Work Rota system- reading text to work out hours

Hello experts,

I am trying to create work rota system, and would really appreciate some help.

The concept is the user enters the shift into a cell (A1) either as a code ‘E’(early shift)/’L’(late Shift) or as a specific time e.g ‘2-7’. Both are in a text format. And I want the other cell (B1) to calculate the number of hours in that shift:

A1= E
B1= 8

and

A1= 2-7
B1= 5


For the first example, I have created a search function in combination with ‘if’ statements, to check to see if the user has entered either E/L. that’s working perfectly, (the last if statement is for the manual entry of the shift which I am having difficulties with):

=IF(ISNUMBER(SEARCH("E",A1)),8,IF(ISNUMBER(SEARCH("L",D9)),7,IF([HELP_NEEDED]))

The issue I am having now is trying to figure out how to determine the other shift type, which is also based on text. Ideally I need a way for the formula to read the numbers between the dash (X-Y) and allow me to manipulate the values (minus Y from X to give the hours of the shift in an integer format). But heres where it gets more tricky some times the shift could even be ‘2:30-5’. Which is a 4.5 hour shift. To do this I would have to do ‘Y – (X+ 0.2)’. is there a way of determining if one of the integers is a float?(decimal point). Therefore the dash should be the splitting point between the 2 numbers.

I do understand there could be much easier ways to do this if separate cells were used to enter the X & Y times. But the coluge I am doing this is not very computer literate and prefers to have this format. Also she tends to enter the time with a colon (2:30) would this be an issue, or could it be possible to make excel convert the text with the colon to a an integer with a decimal.

Would anyone know how to do this? Or how to go about doing this?

Thank you very much