import re

def get_environment():
    production_website = "https://www.delivery.com"

    environment_regex = "([a-zA-Z]{1,4}?-\d{1,4}|release_\d{1,3}?\.\d{1,3})"

    print("\nPlease enter the ticket number, release stage or leave blank for production.")
    print("(e.g. MRD-1234, release_12.34... etc)\n")
    
    ticket_id = input("Environment: ").strip()
    if not ticket_id:
        return production_website

    valid_id = re.match(environment_regex, ticket_id)

    while not valid_id:
        print("Please enter a valid ticket or release ID. ")
        ticket_id = input("Environment: ").strip()
        valid_id = re.match(environment_regex, ticket_id)
    
    ticket_url_entry = re.sub("[-_\.]", "", ticket_id).lower()
    environment_url = f"https://www-{ticket_url_entry}.staging.delivery.com"

    return environment_url