import uuid
from enum import Enum

from django.db import models
from django.db.models import UniqueConstraint, Value
from django.db.models.functions import Replace
from django.utils.text import slugify
from django.utils.translation import gettext_lazy as _
from grapple.models import GraphQLString
from wagtail.models import Page

from vbv_lernwelt.core.model_utils import find_available_slug
from vbv_lernwelt.core.models import User
from vbv_lernwelt.course.serializer_helpers import get_course_serializer_class
from vbv_lernwelt.files.models import UploadFile


class CircleContactType(Enum):
    EXPERT = "EXPERT"
    LEARNING_MENTOR = "LEARNING_MENTOR"


class Course(models.Model):
    title = models.CharField(_("Titel"), max_length=255)
    category_name = models.CharField(
        _("Kategorie-Name"), max_length=255, default="Kategorie"
    )
    slug = models.SlugField(
        _("Slug"), max_length=255, unique=True, blank=True, allow_unicode=True
    )
    enable_circle_documents = models.BooleanField(
        _("Trainer Dokumente in Circles"), default=True
    )
    circle_contact_type = models.CharField(
        max_length=50,
        choices=[(cct.value, cct.value) for cct in CircleContactType],
        default=CircleContactType.EXPERT.value,
    )

    def get_course_url(self):
        return f"/course/{self.slug}"

    def get_cockpit_url(self):
        return f"/{self.get_course_url()}/cockpit"

    def get_learning_path(self):
        from vbv_lernwelt.learnpath.models import LearningPath

        return self.coursepage.get_children().exact_type(LearningPath).first().specific

    def get_action_competences(self):
        from vbv_lernwelt.competence.models import ActionCompetence

        return self.coursepage.get_descendants().exact_type(ActionCompetence).specific()

    def get_media_library_url(self):
        from vbv_lernwelt.media_library.models import MediaLibraryPage

        media_library_page = (
            self.coursepage.get_children().exact_type(MediaLibraryPage).first()
        )
        return media_library_page.specific.get_frontend_url()

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


class CourseCategory(models.Model):
    # Die Handlungsfelder im "Versicherungsvermittler/in"
    title = models.CharField(_("Titel"), max_length=255, blank=True)
    course = models.ForeignKey("course.Course", on_delete=models.CASCADE)
    general = models.BooleanField(_("Allgemein"), default=False)

    def __str__(self):
        return f"{self.course} / {self.title}"


class CourseBasePage(Page):
    class Meta:
        abstract = True

    serialize_field_names = []
    serialize_base_field_names = [
        "id",
        "title",
        "slug",
        "content_type",
        "translation_key",
        "frontend_url",
    ]

    graphql_fields = [
        GraphQLString(
            field_name="frontend_url",
            source="get_graphql_frontend_url",
        )
    ]

    def get_graphql_frontend_url(self, values):
        return self.get_frontend_url()

    def get_course_parent(self):
        return self.get_ancestors(inclusive=True).exact_type(CoursePage).last()

    def get_course(self):
        course_parent_page = self.get_course_parent()
        if course_parent_page:
            return course_parent_page.specific.course
        return None

    def get_circle(self):
        from vbv_lernwelt.learnpath.models import Circle

        try:
            return self.get_ancestors().exact_type(Circle).first()
        except Exception:
            # noop
            pass
        return None

    def get_circles(self):
        course_parent_page = self.get_course_parent()

        if course_parent_page:
            from vbv_lernwelt.learnpath.models import Circle, LearningPath

            circles = (
                course_parent_page.get_children()
                .exact_type(LearningPath)
                .first()
                .get_children()
                .exact_type(Circle)
            )
            return circles

        return None

    @classmethod
    def get_serializer_class(cls):
        return get_course_serializer_class(
            cls,
            field_names=cls.serialize_field_names,
            base_field_names=cls.serialize_base_field_names,
        )

