Write a shell script for pulling a zip file from a folder convert the csv file to into a tilda separated file and then pushing it back to same location

Need a shell script to
1. pull a zip file(name of the zip file will be todays date) from a sftp folder. Connection will be
2. Extract the contents of the zip file.
3. Check if the contents is a csv file
4. convert the csv file into tilda separated file using a utility like csvkit
5. Put the tilda separated file into another zip file
6. Send the zip file back to the sftp folder

SFTP folder will be protected by .pem file