Your task is to write a PHP utility script to allow users to:
1) upload own contact data AND a template data with their own custom fields
2) Warn if the register is too big (2M or more probably or what you find)
3) Let the user match the first row or header row with the template data in which format everything will be written to, AND let the user assign one column data as notes and, optionally, anoter as the date/time of those notes or the last note.
4) Upload the data to a database in the template format,
5) Get a contact id for all back, and then upload the notes for each such contact id
The API is based on REST and has full on-line interactive documentation using swagger.