public ScreenshotAnalysisService(Uri ollamaEndpoint, string modelId)
{
    var ollamaApiClient = new OllamaApiClient(ollamaEndpoint, modelId);
    _agent = new ChatClientAgent(
        ollamaApiClient,
        instructions:
        """
        You analyze desktop screenshots.
        Reply in Chinese with 1-2 sentences.
        Name the visible application, page, or document whenever it can be identified.
        Describe the current task and include only details that are actually visible.
        If a detail is unclear, say so instead of guessing.
        """);
}

public async Task<string> AnalyzeAsync(
    string imagePath,
    DateTimeOffset capturedAt,
    IReadOnlyCollection<SnapshotAnalysisContext> recentContexts,
    CancellationToken cancellationToken = default)
{
    var imageBytes = await File.ReadAllBytesAsync(imagePath, cancellationToken);
    var message = new ChatMessage
    {
        Role = ChatRole.User,
        Contents =
        [
            new TextContent(BuildPrompt(capturedAt, recentContexts)),
            new DataContent(imageBytes, GetImageMimeType(imagePath))
        ]
    };
    var response = await _agent.RunAsync(message);
    return response.Text?.Trim() ?? "模型没有返回可用的解读内容。";
}

private async Task RunCaptureLoopAsync(CancellationToken cancellationToken)
{
    while (!cancellationToken.IsCancellationRequested)
    {
        foreach (var display in _screenSnapshotProvider.GetDisplays())
        {
            var stopwatch = Stopwatch.StartNew();
            await CaptureAndAnalyzeDisplayAsync(display, cancellationToken);
            // 保证两次截图间隔至少10秒
            var remainingDelay = MinimumCaptureInterval - stopwatch.Elapsed;
            if (remainingDelay > TimeSpan.Zero)
            {
                await Task.Delay(remainingDelay, cancellationToken);
            }
        }
    }
}

private async Task<StorageCleanupResult> CleanupStorageIfNeededAsync(CancellationToken cancellationToken)
{
    return await Task.Run(() =>
    {
        var directoryInfo = new DirectoryInfo(StorageFolderPath);
        var totalSize = directoryInfo.EnumerateFiles().Sum(file => file.Length);
        if (totalSize <= 1024L * 1024 * 1024) // 1G存储上限
        {
            return StorageCleanupResult.Empty;
        }
        // 按创建时间升序，优先删除最旧的截图
        var filesToDelete = directoryInfo.EnumerateFiles()
            .Where(file => SnapshotImageExtensions.Contains(file.Extension))
            .OrderBy(file => file.CreationTimeUtc)
            .ToList();
        long releasedBytes = 0;
        int deletedCount = 0;
        foreach (var file in filesToDelete)
        {
            if (totalSize <= 1024L * 1024 * 1024) break;
            var length = file.Length;
            file.Delete();
            totalSize -= length;
            releasedBytes += length;
            deletedCount++;
        }
        return new StorageCleanupResult(deletedCount, releasedBytes);
    }, cancellationToken);
}