import uuid

from django.contrib.auth.models import User
from django.core.exceptions import ValidationError
from django.db import models

from .managers import (
    CategoryManager,
    LabelManager,
    RelationManager,
    SpanManager,
    TextLabelManager,
)
from examples.models import Example
from label_types.models import CategoryType, RelationType, SpanType


class Label(models.Model):
    objects = LabelManager()

    uuid = models.UUIDField(default=uuid.uuid4, unique=True)
    prob = models.FloatField(default=0.0)
    manual = models.BooleanField(default=False)
    user = models.ForeignKey(User, on_delete=models.CASCADE)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        abstract = True


class Category(Label):
    objects = CategoryManager()
    example = models.ForeignKey(to=Example, on_delete=models.CASCADE, related_name="categories")
    label = models.ForeignKey(to=CategoryType, on_delete=models.CASCADE)

    class Meta:
        unique_together = ("example", "user", "label")


class Span(Label):
    objects = SpanManager()
    example = models.ForeignKey(to=Example, on_delete=models.CASCADE, related_name="spans")
    label = models.ForeignKey(to=SpanType, on_delete=models.CASCADE)
    start_offset = models.IntegerField()
    end_offset = models.IntegerField()

    def __str__(self):
        text = self.example.text[self.start_offset:self.end_offset]
        return f"({text}, {self.start_offset}, {self.end_offset}, {self.label.text})"

    def validate_unique(self, exclude=None):
        allow_overlapping = getattr(self.example.project, "allow_overlapping", False)
        is_collaborative = self.example.project.collaborative_annotation
        if allow_overlapping:
            super().validate_unique(exclude=exclude)
            return

        overlapping_span = (
            Span.objects.exclude(id=self.id)
            .filter(example=self.example)
            .filter(
                models.Q(start_offset__gte=self.start_offset, start_offset__lt=self.end_offset)
                | models.Q(end_offset__gt=self.start_offset, end_offset__lte=self.end_offset)
                | models.Q(start_offset__lte=self.start_offset, end_offset__gte=self.end_offset)
            )
        )
        if is_collaborative:
            if overlapping_span.exists():
                raise ValidationError("This overlapping is not allowed in this project.")
        else:
            if overlapping_span.filter(user=self.user).exists():
                raise ValidationError("This overlapping is not allowed in this project.")

    def save(self, force_insert=False, force_update=False, using=None, update_fields=None):
        self.full_clean()
        super().save(force_insert, force_update, using, update_fields)

    def is_overlapping(self, other: "Span"):
        return (
            (other.start_offset <= self.start_offset < other.end_offset)
            or (other.start_offset < self.end_offset <= other.end_offset)
            or (self.start_offset < other.start_offset and other.end_offset < self.end_offset)
        )

    class Meta:
        constraints = [
            models.CheckConstraint(check=models.Q(start_offset__gte=0), name="startOffset >= 0"),
            models.CheckConstraint(check=models.Q(end_offset__gte=0), name="endOffset >= 0"),
            models.CheckConstraint(check=models.Q(start_offset__lt=models.F("end_offset")), name="start < end"),
        ]


class TextLabel(Label):
    objects = TextLabelManager()
    example = models.ForeignKey(to=Example, on_delete=models.CASCADE, related_name="texts")
    text = models.TextField()

    def is_same_text(self, other: "TextLabel"):
        return self.text == other.text

    class Meta:
        unique_together = ("example", "user", "text")


class Relation(Label):
    objects = RelationManager()
    from_id = models.ForeignKey(Span, on_delete=models.CASCADE, related_name="from_relations")
    to_id = models.ForeignKey(Span, on_delete=models.CASCADE, related_name="to_relations")
    type = models.ForeignKey(RelationType, on_delete=models.CASCADE)
    example = models.ForeignKey(to=Example, on_delete=models.CASCADE, related_name="relations")

    def __str__(self):
        text = self.example.text
        from_span = text[self.from_id.start_offset: self.from_id.end_offset]
        to_span = text[self.to_id.start_offset: self.to_id.end_offset]
        type_text = self.type.text
        return f"{from_span} - ({type_text}) -> {to_span}"

    def save(self, force_insert=False, force_update=False, using=None, update_fields=None):
        self.full_clean()
        super().save(force_insert, force_update, using, update_fields)

    def clean(self):
        same_example = self.from_id.example == self.to_id.example == self.example
        if not same_example:
            raise ValidationError("You need to label the same example.")
        return super().clean()