using System.Runtime.InteropServices;
using System.IO.Compression;
using System.Text;
using System.Xml.Linq;
using DocumentAutomation.Shared;
using DocxWorkbench.Core;

namespace DocxWorkbench.WordInterop;

public sealed class DocxBodyImporter : IDocxBodyImporter, IDisposable
{
    private readonly StaWordQueue _queue;
    private readonly bool _ownsQueue;
    public DocxBodyImporter() : this(new StaWordQueue(), true) { }
    internal DocxBodyImporter(StaWordQueue queue) : this(queue, false) { }
    private DocxBodyImporter(StaWordQueue queue, bool ownsQueue) { _queue = queue; _ownsQueue = ownsQueue; }

    public Task<BodyImportResult> ImportAsync(DocxBodyImportRequest request, IProgress<WordOperationProgress>? progress, CancellationToken cancellationToken)
        => _queue.Enqueue(() => ImportStandalone(request, progress, cancellationToken), cancellationToken);

    private BodyImportResult ImportStandalone(DocxBodyImportRequest request, IProgress<WordOperationProgress>? progress, CancellationToken token)
    {
        dynamic? application = null; var proxies = new List<object?>(); try { var type = Type.GetTypeFromProgID("Word.Application", false) ?? throw new WordNotInstalledException("Microsoft Word is not installed or is not registered in COM."); application = Activator.CreateInstance(type) ?? throw new WordAutomationException("Could not create Word.Application."); application.Visible = false; application.DisplayAlerts = 0; return ImportOnSta(application, null, request.DestinationRangeHandle, request, progress, token, proxies); } finally { try { if (application is not null) application.Quit(0); } catch { } Release(application); ReleaseAll(proxies); }
    }

    internal BodyImportResult ImportOnSta(dynamic application, dynamic destinationDocument, dynamic destinationRange, DocxBodyImportRequest request, IProgress<WordOperationProgress>? progress, CancellationToken token, List<object?> proxies)
    {
        if (!File.Exists(request.SourcePath)) throw new FileNotFoundException("Source DOCX was not found.", request.SourcePath); if (!request.SourcePath.EndsWith(".docx", StringComparison.OrdinalIgnoreCase)) throw new UnsupportedDocumentFormatException("DocxBodyImporter accepts DOCX only.");
        var plan = BuildPlanFromOpenXml(request.SourcePath);
        var temp = Path.Combine(Path.GetTempPath(), "DocumentAutomation", "body-" + Guid.NewGuid().ToString("N")); Directory.CreateDirectory(temp); var sourceCopy = Path.Combine(temp, "source.docx"); File.Copy(request.SourcePath, sourceCopy, true); NormalizeSourceSections(sourceCopy, request.SectionBreakPolicy); dynamic? sourceDocument = null; dynamic? sourceDocuments = null; dynamic? sourceRange = null; dynamic? importRange = null; var localProxies = new List<object?>();
        try
        {
            token.ThrowIfCancellationRequested(); progress?.Report(new WordOperationProgress { Stage = "OpenSource", Message = "Opening source DOCX read-only" }); sourceDocuments = Own(application.Documents, localProxies); sourceDocument = Own(sourceDocuments.Open(sourceCopy, true, false, false), localProxies); dynamic stories = Own(sourceDocument.StoryRanges, localProxies); sourceRange = Own(stories[1], localProxies); var start = (int)sourceRange.Start; var end = (int)sourceRange.End; if (end > start) end -= 1; importRange = Own(sourceDocument.Range(start, end), localProxies);
            var warnings = new List<string>(); var sourceRevisions = TryCount(importRange.Revisions); var sourceComments = TryCount(importRange.Comments); if (sourceRevisions > 0) { if (request.RevisionPolicy == RevisionImportPolicy.BlockImport) throw new WordAutomationException("Source DOCX contains tracked changes and RevisionPolicy is BlockImport."); if (request.RevisionPolicy == RevisionImportPolicy.AcceptAll) importRange.Revisions.AcceptAll(); if (request.RevisionPolicy == RevisionImportPolicy.RejectAll) importRange.Revisions.RejectAll(); if (request.RevisionPolicy == RevisionImportPolicy.PreserveAndWarn) warnings.Add($"Tracked changes preserved: {sourceRevisions}."); } if (sourceComments > 0) { if (request.CommentPolicy == CommentImportPolicy.BlockImport) throw new WordAutomationException("Source DOCX contains comments and CommentPolicy is BlockImport."); if (request.CommentPolicy == CommentImportPolicy.PreserveAndWarn) warnings.Add($"Comments preserved: {sourceComments}."); }
            progress?.Report(new WordOperationProgress { Stage = "FormattedText", Message = "Copying only the main text story" }); destinationRange.FormattedText = importRange.FormattedText; if (request.CommentPolicy == CommentImportPolicy.Exclude) RemoveImportedComments(destinationRange); if (request.RevisionPolicy == RevisionImportPolicy.PreserveAndWarn) warnings.Add("Revision policy: PreserveAndWarn.");
            plan = plan with { Warnings = warnings }; return new BodyImportResult { Plan = plan, InsertionMode = "FormattedText", Warnings = warnings };
        }
        finally { try { if (sourceDocument is not null) sourceDocument.Close(0); } catch { } ReleaseAll(localProxies); TryDelete(temp); }
    }

