import json
from collections import OrderedDict
from datetime import date, datetime, timedelta

from tabimport import FileFactory

from django.conf import settings
from django.contrib import messages
from django.db.models import Case, Count, When
from django.http import HttpResponse, HttpResponseNotAllowed, HttpResponseRedirect
from django.shortcuts import get_object_or_404
from django.urls import reverse
from django.utils.translation import ugettext as _
from django.views.generic import DetailView, FormView, TemplateView, ListView

from .forms import PeriodForm, StudentImportForm
from .models import (Klass, Section, Student, Corporation, CorpContact, Period,
    Training, Referent, Availability)


def school_year_start():
    """ Return first official day of current school year """
    current_year = date.today().year
    if date(current_year, 8, 1) > date.today():
        return date(current_year-1, 8, 1)
    else:
        return date(current_year, 8, 1)


class CorporationListView(ListView):
    model = Corporation
    template_name = 'corporations.html'


class CorporationView(DetailView):
    model = Corporation
    template_name = 'corporation.html'
    context_object_name = 'corp'

    def get_context_data(self, **kwargs):
        context = super(CorporationView, self).get_context_data(**kwargs)
        # Create a structure like:
        #   {'2011-2012': {'avails': [avail1, avail2, ...], 'stats': {'fil': num}},
        #    '2012-2013': ...}
        school_years = OrderedDict()
        for av in Availability.objects.filter(corporation=self.object
                ).select_related('training__student__klass', 'period__section'
                ).order_by('period__start_date'):
            if av.period.school_year not in school_years:
                school_years[av.period.school_year] = {'avails': [], 'stats': {}}
            school_years[av.period.school_year]['avails'].append(av)
            if av.period.section.name not in school_years[av.period.school_year]['stats']:
                school_years[av.period.school_year]['stats'][av.period.section.name] = 0
            try:
                av.training
                # Only add to stats if training exists
                school_years[av.period.school_year]['stats'][av.period.section.name] += av.period.weeks
            except Training.DoesNotExist:
                pass

        context['years'] = school_years
        return context


class KlassListView(ListView):
    queryset = Klass.objects.all().annotate(num_students=Count(Case(When(student__archived=False, then=1)))
                                 ).filter(num_students__gt=0).order_by('section', 'name')
    template_name = 'classes.html'


class KlassView(DetailView):
    model = Klass
    template_name = 'class.html'
    context_object_name = 'klass'

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        context['students'] = self.object.student_set.filter(archived=False
            ).prefetch_related('training_set').order_by('last_name', 'first_name')
        return context

    def render_to_response(self, context, **response_kwargs):
        if self.request.GET.get('format') != 'xls':
            return super().render_to_response(context, **response_kwargs)

        from openpyxl import Workbook
        from openpyxl.cell import get_column_letter
        from openpyxl.styles import Font, Style
        from openpyxl.writer.excel import save_virtual_workbook

        wb = Workbook()
        ws = wb.get_active_sheet()
        ws.title = self.object.name
        bold = Style(font=Font(bold=True))
        headers = [
            'Nom', 'Prénom', 'Domicile', 'Date de naissance',
            'Stage 1', 'Domaine 1', 'Stage 2', 'Domaine 2', 'Stage 3', 'Domaine 3',
        ]
        col_widths = [18, 15, 20, 14, 25, 12, 25, 12, 25, 12]
        # Headers
        for col_idx, header in enumerate(headers, start=1):
            cell = ws.cell(row=1, column=col_idx)
            cell.value = header
            cell.style = bold
            ws.column_dimensions[get_column_letter(col_idx)].width = col_widths[col_idx - 1]
        # Data
        for row_idx, student in enumerate(context['students'], start=2):
            ws.cell(row=row_idx, column=1).value = student.last_name
            ws.cell(row=row_idx, column=2).value = student.first_name
            ws.cell(row=row_idx, column=3).value = " ".join([student.pcode, student.city])
            ws.cell(row=row_idx, column=4).value = student.birth_date
            col_idx = 5
            for training in student.training_set.select_related(
                        'availability', 'availability__corporation', 'availability__domain'
                    ).all():
                ws.cell(row=row_idx, column=col_idx).value = training.availability.corporation.name
                ws.cell(row=row_idx, column=col_idx + 1).value = training.availability.domain.name
                col_idx += 2

