"""
ORIGINAL FILENAME:
    gtoken.py
SOURCE PROJECT:
    ssut/py-googletrans (https://github.com/ssut/py-googletrans)
AUTHOR:
    SuHun Han (@ssut on GitHub)
EXPLANATION:
    Generates a ticket to access Google Translate's API
    Reverse engineered by ssut on the obfuscated and minified code used by Google to generate such token, and implemented on the top of Python.
    However, this could be blocked at any time.
COPYRIGHT:
    Copyright (c) 2015 SuHun Han
LICENSE:
    The MIT License (MIT)

    Copyright (c) 2015 SuHun Han

    Permission is hereby granted, free of charge, to any person obtaining a copy
    of this software and associated documentation files (the "Software"), to deal
    in the Software without restriction, including without limitation the rights
    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    copies of the Software, and to permit persons to whom the Software is
    furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be included in all
    copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
    SOFTWARE.
"""

import ast
from time import time
from math import floor
from re import compile, DOTALL

from requests import get

HEADERS = {
    "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
    "Pragma": "no-cache",
    "Cache-Control": "no-cache",
    "Host": "translate.google.com",
    "User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_6) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/14.0.1 Safari/605.1.15",
    "Accept-Language": "fr-fr",
    "Accept-Encoding": "gzip, deflate, br",
    "Connection": "keep-alive"
}

class TokenAcquirer:
    """Google Translate API token generator

    translate.google.com uses a token to authorize the requests. If you are
    not Google, you do have this token and will have to pay for use.
    This class is the result of reverse engineering on the obfuscated and
    minified code used by Google to generate such token.

    The token is based on a seed which is updated once per hour and on the
    text that will be translated.
    Both are combined - by some strange math - in order to generate a final
    token (e.g. 744915.856682) which is used by the API to validate the
    request.

    This operation will cause an additional request to get an initial
    token from translate.google.com.

    Example usage:
        >>> from googletrans.gtoken import TokenAcquirer
        >>> acquirer = TokenAcquirer()
        >>> text = 'test'
        >>> tk = acquirer.do(text)
        >>> tk
        950629.577246
    """

    RE_TKK = compile(r'tkk:\'(.+?)\'', DOTALL)
    RE_RAWTKK = compile(r'tkk:\'(.+?)\'', DOTALL)

    def __init__(self, host='translate.google.com'):
        self.tkk = '0'
        self.host = host if 'http' in host else 'https://' + host

    def _update(self):
        """update tkk
        """
        # we don't need to update the base TKK value when it is still valid
        now = floor(int(time() * 1000) / 3600000.0)
        if self.tkk and int(self.tkk.split('.')[0]) == now:
            return

        r = get(self.host, headers=HEADERS)

        raw_tkk = self.RE_TKK.search(r.text)
        if raw_tkk:
            self.tkk = raw_tkk.group(1)
            return

        try:
            # this will be the same as python code after stripping out a reserved word 'var'
            code = self.RE_TKK.search(r.text).group(1).replace('var ', '')
            # unescape special ascii characters such like a \x3d(=)
            code = code.encode().decode('unicode-escape')
        except AttributeError:
            raise Exception('Could not find TKK token for this request.\nSee https://github.com/ssut/py-googletrans/issues/234 for more details.')
        except Exception:
            raise

        if code:
            tree = ast.parse(code)
            visit_return = False
            operator = '+'
            n, keys = 0, dict(a=0, b=0)
            for node in ast.walk(tree):
                if isinstance(node, ast.Assign):
                    name = node.targets[0].id
                    if name in keys:
                        if isinstance(node.value, ast.Num):
                            keys[name] = node.value.n
                        # the value can sometimes be negative
                        elif isinstance(node.value, ast.UnaryOp) and \
                                isinstance(node.value.op, ast.USub):  # pragma: nocover
                            keys[name] = -node.value.operand.n
                elif isinstance(node, ast.Return):
                    # parameters should be set after this point
                    visit_return = True
                elif visit_return and isinstance(node, ast.Num):
                    n = node.n
                elif visit_return and n > 0:
                    # the default operator is '+' but implement some more for
                    # all possible scenarios
                    if isinstance(node, ast.Add):  # pragma: nocover
                        pass
                    elif isinstance(node, ast.Sub):  # pragma: nocover
                        operator = '-'
                    elif isinstance(node, ast.Mult):  # pragma: nocover
                        operator = '*'
                    elif isinstance(node, ast.Pow):  # pragma: nocover
                        operator = '**'
                    elif isinstance(node, ast.BitXor):  # pragma: nocover
                        operator = '^'
            # a safety way to avoid Exceptions
            clause = compile('{1}{0}{2}'.format(
                operator, keys['a'], keys['b']), '', 'eval')
            value = eval(clause, dict(__builtin__={}))
            result = '{}.{}'.format(n, value)

            self.tkk = result

    def _lazy(self, value):
        """like lazy evaluation, this method returns a lambda function that
        returns value given.
        We won't be needing this because this seems to have been built for
        code obfuscation.

        the original code of this method is as follows:

           ... code-block: javascript

               var ek = function(a) {
                return function() {
                    return a;
                };
               }
        """
        return lambda: value

    def _xr(self, a, b):
        size_b = len(b)
        c = 0
        while c < size_b - 2:
            d = b[c + 2]
            d = ord(d[0]) - 87 if 'a' <= d else int(d)
            d = (a % 0x100000000) >> d if '+' == b[c + 1] else a << d
            a = a + d & 4294967295 if '+' == b[c] else a ^ d

            c += 3
        return a

    def acquire(self, text):
        a = []
        # Convert text to ints
        for i in text:
            val = ord(i)
            if val < 0x10000:
                a += [val]
            else:
                # Python doesn't natively use Unicode surrogates, so account for those
                a += [
                    floor((val - 0x10000) / 0x400 + 0xD800),
                    floor((val - 0x10000) % 0x400 + 0xDC00)
                ]

        b = self.tkk if self.tkk != '0' else ''
        d = b.split('.')
        b = int(d[0]) if len(d) > 1 else 0

        # assume e means char code array
        e = []
        g = 0
        size = len(a)
        while g < size:
            l = a[g]
            # just append if l is less than 128(ascii: DEL)
            if l < 128:
                e.append(l)
            # append calculated value if l is less than 2048
            else:
                if l < 2048:
                    e.append(l >> 6 | 192)
                else:
                    # append calculated value if l matches special condition
                    if (l & 64512) == 55296 and g + 1 < size and \
                            a[g + 1] & 64512 == 56320:
                        g += 1
                        l = 65536 + ((l & 1023) << 10) + (a[g] & 1023)  # This bracket is important
                        e.append(l >> 18 | 240)
                        e.append(l >> 12 & 63 | 128)
                    else:
                        e.append(l >> 12 | 224)
                    e.append(l >> 6 & 63 | 128)
                e.append(l & 63 | 128)
            g += 1
        a = b
        for i, value in enumerate(e):
            a += value
            a = self._xr(a, '+-a^+6')
        a = self._xr(a, '+-3^+b+-f')
        a ^= int(d[1]) if len(d) > 1 else 0
        if a < 0:  # pragma: nocover
            a = (a & 2147483647) + 2147483648
        a %= 1000000  # int(1E6)

        return '{}.{}'.format(a, a ^ b)

    def do(self, text):
        self._update()
        tk = self.acquire(text)
        return tk