namespace QWERTYkez.WordProcessor;

/// <summary>
/// Вспомогательный класс для динамической замены параграфов, содержащих "$key|param$",
/// на текст, построенный через <see cref="IText"/>.
/// </summary>
internal static class DynamicReplaceToTextExt
{
    internal static void ReplaceParagraphsContainingTextToTextDynamic(
        Body body,
        string oldValue,
        Action<string, IText> buildText)
    {
        if (body is null || string.IsNullOrEmpty(oldValue) || buildText is null)
            return;

        DynamicReplaceExt.ParsePattern(oldValue, out var prefix, out var suffix);

        var paragraphs = body.Elements<Paragraph>().ToList();
        if (paragraphs.Count == 0)
            return;

        for (int i = paragraphs.Count - 1; i >= 0; i--)
        {
            var paragraph = paragraphs[i];
            if (paragraph is null) continue;

            var paraText = paragraph.InnerText;
            if (string.IsNullOrEmpty(paraText)) continue;

            int pStart = paraText.IndexOf(prefix, StringComparison.OrdinalIgnoreCase);
            if (pStart < 0) continue;

            int paramStart = pStart + prefix.Length;
            int pEnd = string.IsNullOrEmpty(suffix)
                ? paraText.Length
                : paraText.IndexOf(suffix, paramStart, StringComparison.OrdinalIgnoreCase);
            if (pEnd < 0) continue;

            string param = paraText.Substring(paramStart, pEnd - paramStart);
            string matchedText = paraText.Substring(pStart, pEnd + suffix.Length - pStart);

            var fontProps = ExtractFontPropsFromParagraph(paragraph, matchedText);
            var paragraphProps = paragraph.ParagraphProperties?.CloneNode(true) as ParagraphProperties;

            var capturedParam = param;
            ReplaceWithTextBuilder(paragraph, tb => buildText(capturedParam, tb), fontProps, paragraphProps);
        }
    }

    // ------------------------------------------------------------
    // Ниже — 1:1 копия из ReplaceToTextExt (private helper-методы)
    // ------------------------------------------------------------

    private static void ReplaceWithTextBuilder(
        Paragraph paragraph,
        Action<IText> buildText,
        FontProps? baseFont,
        ParagraphProperties? baseParagraphProps)
    {
        if (paragraph is null || paragraph.Parent is null || buildText is null)
            return;

        var parent = paragraph.Parent;

        var builder = TextBuilder.Create(baseFont, baseParagraphProps);
        buildText(builder);
        var newParagraphs = builder.Build();

        int paraIndex = -1;
        var children = parent.ChildElements;

        for (int i = 0; i < children.Count; i++)
        {
            if (children[i] == paragraph)
            {
                paraIndex = i;
                break;
            }
        }

        if (paraIndex == -1)
            return;

        parent.RemoveChild(paragraph);

        for (int i = 0; i < newParagraphs.Count; i++)
        {
            parent.InsertAt(newParagraphs[i], paraIndex + i);
        }
    }

    private static FontProps? ExtractFontPropsFromParagraph(Paragraph paragraph, string searchText)
    {
        if (paragraph is null || string.IsNullOrEmpty(searchText))
            return null;

        var runs = paragraph.Descendants<Run>().ToList();
        if (runs.Count == 0)
            return null;

        var runInfos = new List<(Run Run, int Start, int End, string Text)>();
        int currentPosition = 0;

        foreach (var run in runs)
        {
            var runText = GetRunText(run);
            if (!string.IsNullOrEmpty(runText))
            {
                runInfos.Add((run, currentPosition, currentPosition + runText.Length, runText));
                currentPosition += runText.Length;
            }
        }

        foreach (var (run, start, end, text) in runInfos)
        {
            if (text.IndexOf(searchText, StringComparison.OrdinalIgnoreCase) >= 0)
            {
                return CreateFontPropsFromRun(run);
            }
        }

        var fullText = string.Concat(runInfos.Select(r => r.Text));
        int textIndex = fullText.IndexOf(searchText, StringComparison.OrdinalIgnoreCase);

        if (textIndex >= 0)
        {
            var intersectingRun = runInfos.FirstOrDefault(r =>
                r.Start <= textIndex && r.End > textIndex);

            if (intersectingRun.Run is not null)
            {
                return CreateFontPropsFromRun(intersectingRun.Run);
            }
        }

        return null;
    }

    private static FontProps CreateFontPropsFromRun(Run run)
    {
        var runProperties = run.RunProperties;
        if (runProperties is null)
            return new FontProps();

        var fontProps = new FontProps();

        var runFonts = runProperties.GetFirstChild<RunFonts>();
        if (runFonts is not null)
        {
            fontProps = fontProps with
            {
                FontFamily = runFonts.Ascii ?? runFonts.HighAnsi ?? runFonts.ComplexScript
            };
        }

        var fontSize = runProperties.GetFirstChild<FontSize>();
        if (fontSize is not null && !string.IsNullOrEmpty(fontSize.Val) &&
            uint.TryParse(fontSize.Val, out uint halfPoints))
        {
            fontProps = fontProps with { Size = halfPoints / 2.0 };
        }

        var bold = runProperties.GetFirstChild<Bold>();
        if (bold is not null)
        {
            bool isBold = true;
            if (bold.Val is not null)
                isBold = bold.Val.Value;
            fontProps = fontProps with { IsBold = isBold };
        }

        var italic = runProperties.GetFirstChild<Italic>();
        if (italic is not null)
        {
            bool isItalic = true;
            if (italic.Val is not null)
                isItalic = italic.Val.Value;
            fontProps = fontProps with { IsItalic = isItalic };
        }

        var underline = runProperties.GetFirstChild<Underline>();
        if (underline is not null && underline.Val is not null)
        {
            fontProps = fontProps with { Underline = underline.Val.Value };
        }

        var color = runProperties.GetFirstChild<Color>();
        if (color is not null && !string.IsNullOrEmpty(color.Val))
        {
            fontProps = fontProps with { Color = color.Val };
        }

        var verticalAlignment = runProperties.GetFirstChild<VerticalTextAlignment>();
        if (verticalAlignment is not null && verticalAlignment.Val is not null)
        {
            fontProps = fontProps with { SubSup = verticalAlignment.Val.Value };
        }

        return fontProps;
    }

    private static string GetRunText(Run run)
    {
        if (run is null) return string.Empty;

        var sb = new StringBuilder();
        foreach (var text in run.Elements<Text>())
        {
            sb.Append(text.Text ?? string.Empty);
        }
        return sb.ToString();
    }
}