# Contains functions having to do with logging in

import urllib
import json
from youtube import common
import re
import settings
import http.cookiejar
import io
import os

try:
    with open(os.path.join(settings.data_dir, 'accounts.txt'), 'r', encoding='utf-8') as f:
        accounts = json.loads(f.read())
except FileNotFoundError:
    # global var for temporary storage of account info
    accounts = {}

def save_accounts():
    to_save = {username: account for username, account in accounts.items() if account['save']}
    with open(os.path.join(settings.data_dir, 'accounts.txt'), 'w', encoding='utf-8') as f:
        f.write(json.dumps(to_save))

def add_account(username, password, save):
    cookie_jar = http.cookiejar.LWPCookieJar()
    _login(username, password, cookie_jar)
    accounts[username] = {
        "save":save,
        "cookies":cookie_jar.as_lwp_str(ignore_discard=False, ignore_expires=False),
    }

def cookie_jar_from_lwp_str(lwp_str):
    cookie_jar = http.cookiejar.LWPCookieJar()
    # HACK: cookiejar module insists on using filenames and reading files for you,
    #  so present a StringIO to this internal method which takes a filelike object
    cookie_jar._really_load(self, io.StringIO(lwp_str), "", False, False)
    return cookie_jar

def account_cookie_jar(username):
    return cookie_jar_from_lwp_str(accounts[username]['cookies'])

def get_account_login_page(query_string):
    style = ''' 
    main{
        display: grid;
        grid-template-columns: minmax(0px, 3fr) 640px 40px 500px minmax(0px,2fr);
    }

    main form{
        margin-top:20px;
        grid-column:2;
        display:grid;
        justify-items: start;
        align-content: start;
        grid-row-gap: 10px;
    }

    #username, #password{
        grid-column:2;
        width: 250px;
    }
    #add-account-button{
        margin-top:20px;
    }
    '''

    page = '''
    <form action="''' + common.URL_ORIGIN + '''/login" method="POST">
        <div class="form-field">
            <label for="username">Username:</label>
            <input type="text" id="username" name="username">
        </div>
        <div class="form-field">
            <label for="password">Password:</label>
            <input type="password" id="password" name="password">
        </div>
        <div id="save-account-checkbox">
            <input type="checkbox" id="save-account" name="save" checked>
            <label for="save-account">Save account info to disk (password will not be saved, only the login cookie)</label>
        </div>
        <input type="submit" value="Add account" id="add-account-button">
    </form>
    '''

    return common.yt_basic_template.substitute(
        page_title = "Login",
        style = style,
        header = common.get_header(),
        page = page,
    )



# ---------------------------------
# Code ported from youtube-dl
# ---------------------------------
from html.parser import HTMLParser as compat_HTMLParser
import http.client as compat_http_client

class HTMLAttributeParser(compat_HTMLParser):
    """Trivial HTML parser to gather the attributes for a single element"""
    def __init__(self):
        self.attrs = {}
        compat_HTMLParser.__init__(self)

    def handle_starttag(self, tag, attrs):
        self.attrs = dict(attrs)

def extract_attributes(html_element):
    """Given a string for an HTML element such as
    <el
         a="foo" B="bar" c="&98;az" d=boz
         empty= noval entity="&amp;"
         sq='"' dq="'"
    >
    Decode and return a dictionary of attributes.
    {
        'a': 'foo', 'b': 'bar', c: 'baz', d: 'boz',
        'empty': '', 'noval': None, 'entity': '&',
        'sq': '"', 'dq': '\''
    }.
    NB HTMLParser is stricter in Python 2.6 & 3.2 than in later versions,
    but the cases in the unit test will work for all of 2.6, 2.7, 3.2-3.5.
    """
    parser = HTMLAttributeParser()
    parser.feed(html_element)
    parser.close()

