#
# This file is part of pretix (Community Edition).
#
# Copyright (C) 2014-2020  Raphael Michel and contributors
# Copyright (C) 2020-today pretix GmbH and contributors
#
# This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General
# Public License as published by the Free Software Foundation in version 3 of the License.
#
# ADDITIONAL TERMS APPLY: Pursuant to Section 7 of the GNU Affero General Public License, additional terms are
# applicable granting you additional permissions and placing additional restrictions on your usage of this software.
# Please refer to the pretix LICENSE file to obtain the full terms applicable to this work. If you did not receive
# this file, see <https://pretix.eu/about/en/license>.
#
# This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for more
# details.
#
# You should have received a copy of the GNU Affero General Public License along with this program.  If not, see
# <https://www.gnu.org/licenses/>.
#
import json
import logging
import mimetypes
from datetime import timedelta
from decimal import Decimal
from io import BytesIO

from django.conf import settings
from django.core.files import File
from django.core.files.base import ContentFile
from django.core.files.storage import default_storage
from django.http import (
    FileResponse, HttpResponse, HttpResponseBadRequest, JsonResponse,
)
from django.shortcuts import get_object_or_404, render
from django.urls import reverse
from django.utils.crypto import get_random_string
from django.utils.timezone import now
from django.utils.translation import gettext as _
from django.views.generic import TemplateView
from pypdf import PdfReader, PdfWriter
from pypdf.errors import PdfReadError
from reportlab.lib.units import mm

from pretix.base.i18n import language
from pretix.base.models import (
    CachedFile, InvoiceAddress, ItemProgramTime, OrderPosition,
)
from pretix.base.pdf import get_images, get_variables
from pretix.base.settings import PERSON_NAME_SCHEMES
from pretix.control.permissions import EventPermissionRequiredMixin
from pretix.helpers.database import rolledback_transaction
from pretix.presale.style import get_fonts

logger = logging.getLogger(__name__)


class BaseEditorView(EventPermissionRequiredMixin, TemplateView):
    template_name = 'pretixcontrol/pdf/index.html'
    permission = 'event.settings.general:write'
    accepted_formats = (
        'application/pdf',
    )
    maxfilesize = settings.FILE_UPLOAD_MAX_SIZE_IMAGE
    minfilesize = 10
    title = None

    def get(self, request, *args, **kwargs):
        if 'placeholders' in request.GET:
            return self.get_placeholders_help(request)
        resp = super().get(request, *args, **kwargs)
        resp._csp_ignore = True
        return resp

    def get_placeholders_help(self, request):
        ctx = {}
        ctx['variables'] = self.get_variables()
        return render(request, 'pretixcontrol/pdf/placeholders.html', ctx)

    def process_upload(self):
        f = self.request.FILES.get('background')
        error = False
        if f.size > self.maxfilesize:
            error = _('The uploaded PDF file is too large.')
        if f.size < self.minfilesize:
            error = _('The uploaded PDF file is too small.')
        if mimetypes.guess_type(f.name)[0] not in self.accepted_formats:
            error = _('Please only upload PDF files.')
        # if there was an error, add error message to response_data and return
        if error:
            return error, None
        return None, f

    def _get_preview_position(self):
        item = self.request.event.items.create(name=_("Sample product"), default_price=Decimal('42.23'),
                                               description=_("Sample product description"))
        item2 = self.request.event.items.create(name=_("Sample workshop"), default_price=Decimal('23.40'))

        ItemProgramTime.objects.create(start=now(), end=now(), item=item)
        ItemProgramTime.objects.create(start=now(), end=now(), item=item2)

        from pretix.base.models import Order
        order = self.request.event.orders.create(status=Order.STATUS_PENDING, datetime=now(),
                                                 email='sample@pretix.eu',
                                                 sales_channel=self.request.event.organizer.sales_channels.get(identifier="web"),
                                                 locale=self.request.event.settings.locale,
                                                 expires=now(), code="PREVIEW1234", total=Decimal('119.00'))

        scheme = PERSON_NAME_SCHEMES[self.request.event.settings.name_scheme]
        sample = {k: str(v) for k, v in scheme['sample'].items()}
        p = order.positions.create(
            item=item,
            attendee_name_parts=sample,
            company=_("Sample company"),
            price=item.default_price
        )
        order.positions.create(
            item=item2,
            attendee_name_parts=sample,
            company=_("Sample company"),
            price=item.default_price,
            addon_to=p
        )
        order.positions.create(
            item=item2,
            attendee_name_parts=sample,
            company=_("Sample company"),
            price=item.default_price,
            addon_to=p
        )

        InvoiceAddress.objects.create(order=order, name_parts=sample, company=_("Sample company"))
        return p

    def generate(self, p: OrderPosition, override_layout=None, override_background=None):
        raise NotImplementedError()

    def get_layout_settings_key(self):
        raise NotImplementedError()

    def get_background_settings_key(self):
        raise NotImplementedError()

    def get_default_background(self):
        raise NotImplementedError()

    def get_current_background(self):
        return (
            self.request.event.settings.get(self.get_background_settings_key()).url
            if self.request.event.settings.get(self.get_background_settings_key())
            else self.get_default_background()
        )

    def get_current_layout(self):
        return self.request.event.settings.get(self.get_layout_settings_key(), as_type=list)

    def save_layout(self):
        self.request.event.settings.set(self.get_layout_settings_key(), self.request.POST.get("data"))

    def save_background(self, f: CachedFile):
        fexisting = self.request.event.settings.get(self.get_background_settings_key(), as_type=File)
        if fexisting:
            try:
                default_storage.delete(fexisting.name)
            except OSError:  # pragma: no cover
                logger.error('Deleting file %s failed.' % fexisting.name)

