import base64
import json
import os
from cryptography.fernet import Fernet
from pathlib import Path

from django.conf import settings
from django.contrib.auth.models import User
from django.db import models

from troggle.core.models.troggle import DataIssue, Person

"""This imports the registered troggle users, who are nearly-all, but not quite, Persons.
exceptions are "expo" and "expoadmin" which are created by the databaseReset.py import program.

This can import unencrypted email addresses but never exports them.

Passwords are only ever stored as hashes using the standard Django functions.
"""

todo = """  
- Make all this work with New people who have never been on expo before
"""

USERS_FILE = "users.json"
ENCRYPTED_DIR = "encrypted"

def register_user(u, email, password=None, pwhash=None):
    try:
        if existing_user := User.objects.filter(username=u): # WALRUS
            print(f" - deleting existing user '{existing_user[0]}' before importing")
            existing_user[0].delete()
        user = User.objects.create_user(u, email)
        if pwhash:
            user.password = pwhash
        elif password:
            user.set_password(password) # function creates hash and stores hash 
            print(f" # hashing provided clear-text password {password} to make pwhash for user {u}")
        else:
            user.set_password('secret') # function creates hash and stores hash 
            print(f" # hashing 'secret' password to make pwhash for user {u}")
        user.is_staff = False
        user.is_superuser = False
        user.save()
        print(f" - receated and reset user '{user}'")
    except Exception as e:
        print(f"Exception <{e}>\n{len(User.objects.all())} users now in db:\n{User.objects.all()}")
        raise   
        
    expoers = Person.objects.filter(slug=u)
    if len(expoers) == 1:
        person = expoers[0]
        person.user = user
        person.save()
    return user

def get_encryptor():
    key = settings.LONGTERM_SECRET_KEY # Django generated
    k = base64.urlsafe_b64encode(key.encode("utf8")[:32]) # make Fernet compatible 
    f = Fernet(k)
    return f
 
def load_users():
    """These are the previously registered users of the troggle system.
    """
    PARSER_USERS = "_users"
    DataIssue.objects.filter(parser=PARSER_USERS).delete()

    f = get_encryptor()
    
    jsonfile = settings.EXPOWEB / ENCRYPTED_DIR / USERS_FILE
    jsonurl = "/" + str(Path(ENCRYPTED_DIR) / USERS_FILE)
    if not (jsonfile.is_file()):
        message = f"   ! Users json file does not exist: '{jsonfile}'"
        DataIssue.objects.create(parser=PARSER_USERS, message=message)
        print(message)
        return None
         
    with open(jsonfile, 'r', encoding='utf-8') as json_f:
        message = ""
        try:
            registered_users_dict = json.load(json_f)
        except FileNotFoundError:
            message = f"File {jsonfile} not found!"
        except json.JSONDecodeError:
            message = f"Invalid JSON format! - JSONDecodeError for  {jsonfile}"
        except Exception as e:
            message = f"! Troggle USERs.  Failed to load {jsonfile} JSON file. Exception <{e}>"
        if message:
            print(message)
            DataIssue.objects.update_or_create(parser=PARSER_USERS, message=message, url=jsonurl)
            return None
    users_list = registered_users_dict["registered_users"]
    
    print(f" - {len(users_list)} users read from JSON")
    for userdata in users_list:   
        if not userdata["username"]:
            message = f"! user: BAD username for {userdata} in {jsonfile}"
            print(message)
            DataIssue.objects.update_or_create(parser=PARSER_USERS, message=message, url=jsonurl)
            continue
        else:
            if userdata["username"] in [ "expo", "expoadmin" ]:
                continue
            if "encrypted" not in userdata:
                userdata["encrypted"] = True
            try:
                u = userdata["username"]
                email = userdata["email"]
                if userdata["encrypted"]: 
                    email = f.decrypt(email).decode()
                print(f" - user: '{u} <{email}>' ")
            except Exception as e:
                print(f"Exception <{e}>\n")
                formatted_json = json.dumps(userdata, indent=4)
                print(formatted_json)
                raise
                return None
            if "pwhash" in userdata:
                pwhash = userdata["pwhash"]
                new_user = register_user(u, email, pwhash=pwhash)
            else:
                new_user = register_user(u, email)
    # save_users() no need on initial parsing