A simple android app for manually recording a pH reading with changeable timestamp.

When the app opens it should have 5 big buttons, 1 Record Value", 2 " Review Values", 3 "Send Records", 4 "User input", 5 "Exit".
"User input" sould request First Name, Family Name, e-mail, Date of birth, weight, hight, sex. Family name is not mandatory. The other fields are. Upon opening the app the first time it should go to screen 4.
"Record value" will show prefilled the current date and time but allow date and time to be edited. One field "pH reading" - for a number like 7.25 between 0 and 14 to be entered. One field "hours after food" - allow numbers like 2.5 between 0 and 72 to be entered. One field for "comments" -text with 100 character. Only the ph field is mandatory.
"Send records" should trigger a mail with an attachment of a csv file with all the readings.
"Review values" the app can scoll through the readings in table format.

"How many hours would this take?