Add error codes for "exceeds length" and "db exists"

SoftPlc/Exceptions/DbAccessException.cs

@@ -0,0 +1,102 @@
+namespace SoftPlc.Exceptions;
+
+public abstract class DbAccessException : Exception
+{
+    protected DbAccessException(string message, Exception? innerException = null) : base(message, innerException)
+    {
+    }
+
+    public abstract int StatusCode { get; }
+    public abstract string Title { get; }
+}
+
+public class InvalidDbSizeException : DbAccessException
+{
+    public InvalidDbSizeException(int size) : base($"DB size must be > 0 but was {size}.")
+    {
+        Size = size;
+    }
+
+    public int Size { get; }
+
+    public override int StatusCode => StatusCodes.Status400BadRequest;
+    public override string Title => "Invalid DB size";
+
+    public static void ThrowIfInvalid(int size)
+    {
+        if (size < 1)
+            throw new InvalidDbSizeException(size);
+    }
+}
+
+public class DbOutOfRangeException : DbAccessException
+{
+    public DbOutOfRangeException(string message, int dbNo, Exception? innerException = null) : base(message, innerException)
+    {
+        DbNo = dbNo;
+    }
+
+    public DbOutOfRangeException(int dbNo) : base($"DB number must be positive, but is {dbNo}.")
+    {
+        DbNo = dbNo;
+    }
+
+    public int DbNo { get; }
+
+    public override int StatusCode => StatusCodes.Status400BadRequest;
+    public override string Title => "DB out of range";
+
+    public static void ThrowIfInvalid(int dbNo)
+    {
+        if (dbNo < 1)
+            throw new DbOutOfRangeException(dbNo);
+    }
+}
+
+public class DbNotFoundException : DbAccessException
+{
+    public DbNotFoundException(int dbNo) : base($"DB {dbNo} not found.")
+    {
+        DbNo = dbNo;
+    }
+
+    public DbNotFoundException(string message, int dbNo, Exception? innerException = null) : base(message, innerException)
+    {
+        DbNo = dbNo;
+    }
+
+    public int DbNo { get; }
+
+    public override int StatusCode => StatusCodes.Status404NotFound;
+    public override string Title => "DB not found";
+}
+
+public class DbExistsException : DbAccessException
+{
+    public DbExistsException(int dbNo) : base($"DB {dbNo} already exists.")
+    {
+        DbNo = dbNo;
+    }
+
+    public int DbNo { get; }
+
+    public override int StatusCode => StatusCodes.Status409Conflict;
+    public override string Title => "DB already exists";
+}
+
+public class DateExceedsDbLengthException : DbAccessException
+{
+    public DateExceedsDbLengthException(int dbNo, int dbLength, int dataLength) : base($"Data with {dataLength} bytes exceeds length of DB {dbNo} of {dbLength} bytes.")
+    {
+        DbNo = dbNo;
+        DBLength = dbLength;
+        DataLength = dataLength;
+    }
+
+    public int DataLength { get; }
+    public int DBLength { get; }
+    public int DbNo { get; }
+
+    public override int StatusCode => StatusCodes.Status400BadRequest;
+    public override string Title => "Data exceeds DB length";
+}

SoftPlc/Exceptions/DbAccessExceptionHandler.cs

@@ -10,37 +10,20 @@ public async ValueTask<bool> TryHandleAsync(
         Exception exception,
         CancellationToken cancellationToken)
     {
-        if (exception is DbNotFoundException dbNotFound)
-        {
-            var problemDetails = new ProblemDetails
-            {
-                Status = StatusCodes.Status404NotFound,
-                Title = "DB not found",
-                Detail = dbNotFound.Message
-            };
-
-            httpContext.Response.StatusCode = problemDetails.Status.Value;
+        if (exception is not DbAccessException dbAccessException)
+            return false;
 
-            await httpContext.Response.WriteAsJsonAsync(problemDetails, cancellationToken);
-            return true;
-        }
-
-        if (exception is DbOutOfRangeException outOfRange)
-        {
-            var problemDetails = new ProblemDetails
+        var problemDetails =
+            new ProblemDetails
             {
-                Status = StatusCodes.Status400BadRequest,
-                Title = "DB out of range",
-                Detail = outOfRange.Message
+                Status = dbAccessException.StatusCode,
+                Title = dbAccessException.Title,
+                Detail = dbAccessException.Message
             };
 
-            httpContext.Response.StatusCode = problemDetails.Status.Value;
-
-            await httpContext.Response.WriteAsJsonAsync(problemDetails, cancellationToken);
-            return true;
-        }
-
+        httpContext.Response.StatusCode = problemDetails.Status.Value;
 
-        return false;
+        await httpContext.Response.WriteAsJsonAsync(problemDetails, cancellationToken);
+        return true;
     }
 }

SoftPlc/Services/PlcService.cs

@@ -135,11 +135,12 @@ public void AddDatablock(int id, int size)
 		{
 			CheckServerRunning();
             DbOutOfRangeException.ThrowIfInvalid(id);
+            InvalidDbSizeException.ThrowIfInvalid(size);
 
-            if (size < 1) throw new ArgumentException("Invalid size for datablock - size must be > 1", nameof(size));
-			if (datablocks.ContainsKey(id)) throw new InvalidOperationException($"A Datablock with id = {id} already exists");
 			var db = new DatablockDescription(id, size);
-			while(!datablocks.TryAdd(id, db)){ }
+			if (!datablocks.TryAdd(id, db))
+                throw new DbExistsException(id);
+
 			server.RegisterArea(S7Server.srvAreaDB, id, ref datablocks[id].Data, datablocks[id].Data.Length);
 		}
 
@@ -150,9 +151,10 @@ public void UpdateDatablockData(int id, byte[] data)
             if (!datablocks.TryGetValue(id, out var db))
                 throw new DbNotFoundException(id);
 
-			if (data != null && data.Length > db.Data.Length) throw new ArgumentException("Too much data as expected", nameof(data));
-			if(data != null)
-				Array.Copy(data, datablocks[id].Data, data.Length);
+			if (data.Length > db.Data.Length) 
+                throw new DateExceedsDbLengthException(id, db.Data.Length, data.Length);
+
+			Array.Copy(data, datablocks[id].Data, data.Length);
 		}
 
 		public void RemoveDatablock(int id)