OF-DL/OF DL.Gui/Services/AvaloniaDownloadEventHandler.cs

using OF_DL.Models.Downloads;
using OF_DL.Services;

namespace OF_DL.Gui.Services;

internal sealed class AvaloniaDownloadEventHandler(
    Action<string> activitySink,
    Action<string> progressStatusUpdate,
    Action<string, long, bool> progressStart,
    Action<long> progressIncrement,
    Action progressStop,
    Func<bool> isCancellationRequested,
    CancellationToken cancellationToken) : IDownloadEventHandler
{
    private string _lastProgressDescription = string.Empty;

    public CancellationToken CancellationToken { get; } = cancellationToken;

    public async Task<T> WithStatusAsync<T>(string statusMessage, Func<IStatusReporter, Task<T>> work)
    {
        ThrowIfCancellationRequested();
        progressStart(statusMessage, 0, false);
        try
        {
            AvaloniaStatusReporter statusReporter = new(progressStatusUpdate, isCancellationRequested);
            return await work(statusReporter);
        }
        finally
        {
            progressStop();
        }
    }

    public async Task<T> WithProgressAsync<T>(string description, long maxValue, bool showSize,
        Func<IProgressReporter, Task<T>> work)
    {
        ThrowIfCancellationRequested();
        _lastProgressDescription = description;
        progressStart(description, maxValue, showSize);
        try
        {
            AvaloniaProgressReporter reporter = new(progressIncrement, isCancellationRequested, CancellationToken);
            return await work(reporter);
        }
        finally
        {
            progressStop();
        }
    }

    public void OnContentFound(string contentType, int mediaCount, int objectCount)
    {
        ThrowIfCancellationRequested();
        progressStatusUpdate($"Found {mediaCount} media from {objectCount} {contentType}.");
    }

    public void OnNoContentFound(string contentType)
    {
        ThrowIfCancellationRequested();
        progressStatusUpdate($"Found 0 {contentType}.");
    }

    public void OnDownloadComplete(string contentType, DownloadResult result)
    {
        ThrowIfCancellationRequested();
        progressStatusUpdate(
            $"{contentType} complete. Existing: {result.ExistingDownloads}, New: {result.NewDownloads}, Total: {result.TotalCount}.");
    }

    public void OnUserStarting(string username)
    {
        ThrowIfCancellationRequested();
        activitySink($"Starting scrape for {username}.");
        progressStatusUpdate($"Scraping data for {username}...");
    }

    public void OnUserComplete(string username, CreatorDownloadResult result)
    {
        ThrowIfCancellationRequested();
        activitySink(
            $"Completed {username}. PaidPosts={result.PaidPostCount}, Posts={result.PostCount}, Archived={result.ArchivedCount}, Streams={result.StreamsCount}, Stories={result.StoriesCount}, Highlights={result.HighlightsCount}, Messages={result.MessagesCount}, PaidMessages={result.PaidMessagesCount}.");
    }

    public void OnPurchasedTabUserComplete(string username, int paidPostCount, int paidMessagesCount)
    {
        ThrowIfCancellationRequested();
        activitySink($"Purchased tab complete for {username}. PaidPosts={paidPostCount}, PaidMessages={paidMessagesCount}.");
    }

    public void OnScrapeComplete(TimeSpan elapsed)
    {
        ThrowIfCancellationRequested();
        string summary = BuildCompletionSummary(elapsed);
        activitySink(summary);
    }

    public void OnMessage(string message)
    {
        ThrowIfCancellationRequested();
        progressStatusUpdate(message);
    }

    private void ThrowIfCancellationRequested()
    {
        if (isCancellationRequested())
        {
            throw new OperationCanceledException("Operation canceled by user.");
        }
    }

    private string BuildCompletionSummary(TimeSpan elapsed)
    {
        if (string.IsNullOrWhiteSpace(_lastProgressDescription))
        {
            return $"Download completed in {elapsed.TotalMinutes:0.0} minutes.";
        }

        string normalized = _lastProgressDescription.Trim().TrimEnd('.');
        if (normalized.StartsWith("Downloading ", StringComparison.OrdinalIgnoreCase))
        {
            string remainder = normalized["Downloading ".Length..].ToLowerInvariant();
            return $"Downloaded {remainder} in {elapsed.TotalMinutes:0.0} minutes.";
        }

        return $"{normalized} in {elapsed.TotalMinutes:0.0} minutes.";
    }
}