Number(row.Cells[5], i.Medium, i.Medium > 0 ? Medium : Muted);
        }
    }

    private static void Findings(Section section, ReportData data)
    {
        section.AddParagraph("Kritiske fund og fund med høj alvor", StyleNames.Heading1);
        var findings = data.Active.Where(f => f.Severity >= Severity.High).OrderByDescending(f => f.Severity).ThenBy(f => f.FirstSeenAt).ToList();
        if (findings.Count == 0)
        {
            section.AddParagraph("Ingen.");
            return;
        }

        var table = Table(section, ("Alvor", 1.9), ("Instans", 3.2), ("Fund", 8.3), ("Set første gang", 2.6), ("Dage", 1));
        foreach (var f in findings.Take(MaxFindingRows))
        {
            var row = table.AddRow();
            var severity = row.Cells[0].AddParagraph(f.Severity == Severity.Critical ? "Kritisk" : "Høj");
            severity.Format.Font.Bold = true;
            severity.Format.Font.Color = f.Severity == Severity.Critical ? Critical : High;
            row.Cells[1].AddParagraph(f.InstanceName);
            row.Cells[2].AddParagraph(f.Title);
            row.Cells[3].AddParagraph(Date(data, new DateTimeOffset(System.DateTime.SpecifyKind(f.FirstSeenAt, DateTimeKind.Utc))));
            Number(row.Cells[4], (int)(data.GeneratedAt.UtcDateTime - f.FirstSeenAt).TotalDays, Text);
        }

        if (findings.Count > MaxFindingRows)
        {
            section.AddParagraph($"… og {findings.Count - MaxFindingRows} flere. Se alle i SQLInsight Pro.").Style = "Muted";
        }
    }

    private static void ConfigurationChanges(Section section, ReportData data)
    {
        section.AddParagraph("Konfigurationsændringer i perioden", StyleNames.Heading1);
        section.AddParagraph("Ændringer af serverindstillinger (sp_configure), trace flags, tjenestekonti, version og tempdb, som SQLInsight Pro har registreret. Tidspunktet er, hvornår ændringen blev opdaget (højst 15 minutter efter).").Style = "Muted";
        if (data.ConfigurationChanges.Count == 0)
        {
            section.AddParagraph("Ingen.");
            return;
        }

        var table = Table(section, ("Opdaget", 2.6), ("Instans", 3.2), ("Indstilling", 5.4), ("Fra", 2.6), ("Til", 2.6));
        foreach (var c in data.ConfigurationChanges.Take(MaxFindingRows))
        {
            var row = table.AddRow();
            row.Cells[0].AddParagraph(Date(data, new DateTimeOffset(System.DateTime.SpecifyKind(c.DetectedAt, DateTimeKind.Utc))));
            row.Cells[1].AddParagraph(c.InstanceName);
            row.Cells[2].AddParagraph($"{c.Area}: {c.Name}");
            row.Cells[3].AddParagraph(c.OldValue ?? "–");
            row.Cells[4].AddParagraph(c.NewValue ?? "–");
        }

        if (data.ConfigurationChanges.Count > MaxFindingRows)
        {
            section.AddParagraph($"… og {data.ConfigurationChanges.Count - MaxFindingRows} flere. Se dem under Konfiguration på instansens side.").Style = "Muted";
        }
    }

    private static void About(Section section, ReportData data)
    {
        section.AddParagraph("Om rapporten", StyleNames.Heading1);
        section.AddParagraph(
            "Rapporten er dannet automatisk af SQLInsight Pro ud fra målinger på SQL Server-instanserne. Hvert fund har en forklaring, "
            + "målingerne bag og en anbefaling i SQLInsight Pro. Alvor: kritisk kan give nedetid eller datatab nu; høj bør løses inden for dage.").Style = "Muted";
        section.AddParagraph($"SQLInsight Pro {data.Version}{(data.RulePack is { Length: > 0 } pack ? $", regelpakke {pack}" : "")}.").Style = "Muted";
    }

    private static Table Table(Section section, params (string Header, double Width)[] columns)
    {
        var table = section.AddTable();
        table.Borders.Bottom = new Border { Width = 0.5, Color = Border };
        table.Rows.LeftIndent = 0;
        foreach (var (_, width) in columns)
        {
            var column = table.AddColumn(Unit.FromCentimeter(width));
            column.LeftPadding = Unit.FromPoint(4);
            column.RightPadding = Unit.FromPoint(4);
        }

        var header = table.AddRow();
        header.HeadingFormat = true;
        header.Shading.Color = Surface;
        header.Format.Font.Bold = true;
        header.Format.Font.Size = 8;
        header.Format.Font.Color = Muted;
        for (var i = 0; i < columns.Length; i++)
        {
            header.Cells[i].AddParagraph(columns[i].Header.ToUpperInvariant());
        }

        table.Format.SpaceBefore = Unit.FromPoint(3);
        table.Format.SpaceAfter = Unit.FromPoint(3);
        return table;
    }

    private static void Number(Cell cell, int value, Color color)
    {
        var paragraph = cell.AddParagraph(value.ToString(Danish));
        paragraph.Format.Font.Color = color;
        paragraph.Format.Font.Bold = value > 0 && color != Muted;
    }

    private static string VersionText(InstanceOverview i)
    {
        if (i.ProductVersion is not { } text || !SqlServerVersion.TryParse(text, out var version))
        {
            return "Ukendt";
        }

        var release = i.EngineEdition == 8 ? SqlServerRelease.AzureSqlManagedInstance : version.Release;
        var level = $"{i.ProductLevel} {i.ProductUpdateLevel}".Trim();
        return $"{release.DisplayName()}{(level.Length > 0 ? $" {level}" : "")} ({text})";
    }

    private static string Date(ReportData data, DateTimeOffset value) =>
        TimeZoneInfo.ConvertTime(value, data.TimeZone).ToString("d. MMM yyyy", Danish);

    private static string DateTime(ReportData data, DateTimeOffset value) =>
        TimeZoneInfo.ConvertTime(value, data.TimeZone).ToString("d. MMM yyyy HH:mm", Danish);
}