from datetime import date, timedelta
import sys

from django.core.management.base import BaseCommand, CommandError
from django.template.loader import get_template
from django.core.mail import send_mail, BadHeaderError

from input.models import Project, Library, HonoraryCertificate, Travel, Email, BusinessCard, List
from input.settings import URLPREFIX, IF_EMAIL, SURVEYPREFIX

class Command(BaseCommand):
    ''' mails will be send here:

    - two weeks after confirmation of support for volunteer (/extern) send link
    with surveylink

    - same for HonoraryCertificate (/intern)

    - travel: mail 3 weeks after end of project.

    - assumed end of project (/project) reached: mail to IF, link to project-editpage

    - 4 weeks after end of project reached: mail with surveylink
    '''

    help = '''This command sends mail with some links to the database or to the survey
              after some amount of time.'''

    def survey_link(self, email, type, pid, name, realname):
        context = {'realname': realname,
                       'type': type,
                       'name': name,
                       'pid': pid,
                       'SURVEYPREFIX': SURVEYPREFIX, }
        mail_template = get_template('input/survey_mail.txt')
        try:
            send_mail('Projektende erreicht',
                  mail_template.render(context),
                  IF_EMAIL,
                  [email],
                  fail_silently=False)
        except BadHeaderError:
            return HttpResponse('Invalid header found.')

        print(f'send surveylinkemail to {email}...')

    def end_of_projects_reached(self):
        ''' end of project reached '''
        # get all projects which ended
        old = Project.objects.filter(end__lt = date.today())\
                             .exclude(end_mail_send = True)

        mail_template = get_template('input/if_end_of_project.txt')
        for project in old:
            context = {'project': project}
            context['URLPREFIX'] = URLPREFIX
            try:
                send_mail('Projektende erreicht',
                          mail_template.render(context),
                          IF_EMAIL,
                          [IF_EMAIL],
                          fail_silently=False)
                project.end_mail_send = True
                project.save()
            except BadHeaderError:
                self.stdout.write(self.style.ERROR('Invalid header found.'))

        self.stdout.write(self.style.SUCCESS('end_of_projects_reached() executed.'))

    def surveymails_to_object(self, supported, name='', type='LIB'):
        mytype=type
        myname = name
        for item in supported:
            if type == 'LIB':
                mytype = item.type
            elif type not in ('MAIL','VIS','LIST'):
                myname = getattr(item,name)
            self.survey_link(email=item.email,
                         type=mytype,
                         pid=f'{mytype}{item.pk}',
                         name=myname,
                         realname=item.realname)
            item.survey_mail_send = True
            item.save()
        self.stdout.write(self.style.SUCCESS(f'surveymails for object type {type} sent'))


    ''' TODO: there could be some more removing of duplicated code in the following functions '''

    def surveymails_to_lib(self):
        '''get all library objects which where granted two weeks ago'''

        supported = Library.objects.filter(granted=True)\
                                   .filter(granted_date__lt = date.today() - timedelta(days=14))\
                                   .exclude(survey_mail_send=True)
        self.surveymails_to_object(supported,name='library')

    def surveymails_to_hon(self):
        '''get all HonoraryCertificate objects which where granted two weeks ago'''

        supported = HonoraryCertificate.objects.filter(granted=True)\
                                   .filter(granted_date__lt = date.today() - timedelta(days=14))\
                                   .exclude(survey_mail_send=True)
        self.surveymails_to_object(supported, type='HON', name='request_url')

    def surveymails_to_project(self):
        '''send survey link 4 weeks after end of project reached'''
        supported = Project.objects.filter(granted=True)\
                                   .filter(granted_date__lt = date.today() - timedelta(days=28))\
                                   .exclude(survey_mail_send=True)
        self.surveymails_to_object(supported, type='PRO', name='realname')

    def surveymails_to_travel(self):
        '''send survey link 3 weeks after end of project reached'''

        supported = Travel.objects.filter(project__granted=True)\
                                   .filter(project__granted_date__lt = date.today() - timedelta(days=21))\
                                   .exclude(survey_mail_send=True)
        self.surveymails_to_object(supported, type='TRAV', name='request_url')

    def surveymails_to_mail_vis_lis(self):
        '''send survey link 2 weeks after mailadresss, mailinglist or businesscards are granted'''
        lastdate = date.today() - timedelta(days=14)

        typefield = ('MAIL','VIS','LIST')
        count = 0
        for c in ('Email', 'BusinessCard', 'List'):
            # get class via string
            supported = getattr(sys.modules[__name__], c).objects.filter(granted=True)\
                                       .filter(granted_date__lt = lastdate)\
                                       .exclude(survey_mail_send=True)
            self.surveymails_to_object(supported, type=typefield[count])
            count += 1


    def handle(self, *args, **options):
        '''the main function which is called by the custom command'''

        self.end_of_projects_reached()
        self.surveymails_to_lib()
        self.surveymails_to_hon()
        self.surveymails_to_project()
        self.surveymails_to_travel()
        self.surveymails_to_mail_vis_lis()

        self.stdout.write(self.style.SUCCESS('sendmails custom command executed'))