from django.contrib import admin
from django.contrib.gis import admin as geo_admin
from django.db import models
from django.db.models import Q
from django.forms import ModelForm, BaseInlineFormSet
from django.utils import timezone
from django.core.urlresolvers import reverse
from django.utils.html import format_html
from django.core.mail import mail_managers

from adhesions.models import Adhesion
from .models import Service, ServiceType, IPResource, Route, ServiceAllocation, Antenna, AntennaAllocation, Allocation
from .utils import notify_allocation


### Filters

class ResourceInUseFilter(admin.SimpleListFilter):
    title = 'disponibilité'
    parameter_name = 'available'

    def lookups(self, request, model_admin):
        return (
            (1, 'Disponible'),
            (0, 'Non disponible'),
        )

    def queryset(self, request, queryset):
        available_filter = Q(reserved=False, in_use=False)
        if self.value() == '0': # non disponible
            return queryset.exclude(available_filter)
        if self.value() == '1': # disponible
            return queryset.filter(available_filter)


### Inlines

class AllocationInlineFormSet(BaseInlineFormSet):
    def save_new(self, form, commit=True):
        obj = super().save_new(form, commit)
        if type(obj) == ServiceAllocation:
            notify_allocation(self.request, obj)
        return obj

    def save_existing(self, form, instance, commit=True):
        old = type(instance).objects.get(pk=instance.pk)
        if type(instance) == ServiceAllocation:
            notify_allocation(self.request, instance, old)
        return super().save_existing(form, instance, commit)


class AllocationInline(admin.TabularInline):
    formset = AllocationInlineFormSet
    extra = 0
    verbose_name_plural = 'Allocations'
    show_change_link = True

    def get_formset(self, request, obj=None, **kwargs):
        formset = super().get_formset(request, obj, **kwargs)
        formset.request = request
        return formset

    def get_max_num(self, request, obj=None, **kwargs):
        existing = obj.allocations.count() if obj else 0
        # pour simplifier la validation, on ajoute qu’une allocation à la fois
        # il faudrait surcharger la méthode clean du formset pour supprimer cette limite
        return existing + 1

    def has_delete_permission(self, request, obj=None):
        return False


class ServiceAllocationInline(AllocationInline):
    model = ServiceAllocation
    fields = ('id', 'service', 'resource', 'route', 'start', 'end')
    raw_id_fields = ('service', 'resource',)


class AntennaAllocationInline(AllocationInline):
    model = AntennaAllocation
    fields = ('id', 'antenna', 'resource', 'start', 'end')
    raw_id_fields = ('antenna', 'resource',)


### Actions

def ends_resource(resource, request, queryset):
    now = timezone.now()
    queryset.exclude(start__lte=now, end__isnull=False).update(end=now)
    # TODO: send mail
ends_resource.short_description = 'Terminer les allocations sélectionnées'


### ModelAdmin

class ServiceAdmin(admin.ModelAdmin):
    list_display = ('id', 'get_adhesion_link', 'get_adherent_link', 'service_type', 'label', 'active')
    list_select_related = ('adhesion',) # to reduce database requests
    list_filter = (
        'active',
        ('service_type', admin.RelatedOnlyFieldListFilter),
    )
    inlines = (ServiceAllocationInline,)
    search_fields = ('id', 'service_type__name', 'label', 'adhesion__id',)
    raw_id_fields = ('adhesion',)

    get_adhesion_link = lambda self, service: service.adhesion.get_adhesion_link()
    get_adhesion_link.short_description = Adhesion.get_adhesion_link.short_description

    get_adherent_link = lambda self, service: service.adhesion.get_adherent_link()
    get_adherent_link.short_description = Adhesion.get_adherent_link.short_description

    def get_actions(self, request):
        actions = super().get_actions(request)
        if 'delete_selected' in actions:
            del actions['delete_selected']
        return actions

    def has_delete_permission(self, request, obj=None):
        return False


class IPResourceAdmin(admin.ModelAdmin):
    list_display = ('__str__', 'available_display', 'last_use',)
    list_filter = (
        'category',
        ResourceInUseFilter,
        ('prefixes', admin.RelatedOnlyFieldListFilter),
    )
    fields = ('ip', 'reserved', 'notes')
    readonly_fields = ('ip', 'reserved',)
    search_fields = ('ip',)

    def get_inline_instances(self, request, obj=None):
        if obj:
            if obj.category == 0:
                inlines = (ServiceAllocationInline,)
            elif obj.category == 1:
                inlines = (AntennaAllocationInline,)
        else:
            inlines = ()
        return [inline(self.model, self.admin_site) for inline in inlines]

    def get_queryset(self, request):
        qs = super().get_queryset(request)
        qs = qs.annotate(last_use=models.Case(
                    models.When(category=0, then=models.Max('service_allocation__end')),
                    models.When(category=1, then=models.Max('antenna_allocation__end')),
                ))
        return qs

    def available_display(self, obj):
        return not obj.reserved and not obj.in_use
    available_display.short_description = 'Disponible'
    available_display.boolean = True

    def last_use(self, obj):
        if obj.allocations.exists():
            return obj.allocations.last().end
        else:
            return None
    last_use.short_description = 'Dernière utilisation'
    last_use.admin_order_field = 'last_use'

    def get_actions(self, request):
        actions = super().get_actions(request)
        if 'delete_selected' in actions:
            del actions['delete_selected']
        return actions

    def has_add_permission(self, request, obj=None):
        return False

    def has_delete_permission(self, request, obj=None):
        return False


class RouteAdmin(admin.ModelAdmin):
    fields = ('name',)
    readonly_fields = ('name',)

    def has_add_permission(self, request, obj=None):
        return False

    def get_actions(self, request):
        actions = super().get_actions(request)
        if 'delete_selected' in actions:
            del actions['delete_selected']
        return actions

    def has_delete_permission(self, request, obj=None):
        return False


class ServiceTypeAdmin(admin.ModelAdmin):
    fields = ('name',)
    readonly_fields = ('name',)

    def get_actions(self, request):
        actions = super().get_actions(request)
        if 'delete_selected' in actions:
            del actions['delete_selected']
        return actions

    def has_add_permission(self, request, obj=None):
        return False

    def has_delete_permission(self, request, obj=None):
        return False


class AntennaAdmin(geo_admin.OSMGeoAdmin):
    inlines = (AntennaAllocationInline,)


admin.site.register(ServiceType, ServiceTypeAdmin)
admin.site.register(Service, ServiceAdmin)
admin.site.register(IPResource, IPResourceAdmin)
admin.site.register(Route, RouteAdmin)
geo_admin.site.register(Antenna, AntennaAdmin)