namespace QWERTYkez.WordProcessor;

/// <summary>
/// Выполняет замену всех вхождений ключей из словаря на соответствующие массивы значений.
/// Поддерживает разрывы страниц и смену ориентации (альбомная/книжная) через <see cref="ReplaceItem"/>.
/// </summary>
internal static class MultiReplaceExt
{
    // ---------- ПУБЛИЧНЫЕ МЕТОДЫ (для Body) ----------

    #region Body.Replace с одним ключом

    internal static void Replace(this Body body, string oldValue, IEnumerable<string> newValues, StringComparison comparisonType)
    {
        if (body is null || string.IsNullOrEmpty(oldValue) || newValues is null) return;
        var dict = new Dictionary<string, IEnumerable<string>> { { oldValue, newValues } };
        body.Replace(dict, comparisonType);
    }

    internal static void Replace(this Body body, string oldValue, IEnumerable<ReplaceItem> newValues, StringComparison comparisonType)
    {
        if (body is null || string.IsNullOrEmpty(oldValue) || newValues is null) return;
        var dict = new Dictionary<string, IEnumerable<ReplaceItem>> { { oldValue, newValues } };
        body.Replace(dict, comparisonType);
    }

    #endregion

    #region Body.Replace со словарём массивов

    internal static void Replace(this Body body, IEnumerable<KeyValuePair<string, IEnumerable<string>>> replacements, StringComparison comparisonType)
    {
        if (body is null || replacements is null) return;
        var paragraphs = body.Elements<Paragraph>().ToList();
        for (int i = paragraphs.Count - 1; i >= 0; i--)
        {
            var p = paragraphs[i];
            if (p?.Parent is null) continue;
            var newParas = ProcessMultiReplacements(p, replacements, null, comparisonType);
            if (newParas is not null && newParas.Count > 0)
                ParagraphReplacer.ReplaceParagraph(p, newParas);
        }
    }

    internal static void Replace(this Body body, IEnumerable<KeyValuePair<string, IEnumerable<ReplaceItem>>> replacements, StringComparison comparisonType)
    {
        if (body is null || replacements is null) return;
        var paragraphs = body.Elements<Paragraph>().ToList();
        for (int i = paragraphs.Count - 1; i >= 0; i--)
        {
            var p = paragraphs[i];
            if (p?.Parent is null) continue;
            var newParas = ProcessMultiReplacements(p, null, replacements, comparisonType);
            if (newParas is not null && newParas.Count > 0)
                ParagraphReplacer.ReplaceParagraph(p, newParas);
        }
    }

    #endregion

    #region Paragraph.ReplaceWithMultiple (один ключ)

    internal static bool ReplaceWithMultiple(this Paragraph? paragraph, string oldValue, IEnumerable<string> newValues, StringComparison comparisonType)
    {
        if (paragraph is null || string.IsNullOrEmpty(oldValue) || newValues is null || newValues.Count() == 0)
            return false;

        var dict = new Dictionary<string, IEnumerable<string>> { { oldValue, newValues } };
        var newParas = ProcessMultiReplacements(paragraph, dict, null, comparisonType);
        if (newParas is null || newParas.Count == 0) return false;

        if (paragraph.Parent is not null)
        {
            ParagraphReplacer.ReplaceParagraph(paragraph, newParas);
            return true;
        }
        return false;
    }

    internal static bool ReplaceWithMultiple(this Paragraph? paragraph, string oldValue, IEnumerable<ReplaceItem> newValues, StringComparison comparisonType)
    {
        if (paragraph is null || string.IsNullOrEmpty(oldValue) || newValues is null || newValues.Count() == 0)
            return false;

        var dict = new Dictionary<string, IEnumerable<ReplaceItem>> { { oldValue, newValues } };
        var newParas = ProcessMultiReplacements(paragraph, null, dict, comparisonType);
        if (newParas is null || newParas.Count == 0) return false;

        if (paragraph.Parent is not null)
        {
            ParagraphReplacer.ReplaceParagraph(paragraph, newParas);
            return true;
        }
        return false;
    }