        # Create new file
        nonce = get_random_string(length=8)
        fname = 'pub/%s-%s/%s/%s.%s.%s' % (
            'event', 'settings', self.request.event.pk, self.get_layout_settings_key(), nonce, 'pdf'
        )
        newname = default_storage.save(fname, f.file)
        self.request.event.settings.set(self.get_background_settings_key(), 'file://' + newname)

    def post(self, request, *args, **kwargs):
        if "emptybackground" in request.POST:
            p = PdfWriter()
            try:
                p.add_blank_page(
                    width=Decimal('%.5f' % (float(request.POST.get('width')) * mm)),
                    height=Decimal('%.5f' % (float(request.POST.get('height')) * mm)),
                )
            except ValueError:
                return JsonResponse({
                    "status": "error",
                    "error": "Invalid height/width given."
                })
            buffer = BytesIO()
            p.write(buffer)
            buffer.seek(0)
            c = CachedFile(web_download=True)
            c.expires = now() + timedelta(days=7)
            c.date = now()
            c.filename = 'background_preview.pdf'
            c.type = 'application/pdf'
            c.save()
            c.file.save('empty.pdf', ContentFile(buffer.read()))
            c.refresh_from_db()
            return JsonResponse({
                "status": "ok",
                "id": c.id,
                "url": reverse('control:pdf.background', kwargs={
                    'event': request.event.slug,
                    'organizer': request.organizer.slug,
                    'filename': str(c.id)
                })
            })

        if "background" in request.FILES:
            error, fileobj = self.process_upload()
            if error:
                return JsonResponse({
                    "status": "error",
                    "error": error
                })
            c = CachedFile(web_download=True)
            c.expires = now() + timedelta(days=7)
            c.date = now()
            c.filename = 'background_preview.pdf'
            c.type = 'application/pdf'
            c.file = fileobj
            c.save()
            c.refresh_from_db()

            try:
                bg_bytes = c.file.read()
                PdfReader(BytesIO(bg_bytes), strict=False)
            except PdfReadError as e:
                return JsonResponse({
                    "status": "error",
                    "error": _('Unfortunately, we were unable to process this PDF file ({reason}).').format(
                        reason=str(e)
                    )
                })
            return JsonResponse({
                "status": "ok",
                "id": c.id,
                "url": reverse('control:pdf.background', kwargs={
                    'event': request.event.slug,
                    'organizer': request.organizer.slug,
                    'filename': str(c.id)
                })
            })

        cf = None
        if request.POST.get("background", "").strip():
            try:
                cf = CachedFile.objects.get(id=request.POST.get("background"), web_download=True)
            except CachedFile.DoesNotExist:
                pass

        if "preview" in request.POST:
            with rolledback_transaction(), language(request.event.settings.locale, request.event.settings.region):
                p = self._get_preview_position()
                fname, mimet, data = self.generate(
                    p,
                    override_layout=(json.loads(self.request.POST.get("data"))
                                     if self.request.POST.get("data") else None),
                    override_background=cf.file if cf else None
                )

            resp = HttpResponse(data, content_type=mimet)
            ftype = fname.split(".")[-1]
            if settings.DEBUG:
                # attachment is more secure as we're dealing with user-generated stuff here, but inline is much more convenient during debugging
                resp['Content-Disposition'] = 'inline; filename="ticket-preview.{}"'.format(ftype)
                resp._csp_ignore = True
            else:
                resp['Content-Disposition'] = 'attachment; filename="ticket-preview.{}"'.format(ftype)
            return resp
        elif "data" in request.POST:
            if cf:
                self.save_background(cf)
            self.save_layout()
            return JsonResponse({'status': 'ok'})
        return HttpResponseBadRequest()

    def get_variables(self):
        return get_variables(self.request.event)

    def get_images(self):
        return get_images(self.request.event)

    def get_context_data(self, **kwargs):
        ctx = super().get_context_data(**kwargs)
        ctx['fonts'] = get_fonts(self.request.event, pdf_support_required=True)
        ctx['pdf'] = self.get_current_background()
        ctx['variables'] = self.get_variables()
        ctx['images'] = self.get_images()
        ctx['layout'] = json.dumps(self.get_current_layout())
        ctx['title'] = self.title
        ctx['locales'] = [p for p in settings.LANGUAGES if p[0] in self.request.event.settings.locales]
        ctx['maxfilesize'] = self.maxfilesize
        return ctx


class FontsCSSView(TemplateView):
    content_type = 'text/css'
    template_name = 'pretixcontrol/pdf/webfonts.css'

    def get_context_data(self, **kwargs):
        ctx = super().get_context_data(**kwargs)
        ctx['fonts'] = get_fonts(self.request.event if hasattr(self.request, 'event') else None, pdf_support_required=True)
        return ctx


class PdfView(TemplateView):
    def get(self, request, *args, **kwargs):
        cf = get_object_or_404(CachedFile, id=kwargs.get("filename"), filename="background_preview.pdf")
        resp = FileResponse(cf.file, content_type='application/pdf')
        resp['Content-Disposition'] = 'attachment; filename="{}"'.format(cf.filename)
        return resp