import enum
import random
import unicodedata
import sqlite3

from collections import namedtuple

from passlib.hash import argon2

import config

UserInfo = namedtuple('UserInfo', ('id', 'parent', 'status', 'username', 'email', 'comment'))

# ------------------------------------------------------------------
# General
# ------------------------------------------------------------------

class userstatus(enum.Enum):
	# These will be stored in the database, be mindful of not changing the numbers
	deleted = 0
	normal = 1
	admin = 2

csprng = random.SystemRandom()

def connect():
	"""Connect to the database
	Requires config.load() to have been called beforehand"""
	return sqlite3.connect(config.database_file)

# ------------------------------------------------------------------
# Users
# ------------------------------------------------------------------

def add_user(db, *, username, password, email, parent, status):
	# TODO: Ensure users are unique
	"""Add a user to the database
	Will not commit the changes itself, so run .commit() on the database object yourself"""
	global csprgn

	assert type(username) == str
	assert type(password) == str
	assert type(email) == str
	assert type(parent) == int or parent is None
	assert status in userstatus

	# Generate a user ID. SQLite uses 64 bit signed ints, so generate at max 2⁶³-1
	userid = csprng.randrange(2**63)

	# Unicode normalize the username
	username = unicodedata.normalize('NFKC', username)

	# First unicode normalize the password, then hash it with argon2
	password = unicodedata.normalize('NFKC', password)
	password = argon2.hash(password)

	# Convert status into an int for storage
	status = status.value

	# Add the user into the database
	cursor = db.cursor()
	cursor.execute('PRAGMA foreign_keys = ON;') # Fail if we insert a user with bogus parent field
	cursor.execute('INSERT INTO users VALUES (?, ?, ?, ?, ?, ?, ?);', (userid, parent, status, password, username, email, ''))

def get_userid(db, username):
	"""Returns the user ID associated with given username
	If no user was found, returns None"""
	# Unicode normalize the username
	username = unicodedata.normalize('NFKC', username)

	# Get the user ID
	cursor = db.cursor()
	cursor.execute('SELECT id FROM users WHERE username = ?;', (username,))
	results = cursor.fetchall()

	# If no user was found, return None
	if len(results) != 1:
		return None

	return results[0][0]

def check_password(db, userid, password):
	"""Checks the password for given userid
	Will return True if the password matches and False otherwise"""
	# Unicode normalize the password
	password = unicodedata.normalize('NFKC', password)

	# Get the password and status
	cursor = db.cursor()
	cursor.execute('SELECT password, status FROM users WHERE id = ?;', (userid,))
	results = cursor.fetchall()

	# If no user of that name, fail
	if len(results) != 1:
		return False

	hashed, status = results[0]

	# If user has been deleted, fail
	if status == userstatus.deleted:
		return False

	# Check the password
	return argon2.verify(password, hashed)

def get_user_info(db, userid):
	"""Returns a UserInfo object representing the data associated with a user
	If no user was found, returns None"""
	cursor = db.cursor()
	cursor.execute('SELECT id, parent, status, username, email, comment FROM users WHERE id = ?;', (userid,))
	results = cursor.fetchall()

	# If no user was found, return None
	if len(results) != 1:
		return None

	userid, parent, status, username, email, comment = results[0]

	# Translate status into enum
	status = userstatus(status)

	return UserInfo(userid, parent, status, username, email, comment)

def initialize_users(db, admin_user, admin_password):
	"""Creates a bare-bones user table with only admin user
	This should never be run outside of the initialization script"""

	cursor = db.cursor()

	cursor.execute('''CREATE TABLE users (
		id integer NOT NULL PRIMARY KEY,

		parent integer,
		status integer NOT NULL,

		password text NOT NULL, 

		username text NOT NULL,
		email text NOT NULL,

		comment text NOT NULL,

		FOREIGN KEY(parent) REFERENCES users(id)
	);''')

	add_user(db, username = admin_user, password = admin_password, email = '', parent = None, status = userstatus.admin)

	db.commit()

# ------------------------------------------------------------------
# Boards
# ------------------------------------------------------------------

def list_boards(db):
	"""Lists the boards that exist at the moment"""
	cursor = db.cursor()
	cursor.execute('SELECT name FROM boards;')
	results = cursor.fetchall()

	# The results look like [('foo',), ('bar',), ('baz',)]
	return [i[0] for i in results]

def initialize_boards(db, boards):
	"""Creates a table of boards
	This should never be run outside of the initialization script"""

	cursor = db.cursor()

	cursor.execute('''CREATE TABLE boards (
		id integer NOT NULL PRIMARY KEY,
		name text NOT NULL
	);''')

	# .executemany() wants them in the format [("board1",), ("board2",), …]
	boards = [(board_name,) for board_name in boards]

	# Use NULL to have SQLite generate the IDs automatically
	cursor.executemany('INSERT INTO boards VALUES (NULL, ?);', boards)

	db.commit()