Work on the datta handler

SzCore/SzDataHandler.cs

@@ -1,6 +1,85 @@
+using SzCore.DataObjects;
+
 namespace SzCore;
 
 public class SzDataHandler
 {
+    private Dictionary<string, SzDataset> _loadedDatasets = [];
 
+    public SzDataHandler(){}
+
+    public bool SaveDataset(SzDataset dataset)
+    {
+        var datasetPath = Path.Combine(SZ.LocalFileManager.DatasetsPath, dataset.Id, "dataset.json");
+        try
+        {
+            return SZ.LocalFileManager.SaveFile(datasetPath, SZ.SzParser.SerializeDatasetToJson(dataset));
+        }
+        catch (Exception e)
+        {
+            SZ.Logger.LogError("Error saving dataset: " + e.Message);
+            return false;
+        }
+    }
+
+    public SzDataset? LoadDataset(string datasetId)
+    {
+        if (_loadedDatasets.TryGetValue(datasetId, out SzDataset? value))
+        {
+            if (value is not null) return value;
+        }
+
+        var datasetPath = Path.Combine(SZ.LocalFileManager.DataPath, "datasets", datasetId, "dataset.json");
+        
+        var json = SZ.LocalFileManager.LoadFile(datasetPath);
+        if (json is null) 
+        {
+            SZ.Logger.LogWarning($"Could not load dataset with ID '{datasetId}'");
+            return null;  
+        }
+
+        var parsedDataset = SZ.SzParser.DeserializeDataset(json);
+        if (parsedDataset is null)
+        {
+            SZ.Logger.LogWarning($"Could not load dataset with ID '{datasetId}'");
+            return null;  
+        }
+
+        _loadedDatasets.Add(parsedDataset.Id, parsedDataset);
+        return parsedDataset;
+    }
+
+    // The client should periodically call this to free memory, probably
+    private void ClearLoadedDatasets()
+    {
+        _loadedDatasets.Clear();
+    }
+
+    // Only use this for test purposes, we probably don't want to load all datasets to memory in production
+    private void LoadAllDatasets()
+    {
+        ClearLoadedDatasets();
+        if (!Directory.Exists(SZ.LocalFileManager.DatasetsPath))
+        {
+            throw new Exception("Could not load datasets, the datase directory does not exist.");
+        }
+
+        foreach (var dir in Directory.GetDirectories(SZ.LocalFileManager.DatasetsPath))
+        {
+            var datasetFilePath = Path.Combine(dir, "dataset.json");
+            if (!File.Exists(datasetFilePath)) continue;
+
+            var datasetJson = SZ.LocalFileManager.LoadFile(datasetFilePath);
+            if (datasetJson == null) continue;
+
+            var parsedDataset = SZ.SzParser.DeserializeDataset(datasetJson);
+            if (parsedDataset == null)
+            {
+                SZ.Logger.LogWarning($"Parse error: Could not parse file {datasetFilePath} as an SzDataset");
+                continue;
+            }
+
+            _loadedDatasets.Add(parsedDataset.Id, parsedDataset);
+        }
+    }
 }