    private static BodyImportPlan BuildPlanFromOpenXml(string path)
    {
        using var archive = ZipFile.OpenRead(path);
        var entry = archive.GetEntry("word/document.xml") ?? throw new InvalidDataException("Source DOCX document.xml is missing.");
        using var reader = new StreamReader(entry.Open());
        var document = XDocument.Parse(reader.ReadToEnd(), LoadOptions.PreserveWhitespace);
        var w = XNamespace.Get("http://schemas.openxmlformats.org/wordprocessingml/2006/main");
        var wp = XNamespace.Get("http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawing");
        var body = document.Root?.Element(w + "body") ?? throw new InvalidDataException("Source DOCX body is missing.");
        var sectionMarks = body.Descendants(w + "sectPr").ToList();
        var internalSections = Math.Max(0, sectionMarks.Count - 1);
        var pageBreaks = body.Descendants(w + "br").Count(x => string.Equals((string?)x.Attribute(w + "type"), "page", StringComparison.OrdinalIgnoreCase));
        return new BodyImportPlan
        {
            ParagraphCount = body.Descendants(w + "p").Count(),
            TableCount = body.Descendants(w + "tbl").Count(),
            InlineShapeCount = body.Descendants(wp + "inline").Count(),
            FloatingShapeCount = body.Descendants(wp + "anchor").Count(),
            InternalSectionBreakCount = internalSections,
            PageBreakCount = pageBreaks,
            IncludedStories = ["wdMainTextStory"],
            ExcludedStories = ["wdPrimaryHeaderStory", "wdFirstPageHeaderStory", "wdEvenPagesHeaderStory", "wdPrimaryFooterStory", "wdFirstPageFooterStory", "wdEvenPagesFooterStory"],
            Warnings = []
        };
    }

    private static void NormalizeSourceSections(string path, SectionBreakPolicy policy)
    {
        if (policy == SectionBreakPolicy.ConvertToParagraph) policy = SectionBreakPolicy.Remove;
        using var archive = ZipFile.Open(path, ZipArchiveMode.Update); var entry = archive.GetEntry("word/document.xml") ?? throw new InvalidDataException("Source DOCX document.xml is missing."); string xml; using (var reader = new StreamReader(entry.Open())) xml = reader.ReadToEnd(); var w = XNamespace.Get("http://schemas.openxmlformats.org/wordprocessingml/2006/main"); var document = XDocument.Parse(xml, LoadOptions.PreserveWhitespace); var body = document.Root?.Element(w + "body") ?? throw new InvalidDataException("Source DOCX body is missing."); var sections = body.Descendants(w + "sectPr").ToList(); for (var i = 0; i < sections.Count; i++) { var section = sections[i]; var parent = section.Parent; var paragraph = parent?.Name == w + "pPr" ? parent.Parent : null; section.Remove(); if (i < sections.Count - 1 && policy == SectionBreakPolicy.ConvertToPageBreak && paragraph is not null) paragraph.Add(new XElement(w + "r", new XElement(w + "br", new XAttribute(w + "type", "page")))); } entry.Delete(); var replacement = archive.CreateEntry("word/document.xml", CompressionLevel.Optimal); using var stream = replacement.Open(); using var writer = new StreamWriter(stream, new UTF8Encoding(false)); document.Save(writer, SaveOptions.DisableFormatting);
    }

    private static void RemoveImportedComments(dynamic range) { try { dynamic comments = range.Comments; for (var i = comments.Count; i >= 1; i--) comments[i].Delete(); } catch { } }
    private static int TryCount(dynamic collection) { try { return (int)collection.Count; } catch { return 0; } }
    private static T? Own<T>(T? value, List<object?> proxies) where T : class { if (value is not null) proxies.Add(value); return value; }
    private static void Release(object? value) { try { if (value is not null && Marshal.IsComObject(value)) Marshal.FinalReleaseComObject(value); } catch { } }
    private static void ReleaseAll(IEnumerable<object?> values) { foreach (var value in values.Reverse()) Release(value); }
    private static void TryDelete(string path) { try { if (Directory.Exists(path)) Directory.Delete(path, true); } catch { } }
    public void Dispose() { if (_ownsQueue) _queue.Dispose(); }
}