Using the user's email in Firestore Rules? - firebase

Question

In a firestore database, I am using email only as authentication. The database has the following structure:
companies
jobs
users
For sake of readability (and for customer's peace of mind), I am using the email address as the Document ID for the users collection. A user document looks like this:
document id: tbogard#gmail.com
fields
name_first: Terry
name_last: Bogard
jobs_read: ["job_A"]
jobs_readwrite: ["job_B, job_C"]
When I try to grab the request token in the rules, it gives me errors (search for ***):
rules_version = '2';
service cloud.firestore {
match /databases/{database}/documents {
// Helper functions
function userExists(){
// *** Function not found error: Name: [exists]. ***
return exists(/databases/$(database)/documents/users/$(request.auth.token.email));
}
function userData(){
// *** Function [get] called with malformed path: /databases/(default)/documents/users/ ***
return get(/databases/$(database)/documents/users/$(request.auth.token.email)).data;
}
// For now, let's keep it simple, and enforce the User read/readwrite rules on Jobs.
match /jobs/{jobId}{
allow read: if userExists() && (jobId in userData().jobs_read || jobId in userData().jobs_readwrite);
allow write: if userExists() && jobId in userData().jobs_readwrite;
}
// Only allow Users to see their own profile and companies they belong to.
match /companies/{companyId}{
allow read: if userExists() && userData().email in resource.data.employees;
allow write: if false;
}
match /users/{userId}{
allow read: if userExists() && userData().email == resource.data.email;
allow write: if false;
}
}
}
I'm guessing request.auth.token.email is returning something like an optional? I can't find anything in the documentation explaining how the functions get/exists, which require a path, handle this. Is there a way that I could make the Firestore UID for each user the email address instead of the random string, or can I fix these rules some way?