        response = HttpResponse(
            save_virtual_workbook(wb),
            content_type='application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'
        )
        response['Content-Disposition'] = 'attachment; filename=%s_export_%s.xlsx' % (
              self.object.name.replace(' ', '_'), date.strftime(date.today(), '%Y-%m-%d'))
        return response


class AttributionView(TemplateView):
    """
    Base view for the attribution screen. Populate sections and referents.
    All other data are retrieved through AJAX requests:
      * training periods: section_period
      * corp. availabilities for current period: period_availabilities
      * already planned training for current period: TrainingsByPeriodView
      * student list targetted by current period: period_students
    When an availability is chosen:
      * corp. contact list: CorpContactJSONView
    When a student is chosen;
      * details of a student: StudentSummaryView
    """
    template_name = 'attribution.html'

    def get_context_data(self, **kwargs):
        context = super(AttributionView, self).get_context_data(**kwargs)
        # Need 2 queries, because referents with no training item would not appear in the second query
        referents = Referent.objects.filter(archived=False).order_by('last_name', 'first_name')

        # Populate each referent with the number of referencies done during the current school year
        ref_counts = dict([(ref.id, ref.num_refs)
                for ref in Referent.objects.filter(archived=False, training__availability__period__end_date__gte=school_year_start()
                ).annotate(num_refs=Count('training'))])
        for ref in referents:
            ref.num_refs = ref_counts.get(ref.id, 0)

        context.update({
            #'period_form': PeriodForm(),
            'sections': Section.objects.all(),
            'referents': referents,
        })
        return context


class StudentSummaryView(DetailView):
    model = Student
    template_name = 'student_summary.html'

    def get_context_data(self, **kwargs):
        context = super(StudentSummaryView, self).get_context_data(**kwargs)
        context['previous_stages'] = self.object.training_set.all(
            ).select_related('availability__corporation').order_by('availability__period__end_date')
        period_id = self.request.GET.get('period')
        if period_id:
            try:
                period = Period.objects.get(pk=int(period_id))
            except Period.DoesNotExist:
                pass
            else:
                context['age_for_stage'] = self.object.age_at(period.start_date)
                context['age_style'] = 'under_17' if (int(context['age_for_stage'].split()[0]) < 17) else ''
        return context


class AvailabilitySummaryView(DetailView):
    model = Availability
    template_name = 'availability_summary.html'


class TrainingsByPeriodView(ListView):
    template_name = 'trainings_list.html'
    context_object_name = 'trainings'

    def get_queryset(self):
        return Training.objects.select_related('student__klass', 'availability__corporation', 'availability__domain'
            ).filter(availability__period__pk=self.kwargs['pk']
            ).order_by('student__last_name', 'student__first_name')


class CorpContactJSONView(ListView):
    """ Return all contacts from a given corporation """
    return_fields = ['id', 'first_name', 'last_name', 'role', 'is_main']

    def get_queryset(self):
        return CorpContact.objects.filter(corporation__pk=self.kwargs['pk'], archived=False)

    def render_to_response(self, context):
        serialized = [dict([(field, getattr(obj, field)) for field in self.return_fields])
                      for obj in context['object_list']]
        return HttpResponse(json.dumps(serialized), content_type="application/json")

# AJAX views:

def section_periods(request, pk):
    """ Return all periods (until 2 years ago) from a section (JSON) """
    section = get_object_or_404(Section, pk=pk)
    two_years_ago = datetime.now() - timedelta(days=365 * 2)
    periods = [{'id': p.id, 'dates': p.dates, 'title': p.title}
               for p in section.period_set.filter(start_date__gt=two_years_ago).order_by('-start_date')]
    return HttpResponse(json.dumps(periods), content_type="application/json")

def section_classes(request, pk):
    section = get_object_or_404(Section, pk=pk)
    classes = [(k.id, k.name) for k in section.klass_set.all()]
    return HttpResponse(json.dumps(classes), content_type="application/json")


def period_students(request, pk):
    """
    Return all active students from period's section and level,
    with corresponding Training if existing (JSON)
    """
    period = get_object_or_404(Period, pk=pk)
    students = Student.objects.filter(
        archived=False, klass__section=period.section, klass__level=period.relative_level
        ).order_by('last_name')
    trainings = dict((t.student_id, t.id) for t in Training.objects.filter(availability__period=period))
    data = [{
        'name': str(s),
        'id': s.id,
        'training_id': trainings.get(s.id),
        'klass': s.klass.name} for s in students]
    return HttpResponse(json.dumps(data), content_type="application/json")

