from django.conf import settings
from django import forms

from urllib.parse import urlencode

import re
from io import StringIO

from postgresqleu.util.widgets import StaticTextWidget
from postgresqleu.paypal.models import TransactionInfo
from postgresqleu.paypal.util import PaypalAPI
from postgresqleu.invoices.backendforms import BackendInvoicePaymentMethodForm
from postgresqleu.accounting.util import get_account_choices

from . import BasePayment


class BackendPaypalForm(BackendInvoicePaymentMethodForm):
    sandbox = forms.BooleanField(required=False, help_text="Use testing sandbox")
    email = forms.EmailField(required=True, label="Paypal account email")
    clientid = forms.CharField(required=True, label="Client ID",
                               widget=forms.widgets.PasswordInput(render_value=True),
                               help_text='From developer.paypal.com, create app, <a href="/admin/docs/payment#paypal">set permissions</a>')
    clientsecret = forms.CharField(required=True, label="Client secret",
                                   widget=forms.widgets.PasswordInput(render_value=True),
                                   help_text="From developer.paypal.com, app config")
    pdt_token = forms.CharField(required=True, label="PDT token", widget=forms.widgets.PasswordInput(render_value=True),
                                help_text="Settings -> My Selling Tools -> Website preferences -> Payment data transfer")

    donation_text = forms.CharField(required=True,
                                    help_text="Payments with this text will be auto-matched as donations")
    report_receiver = forms.EmailField(required=True)
    accounting_income = forms.ChoiceField(required=True, choices=get_account_choices,
                                          label="Income account")
    accounting_fee = forms.ChoiceField(required=True, choices=get_account_choices,
                                       label="Fees account")
    accounting_transfer = forms.ChoiceField(required=True, choices=get_account_choices,
                                            label="Transfer account",
                                            help_text="Account that transfers from paypal are made to")

    returnurl = forms.CharField(label="Return URL", widget=StaticTextWidget)

    config_fields = ['sandbox', 'email', 'clientid', 'clientsecret', 'pdt_token',
                     'donation_text', 'report_receiver',
                     'accounting_income', 'accounting_fee', 'accounting_transfer',
                     'returnurl', ]
    config_readonly = ['returnurl', ]
    config_fieldsets = [
        {
            'id': 'paypal',
            'legend': 'Paypal',
            'fields': ['email', 'sandbox', 'clientid', 'clientsecret', 'pdt_token'],
        },
        {
            'id': 'integration',
            'legend': 'Integration',
            'fields': ['report_receiver', 'donation_text', ],
        },
        {
            'id': 'accounting',
            'legend': 'Accounting',
            'fields': ['accounting_income', 'accounting_fee', 'accounting_transfer'],
        },
        {
            'id': 'paypalconf',
            'legend': 'Paypal configuration',
            'fields': ['returnurl', ],
        }
    ]

    def fix_fields(self):
        super(BackendPaypalForm, self).fix_fields()
        if self.instance.id:
            self.initial.update({
                'returnurl': """
On the Paypal account, go into <i>Settings</i>, then <i>My Selling Tools</i>,
then <i>Website Preferences</i>. Make sure that <i>Auto Return</i>
is enabled, and enter the url <code>{0}/p/paypal_return/{1}/</code>""".format(
                    settings.SITEBASE,
                    self.instance.id,
                ),
            })

    @classmethod
    def validate_data_for(self, instance):
        pm = instance.get_implementation()
        api = PaypalAPI(pm)

        s = StringIO()
        api.ensure_access_token()
        s.write("Paypal API access credentials correct,\n")
        if 'https://uri.paypal.com/services/reporting/search/read ' not in api.tokenscope:
            s.write("Paypal token does <strong>NOT</strong> have have <i>Transaction search</i> permissions!\n")
        if 'https://api.paypal.com/v1/payments/.* ' not in api.tokenscope:
            s.write("Paypal token does <strong>NOT</strong> have have <i>Accept payments</i> permissions!\n")

        return s.getvalue()


class Paypal(BasePayment):
    backend_form_class = BackendPaypalForm
    description = """
Pay using Paypal. You can use this both
to pay from your Paypal balance if you have a Paypal account, or you can
use it to pay with any credit card supported by Paypal (Visa, Mastercard, American Express).
In most countries, you do not need a Paypal account if you choose to pay
with credit card. However, we do recommend using the payment method called
"Credit card" instead of Paypal if you are paying with a credit card, as it has
lower fees.
"""

    PAYPAL_COMMON = {
        'lc': 'GB',
        'currency_code': settings.CURRENCY_ABBREV,
        'button_subtype': 'services',
        'no_note': '1',
        'no_shipping': '1',
        'bn': 'PP-BuyNowBF:btn_buynowCC_LG.gif-NonHosted',
        'charset': 'utf-8',
        }

    def get_baseurl(self):
        if self.config('sandbox'):
            return 'https://www.sandbox.paypal.com/cgi-bin/webscr'
        return 'https://www.paypal.com/cgi-bin/webscr'

    def build_payment_url(self, invoicestr, invoiceamount, invoiceid, returnurl=None):
        param = self.PAYPAL_COMMON
        param.update({
            'business': self.config('email'),
            'cmd': '_xclick',
            'item_name': invoicestr.encode('utf-8'),
            'amount': '%.2f' % invoiceamount,
            'invoice': invoiceid,
            'return': '%s/p/paypal_return/%s/' % (settings.SITEBASE, self.id),
            })
        if returnurl:
            # If the user cancels, send back to specific URL, instead of
            # the invoice url.
            param['cancel_return'] = returnurl
        return "%s?%s" % (
            self.get_baseurl(),
            urlencode(param))

    _re_paypal = re.compile('^Paypal id ([A-Z0-9]+), ')

    def _find_invoice_transaction(self, invoice):
        m = self._re_paypal.match(invoice.paymentdetails)
        if m:
            try:
                return (TransactionInfo.objects.get(paypaltransid=m.groups(1)[0]), None)
            except TransactionInfo.DoesNotExist:
                return (None, "not found")
        else:
            return (None, "unknown format")

    def payment_fees(self, invoice):
        (trans, reason) = self._find_invoice_transaction(invoice)
        if not trans:
            return reason

        return trans.fee

    def autorefund(self, refund):
        (trans, reason) = self._find_invoice_transaction(refund.invoice)
        if not trans:
            raise Exception(reason)

        api = PaypalAPI(self)
        refund.payment_reference = api.refund_transaction(
            trans.paypaltransid,
            refund.fullamount,
            refund.fullamount == refund.invoice.total_amount,
            '{0} refund {1}'.format(settings.ORG_SHORTNAME, refund.id),
        )
        # At this point, we succeeded. Anything that failed will bubble
        # up as an exception.
        return True

    def used_method_details(self, invoice):
        # Bank transfers don't need any extra information
        return "PayPal"