    return parser.attrs

def _hidden_inputs(html):
    html = re.sub(r'<!--(?:(?!<!--).)*-->', '', html)
    hidden_inputs = {}
    for input in re.findall(r'(?i)(<input[^>]+>)', html):
        attrs = extract_attributes(input)
        if not input:
            continue
        if attrs.get('type') not in ('hidden', 'submit'):
            continue
        name = attrs.get('name') or attrs.get('id')
        value = attrs.get('value')
        if name and value is not None:
            hidden_inputs[name] = value
    return hidden_inputs

def try_get(src, getter, expected_type=None):
    if not isinstance(getter, (list, tuple)):
        getter = [getter]
    for get in getter:
        try:
            v = get(src)
        except (AttributeError, KeyError, TypeError, IndexError):
            pass
        else:
            if expected_type is None or isinstance(v, expected_type):
                return v

def remove_start(s, start):
    return s[len(start):] if s is not None and s.startswith(start) else s

_LOGIN_URL = 'https://accounts.google.com/ServiceLogin'
_TWOFACTOR_URL = 'https://accounts.google.com/signin/challenge'

_LOOKUP_URL = 'https://accounts.google.com/_/signin/sl/lookup'
_CHALLENGE_URL = 'https://accounts.google.com/_/signin/sl/challenge'
_TFA_URL = 'https://accounts.google.com/_/signin/challenge?hl=en&TL={0}'
def _login(username, password, cookie_jar):
    """
    Attempt to log in to YouTube.
    True is returned if successful or skipped.
    False is returned if login failed.

    Taken from youtube-dl
    """
    login_page = common.fetch_url(_LOGIN_URL, report_text='Downloaded login page', cookie_jar_receive=cookie_jar).decode('utf-8')

    if login_page is False:
        return

    login_form = _hidden_inputs(login_page)

    def req(url, f_req, note, errnote):
        data = login_form.copy()
        data.update({
            'pstMsg': 1,
            'checkConnection': 'youtube',
            'checkedDomains': 'youtube',
            'hl': 'en',
            'deviceinfo': '[null,null,null,[],null,"US",null,null,[],"GlifWebSignIn",null,[null,null,[]]]',
            'f.req': json.dumps(f_req),
            'flowName': 'GlifWebSignIn',
            'flowEntry': 'ServiceLogin',
        })
        headers={
            'Content-Type': 'application/x-www-form-urlencoded;charset=utf-8',
            'Google-Accounts-XSRF': 1,
        }
        result = common.fetch_url(url, headers, report_text=note, data=data, cookie_jar_send=cookie_jar, cookie_jar_receive=cookie_jar)
        result = re.sub(r'^[^\[]*', '', result)
        return json.loads(result)

    def warn(message):
        print("Login: " + message)

    lookup_req = [
        username,
        None, [], None, 'US', None, None, 2, False, True,
        [
            None, None,
            [2, 1, None, 1,
             'https://accounts.google.com/ServiceLogin?passive=true&continue=https%3A%2F%2Fwww.youtube.com%2Fsignin%3Fnext%3D%252F%26action_handle_signin%3Dtrue%26hl%3Den%26app%3Ddesktop%26feature%3Dsign_in_button&hl=en&service=youtube&uilel=3&requestPath=%2FServiceLogin&Page=PasswordSeparationSignIn',
             None, [], 4],
            1, [None, None, []], None, None, None, True
        ],
        username,
    ]

    lookup_results = req(
        _LOOKUP_URL, lookup_req,
        'Looking up account info', 'Unable to look up account info')

    if lookup_results is False:
        return False

    user_hash = try_get(lookup_results, lambda x: x[0][2], str)
    if not user_hash:
        warn('Unable to extract user hash')
        return False

    challenge_req = [
        user_hash,
        None, 1, None, [1, None, None, None, [password, None, True]],
        [
            None, None, [2, 1, None, 1, 'https://accounts.google.com/ServiceLogin?passive=true&continue=https%3A%2F%2Fwww.youtube.com%2Fsignin%3Fnext%3D%252F%26action_handle_signin%3Dtrue%26hl%3Den%26app%3Ddesktop%26feature%3Dsign_in_button&hl=en&service=youtube&uilel=3&requestPath=%2FServiceLogin&Page=PasswordSeparationSignIn', None, [], 4],
            1, [None, None, []], None, None, None, True
        ]]

