Merge two table with two dates

Hi, 

I want to merge two tables with a calculation.

A table has three columns (one column is the contract number, one is the start of the contract and the last is the end of the contract)

The second table is a calendar table. (a column with all the dates and one with a period)

I want to merge the two to have a result like this.

My tables :

I wish i had a table with this result : 

With the contrat 25, 3 lignes because the contrat spend 3 months and the number one for the sum

Does anyone have the solution ?

Regards