simplified minimal solution

minimal_auth.py

@@ -1,78 +1,42 @@
 import json
-import pathlib
 import sys
 
-# name of the file where we store the pw database
-PWDB_FLNAME = pathlib.Path('pwdb.json')
-
 def get_credentials():
-    # get input from terminal
     username = input('Enter your username: ')
-    # get password using the appropriate module, so that typed characters are not
-    # echoed to the terminal
     password = input('Enter your password: ')
     return (username, password)
 
 def authenticate(username, password, pwdb):
-    # calculate hash and compare with stored hash
     return password == pwdb[username]
 
 def add_user(username, pwdb):
-    # do not try to add a username twice
-    if username in pwdb:
-        raise Exception(f'Username already exists [{username}]!')
-    else:
     pwdb[username] = input(f'Enter password for {username}: ')
     return pwdb
 
 def read_pwdb(pwdb_path):
-    # try to read from the database
-    # if anything happens, report the error!
-    if not pwdb_path.exists():
-        initialize_pwdb(pwdb_path)
     try:
-        with open(pwdb_path, 'rt') as pwdb_file:
+        pwdb_file = open(pwdb_path, 'rt')
         pwdb = json.load(pwdb_file)
-    except json.decoder.JSONDecodeError as exc:
-        # this happens when the json data is invalid
-        raise Exception(f'Invalid database {pwdb_path}: {exc}')
-    except Exception as exc:
-        # this is a catch-all condition
-        raise Exception(f'Unkown error reading {pwdb_path}: {exc}')
+    except Exception:
+        pwdb = {}
     return pwdb
 
 def write_pwdb(pwdb, pwdb_path):
-    with open(pwdb_path, 'wt') as pwdb_file:
+    pwdb_file = open(pwdb_path, 'wt')
     json.dump(pwdb, pwdb_file)
 
-def initialize_pwdb(pwdb_path):
-    write_pwdb({}, pwdb_path)
+pwdb_path = 'pwdb.json'
+pwdb = read_pwdb(pwdb_path)
 
-def main(pwdb_path):
-    # load the password database from file
-    pwdb = read_pwdb(pwdb_path)
-
-    # if we are passed an argument, we want to add a new user
-    if len(sys.argv) > 1:
+if len(sys.argv) > 1:
     pwdb = add_user(sys.argv[1], pwdb)
     write_pwdb(pwdb, pwdb_path)
-        return
-
-    # ask for credentials
+else:
     username, password = get_credentials()
-
     if username not in pwdb:
         print('Wrong username!')
-        return
-
-    # try to authenticate
+    else:
         if authenticate(username, password, pwdb):
             print('Successfully authenticated!')
         else:
-        # report wrong password
             print('Wrong password!')
-    return
-
-if __name__ == '__main__':
-    main(PWDB_FLNAME)
-