from django.core.exceptions import ValidationError
from django.db import models

from wagtail.wagtailadmin.edit_handlers import (
    FieldPanel,
    MultiFieldPanel,
    PageChooserPanel
)
from wagtail.wagtailcore.fields import RichTextField
from wagtail.wagtailcore.models import Orderable
from wagtail.wagtaildocs.edit_handlers import DocumentChooserPanel
from wagtail.wagtailimages.edit_handlers import ImageChooserPanel
from wagtail.wagtailsnippets.models import register_snippet
from wagtail.contrib.settings.models import BaseSetting, register_setting


class LinkFields(models.Model):
    """
    Adds fields for internal and external links with some methods to simplify the rendering:

    <a href="{{ obj.get_link_url }}">{{ obj.get_link_text }}</a>
    """

    link_page = models.ForeignKey(
        'wagtailcore.Page',
        blank=True,
        null=True,
        on_delete=models.SET_NULL
    )
    link_url = models.URLField(blank=True)
    link_text = models.CharField(blank=True, max_length=255)

    class Meta:
        abstract = True

    def clean(self):
        if not self.link_page and not self.link_url:
            raise ValidationError({
                'link_url': ValidationError("You must specify link page or link url."),
                'link_page': ValidationError("You must specify link page or link url."),
            })

        if self.link_page and self.link_url:
            raise ValidationError({
                'link_url': ValidationError("You must specify link page or link url. You can't use both."),
                'link_page': ValidationError("You must specify link page or link url. You can't use both."),
            })

        if not self.link_page and not self.link_text:
            raise ValidationError({
                'link_text': ValidationError("You must specify link text, if you use the link url field."),
            })

    def get_link_text(self):
        if self.link_text:
            return self.link_text

        if self.link_page:
            return self.link_page.title

        return ''

    def get_link_url(self):
        if self.link_page:
            return self.link_page.get_url

        return self.link_url

    panels = [
        MultiFieldPanel([
            PageChooserPanel('link_page'),
            FieldPanel('link_url'),
            FieldPanel('link_text'),
        ], 'Link'),
    ]


# Related pages
class RelatedPage(Orderable, models.Model):
    page = models.ForeignKey('wagtailcore.Page', null=True, blank=True, on_delete=models.SET_NULL, related_name='+')

    class Meta:
        abstract = True
        ordering = ['sort_order']

    panels = [
        PageChooserPanel('page'),
    ]


# Related documents
class RelatedDocument(Orderable, models.Model):
    title = models.CharField(max_length=255, help_text="Document name")
    document = models.ForeignKey('wagtaildocs.Document', null=True, blank=True, on_delete=models.SET_NULL, related_name='+', help_text="Please upload related documents")

    class Meta:
        abstract = True
        ordering = ['sort_order']

    panels = [
        FieldPanel('title'),
        DocumentChooserPanel('document'),
    ]


# Generic social fields abstract class to add social image/text to any new content type easily.
class SocialFields(models.Model):
    social_image = models.ForeignKey('images.CustomImage', null=True, blank=True, on_delete=models.SET_NULL, related_name='+')
    social_text = models.CharField(max_length=255, blank=True)

    class Meta:
        abstract = True

    promote_panels = [
        MultiFieldPanel([
            ImageChooserPanel('social_image'),
            FieldPanel('social_text'),
        ], 'Social networks'),
    ]


# Generic listing fields abstract class to add listing image/text to any new content type easily.
class ListingFields(models.Model):
    listing_image = models.ForeignKey(
        'images.CustomImage',
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name='+',
        help_text="Choose the image you wish to be displayed when this page appears in listings"
    )
    listing_title = models.CharField(max_length=255, blank=True, help_text="Override the page title used when this page appears in listings")
    listing_summary = models.CharField(max_length=255, blank=True, help_text="The text summary used when this page appears in listings. It's also used as the description for search engines if the 'Search description' field above is not defined.")

    class Meta:
        abstract = True

    promote_panels = [
        MultiFieldPanel([
            ImageChooserPanel('listing_image'),
            FieldPanel('listing_title'),
            FieldPanel('listing_summary'),
        ], 'Listing information'),
    ]


@register_snippet
class CallToActionSnippet(LinkFields):
    title = models.CharField(max_length=255)
    summary = RichTextField(blank=True, max_length=255)
    image = models.ForeignKey('images.CustomImage', null=True, blank=True, on_delete=models.SET_NULL, related_name='+')

    panels = [
        FieldPanel('title'),
        FieldPanel('summary'),
    ] + LinkFields.panels + [
        ImageChooserPanel('image'),
    ]

    def __str__(self):
        return self.title


@register_setting
class SocialMediaSettings(BaseSetting):
    twitter_handle = models.CharField(
        max_length=255,
        blank=True,
        help_text='Your Twitter username without the @, e.g. katyperry',
    )
    facebook_app_id = models.CharField(
        max_length=255,
        blank=True,
        help_text='Your Facebook app ID.',
    )
    default_sharing_text = models.CharField(
        max_length=255,
        blank=True,
        help_text='Default sharing text to use if social text has not been set on a page.',
    )
    site_name = models.CharField(
        max_length=255,
        blank=True,
        default='opentech.fund',
        help_text='Site name, used by Open Graph.',
    )


@register_setting
class SystemMessagesSettings(BaseSetting):
    class Meta:
        verbose_name = 'system messages'

    title_404 = models.CharField(
        "Title",
        max_length=255,
        default='Page not found',
    )
    body_404 = RichTextField(
        "Text",
        default='<p>You may be trying to find a page that doesn&rsquo;t exist or has been moved.</p>'
    )

    panels = [
        MultiFieldPanel([
            FieldPanel('title_404'),
            FieldPanel('body_404'),
        ], '404 page'),
    ]