"""
LiqPay Python SDK
~~~~~~~~~~~~~~~~~
supports python 3 version
requires requests module
"""

__title__ = "LiqPay Python SDK"
__version__ = "1.0"

import base64
from copy import deepcopy
import hashlib
import json
from urllib.parse import urljoin

import requests


class ParamValidationError(Exception):
    pass


class LiqPay(object):
    FORM_TEMPLATE = """\
        <form method="post" action="{action}" accept-charset="utf-8">
        \t{param_inputs}
            <input type="image" src="//static.liqpay.ua/buttons/p1{language}.radius.png" name="btn_text" />
        </form>"""
    INPUT_TEMPLATE = "<input type='hidden' name='{name}' value='{value}'/>"

    SUPPORTED_PARAMS = [
        "public_key", "amount", "currency", "description", "order_id",
        "result_url", "server_url", "type", "signature", "language", "sandbox"
    ]

    def __init__(self, public_key, private_key, host="https://www.liqpay.ua/api/"):
        self._public_key = public_key
        self._private_key = private_key
        self._host = host

    def _make_signature(self, *args):
        joined_fields = "".join(x for x in args)
        joined_fields = joined_fields.encode("utf-8")
        return base64.b64encode(hashlib.sha1(joined_fields).digest()).decode("ascii")

    def _prepare_params(self, params):
        params = {} if params is None else deepcopy(params)
        params.update(public_key=self._public_key)
        return params

    def api(self, url, params=None):
        params = self._prepare_params(params)

        json_encoded_params = json.dumps(params)
        private_key = self._private_key
        signature = self._make_signature(private_key, json_encoded_params, private_key)

        request_url = urljoin(self._host, url)
        request_data = {"data": json_encoded_params, "signature": signature}
        response = requests.post(request_url, data=request_data, verify=False)
        return json.loads(response.content.decode("utf-8"))

    def cnb_form(self, params):
        params = self._prepare_params(params)
        params_validator = (
            ("amount", lambda x: x is not None and float(x) > 0),
            ("description", lambda x: x is not None)
        )
        for key, validator in params_validator:
            if validator(params.get(key)):
                continue

            raise ParamValidationError("Invalid param: '{}'".format(key))

        # spike to set correct values for language, currency and sandbox params
        language = params.get("language", "ru")
        currency = params["currency"]
        params.update(
            language=language,
            currency=currency if currency != "RUR" else "RUB",
            sandbox=int(bool(params.get("sandbox")))
        )

        encoded_data = self.data_to_sign(params)
        params_templ = {"data": encoded_data}

        params_templ["signature"] = self._make_signature(self._private_key, params_templ["data"], self._private_key)
        form_action_url = urljoin(self._host, "3/checkout/")
        format_input = (lambda k, v: self.INPUT_TEMPLATE.format(name=k, value=v))
        inputs = [format_input(k, v) for k, v in params_templ.items()]
        return self.FORM_TEMPLATE.format(
            action=form_action_url,
            language=language,
            param_inputs="\n\t".join(inputs)
        )

    def cnb_signature(self, params):
        params = self._prepare_params(params)

        data_to_sign = self.data_to_sign(params)
        return self._make_signature(self._private_key, data_to_sign, self._private_key)

    def cnb_data(self, params):
        params = self._prepare_params(params)
        return self.data_to_sign(params)

    def str_to_sign(self, str):
        return base64.b64encode(hashlib.sha1(str.encode("utf-8")).digest()).decode("ascii")

    def data_to_sign(self, params):
        return base64.b64encode(json.dumps(params).encode("utf-8")).decode("ascii")

    def decode_data_from_str(self, data):
        """Decoding data that were encoded by base64.b64encode(str)
        Note:
            Often case of using is decoding data from LiqPay Callback.
            Dict contains all information about payment.
            More info about callback params see in documentation
            https://www.liqpay.ua/documentation/api/callback.
        Args:
            data: json string with api params and encoded by base64.b64encode(str).
        Returns:
            Dict
        Example:
            liqpay = LiqPay(settings.LIQPAY_PUBLIC_KEY, settings.LIQPAY_PRIVATE_KEY)
            data = request.POST.get('data')
            response = liqpay.decode_data_from_str(data)
            print(response)
            {'commission_credit': 0.0, 'order_id': 'order_id_1', 'liqpay_order_id': 'T8SRXWM71509085055293216', ...}
        """
        return json.loads(base64.b64decode(data).decode('utf-8'))