    #endregion

    #region ProcessParagraphWithAllReplacements (для обратной совместимости)

    internal static List<Paragraph>? ProcessParagraphWithAllReplacements(
        Paragraph paragraph,
        IEnumerable<KeyValuePair<string, IEnumerable<string>>> replacements,
        StringComparison comparisonType)
    {
        return ProcessMultiReplacements(paragraph, replacements, null, comparisonType);
    }

    internal static List<Paragraph>? ProcessParagraphWithAllReplacements(
        Paragraph paragraph,
        IEnumerable<KeyValuePair<string, IEnumerable<ReplaceItem>>> replacements,
        StringComparison comparisonType)
    {
        return ProcessMultiReplacements(paragraph, null, replacements, comparisonType);
    }

    internal static List<Paragraph>? ProcessParagraphWithAllReplacements(
        Paragraph paragraph,
        IEnumerable<KeyValuePair<string, string>> replacements,
        StringComparison comparisonType)
    {
        Dictionary<string, IEnumerable<string>> dict = replacements
            .Where(kvp => !string.IsNullOrEmpty(kvp.Key))
            .ToDictionary(kvp => kvp.Key, kvp => (IEnumerable<string>)[kvp.Value]);
        return ProcessMultiReplacements(paragraph, dict, null, comparisonType);
    }

    #endregion

    // ---------- ВНУТРЕННЯЯ РЕАЛИЗАЦИЯ ----------

    private class MatchDefinition(string key, IEnumerable<ReplaceItem> values)
    {
        public string Key { get; } = key;
        public IEnumerable<ReplaceItem> Values { get; } = values;
    }

    private class Match
    {
        public MatchDefinition Definition { get; set; } = null!;
        public int Start { get; set; }
        public int End { get; set; }
    }

    private class RunSegment(Run run, string text, int start, int end)
    {
        public Run Run { get; } = run;
        public string Text { get; } = text;
        public int Start { get; } = start;
        public int End { get; } = end;
    }

    private class ParagraphStructure(string fullText, List<RunSegment> segments)
    {
        public string FullText { get; } = fullText;
        public List<RunSegment> Segments { get; } = segments;
    }

    private static ParagraphStructure AnalyzeParagraphStructure(List<Run> runs)
    {
        var segments = new List<RunSegment>();
        var sb = new StringBuilder();
        int pos = 0;
        foreach (var run in runs)
        {
            string text = GetRunText(run);
            if (string.IsNullOrEmpty(text)) continue;
            segments.Add(new RunSegment(run, text, pos, pos + text.Length));
            sb.Append(text);
            pos += text.Length;
        }
        return new ParagraphStructure(sb.ToString(), segments);
    }

    private static string GetRunText(Run run)
    {
        var sb = new StringBuilder();
        foreach (var text in run.Elements<Text>())
            sb.Append(text.Text);
        return sb.ToString();
    }

    /// <summary>Клонирует параграф, удаляя все SectionProperties и PageBreakBefore.</summary>
    private static Paragraph CloneParagraphWithoutSection(Paragraph original)
    {
        var newPara = new Paragraph();
        if (original.ParagraphProperties is not null)
        {
            var newProps = new ParagraphProperties();
            foreach (var child in original.ParagraphProperties.ChildElements)
            {
                if (child is not SectionProperties && child is not PageBreakBefore)
                    newProps.AppendChild(child.CloneNode(true));
            }
            newPara.ParagraphProperties = newProps;
        }
        return newPara;
    }

    private static Paragraph? BuildRemainderParagraph(Paragraph original, ParagraphStructure structure, int position)
    {
        if (position >= structure.FullText.Length) return null;

        var newPara = CloneParagraphWithoutSection(original);
        foreach (var seg in structure.Segments)
        {
            if (seg.End <= position) continue;
            if (seg.Start >= position)
            {
                newPara.AppendChild(seg.Run.CloneNode(true));
            }
            else if (seg.End > position)
            {
                var runClone = (Run)seg.Run.CloneNode(true);
                foreach (var t in runClone.Elements<Text>().ToList()) t.Remove();
                int offset = position - seg.Start;
                string newText = seg.Text.Substring(offset);
                runClone.AppendChild(new Text(newText));
                newPara.AppendChild(runClone);
            }
        }
        foreach (var run in newPara.Descendants<Run>().Where(r => !r.HasChildren).ToList())
            run.Remove();
        if (!newPara.ChildElements.OfType<Run>().Any() && newPara.ParagraphProperties is null)
            return null;
        return newPara;
    }

    private static void InsertFormattedRun(Paragraph para, string text, ParagraphStructure structure, int position)
    {
        var seg = structure.Segments.FirstOrDefault(s => position >= s.Start && position < s.End);
        if (seg is null) return;

        var textRun = new Run();
        if (seg.Run.RunProperties is not null)
            textRun.RunProperties = (RunProperties)seg.Run.RunProperties.CloneNode(true);
        textRun.AppendChild(new Text(text));
        para.AppendChild(textRun);
    }