def period_availabilities(request, pk):
    """ Return all availabilities in the specified period """
    period = get_object_or_404(Period, pk=pk)
    # Sorting by the boolean priority is first with PostgreSQL, last with SQLite :-/
    corps = [{'id': av.id, 'id_corp': av.corporation.id, 'corp_name': av.corporation.name,
              'domain': av.domain.name, 'free': av.free, 'priority': av.priority}
             for av in period.availability_set.select_related('corporation').all(
                                             ).order_by('-priority', 'corporation__name')]
    return HttpResponse(json.dumps(corps), content_type="application/json")

def new_training(request):
    if request.method != 'POST':
        return HttpResponseNotAllowed()
    ref_key = request.POST.get('referent')
    cont_key = request.POST.get('contact')
    try:
        ref = Referent.objects.get(pk=ref_key) if ref_key else None
        contact = CorpContact.objects.get(pk=cont_key) if cont_key else None
        avail = Availability.objects.get(pk=request.POST.get('avail'))
        training = Training.objects.create(
            student=Student.objects.get(pk=request.POST.get('student')),
            availability=avail,
            referent=ref,
        )
        if avail.contact != contact:
            avail.contact = contact
            avail.save()
    except Exception as exc:
        return HttpResponse(str(exc))
    return HttpResponse(b'OK')

def del_training(request):
    """ Delete training and return the referent id """
    if request.method != 'POST':
        return HttpResponseNotAllowed()
    training = get_object_or_404(Training, pk=request.POST.get('pk'))
    ref_id = training.referent_id
    training.delete()
    return HttpResponse(json.dumps({'ref_id': ref_id}), content_type="application/json")


class StudentImportView(FormView):
    template_name = 'student_import.html'
    form_class = StudentImportForm

    def form_valid(self, form):
        try:
            imp_file = FileFactory(form.cleaned_data['upload'])
            created, modified = self.import_data(imp_file)
        except Exception as e:
            if settings.DEBUG:
                raise
            messages.error(self.request, _("The import failed. Error message: %s") % e)
        else:
            messages.info(self.request, _("Created objects: %(cr)d, modified objects: %(mod)d") % {
                'cr': created, 'mod': modified})
        return HttpResponseRedirect(reverse('admin:index'))

    def import_data(self, up_file):
        """ Import Student data from uploaded file. """
        mapping = settings.STUDENT_IMPORT_MAPPING
        rev_mapping = {v: k for k, v in mapping.items()}
        obj_created = obj_modified = 0
        for line in up_file:
            defaults = dict((val, line[key]) for key, val in mapping.items() if val != 'ext_id')
            defaults = Student.prepare_import(defaults)
            obj, created = Student.objects.get_or_create(
                ext_id=line[rev_mapping['ext_id']], defaults=defaults)
            if not created:
                for key, val in defaults.items():
                    setattr(obj, key, val)
                    obj.save()
                obj_modified += 1
            else:
                obj_created += 1
        #FIXME: implement arch_staled
        return obj_created, obj_modified


EXPORT_FIELDS = [
    ('Prénom', 'student__first_name'), ('Nom', 'student__last_name'),
    ('ID externe', 'student__ext_id'),
    ('Classe', 'student__klass__name'),
    ('Filière', 'student__klass__section__name'),
    ('Nom du stage', 'availability__period__title'),
    ('Début', 'availability__period__start_date'), ('Fin', 'availability__period__end_date'),
    ('Remarques stage', 'comment'),
    ('Prénom référent', 'referent__first_name'), ('Nom référent', 'referent__last_name'),
    ('Courriel référent', 'referent__email'),
    ('Institution', 'availability__corporation__name'),
    ('ID externe Inst', 'availability__corporation__ext_id'),
    ('Rue Inst', 'availability__corporation__street'),
    ('NPA Inst', 'availability__corporation__pcode'),
    ('Ville Inst', 'availability__corporation__city'),
    ('Tél Inst', 'availability__corporation__tel'),
    ('Domaine', 'availability__domain__name'),
    ('Remarques Inst', 'availability__comment'),
    ('Civilité contact', 'availability__contact__title'),
    ('Prénom contact', 'availability__contact__first_name'),
    ('Nom contact', 'availability__contact__last_name'),
    ('ID externe contact', 'availability__contact__ext_id'),
    ('Tél contact', 'availability__contact__tel'),
    ('Courriel contact', 'availability__contact__email'),
    ('Courriel contact - copie', None),
]

