Hi- first I would suggest having the window tinted which will cut down on the glare. If that doesn't cut down on the sun, how about a honeycomb shade which will allow light but keep the strong rays out.

Tinted would be a good idea but how about cutting a piece of thin board or thick cardboard that will fit over the inside of the window....Paint the board/cardboard white like the door. Use velcro or thin brads to hold it in the window. That way it will be removable when the sun is not shining in the window. Otherwise, tint or a dark valance hung in front of the window but not sure that would look good.

We have the same thing and tinting with dark tint does the trick.

I would recommend a Hunter Douglas Silhouette. The sheer fabric will let light into the room, but it will soften the glare. You can get it with a manual operation and leave the vanes open all the time. Or, if you want to operate it (open and close the vanes throughout the day), it can be motorized.

If you would need more coverage than a sheer, I would go with something like a honeycomb shade in a semi-opaque fabric. You will still be able to tell it's daylight outside, but it will cut down on the glare.

Hunter Douglas Silhouette Window Shadings · More Info

Hunter Douglas Duette Honeycomb Shades · More Info

You can buy tinted film that is meant for that purpose ... it sticks onto windows to cut down on glare/light.