import binascii
import redis
import sys

# user state

class UserStatus:
    def __init__(self):
        self.current_user = 'guest'
        self.logged = False

def get_user_id(login):
    return 'usr_' + login

# create short link using hash

def generate_short_link(long_link):
    DB.incr('links_cnt')
    ID = DB.get('links_cnt')
    short_link = 'our_site.com/' + str(abs(binascii.crc32(long_link))) + str(ID)
    return short_link

# DB interface functions

def create_user(login, password):
    user_ID = get_user_id(login)
    if DB.exists(user_ID):
        print('User wit login ' + login + ' already exists')
    else:
        user = {'login': login, 'password': password, 'links_created': 0}
        DB.hmset(user_ID, user)
        print('User ' + login + ' has been created!')

def try_login(login, password):
    user_ID = get_user_id(login)
    if DB.exists(user_ID):
        if DB.hget(user_ID, 'password') == password:
            return True
    return False

def add_link(short_link, long_link, user_login):
    user_ID = get_user_id(user_login)
    value = {'link': long_link, 'counter': 0}
    DB.hincrby(user_ID, 'links_created');
    DB.hmset(short_link, value)

def get_link(short_link):
    DB.hincrby(short_link, "counter")
    return DB.hget(short_link, 'link')

def get_stat(short_link):
    return DB.hget(short_link, 'counter')

def get_user_links_count(login):
    user_ID = get_user_id(login)
    if DB.exists(user_ID):
        return DB.hget(user_ID, 'links_created')
    else:
        return -1;

# parse commands functions

def get_command_name(full_command):
    parsed_command = full_command.split(" ")
    return parsed_command[0]

def process_command(command_name, full_command, user_state):
    parsed_command = full_command.split(" ")

    if user_state.logged is False:
        if command_name == 'create_user':
            login = parsed_command[1]
            password = parsed_command[2]
            create_user(login, password)
        elif command_name == 'login':
            if user_state.logged == False:
                login = parsed_command[1]
                password = parsed_command[2]
                if try_login(login, password):
                    user_state.current_user = login
                    user_state.logged = True
                    print ('Login successful!')
                else:
                    print ('Incorrect login info!')
            else:
                print('You already logged as ' + user_state.current_user)
        elif command_name == 'exit':
            print('Aborting...')
        else:
            print('On guest user you can only create user or login!')
    else:
        if command_name == 'logout':
            user_state.logged = False
            user_state.current_user = 'guest'
        elif command_name == 'get_user_stat':
            user_to_check = parsed_command[1]
            links_count = get_user_links_count(user_to_check)
            if links_count != -1:
                print('User ' + user_to_check + ' created ' + links_count + " links.")
            else:
                print('Invalid user name!')
        elif command_name == 'add_link':
            long_link = parsed_command[1]
            short_link = generate_short_link(long_link)
            add_link(short_link, long_link, user_state.current_user)
            print('Added ' + short_link + ' to database.')
        elif command_name == 'get_link':
            short_link = parsed_command[1]
            print('Corresponding link: ' + get_link(short_link))
        elif command_name == 'get_link_stat':
            short_link = parsed_command[1]
            print('Link ' + short_link + ' used ' + get_stat(short_link) + ' times')
        elif command_name == 'exit':
            print('Aborting...')
        else:
            print('Invalid command!')

# main program text

command = 'empty'
user_state = UserStatus()
DB = redis.StrictRedis(host='localhost', port=6379, db=0)

while command != 'exit':
    command = raw_input(user_state.current_user + " $: ")
    command_name = get_command_name(command)
    try:
        process_command(command_name, command, user_state)
    except IndexError:
        print 'Not enough command parameters!'
    print("\n");

print('See you around!')