messagix/bloks,dependencies: Handle phone number login

[radon-at-beeper]

• add phonenumbers library
• use it regexp to check if the user tried to login to messenger with a phone number, and error out if so
  • instead of checking whether the user gave a phone number, check whether they gave an email (must contain at-sign) or username (rules: only supports ASCII alphanumeric and periods, must have at least one letter)
• set machine id to an empty string to match native client behavior on new device
• add comments explaining how we would get phone number login to work if we want to

[tulir]

Instagram seems to allow 1 character usernames as well as underscores, so the username part should probably just be [a-zA-Z0-9._]*[a-zA-Z][a-zA-Z0-9._]*? (so no +* and *+ as separate options)

1 number/dot/underscore usernames don't exist fortunately

Suggested change

	var usernameOrEmailRegexp = regexp.MustCompile(`^([a-zA-Z0-9.]+[a-zA-Z][a-zA-Z0-9.]*|[a-zA-Z0-9.]*[a-zA-Z][a-zA-Z0-9.]+|.+@.+)$`)
	var usernameOrEmailRegexp = regexp.MustCompile(`^([a-zA-Z0-9._]*[a-zA-Z][a-zA-Z0-9._]*|.+@.+)$`)

[tulir]

wait I'm dumb this is messenger only, anyway, probably no need for the 2 cases?

[tulir]

(actually in theory we might want this for instagram in the future? they use the same bloks stuff, not sure how reusable the code is though)

[radon-at-beeper]

I guess there is no harm doing it the way you suggested, it is not a valid username but we only need this regex to filter out phone numbers. Making a tweak

[radon-at-beeper]

It's called the "definitely not a phone number" regexp now, and I just check if it contains at least an at-sign or letter

[tulir]

Oh yeah that regex is much simpler and should do the trick

[tulir]

Looks fine other than the potential minor tweak to the regex