import webapp2


form = """
    <form method = "post">
    <div> Signup </div>
    <br>
    <br

    <div>
    <label> Username
        <input type="textarea" name="username" value="%(username)s">
    </label> <span style="color: red">%(us_error)s</span>
    </div>

    <div>
    <label> Password
        <input type="textarea" name="password" value="">
    </label> <span style="color: red">%(pw_error)s</span>
    </div>

    <div>
    <label> Verify Password
        <input type="textarea" name="verify" value="">
    </label> <span style="color: red">%(vpw_error)s</span>
    </div>

    <div>
    <label> Email (optional)
        <input type="textarea" name="email" value="%(email)s">
    </label> <span style="color: red">%(em_error)s</span>
    </div>

    <br>
    <input type="submit">
</form>
"""
import cgi

def escape_html(s):
    return cgi.escape(s, quote = True)
import re
USER_RE = re.compile(r"^[a-zA-Z0-9_-]{3,20}$")
USER_PW = re.compile(r"^.{3,20}$")
USER_EM = re.compile(r"^[\S]+@[\S]+\.[\S]+$")

def valid_username(username):
    return USER_RE.match(username)

def valid_password(password):
    return USER_PW.match(password)

def valid_email(email):
    return USER_EM.match(email)





class MainHandler(webapp2.RequestHandler):
    def write_form(self, us_error="", pw_error="", vpw_error="", em_error="", username="", email=""):
        self.response.write(form % {"us_error": us_error,
                                    "pw_error": pw_error,
                                    "vpw_error": vpw_error,
                                    "em_error": em_error,
                                    "username": username,
                                    "email": email})

    def get(self):
        self.write_form()

    def post(self):
        user_name = escape_html(self.request.get('username'))
        pass_word = escape_html(self.request.get('password'))
        vpass_word = escape_html(self.request.get('verify'))
        e_mail = escape_html(self.request.get('email'))

        username = valid_username(user_name)
        password = valid_password(pass_word)
        email = valid_email(e_mail)

        us_error = ""
        pw_error = ""
        vpw_error = ""
        em_error = ""
        if username == None:
            username = user_name

        if email == None:
            email = e_mail

        if not username:
            us_error = "That's not a valid username."
        if not password:
            pw_error = "That's not a valid password."
        if pass_word != vpass_word:
            vpw_error = "Your passwords didn't match."
        if e_mail:
            if not email:
                em_error =  "That's not a valid email."

        self.write_form(us_error, pw_error, vpw_error, em_error, user_name, e_mail)

        if not (us_error or pw_error or vpw_error):

            self.redirect("/welcome")

class WelcomeHandler(webapp2.RequestHandler):
    def get(self):
        user = self.request.get('username')
        self.response.write("Welcome" + "," + " " + user)









app = webapp2.WSGIApplication([('/', MainHandler), ("/welcome", WelcomeHandler)], debug=True)