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

    def _update_descendant_slugs(self, old_slug, new_slug):
        """
        this method is inspired by `_update_descendant_url_paths` from wagtail Page
        """
        Page.objects.filter(path__startswith=self.path).exclude(pk=self.pk).update(
            slug=Replace("slug", Value(old_slug), Value(new_slug))
        )

    def save(self, clean=True, user=None, log_action=False, **kwargs):
        slug_changed = False

        if not self.id is None:
            old_record = Page.objects.get(id=self.id).specific
            if old_record.slug != self.slug:
                self.set_url_path(self.get_parent())
                slug_changed = True
                old_slug = old_record.slug
                new_slug = self.slug

        super().save(**kwargs)

        if slug_changed:
            self._update_descendant_slugs(old_slug, new_slug)


class CoursePage(CourseBasePage):
    content_panels = Page.content_panels
    # subpage_types = [
    #     "learnpath.LearningPath",
    #     "competence.CompetenceProfilePage",
    #     "media_library.MediaLibraryPage",
    #     "assignment.AssignmentListPage",
    # ]
    course = models.OneToOneField("course.Course", on_delete=models.PROTECT)

    class Meta:
        verbose_name = _("Lehrgang-Seite")

    def save(self, *args, **kwargs):
        self.slug = find_available_slug(
            slugify(self.title, allow_unicode=True), ignore_page_id=self.id
        )
        super(CoursePage, self).save(*args, **kwargs)

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


class CourseCompletionStatus(Enum):
    SUCCESS = "SUCCESS"
    FAIL = "FAIL"
    UNKNOWN = "UNKNOWN"


class CourseCompletion(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)

    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    user = models.ForeignKey(User, on_delete=models.CASCADE)

    # page can logically be a LearningContent or a PerformanceCriteria for now
    page = models.ForeignKey(Page, on_delete=models.CASCADE)

    # store for convenience and performance...
    page_type = models.CharField(max_length=255, default="", blank=True)

    course_session = models.ForeignKey("course.CourseSession", on_delete=models.CASCADE)

    completion_status = models.CharField(
        max_length=255,
        choices=[(status, status.value) for status in CourseCompletionStatus],
        default=CourseCompletionStatus.UNKNOWN.value,
    )
    additional_json_data = models.JSONField(default=dict, blank=True)

    class Meta:
        constraints = [
            UniqueConstraint(
                fields=["user", "page", "course_session"],
                name="course_completion_unique_user_page_key",
            )
        ]


class CourseSession(models.Model):
    """
    Die Durchführung eines Kurses
    Benutzer die an eine CourseSession gehängt sind können diesen Lehrgang sehen
    Das anhängen kann via CourseSessionUser oder "Schulklasse (TODO)" geschehen
    """

    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    course = models.ForeignKey("course.Course", on_delete=models.CASCADE)
    title = models.TextField(unique=True)

    import_id = models.TextField(blank=True, default="")

    generation = models.TextField(blank=True, default="")
    region = models.TextField(blank=True, default="")
    group = models.TextField(blank=True, default="")

    start_date = models.DateField(null=True, blank=True)
    end_date = models.DateField(null=True, blank=True)

    additional_json_data = models.JSONField(default=dict, blank=True)

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

    class Meta:
        ordering = ["title"]


class CourseSessionUser(models.Model):
    """
    Ein Benutzer der an einer Durchführung teilnimmt
    """

    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)

    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    course_session = models.ForeignKey("course.CourseSession", on_delete=models.CASCADE)
    user = models.ForeignKey(User, on_delete=models.CASCADE)

    class Role(models.TextChoices):
        MEMBER = "MEMBER", _("Teilnehmer")
        EXPERT = "EXPERT", _("Experte/Trainer")

    role = models.CharField(choices=Role.choices, max_length=255, default=Role.MEMBER)

    expert = models.ManyToManyField(
        "learnpath.Circle", related_name="expert", blank=True
    )

    class Meta:
        constraints = [
            UniqueConstraint(
                fields=[
                    "course_session",
                    "user",
                ],
                name="course_session_user_unique_course_session_user",
            )
        ]
        ordering = ["user__last_name", "user__first_name", "user__email"]

    def __str__(self):
        return f"{self.user} ({self.course_session.title})"


class CircleDocument(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)

    created_at = models.DateTimeField(auto_now_add=True)
    file = models.OneToOneField(UploadFile, on_delete=models.CASCADE)
    name = models.CharField(max_length=100)

    course_session = models.ForeignKey("course.CourseSession", on_delete=models.CASCADE)
    learning_sequence = models.ForeignKey(
        "learnpath.LearningSequence", on_delete=models.CASCADE
    )

    def get_circle(self):
        return self.learning_sequence.get_circle()

    @property
    def url(self) -> str:
        return self.file.url

    @property
    def file_name(self) -> str:
        return self.file.original_file_name

    def delete(self, *args, **kwargs):
        self.file.upload_finished_at = None
        self.file.save()
        return super().delete(*args, **kwargs)