from django.db import models
from django.contrib.contenttypes.models import ContentType
from django.contrib.contenttypes import fields

from tinymce import models as tinymce

from ram.models import Document
from metadata.models import Decoder, Tag
from roster.models import RollingStock
from bookshelf.models import BaseBook


class GenericDocument(Document):
    notes = tinymce.HTMLField(blank=True)
    tags = models.ManyToManyField(Tag, blank=True, related_name="document")

    class Meta:
        verbose_name_plural = "Generic Documents"


class InvoiceDocument(Document):
    content_type = models.ForeignKey(ContentType)
    object_id = models.PositiveIntegerField()
    content_object = fields.GenericForeignKey("content_type", "object_id")


class DecoderDocument(Document):
    decoder = models.ForeignKey(
        Decoder, on_delete=models.CASCADE, related_name="document"
    )

    class Meta:
        constraints = [
            models.UniqueConstraint(
                fields=["decoder", "file"],
                name="unique_decoder_file"
            )
        ]


class BaseBookDocument(Document):
    book = models.ForeignKey(
        BaseBook, on_delete=models.CASCADE, related_name="document"
    )

    class Meta:
        verbose_name_plural = "Documents"
        constraints = [
            models.UniqueConstraint(
                fields=["book", "file"],
                name="unique_book_file"
            )
        ]


class RollingStockDocument(Document):
    rolling_stock = models.ForeignKey(
        RollingStock, on_delete=models.CASCADE, related_name="document"
    )

    class Meta:
        constraints = [
            models.UniqueConstraint(
                fields=["rolling_stock", "file"],
                name="unique_stock_file"
            )
        ]