import datetime

from django.conf import settings
from django.contrib import admin
from django.utils import timezone, formats
import django.utils.html
import django.forms.models

from qrurls.models import URL, URLItem, URLImage

class URLItemFormset (django.forms.models.BaseInlineFormSet) :
    """
        Uses the existing URLItems for the URLFeed to determine the initial publishing
        times for new items.
    """

    def __init__ (self, *args, **kwargs) :
        urlfeed = kwargs.get('instance')

        publishing_date = None
        publishing_time = datetime.time()
        
        # hack to get at the URLFeed to determine our initial values..
        if urlfeed and isinstance(urlfeed, URL) :
            publishing_date = urlfeed.last_item().published.date()
            publishing_time = urlfeed.publishing_time
        
        def publishing_schedule (count) :
            if not publishing_date :
                # starting today
                start_date = datetime.date.today()
                offset = 0
            else :
                # starting from the following day
                start_date = publishing_date
                offset = 1

            for days in xrange(offset, count + offset) :
                yield datetime.datetime.combine(
                        start_date + datetime.timedelta(days=days),
                        publishing_time
                )

        kwargs.update(initial=[
                dict(published=publish) for publish in publishing_schedule(count=5)
        ])
        super(URLItemFormset, self).__init__(*args, **kwargs)

class URLItemInline (admin.TabularInline) :
    """
        Inline set of URLItems for an URLFeed.
    """

    model = URLItem
    formset = URLItemFormset

class URLAdmin (admin.ModelAdmin) :
    def timezone (self, obj) :
        now = timezone.localtime(obj.now())
        tz = now.tzinfo
        td = now.tzinfo.utcoffset(now)

        if td :
            minutes, seconds = divmod(td.total_seconds(), 60)
            hours, minutes = divmod(minutes, 60)
            offset = "(UTC%+03d:%02d)" % (hours, minutes)
        else :
            offset = ""

        return u"%s %s" % (tz, offset)

    def qrcode_url (self, obj) :
        warn = None

        if obj.shorturl.upper() != obj.shorturl :
            warn = "Shorturl should be UPPERCASE for most compact QR code"

        return '<a href="{url}">{url}</a>{warn}'.format(
                url     = django.utils.html.escape(obj.qrcode_url()),
                warn    = '<p class="errornote">{warn}</p>'.format(warn=warn) if warn else '',
        )
    qrcode_url.allow_tags = True

    def qrcode_img (self, obj) :
        return '<img src="{img}" />'.format(
                img=django.utils.html.escape(obj.qrcode_img()),
        )
    qrcode_img.allow_tags = True
    
    # XXX: a whole bunch of ugly datetime-formatting for display...
    def active (self, obj) :
        item = obj.active_item()
        if item :
            return "%s %s" % (formats.localize(timezone.localtime(item.published)), item)
        else :
            return ""

    def now (self, obj) :
        return formats.localize(timezone.localtime(obj.now()))

    def upcoming (self, obj) :
        item = obj.upcoming_item()
        if item :
            return "%s %s" % (formats.localize(timezone.localtime(item.published)), item)
        else :
            return ""

    readonly_fields = (
        'timezone',
        'qrcode_url',
        'qrcode_img',
        'active_item',
        'upcoming_item',
        'active',
        'now',
        'upcoming',
    )
    list_display = (
        'get_absolute_url',
        'active_item',
        'upcoming_item',
    )
    fieldsets = (
        (None, {
            'fields': (
                'shorturl', 
                'publishing_time', 
                'timezone',
            ),
        }),
        ("QRCode", {
            'fields': ('qrcode_url', 'qrcode_img'),
        }),
        ("Item publishing overview", {
            'fields': (
                'active',
                'now',
                'upcoming',
            ),
        }),
    )
    inlines = (URLItemInline, )

class URLItemAdmin (admin.ModelAdmin) :
    list_display = (
        'shorturl', 'published_state', 'get_absolute_url', 'image', 'published',
    )
    readonly_fields = ('published_state', 'published')
    fieldsets = (
        ("Publishing", {
            'fields': ('shorturl', 'published', ),
        }),
        ("Target", {
            'fields': ('url', 'image'),
        }),
    )

class URLImageAdmin (admin.ModelAdmin) :
    list_display = (
        'title',
        'uploaded',
    )
    # hide the "uploaded" field
    fields = (
        'image',
        'title',
    )
    readonly_fields = (
        'uploaded',
    )
    
    inlines = (URLItemInline, )

admin.site.register(URL, URLAdmin)
admin.site.register(URLItem, URLItemAdmin)
admin.site.register(URLImage, URLImageAdmin)