# v0.1

import time
import config
from selenium import webdriver
from selenium.webdriver.chrome.service import Service

from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC

friend_list = []
me_friend_page = "https://www.facebook.com/me/friends"


def scroll_down():
    SCROLL_PAUSE_TIME = 1

    # Get scroll height
    last_height = browser.execute_script("return document.body.scrollHeight")

    while True:
        # Scroll down to bottom
        browser.execute_script("window.scrollTo(0, document.body.scrollHeight);")

        # Wait to load page
        time.sleep(SCROLL_PAUSE_TIME)

        # Calculate new scroll height and compare with last scroll height
        new_height = browser.execute_script("return document.body.scrollHeight")
        if new_height == last_height:
            break
        last_height = new_height


def get_friend_list():
    # get list which contains multiple instances of class below
    find_href_list = browser.find_elements(By.XPATH,
        '//*[@class="oajrlxb2 g5ia77u1 qu0x051f esr5mh6w e9989ue4 r7d6kgcz rq0escxv nhd2j8a9 nc684nl6 p7hjln8o kvgmc6g5 cxmmr5t8 oygrvhab hcukyx3x jb3vyjys rz4wbd8a qt6c0cv9 a8nywdso i1ao9s8h esuyzwwr f1sip0of lzcic4wl gmql0nx0 gpro0wi8"]')

    # extract each class instance from list
    for my_href in find_href_list:
        # get attribute href from each class - wa need friend links only
        # if link contains 3x char "/"add it to list - link is valid
        if my_href.get_attribute("href").count('/') == 3:
            friend_list.append(my_href.get_attribute("href"))

    return friend_list


# disable pop-up window with block/allow notification options
# https://stackoverflow.com/questions/38684175/how-to-click-allow-on-show-notifications-popup-using-selenium-webdriver
options = webdriver.ChromeOptions()
options.add_argument("--disable-notifications")

s = Service(config.chrome_driver_path)
browser = webdriver.Chrome(service=s, options= options)

browser.get("https://facebook.com")

# accept all cookies
browser.find_element(By.XPATH, '//*[@class="_42ft _4jy0 _9xo7 _4jy3 _4jy1 selected _51sy"]').click()

# enter username and password
browser.find_element(By.ID, "email").send_keys(config.username)
browser.find_element(By.ID, "pass").send_keys(config.password)

# click login button
browser.find_element(By.NAME, "login").click()

# wait for the main page to load -check if field 'what is on your mind' is presented
WebDriverWait(browser, 20).until(
    EC.presence_of_all_elements_located((By.XPATH, '//*[@class="a8c37x1j ni8dbmo4 stjgntxs l9j0dhe7"]')))

# click friends link
browser.get(me_friend_page)

# wait until New message icon is presented
WebDriverWait(browser, 20).until(
    EC.presence_of_all_elements_located((By.CSS_SELECTOR, "[aria-label='New message']")))

# scroll down to bottom of page so all friends can be collected
scroll_down()

friend_list = get_friend_list()