NON_ATTR_EXPORT_FIELDS = [
    ('Filière', 'period__section__name'),
    ('Nom du stage', 'period__title'),
    ('Début', 'period__start_date'), ('Fin', 'period__end_date'),
    ('Institution', 'corporation__name'),
    ('Rue Inst', 'corporation__street'),
    ('NPA Inst', 'corporation__pcode'),
    ('Ville Inst', 'corporation__city'),
    ('Tél Inst', 'corporation__tel'),
    ('Domaine', 'domain__name'),
    ('Remarques Inst', 'comment'),
    ('Civilité contact', 'contact__title'),
    ('Prénom contact', 'contact__first_name'),
    ('Nom contact', 'contact__last_name'),
    ('Tél contact', 'contact__tel'),
    ('Courriel contact', 'contact__email'),
    ('Courriel contact - copie', None),
]

def stages_export(request, scope=None):
    from openpyxl import Workbook
    from openpyxl.styles import Font, Style
    from openpyxl.writer.excel import save_virtual_workbook

    period_filter = request.GET.get('period')
    non_attributed = bool(int(request.GET.get('non_attr', 0)))

    export_fields = OrderedDict(EXPORT_FIELDS)
    contact_test_field = 'availability__contact__last_name'
    corp_name_field = 'availability__corporation__name'

    if period_filter:
        if non_attributed:
            # Export non attributed availabilities for a specific period
            query = Availability.objects.filter(period_id=period_filter, training__isnull=True)
            export_fields = OrderedDict(NON_ATTR_EXPORT_FIELDS)
            contact_test_field = 'contact__last_name'
            corp_name_field = 'corporation__name'
        else:
            # Export trainings for a specific period
            query = Training.objects.filter(availability__period_id=period_filter)
    else:
        if scope and scope == 'all':
            # Export all trainings in the database
            query = Training.objects.all()
        else:
            query = Training.objects.filter(availability__period__end_date__gt=school_year_start())

    # Prepare "default" contacts (when not defined on training)
    section_names = Section.objects.all().values_list('name', flat=True)
    default_contacts = dict(
        (c, {s: '' for s in section_names})
        for c in Corporation.objects.all().values_list('name', flat=True)
    )
    always_ccs = dict(
        (c, {s: [] for s in section_names})
        for c in Corporation.objects.all().values_list('name', flat=True)
    )
    for contact in CorpContact.objects.all().select_related('corporation'
            ).prefetch_related('sections').order_by('corporation'):
        for section in contact.sections.all():
            if not default_contacts[contact.corporation.name][section.name] or contact.is_main is True:
                default_contacts[contact.corporation.name][section.name] = contact
            if contact.always_cc:
                always_ccs[contact.corporation.name][section.name].append(contact)

    wb = Workbook()
    ws = wb.get_active_sheet()
    ws.title = 'Stages'
    bold = Style(font=Font(bold=True))
    # Headers
    for col_idx, header in enumerate(export_fields.keys(), start=1):
        cell = ws.cell(row=1, column=col_idx)
        cell.value = header
        cell.style = bold
    # Data
    query_keys = [f for f in export_fields.values() if f is not None]
    for row_idx, tr in enumerate(query.values(*query_keys), start=2):
        for col_idx, field in enumerate(query_keys, start=1):
            ws.cell(row=row_idx, column=col_idx).value = tr[field]
        if tr[contact_test_field] is None:
            # Use default contact
            contact = default_contacts.get(tr[corp_name_field], {}).get(tr[export_fields['Filière']])
            if contact:
                ws.cell(row=row_idx, column=col_idx-3).value = contact.title
                ws.cell(row=row_idx, column=col_idx-2).value = contact.first_name
                ws.cell(row=row_idx, column=col_idx-1).value = contact.last_name
                ws.cell(row=row_idx, column=col_idx).value = contact.email
        if always_ccs[tr[corp_name_field]].get(tr[export_fields['Filière']]):
            ws.cell(row=row_idx, column=col_idx+1).value = "; ".join(
                [c.email for c in always_ccs[tr[corp_name_field]].get(tr[export_fields['Filière']])]
            )

    response = HttpResponse(
        save_virtual_workbook(wb),
        content_type='application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'
    )
    response['Content-Disposition'] = 'attachment; filename=%s%s.xlsx' % (
          'stages_export_', date.strftime(date.today(), '%Y-%m-%d'))
    return response