from typing import final

from tortoise import Model, fields


@final
class Teilchen(Model):
    name = fields.TextField()
    description = fields.TextField()
    number = fields.IntField()  # validate values >= 0

    created_at = fields.DatetimeField(auto_now_add=True)
    modified_at = fields.DatetimeField(auto_now=True)

    tags = fields.ManyToManyField(
        "models.Tag",
        through="models.TeilchenTag",
        related_name="teilchen",
        forward_key="tag_id",
        backward_key="teilchen_id",
    )


@final
class Tag(Model):
    name = fields.CharField(max_length=20)

    created_at = fields.DatetimeField(auto_now_add=True)
    modified_at = fields.DatetimeField(auto_now=True)


@final
class TeilchenTag(Model):
    teilchen: fields.ForeignKeyRelation[Teilchen] = fields.ForeignKeyField(
        "models.Teilchen"
    )
    tag: fields.ForeignKeyRelation[Tag] = fields.ForeignKeyField("models.Tag")
    weight = fields.IntField()