import django.contrib.auth.models as amodels
from django.conf import settings
from django.db import models


class ModelWithPerms(models.Model):
    users_read = models.ManyToManyField(
        amodels.User,
        related_name="%(class)s_read"
    )
    users_write = models.ManyToManyField(
        amodels.User,
        related_name="%(class)s_write"
    )
    groups_read = models.ManyToManyField(
        amodels.Group,
        related_name="%(class)s_read"
    )
    groups_write = models.ManyToManyField(
        amodels.Group,
        related_name="%(class)s_write"
    )

    class Meta:
        abstract = True


class DataSource(ModelWithPerms):
    # an mqtt topic can be as long as 65,535 bytes when UTF-8 encoded,
    # which is probably too much for a sensible db
    topic = models.CharField(max_length=512)
    path = models.FilePathField(
        path=settings.RRD_DB_PATH,
        recursive=True,
        max_length=512,
    )
    rrd_config = models.TextField()
    active = models.BooleanField(
        default=True,
    )


class Graph(ModelWithPerms):
    title = models.CharField(max_length=64)
    data_sources = models.ManyToManyField(DataSource)
    path = models.FilePathField(
        path=settings.RRD_GRAPH_PATH,
        recursive=True,
        max_length=512,
    )
    rrd_config = models.TextField()


class Dashboard(ModelWithPerms):
    title = models.CharField(max_length=64)
    graphs = models.ManyToManyField(Graph)
    data_sources = models.ManyToManyField(DataSource)
    template = models.TextField()