    /// <summary>
    /// Добавляет SectionProperties к параграфу. Все значения (PageSize, PageMargin) берутся из документа.
    /// Для книжных секций (addPageSize=false) Orient не устанавливается (not set).
    /// </summary>
    private static void AddSectionProperties(
        Paragraph para,
        BreakType splitValue,
        bool addPageSize,
        SectionProperties sourceSection,
        SectionProperties portraitSection)
    {
        if (para is null) return;

        if (para.ParagraphProperties is not null)
        {
            var sections = para.ParagraphProperties.Elements<SectionProperties>().ToList();
            foreach (var sec in sections) sec.Remove();
            var pageBreaks = para.ParagraphProperties.Elements<PageBreakBefore>().ToList();
            foreach (var pb in pageBreaks) pb.Remove();
        }

        para.ParagraphProperties ??= new ParagraphProperties();
        var sectionProps = new SectionProperties();

        var pageSizeClone = CreatePageSizeClone(addPageSize, splitValue, sourceSection, portraitSection);
        if (pageSizeClone is not null)
            sectionProps.AppendChild(pageSizeClone);

        var marginClone = CreateMarginClone(addPageSize, splitValue, sourceSection, portraitSection);
        if (marginClone is not null)
            sectionProps.AppendChild(marginClone);

        sectionProps.AppendChild(new SectionType { Val = SectionMarkValues.NextPage });
        para.ParagraphProperties.AppendChild(sectionProps);
    }

    private static PageSize? CreatePageSizeClone(
        bool addPageSize,
        BreakType splitValue,
        SectionProperties sourceSection,
        SectionProperties portraitSection)
    {
        if (!addPageSize && splitValue != BreakType.NewLandscapeSection)
            return null;

        SectionProperties? sizeSource = addPageSize ? sourceSection : portraitSection;
        var sourcePageSize = sizeSource?.GetFirstChild<PageSize>()
                              ?? portraitSection.GetFirstChild<PageSize>()
                              ?? sourceSection.GetFirstChild<PageSize>();

        if (sourcePageSize is null)
            return null;

        var clone = (PageSize)sourcePageSize.CloneNode(true);
        bool sourceIsLandscape = clone.Orient?.Value == PageOrientationValues.Landscape ||
                                 (clone.Width?.Value > clone.Height?.Value);

        bool targetIsLandscape = addPageSize && splitValue == BreakType.NewLandscapeSection;

        if (targetIsLandscape && !sourceIsLandscape)
        {
            clone.SwapValues();
            clone.Orient = PageOrientationValues.Landscape;
        }
        else if (!targetIsLandscape && sourceIsLandscape)
        {
            clone.SwapValues();
            clone.Orient = addPageSize ? PageOrientationValues.Portrait : null;
        }
        else
        {
            clone.Orient = targetIsLandscape ? PageOrientationValues.Landscape :
                           addPageSize ? PageOrientationValues.Portrait : null;
        }

        return clone;
    }

    private static PageMargin? CreateMarginClone(
        bool addPageSize,
        BreakType splitValue,
        SectionProperties sourceSection,
        SectionProperties portraitSection)
    {
        PageMargin? marginToUse = null;

        if (addPageSize)
        {
            var sourceMargin = sourceSection?.GetFirstChild<PageMargin>()
                               ?? portraitSection?.GetFirstChild<PageMargin>();
            if (sourceMargin is not null)
            {
                var clone = (PageMargin)sourceMargin.CloneNode(true);
                var sourceOrient = sourceSection?.GetFirstChild<PageSize>()?.Orient;
                bool sourceIsLandscape = sourceOrient?.Value == PageOrientationValues.Landscape ||
                                         (sourceSection?.GetFirstChild<PageSize>()?.Width?.Value > sourceSection?.GetFirstChild<PageSize>()?.Height?.Value);

                if ((splitValue == BreakType.NewLandscapeSection && !sourceIsLandscape) ||
                    (splitValue == BreakType.NewPortraitSection && sourceIsLandscape))
                {
                    clone.SwapBottomRight();
                }
                marginToUse = clone;
            }
        }
        else
        {
            var portraitMargin = portraitSection?.GetFirstChild<PageMargin>();
            if (portraitMargin is not null)
                marginToUse = (PageMargin)portraitMargin.CloneNode(true);
        }

