Implement new user registration

src/login.py

@@ -1,6 +1,7 @@
 import hmac
 import json
 import pandas as pd
+import re
 import streamlit as st
 from streamlit_gsheets import GSheetsConnection
 from streamlit.runtime.secrets import AttrDict, secrets_singleton
@@ -39,30 +40,67 @@ class HFFriendlyGSheetsConnection(GSheetsConnection):
 conn = st.connection("gsheets", type=HFFriendlyGSheetsConnection)
 
 
-def check_password():
-    """Returns `True` if the user had a correct password."""
+# Make a regular expression
+# for validating an Email
+regex_email = r"\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,7}\b"
+
+
+# Define a function for
+# for validating an Email
+def check_email(email: str) -> bool:
+    return bool(re.fullmatch(regex_email, email))
+
+
+def new_user_form():
+    """Form to collect new user information and submit"""
+    with st.form("New User Registration"):
+        st.text_input("Email Address", key="new_user_email")
+        st.text_input("Name", key="new_user_name")
+        st.form_submit_button("Submit", on_click=new_user_submitted)
+
+
+def create_new_user_request(email: str, name: str):
+    conn.update(
+        worksheet="new-user",
+        data=pd.DataFrame(
+            {
+                "email": email,
+                "name": name,
+            },
+            index=[0],
+        ),
+    )
+    st.info("New user request submitted.  Please check your email for a login url with a few minutes.")
+
+
+def new_user_submitted():
+    if not check_email(email := st.session_state["new_user_email"]):
+        st.warning("Sorry email is invalid.  Please try a valid email address.")
+        return
 
-    def login_form():
-        """Form with widgets to collect user information"""
-        with st.form("Credentials"):
-            st.text_input("Login token", type="password", key="password")
-            st.form_submit_button("Log in", on_click=password_entered)
+    if not (name := st.session_state["new_user_name"]):
+        st.warning("No name entered.  Please enter your name for display.")
+        return
 
-    def password_entered():
-        """Checks whether a password entered by the user is correct."""
-        # check if token exists
-        if login_by_token(st.session_state["password"]):
-            return
-        st.session_state["password_correct"] = False
+    if email_exists(email):
+        st.warning(
+            "User with that email already exists.  If you would like a new login url, please click the New Login URL button."
+        )
+        return
+    create_new_user_request(email, name)
+
+
+def check_password():
+    # if not logged in offer new user registration
+    if logged_in_user := st.session_state.get("logged_in_user"):
+        st.write(f"Logged in as: {logged_in_user}")
+        return True
+    else:
+        new_user_form()
 
     # Return True if the token is validated.
     if st.session_state.get("password_correct", False):
         return True
-
-    # Show inputs for email + password.
-    login_form()
-    if st.session_state.get("password_correct", True) is False:
-        st.error("😕 Token incorrect")
     return False
 
 
@@ -100,3 +138,12 @@ def login_by_token(token: str):
             st.session_state["logged_in_user"] = user_id
             return True
     return False
+
+
+def email_exists(email: str):
+    df = conn.read(
+        worksheet="users",
+        usecols=[1],
+        ttl=1,
+    )
+    return bool(email in df.email.tolist())