namespace QWERTYkez.ExcelProcessor;

internal static class ReplaceStringExtensions
{
    // --- Публичный метод для одиночной замены ---
    internal static void Replace(this SpreadsheetDocument doc, string oldValue, string newValue, StringComparison comparisonType = StringComparison.OrdinalIgnoreCase)
    {
        if (string.IsNullOrEmpty(oldValue)) return;
        WorksheetPart[] worksheets = [.. doc.WorkbookPart?.WorksheetParts!];
        if (worksheets.Length < 1) return;

        var replacement = new Dictionary<string, string> { [oldValue] = newValue };
        ReplaceCore(doc, worksheets, replacement, comparisonType);
    }

    // --- Публичный метод для множественной замены ---
    internal static void Replace(this SpreadsheetDocument doc, IEnumerable<KeyValuePair<string, string>> replacements, StringComparison comparisonType = StringComparison.OrdinalIgnoreCase)
    {
        if (replacements is null) return;
        WorksheetPart[] worksheets = [.. doc.WorkbookPart?.WorksheetParts!];
        if (worksheets.Length < 1) return;

        var comparer = GetComparerForStringComparison(comparisonType);
        var replacementDict = new Dictionary<string, string>(comparer);
        foreach (var kvp in replacements)
            if (!string.IsNullOrEmpty(kvp.Key))
                replacementDict[kvp.Key] = kvp.Value;
        if (replacementDict.Count == 0) return;
        ReplaceCore(doc, worksheets, replacementDict, comparisonType);
    }

    // --- Общий приватный метод, содержащий всю логику замены ---
    private static void ReplaceCore(SpreadsheetDocument doc, WorksheetPart[] worksheets, Dictionary<string, string> replacementDict, StringComparison comparisonType)
    {
        var workbookPart = doc.WorkbookPart!;

        // 1. Собрать все изменения для ячеек
        var cellChanges = new Dictionary<Cell, string>();
        var allSharedStrings = new List<string>();
        var sharedStringTable = workbookPart.SharedStringTablePart?.SharedStringTable;
        if (sharedStringTable is not null)
        {
            foreach (var item in sharedStringTable.Elements<SharedStringItem>())
                allSharedStrings.Add(string.Concat(item.Descendants<Text>().Select(t => t.Text)));
        }

        foreach (var worksheetPart in worksheets)
            CollectCellChanges(worksheetPart, replacementDict, comparisonType, cellChanges, allSharedStrings);

        // 2. Применить изменения к ячейкам
        ApplyCellChanges(cellChanges, allSharedStrings);

        // 3. Обновить SharedStringTable
        UpdateSharedStringTable(workbookPart, allSharedStrings);

        // 4. Обработать колонтитулы
        foreach (var worksheetPart in worksheets)
            ReplaceInHeadersFooters(worksheetPart, replacementDict, comparisonType);

        // 5. Обработать комментарии
        foreach (var worksheetPart in worksheets)
            ReplaceInComments(worksheetPart, replacementDict, comparisonType);
    }

    // --- Остальные вспомогательные методы (без изменений) ---
    private static IEqualityComparer<string> GetComparerForStringComparison(StringComparison comparisonType) =>
        comparisonType switch
        {
            StringComparison.Ordinal => StringComparer.Ordinal,
            StringComparison.OrdinalIgnoreCase => StringComparer.OrdinalIgnoreCase,
            StringComparison.InvariantCulture => StringComparer.InvariantCulture,
            StringComparison.InvariantCultureIgnoreCase => StringComparer.InvariantCultureIgnoreCase,
            StringComparison.CurrentCulture => StringComparer.CurrentCulture,
            StringComparison.CurrentCultureIgnoreCase => StringComparer.CurrentCultureIgnoreCase,
            _ => StringComparer.OrdinalIgnoreCase,
        };

    private static void CollectCellChanges(WorksheetPart worksheetPart, Dictionary<string, string> replacementDict, StringComparison comparisonType, Dictionary<Cell, string> cellChanges, List<string> allSharedStrings)
    {
        var worksheet = worksheetPart.Worksheet;
        if (worksheet is null) return;
        var sheetData = worksheet.GetFirstChild<SheetData>();
        if (sheetData is null) return;

        foreach (var row in sheetData.Elements<Row>())
            foreach (var cell in row.Elements<Cell>())
            {
                string originalText = GetCellText(cell, allSharedStrings);
                if (string.IsNullOrEmpty(originalText)) continue;
                string newText = ProcessReplacements(originalText, replacementDict, comparisonType);
                if (newText != originalText)
                    cellChanges[cell] = newText;
            }
    }