        return marginToUse;
    }

    private static void EnsureBodyLandscapeSection(
        Body body,
        SectionProperties sourceSection,
        bool sectionChangeInsideGroup,
        BreakType? lastOrientation)
    {
        if (body is null || sourceSection is null) return;

        var sourcePageSize = sourceSection.GetFirstChild<PageSize>();
        if (sourcePageSize is null) return;

        bool sourceIsLandscape = sourcePageSize.Orient?.Value == PageOrientationValues.Landscape ||
                                 (sourcePageSize.Width?.Value > sourcePageSize.Height?.Value);
        bool lastIsPortrait = lastOrientation.HasValue && lastOrientation.Value == BreakType.NewPortraitSection;

        if (!(sourceIsLandscape && sectionChangeInsideGroup && lastIsPortrait))
            return;

        foreach (var bodySec in body.Elements<SectionProperties>())
        {
            var ps = bodySec.GetFirstChild<PageSize>();
            if (ps is not null && ps.Orient?.Value == PageOrientationValues.Landscape)
                return;
        }

        var bodySection = new SectionProperties();
        var pageSizeClone = (PageSize)sourcePageSize.CloneNode(true);
        if (pageSizeClone.Orient?.Value != PageOrientationValues.Landscape)
        {
            pageSizeClone.SwapValues();
            pageSizeClone.Orient = PageOrientationValues.Landscape;
        }
        bodySection.AppendChild(pageSizeClone);

        var sourceMargin = sourceSection.GetFirstChild<PageMargin>();
        if (sourceMargin is not null)
        {
            var marginClone = (PageMargin)sourceMargin.CloneNode(true);
            if (sourceSection.GetFirstChild<PageSize>()?.Orient?.Value != PageOrientationValues.Landscape)
                marginClone.SwapBottomRight();
            bodySection.AppendChild(marginClone);
        }

        bodySection.AppendChild(new SectionType { Val = SectionMarkValues.NextPage });
        body.AppendChild(bodySection);
    }

    private static void MergeParagraph(Paragraph target, Paragraph source)
    {
        foreach (var child in source.ChildElements)
            target.AppendChild(child.CloneNode(true));
    }

    /// <summary>Основной алгоритм множественной замены с поддержкой разрывов и смены ориентации.</summary>
    private static List<Paragraph>? ProcessMultiReplacements(
        Paragraph original,
        IEnumerable<KeyValuePair<string, IEnumerable<string>>>? stringReplacements,
        IEnumerable<KeyValuePair<string, IEnumerable<ReplaceItem>>>? itemReplacements,
        StringComparison comparisonType)
    {
        var body = original.Ancestors<Body>().FirstOrDefault();

        // 1. Сбор определений
        var definitions = new List<MatchDefinition>();
        if (stringReplacements is not null)
        {
            foreach (var kvp in stringReplacements)
            {
                if (string.IsNullOrEmpty(kvp.Key) || kvp.Value is null || kvp.Value.Count() == 0) continue;
                var items = kvp.Value.Select(v => new ReplaceItem(v));
                definitions.Add(new MatchDefinition(kvp.Key, items));
            }
        }
        if (itemReplacements is not null)
        {
            foreach (var kvp in itemReplacements)
            {
                if (string.IsNullOrEmpty(kvp.Key) || kvp.Value is null || kvp.Value.Count() == 0) continue;
                definitions.Add(new MatchDefinition(kvp.Key, kvp.Value));
            }
        }
        if (definitions.Count == 0) return null;

        // 2. Анализ структуры параграфа
        var runs = original.Descendants<Run>().ToList();
        if (runs.Count == 0) return null;
        var structure = AnalyzeParagraphStructure(runs);
        string fullText = structure.FullText;
        if (fullText.Length == 0) return null;

        // 3. Поиск всех вхождений
        var matches = new List<Match>();
        foreach (var def in definitions)
        {
            int pos = 0;
            while ((pos = fullText.IndexOf(def.Key, pos, comparisonType)) != -1)
            {
                matches.Add(new Match
                {
                    Definition = def,
                    Start = pos,
                    End = pos + def.Key.Length
                });
                pos += def.Key.Length;
            }
        }
        if (matches.Count == 0) return null;
        matches.Sort((a, b) => a.Start.CompareTo(b.Start));

