Restructure solution layout by module

src/Signals/StellaOps.Signals/Storage/FileSystemCallgraphArtifactStore.cs

@@ -0,0 +1,60 @@
+using System;
+using System.Globalization;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+using StellaOps.Signals.Options;
+using StellaOps.Signals.Storage.Models;
+
+namespace StellaOps.Signals.Storage;
+
+/// <summary>
+/// Stores callgraph artifacts on the local filesystem.
+/// </summary>
+internal sealed class FileSystemCallgraphArtifactStore : ICallgraphArtifactStore
+{
+    private readonly SignalsArtifactStorageOptions storageOptions;
+    private readonly ILogger<FileSystemCallgraphArtifactStore> logger;
+
+    public FileSystemCallgraphArtifactStore(IOptions<SignalsOptions> options, ILogger<FileSystemCallgraphArtifactStore> logger)
+    {
+        ArgumentNullException.ThrowIfNull(options);
+        storageOptions = options.Value.Storage;
+        this.logger = logger ?? throw new ArgumentNullException(nameof(logger));
+    }
+
+    public async Task<StoredCallgraphArtifact> SaveAsync(CallgraphArtifactSaveRequest request, Stream content, CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(request);
+        ArgumentNullException.ThrowIfNull(content);
+
+        var root = storageOptions.RootPath;
+        var directory = Path.Combine(root, Sanitize(request.Language), Sanitize(request.Component), Sanitize(request.Version));
+        Directory.CreateDirectory(directory);
+
+        var fileName = string.IsNullOrWhiteSpace(request.FileName)
+            ? FormattableString.Invariant($"artifact-{DateTimeOffset.UtcNow.ToUnixTimeMilliseconds()}.bin")
+            : request.FileName.Trim();
+
+        var destinationPath = Path.Combine(directory, fileName);
+
+        await using (var fileStream = File.Create(destinationPath))
+        {
+            await content.CopyToAsync(fileStream, cancellationToken).ConfigureAwait(false);
+        }
+
+        var fileInfo = new FileInfo(destinationPath);
+        logger.LogInformation("Stored callgraph artifact at {Path} (length={Length}).", destinationPath, fileInfo.Length);
+
+        return new StoredCallgraphArtifact(
+            Path.GetRelativePath(root, destinationPath),
+            fileInfo.Length,
+            request.Hash,
+            request.ContentType);
+    }
+
+    private static string Sanitize(string value)
+        => string.Join('_', value.Split(Path.GetInvalidFileNameChars(), StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries)).ToLowerInvariant();
+}