from django import forms
from django.db import models
from django.utils import timezone
from django.utils.translation import gettext as _
from wagtail.admin.forms import WagtailAdminPageForm
from wagtail.admin.panels import FieldPanel, TabbedInterface, ObjectList
from wagtail.fields import RichTextField

from core.constants import DEFAULT_RICH_TEXT_FEATURES
from core.wagtail_utils import StrictHierarchyPage, get_default_settings
from users.models import SchoolClass

EXACT = "exact"

FILTER_ATTRIBUTE_TYPE = (("all", "All"), (EXACT, "Exact"))


class ModuleLevel(models.Model):
    name = models.CharField(max_length=255, unique=True)
    filter_attribute_type = models.CharField(
        max_length=16, choices=FILTER_ATTRIBUTE_TYPE, default=EXACT
    )
    order = models.PositiveIntegerField(
        null=False, blank=False, default=99, help_text="Order in the Dropdown List"
    )

    class Meta:
        verbose_name_plural = _("module Levels")
        verbose_name = _("module level")
        ordering = ("order", "name")

    def __str__(self):
        return self.name


class ModuleCategory(models.Model):
    name = models.CharField(max_length=255)
    filter_attribute_type = models.CharField(
        max_length=16, choices=FILTER_ATTRIBUTE_TYPE, default=EXACT
    )
    order = models.PositiveIntegerField(
        null=False, blank=False, default=99, help_text="Order in the Dropdown List"
    )

    class Meta:
        verbose_name = _("module type")
        verbose_name_plural = _("module types")
        ordering = ("order", "name")

    def __str__(self):
        return f"{self.name}"


class ModulePageForm(WagtailAdminPageForm):
    def clean(self):
        cleaned_data = super().clean()
        if "slug" in self.cleaned_data:
            page_slug = cleaned_data["slug"]
            if not Module._slug_is_available(page_slug, self.instance):
                self.add_error(
                    "slug",
                    forms.ValidationError(
                        _("The slug '%(page_slug)s' is already in use")
                        % {"page_slug": page_slug}
                    ),
                )
        return cleaned_data


class Module(StrictHierarchyPage):
    class Meta:
        verbose_name = "Modul"
        verbose_name_plural = "Module"

    meta_title = models.CharField(max_length=255, help_text="e.g. 'Intro' or 'Modul 1'")
    level = models.ForeignKey(
        ModuleLevel, on_delete=models.SET_NULL, blank=True, null=True
    )
    category = models.ForeignKey(
        ModuleCategory, on_delete=models.SET_NULL, blank=True, null=True
    )

    hero_image = models.ForeignKey(
        "wagtailimages.Image",
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name="+",
    )
    hero_source = models.CharField(
        max_length=255, help_text="e.g. 'Reuters', 'Wikipedia'", blank=True
    )

    teaser = models.TextField()
    intro = RichTextField(features=DEFAULT_RICH_TEXT_FEATURES)

    solutions_enabled_for = models.ManyToManyField(SchoolClass)

    content_panels = [
        FieldPanel("title", classname="full title"),
        FieldPanel("meta_title", classname="full title"),
        FieldPanel("level"),
        FieldPanel("category"),
        FieldPanel("hero_image"),
        FieldPanel("hero_source"),
        FieldPanel("teaser"),
        FieldPanel("intro"),
    ]
    base_form_class = ModulePageForm

    edit_handler = TabbedInterface(
        [ObjectList(content_panels, heading="Content"), get_default_settings()]
    )

    template = "generic_page.html"

    parent_page_types = ["books.Topic"]
    subpage_types = ["books.Chapter"]

    def is_translated(self) -> bool:
        return self.get_translations().count() > 0

    # todo: isn't this a duplicate definition?
    def get_child_ids(self):
        return self.get_children().values_list("id", flat=True)

    @property
    def route(self):
        return f"module/{self.slug}"

    def sync_from_school_class(self, school_class_template, school_class_to_sync):
        # import here so we don't get a circular import error
        from books.models import Chapter, ContentBlock

        # get chapters of module
        chapters = Chapter.get_by_parent(self)
        content_block_query = ContentBlock.objects.none()

        # get content blocks of chapters
        for chapter in chapters:
            content_block_query = content_block_query.union(
                ContentBlock.get_by_parent(chapter)
            )

        # clear all `hidden for` and `visible for` for class `school_class_to_sync`
        for content_block in school_class_to_sync.hidden_content_blocks.intersection(
            content_block_query
        ):
            content_block.hidden_for.remove(school_class_to_sync)
        for content_block in school_class_to_sync.visible_content_blocks.intersection(
            content_block_query
        ):
            content_block.visible_for.remove(school_class_to_sync)

        # get all content blocks with `hidden for`  for class `school_class_pattern`
        for content_block in school_class_template.hidden_content_blocks.intersection(
            content_block_query
        ):
            # add `school_class_to_sync` to these blocks' `hidden for`
            content_block.hidden_for.add(school_class_to_sync)

        # get all content blocks with `visible for` for class `school_class_pattern`
        for content_block in school_class_template.visible_content_blocks.intersection(
            content_block_query
        ):
            # add `school_class_to_sync` to these blocks' `visible for`
            content_block.visible_for.add(school_class_to_sync)

        for chapter in chapters:
            chapter.sync_title_visibility(school_class_template, school_class_to_sync)
            chapter.sync_description_visibility(
                school_class_template, school_class_to_sync
            )

        objective_groups = self.objective_groups.all()

        for objective_group in objective_groups:
            objective_group.sync_visibility(school_class_template, school_class_to_sync)

    def get_admin_display_title(self):
        return f"{self.meta_title} - {self.title}"

    @staticmethod
    def _slug_is_available(slug, page):
        # modeled after `Page._slug_is_available`
        modules = Module.objects.filter(slug=slug).not_page(page)

        return not modules.exists()


class RecentModule(models.Model):
    module = models.ForeignKey(
        Module, on_delete=models.CASCADE, related_name="recent_modules"
    )
    user = models.ForeignKey("users.User", on_delete=models.CASCADE)
    visited = models.DateTimeField(default=timezone.now)

    class Meta:
        get_latest_by = "visited"