    private static void ApplyCellChanges(Dictionary<Cell, string> cellChanges, List<string> allSharedStrings)
    {
        foreach (var kvp in cellChanges)
        {
            var cell = kvp.Key;
            var newText = kvp.Value;
            if (cell.InlineString is not null)
            {
                var texts = cell.InlineString.Descendants<Text>().ToList();
                foreach (var t in texts) t.Remove();
                cell.InlineString.AppendChild(new Text(newText));
            }
            else
            {
                int newIndex = AddOrFindStringIndex(allSharedStrings, newText);
                cell.DataType = new EnumValue<CellValues>(CellValues.SharedString);
                cell.CellValue = new CellValue(newIndex.ToString());
            }
        }
    }

    private static void UpdateSharedStringTable(WorkbookPart workbookPart, List<string> allSharedStrings)
    {
        var ssPart = workbookPart.SharedStringTablePart;
        ssPart ??= workbookPart.AddNewPart<SharedStringTablePart>();
        var sharedStringTable = ssPart.SharedStringTable ?? new SharedStringTable();
        sharedStringTable.RemoveAllChildren<SharedStringItem>();
        foreach (var str in allSharedStrings)
            sharedStringTable.AppendChild(new SharedStringItem(new Text(str)));
        sharedStringTable.Save();
    }

    private static string ProcessReplacements(string input, Dictionary<string, string> replacementDict, StringComparison comparisonType)
    {
        if (string.IsNullOrEmpty(input) || replacementDict.Count == 0) return input;
        string result = input;
        foreach (string key in replacementDict.Keys.OrderByDescending(k => k.Length))
        {
            string value = replacementDict[key];
            result = ReplaceInString(result, key, value, comparisonType);
        }
        return result;
    }

    private static string ReplaceInString(string original, string oldValue, string newValue, StringComparison comparisonType)
    {
        int idx = original.IndexOf(oldValue, comparisonType);
        if (idx < 0) return original;
        var sb = new StringBuilder(original.Length + newValue.Length - oldValue.Length);
        int last = 0;
        while (idx >= 0)
        {
            sb.Append(original, last, idx - last);
            sb.Append(newValue);
            last = idx + oldValue.Length;
            idx = original.IndexOf(oldValue, last, comparisonType);
        }
        sb.Append(original, last, original.Length - last);
        return sb.ToString();
    }

    private static string GetCellText(Cell cell, List<string> allSharedStrings)
    {
        if (cell?.CellValue is null) return string.Empty;
        if (cell.InlineString is not null)
            return string.Concat(cell.InlineString.Descendants<Text>().Select(t => t.Text));
        string value = cell.CellValue.InnerText;
        if (cell.DataType?.Value == CellValues.SharedString)
        {
            if (int.TryParse(value, out int idx) && idx >= 0 && idx < allSharedStrings.Count)
                return allSharedStrings[idx];
            return string.Empty;
        }
        return value;
    }

    private static int AddOrFindStringIndex(List<string> allSharedStrings, string text)
    {
        int idx = allSharedStrings.IndexOf(text);
        if (idx >= 0) return idx;
        allSharedStrings.Add(text);
        return allSharedStrings.Count - 1;
    }

    // --- Колонтитулы (обобщённый метод) ---
    private static void ReplaceInHeadersFooters(WorksheetPart worksheetPart, Dictionary<string, string> replacementDict, StringComparison comparisonType)
    {
        var worksheet = worksheetPart.Worksheet;
        if (worksheet is null) return;
        var headerFooter = worksheet.Descendants<HeaderFooter>().FirstOrDefault();
        if (headerFooter is null) return;

        foreach (var elem in new OpenXmlLeafTextElement?[] { headerFooter.OddHeader, headerFooter.OddFooter, headerFooter.EvenHeader, headerFooter.EvenFooter, headerFooter.FirstHeader, headerFooter.FirstFooter })
            ReplaceHeaderFooter(elem, replacementDict, comparisonType);
    }

    private static void ReplaceHeaderFooter(OpenXmlLeafTextElement? element, Dictionary<string, string> replacementDict, StringComparison comparisonType)
    {
        if (element?.Text is null) return;
        string original = element.Text;
        string processed = ProcessReplacements(original, replacementDict, comparisonType);
        if (processed != original)
            element.Text = processed;
    }

    // --- Комментарии ---
    private static void ReplaceInComments(WorksheetPart worksheetPart, Dictionary<string, string> replacementDict, StringComparison comparisonType)
    {
        var commentsPart = worksheetPart.WorksheetCommentsPart;
        if (commentsPart?.Comments is null) return;
        foreach (var comment in commentsPart.Comments.Elements<Comment>())
        {
            var textElement = comment.Descendants<CommentText>().FirstOrDefault();
            if (textElement?.Text is null) continue;
            string original = textElement.Text.Text;
            if (string.IsNullOrEmpty(original)) continue;
            string processed = ProcessReplacements(original, replacementDict, comparisonType);
            if (processed != original)
                textElement.Text.Text = processed;
        }
    }
}