I created a series of command blocks that summon a fireball and then uses trigonometry to calculate the movement requred for it to go where the player is facing. This is then used to modify the fireball's nbt Motion data. The fireball flies off course and corrects itself in a glitchy manner. 

Note that it is controlled by a single impulse command block so nothing is happening to the fireball while it's in the air.

Recreation:

 - Download the datapack and unzip it

 - Add it to a singleplayer world

• use the command: /function fb:fire