        // 4. Получаем исходную секцию для копирования (из original или из документа)
        SectionProperties? sourceSection = original.ParagraphProperties?.GetFirstChild<SectionProperties>()?.CloneNode(true) as SectionProperties;
        if (sourceSection is null && body is not null)
        {
            sourceSection = body.Elements<SectionProperties>().LastOrDefault()?.CloneNode(true) as SectionProperties;
        }
        sourceSection ??= new SectionProperties();

        SectionProperties? portraitSection = null;
        if (body is not null)
        {
            portraitSection = body.Elements<SectionProperties>().FirstOrDefault()?.CloneNode(true) as SectionProperties;
        }
        portraitSection ??= new SectionProperties();

        // 5. Построение результата
        var resultParas = new List<Paragraph>();
        Paragraph? currentPara = null;
        int currentPos = 0;
        bool sectionChangeInsideGroup = false;
        BreakType? lastOrientation = null;

        // Состояние обработки группы
        bool pageBreakBeforeNext = false;
        BreakType? pendingOrientation = null;
        bool firstSplitMarkerHandled = false;
        int textCount = 0;
        Paragraph? lastTextPara = null;

        for (int i = 0; i < matches.Count; i++)
        {
            var match = matches[i];

            // Текст перед совпадением
            if (currentPos < match.Start)
            {
                var beforePara = CloneParagraphWithoutSection(original);
                foreach (var seg in structure.Segments)
                {
                    if (seg.End <= currentPos) continue;
                    if (seg.Start >= match.Start) break;
                    if (seg.Start >= currentPos && seg.End <= match.Start)
                    {
                        beforePara.AppendChild(seg.Run.CloneNode(true));
                    }
                    else if (seg.Start < match.Start && seg.End > currentPos)
                    {
                        int startOffset = Math.Max(0, currentPos - seg.Start);
                        int endOffset = Math.Min(seg.Text.Length, match.Start - seg.Start);
                        var runClone = (Run)seg.Run.CloneNode(true);
                        foreach (var t in runClone.Elements<Text>().ToList()) t.Remove();
                        string textPart = seg.Text.Substring(startOffset, endOffset - startOffset);
                        runClone.AppendChild(new Text(textPart));
                        beforePara.AppendChild(runClone);
                    }
                }
                if (beforePara.ChildElements.OfType<Run>().Any())
                {
                    resultParas.Add(beforePara);
                    currentPara = beforePara;
                    lastTextPara = beforePara;
                }
            }

            var values = match.Definition.Values.ToList();
            if (values.Count == 0) continue;

            // Сбрасываем флаги для новой группы
            pageBreakBeforeNext = false;
            pendingOrientation = null;
            firstSplitMarkerHandled = false;
            textCount = 0;
            lastTextPara = null;

            foreach (var item in values)
            {
                if (!string.IsNullOrEmpty(item.Text))
                {
                    // Если есть отложенная ориентация — применяем её
                    if (pendingOrientation.HasValue)
                    {
                        var newPara = CloneParagraphWithoutSection(original);
                        resultParas.Add(newPara);
                        currentPara = newPara;

                        bool addPageSize = (pendingOrientation.Value == BreakType.NewLandscapeSection);
                        AddSectionProperties(currentPara, pendingOrientation.Value, addPageSize, sourceSection, portraitSection);
                        lastOrientation = pendingOrientation;
                        sectionChangeInsideGroup = true;
                        pendingOrientation = null;
                        textCount++;
                        lastTextPara = currentPara;

                        if (pageBreakBeforeNext)
                        {
                            var breakRun = new Run(new Break { Type = BreakValues.Page });
                            currentPara.InsertAt(breakRun, 0);
                            pageBreakBeforeNext = false;
                        }

                        InsertFormattedRun(currentPara, item.Text, structure, match.Start);
                    }
                    else
                    {
                        var newPara = CloneParagraphWithoutSection(original);
                        resultParas.Add(newPara);
                        currentPara = newPara;
                        textCount++;
                        lastTextPara = currentPara;

                        if (pageBreakBeforeNext)
                        {
                            var breakRun = new Run(new Break { Type = BreakValues.Page });
                            currentPara.InsertAt(breakRun, 0);
                            pageBreakBeforeNext = false;
                        }

