using Microsoft.Extensions.Logging;
using PatchProbe.Shared.Contracts;
using PatchProbe.Shared.Models;

namespace PatchProbe.Cli.Collectors;

public sealed class WindowsUpdateCollector(ILogger<WindowsUpdateCollector> logger) : ICollector<WindowsUpdateInfo>
{
    public Task<WindowsUpdateInfo> CollectAsync(CancellationToken cancellationToken = default)
    {
        logger.LogInformation("Collecting Windows Update information via WUA COM");

        var applicable = new List<ApplicableUpdate>();
        var history = new List<UpdateHistoryEntry>();
        string? searchError = null;

        try
        {
            var sessionType = Type.GetTypeFromProgID("Microsoft.Update.Session")
                ?? throw new InvalidOperationException("Microsoft.Update.Session ProgID not found");
            dynamic session = Activator.CreateInstance(sessionType)!;
            dynamic searcher = session.CreateUpdateSearcher();

            logger.LogInformation("Searching for applicable updates (IsInstalled=0 and IsHidden=0)");
            dynamic result = searcher.Search("IsInstalled=0 and IsHidden=0");

            for (int i = 0; i < result.Updates.Count; i++)
            {
                dynamic u = result.Updates.Item(i);
                string kbId = ExtractKbId(u);
                string category = ExtractFirstCategory(u);

                applicable.Add(new ApplicableUpdate
                {
                    UpdateId = TryGet<string>(() => u.Identity.UpdateID),
                    Title = TryGet<string>(() => u.Title),
                    KbArticleId = kbId,
                    Category = category,
                    Severity = TryGet<string>(() => u.MsrcSeverity),
                    RebootRequired = TryGet<bool>(() => u.RebootRequired),
                    IsDownloaded = TryGet<bool>(() => u.IsDownloaded),
                    Description = TryGet<string>(() => u.Description),
                    SupportUrl = TryGet<string>(() => u.SupportUrl),
                });
            }

            logger.LogInformation("Found {Count} applicable updates", applicable.Count);

            int totalHistoryCount = searcher.GetTotalHistoryCount();
            int historyLimit = Math.Min(totalHistoryCount, 100);

            if (historyLimit > 0)
            {
                dynamic historyEntries = searcher.QueryHistory(0, historyLimit);
                for (int i = 0; i < historyEntries.Count; i++)
                {
                    dynamic e = historyEntries.Item(i);
                    history.Add(new UpdateHistoryEntry
                    {
                        UpdateId = TryGet<string>(() => e.UpdateIdentity.UpdateID),
                        Title = TryGet<string>(() => e.Title),
                        KbArticleId = ExtractKbIdFromTitle(TryGet<string>(() => e.Title)),
                        ResultCode = TryGet<int>(() => (int)e.ResultCode),
                        HResult = TryGet<int>(() => e.HResult),
                        Date = TryGetDate(() => e.Date),
                        Operation = TryGet<int>(() => (int)e.Operation) switch
                        {
                            1 => "Installation",
                            2 => "Uninstallation",
                            _ => "Unknown"
                        },
                        ServerSelection = TryGet<int>(() => (int)e.ServerSelection) switch
                        {
                            0 => "Default",
                            1 => "ManagedServer",
                            2 => "WindowsUpdate",
                            3 => "Others",
                            _ => "Unknown"
                        },
                    });
                }
            }
        }
        catch (Exception ex)
        {
            logger.LogWarning(ex, "WUA search failed");
            searchError = ex.Message;
        }

        return Task.FromResult(new WindowsUpdateInfo
        {
            ApplicableUpdates = applicable,
            History = history,
            SearchError = searchError,
        });
    }

    private static string ExtractKbId(dynamic update)
    {
        try
        {
            if (update.KBArticleIDs.Count > 0)
                return "KB" + update.KBArticleIDs.Item(0);
        }
        catch { /* fall through to title parse */ }
        return ExtractKbIdFromTitle(TryGet<string>(() => update.Title));
    }

    private static string ExtractFirstCategory(dynamic update)
    {
        try
        {
            if (update.Categories.Count > 0)
                return update.Categories.Item(0).Name;
        }
        catch { }
        return string.Empty;
    }

    private static string ExtractKbIdFromTitle(string? title)
    {
        if (string.IsNullOrEmpty(title)) return string.Empty;
        var match = System.Text.RegularExpressions.Regex.Match(title, @"KB\d+", System.Text.RegularExpressions.RegexOptions.IgnoreCase);
        return match.Success ? match.Value.ToUpperInvariant() : string.Empty;
    }

    private static T TryGet<T>(Func<T> getter)
    {
        try { return getter(); }
        catch { return default!; }
    }

    private static DateTimeOffset? TryGetDate(Func<object> getter)
    {
        try
        {
            var raw = getter();
            if (raw is DateTime dt) return new DateTimeOffset(dt, TimeSpan.Zero);
            if (raw is DateTimeOffset dto) return dto;
            if (DateTime.TryParse(raw?.ToString(), out var parsed)) return new DateTimeOffset(parsed, TimeSpan.Zero);
        }
        catch { }
        return null;
    }
}