from django import forms
from django.db import models
from django.contrib import admin
from django.conf import settings
from django.forms.widgets import TextInput
from django.utils.text import Truncator
from django.utils.translation import ugettext_lazy as _

from .fields import CommaSeparatedEmailField
from .models import Attachment, Log, Email, EmailTemplate, STATUS


def get_message_preview(instance):
    return ('{0}...'.format(instance.message[:25]) if len(instance.message) > 25
            else instance.message)

get_message_preview.short_description = 'Message'


class AttachmentInline(admin.StackedInline):
    model = Attachment.emails.through
    extra = 0


class LogInline(admin.StackedInline):
    model = Log
    extra = 0


class CommaSeparatedEmailWidget(TextInput):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.attrs.update({'class': 'vTextField'})

    def format_value(self, value):
        # If the value is a string wrap it in a list so it does not get sliced.
        if not value:
            return ''
        if isinstance(value, str):
            value = [value, ]
        return ','.join([item for item in value])


def requeue(modeladmin, request, queryset):
    """An admin action to requeue emails."""
    queryset.update(status=STATUS.queued)


requeue.short_description = 'Requeue selected emails'


class EmailAdmin(admin.ModelAdmin):
    list_display = ('id', 'to_display', 'subject', 'template',
                    'status', 'last_updated')
    search_fields = ['to', 'subject']
    date_hierarchy = 'last_updated'
    inlines = [AttachmentInline, LogInline]
    list_filter = ['status', 'template__language', 'template__name']
    formfield_overrides = {
        CommaSeparatedEmailField: {'widget': CommaSeparatedEmailWidget}
    }
    actions = [requeue]

    def get_queryset(self, request):
        return super().get_queryset(request).select_related('template')

    def to_display(self, instance):
        return ', '.join(instance.to)

    to_display.short_description = 'to'
    to_display.admin_order_field = 'to'


class LogAdmin(admin.ModelAdmin):
    list_display = ('date', 'email', 'status', get_message_preview)


class SubjectField(TextInput):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.attrs.update({'style': 'width: 610px;'})


class EmailTemplateAdminForm(forms.ModelForm):

    language = forms.ChoiceField(choices=settings.LANGUAGES, required=False,
                                 help_text=_("Render template in alternative language"),
                                 label=_("Language"))

    class Meta:
        model = EmailTemplate
        fields = ('name', 'description', 'subject',
                  'content', 'html_content', 'language', 'default_template')


class EmailTemplateInline(admin.StackedInline):
    form = EmailTemplateAdminForm
    model = EmailTemplate
    extra = 0
    fields = ('language', 'subject', 'content', 'html_content',)
    formfield_overrides = {
        models.CharField: {'widget': SubjectField}
    }

    def get_max_num(self, request, obj=None, **kwargs):
        return len(settings.LANGUAGES)


class EmailTemplateAdmin(admin.ModelAdmin):
    form = EmailTemplateAdminForm
    list_display = ('name', 'description_shortened', 'subject', 'languages_compact', 'created')
    search_fields = ('name', 'description', 'subject')
    fieldsets = [
        (None, {
            'fields': ('name', 'description'),
        }),
        (_("Default Content"), {
            'fields': ('subject', 'content', 'html_content'),
        }),
    ]
    inlines = (EmailTemplateInline,) if settings.USE_I18N else ()
    formfield_overrides = {
        models.CharField: {'widget': SubjectField}
    }

    def get_queryset(self, request):
        return self.model.objects.filter(default_template__isnull=True)

    def description_shortened(self, instance):
        return Truncator(instance.description.split('\n')[0]).chars(200)
    description_shortened.short_description = _("Description")
    description_shortened.admin_order_field = 'description'

    def languages_compact(self, instance):
        languages = [tt.language for tt in instance.translated_templates.order_by('language')]
        return ', '.join(languages)
    languages_compact.short_description = _("Languages")

    def save_model(self, request, obj, form, change):
        obj.save()

        # if the name got changed, also change the translated templates to match again
        if 'name' in form.changed_data:
            obj.translated_templates.update(name=obj.name)


class AttachmentAdmin(admin.ModelAdmin):
    list_display = ('name', 'file', )


admin.site.register(Email, EmailAdmin)
admin.site.register(Log, LogAdmin)
admin.site.register(EmailTemplate, EmailTemplateAdmin)
admin.site.register(Attachment, AttachmentAdmin)