New checks in combineGrids to enable maintaining full block names (#73)

* New checks in combineGrids

* Fix formatting

cgnsutilities/cgnsutilities.py

@@ -3395,7 +3395,7 @@ def faceID(ptRange, blk):
     return grid
 
 
-def combineGrids(grids, useOldNames=False):
+def combineGrids(grids, useOldNames=False, useOldNumbers=False):
     """Method that takes in a list of grids and returns a new grid object
     containing all zones from each grid. The blocks are renamed as
     there could (almost most certainly) be conflicts between the zone
@@ -3404,7 +3404,16 @@ def combineGrids(grids, useOldNames=False):
 
     If useOldNames=True we will preserve the domain names after merging
     the blocks, otherwise, we will replace all names by the filenames.
+    However, it will still update the block name's numbers. To preserve
+    the original numbers, set useOldNumbers=True.
     """
+    # Check that no grids have the same name. If they do, they will
+    # overwrite each other when added to the grid dict.
+    gridNames = set()
+    for grid in grids:
+        if grid.name in gridNames:
+            raise RuntimeError(f"Two grids have the name {grid.name}, but grid names must be unique")
+        gridNames.add(grid.name)
 
     # Create a dictionary to contain grid objects with their names
     # as the corresponding keys
@@ -3434,13 +3443,18 @@ def combineGrids(grids, useOldNames=False):
         # Loop over the blocks and obtain the name mapping
         for blk in grid.blocks:
             nBlock += 1
-            if not useOldNames:
-                blockName = name
+            if useOldNames and useOldNumbers:
+                blockName = blk.name
+                if blockName in zoneMap.keys():
+                    raise RuntimeError(
+                        f"Duplicate block name {blockName}, try without useOldNumbers or rename the block"
+                    )
+            elif useOldNames:
+                blockName = blk.name.split(".")[0] + f".{nBlock:05}"
             else:
-                blockName = blk.name.split(".")[0]
-            newName = blockName + f".{nBlock:05}"
-            zoneMap[blk.name] = newName
-            blk.name = newName
+                blockName = name + f".{nBlock:05}"
+            zoneMap[blk.name] = blockName
+            blk.name = blockName
 
         # Now loop back over the blocks, replacing the donorName using
         # the map we defined above