    challenge_results = req(
        _CHALLENGE_URL, challenge_req,
        'Logging in', 'Unable to log in')

    if challenge_results is False:
        return

    login_res = try_get(challenge_results, lambda x: x[0][5], list)
    if login_res:
        login_msg = try_get(login_res, lambda x: x[5], str)
        warn(
            'Unable to login: %s' % 'Invalid password'
            if login_msg == 'INCORRECT_ANSWER_ENTERED' else login_msg)
        return False

    res = try_get(challenge_results, lambda x: x[0][-1], list)
    if not res:
        warn('Unable to extract result entry')
        return False

    login_challenge = try_get(res, lambda x: x[0][0], list)
    if login_challenge:
        challenge_str = try_get(login_challenge, lambda x: x[2], str)
        if challenge_str == 'TWO_STEP_VERIFICATION':
            # SEND_SUCCESS - TFA code has been successfully sent to phone
            # QUOTA_EXCEEDED - reached the limit of TFA codes
            status = try_get(login_challenge, lambda x: x[5], str)
            if status == 'QUOTA_EXCEEDED':
                warn('Exceeded the limit of TFA codes, try later')
                return False

            tl = try_get(challenge_results, lambda x: x[1][2], str)
            if not tl:
                warn('Unable to extract TL')
                return False

            tfa_code = self._get_tfa_info('2-step verification code')

            if not tfa_code:
                warn(
                    'Two-factor authentication required. Provide it either interactively or with --twofactor <code>'
                    '(Note that only TOTP (Google Authenticator App) codes work at this time.)')
                return False

            tfa_code = remove_start(tfa_code, 'G-')

            tfa_req = [
                user_hash, None, 2, None,
                [
                    9, None, None, None, None, None, None, None,
                    [None, tfa_code, True, 2]
                ]]

            tfa_results = req(
                _TFA_URL.format(tl), tfa_req,
                'Submitting TFA code', 'Unable to submit TFA code')

            if tfa_results is False:
                return False

            tfa_res = try_get(tfa_results, lambda x: x[0][5], list)
            if tfa_res:
                tfa_msg = try_get(tfa_res, lambda x: x[5], str)
                warn(
                    'Unable to finish TFA: %s' % 'Invalid TFA code'
                    if tfa_msg == 'INCORRECT_ANSWER_ENTERED' else tfa_msg)
                return False

            check_cookie_url = try_get(
                tfa_results, lambda x: x[0][-1][2], str)
        else:
            CHALLENGES = {
                'LOGIN_CHALLENGE': "This device isn't recognized. For your security, Google wants to make sure it's really you.",
                'USERNAME_RECOVERY': 'Please provide additional information to aid in the recovery process.',
                'REAUTH': "There is something unusual about your activity. For your security, Google wants to make sure it's really you.",
            }
            challenge = CHALLENGES.get(
                challenge_str,
                '%s returned error %s.' % ('youtube', challenge_str))
            warn('%s\nGo to https://accounts.google.com/, login and solve a challenge.' % challenge)
            return False
    else:
        check_cookie_url = try_get(res, lambda x: x[2], str)

    if not check_cookie_url:
        warn('Unable to extract CheckCookie URL')
        return False

    try:
        check_cookie_results = common.fetch_url(check_cookie_url, report_text="Checked cookie", cookie_jar_send=cookie_jar, cookie_jar_receive=cookie_jar).decode('utf-8')
    except (urllib.error.URLError, compat_http_client.HTTPException, socket.error) as err:
        return False

    if 'https://myaccount.google.com/' not in check_cookie_results:
        warn('Unable to log in')
        return False

    return True