                        InsertFormattedRun(currentPara, item.Text, structure, match.Start);
                    }
                }
                else if (item.BreakValue.HasValue)
                {
                    var breakType = item.BreakValue.Value;
                    if (breakType == BreakType.PageBreak)
                    {
                        if (currentPara is not null)
                        {
                            var breakRun = new Run(new Break { Type = BreakValues.Page });
                            var lastRun = currentPara.Descendants<Run>().LastOrDefault();
                            if (lastRun?.RunProperties is not null)
                                breakRun.RunProperties = (RunProperties)lastRun.RunProperties.CloneNode(true);
                            currentPara.AppendChild(breakRun);
                        }
                        else
                        {
                            pageBreakBeforeNext = true;
                        }
                    }
                    else if (breakType == BreakType.NewLandscapeSection || breakType == BreakType.NewPortraitSection)
                    {
                        if (currentPara is null)
                        {
                            var newPara = CloneParagraphWithoutSection(original);
                            resultParas.Add(newPara);
                            currentPara = newPara;
                            AddSectionProperties(currentPara, breakType, false, sourceSection, portraitSection);
                            lastOrientation = breakType;
                            sectionChangeInsideGroup = true;
                            firstSplitMarkerHandled = true;
                            pendingOrientation = null;
                            textCount = 0;
                            lastTextPara = null;
                        }
                        else
                        {
                            if (!firstSplitMarkerHandled)
                            {
                                if (lastTextPara is not null)
                                {
                                    if (lastTextPara.ParagraphProperties?.GetFirstChild<SectionProperties>() is null)
                                    {
                                        lastTextPara.ParagraphProperties ??= new ParagraphProperties();

                                        var sourcePageSize = sourceSection.GetFirstChild<PageSize>();
                                        if (sourcePageSize is not null)
                                        {
                                            lastTextPara.ParagraphProperties.AppendChild(sourceSection.CloneNode(true));
                                        }
                                        else
                                        {
                                            AddSectionProperties(lastTextPara, breakType, false, sourceSection, portraitSection);
                                        }
                                        lastOrientation = breakType;
                                        sectionChangeInsideGroup = true;
                                    }
                                    firstSplitMarkerHandled = true;
                                    pendingOrientation = null;
                                }
                                else
                                {
                                    AddSectionProperties(currentPara, breakType, false, sourceSection, portraitSection);
                                    lastOrientation = breakType;
                                    sectionChangeInsideGroup = true;
                                    firstSplitMarkerHandled = true;
                                    pendingOrientation = null;
                                }
                            }
                            else
                            {
                                pendingOrientation = breakType;
                            }
                        }
                    }
                }
            }

            // Закрываем секцию, если была смена
            if (sectionChangeInsideGroup && lastOrientation.HasValue && currentPara is not null)
            {
                if (currentPara.ParagraphProperties?.GetFirstChild<SectionProperties>() is null)
                {
                    bool addPageSize = (lastOrientation.Value == BreakType.NewLandscapeSection);
                    AddSectionProperties(currentPara, lastOrientation.Value, addPageSize, sourceSection, portraitSection);
                }
            }

            EnsureBodyLandscapeSection(body!, sourceSection, sectionChangeInsideGroup, lastOrientation);

            currentPos = match.End;
        }

        // 6. Обработка остатка текста
        if (currentPos < fullText.Length)
        {
            var remainderPara = BuildRemainderParagraph(original, structure, currentPos);
            if (remainderPara is not null)
            {
                if (pendingOrientation.HasValue)
                {
                    var breakRun = new Run(new Break { Type = BreakValues.Page });
                    remainderPara.InsertAt(breakRun, 0);
                    bool addPageSize = (pendingOrientation.Value == BreakType.NewLandscapeSection);
                    AddSectionProperties(remainderPara, pendingOrientation.Value, addPageSize, sourceSection, portraitSection);
                    pendingOrientation = null;
                }
                else if (sectionChangeInsideGroup && lastOrientation.HasValue)
                {
                    var breakRun = new Run(new Break { Type = BreakValues.Page });
                    remainderPara.InsertAt(breakRun, 0);
                    bool addPageSize = (lastOrientation.Value == BreakType.NewLandscapeSection);
                    AddSectionProperties(remainderPara, lastOrientation.Value, addPageSize, sourceSection, portraitSection);
                }
                resultParas.Add(remainderPara);
            }
        }

        // 7. Очистка пустых параграфов
        for (int i = resultParas.Count - 1; i >= 0; i--)
        {
            var p = resultParas[i];
            if (!p.ChildElements.OfType<Run>().Any() && p.ParagraphProperties is null)
                resultParas.RemoveAt(i);
        }

        return resultParas.Count > 0 ? resultParas : null;
    }
}