"""Projekte (docs/projects.md): a project of a preset (Forschung first), its sources and notes.

End-to-end encrypted like the books: a project's name and settings, and every item's content
(a note's text, a source's citation data, a remark) are AES-GCM blobs the server can't read.
What it knows: that a project exists, its preset, and which book, episode or article an item
points to (kind + ref) — the ids, never their titles."""
from django.contrib.auth.models import User
from django.db import models


class Project(models.Model):
    RESEARCH = 'research'
    PRESETS = [(RESEARCH, 'Forschung')]

    user = models.ForeignKey(User, on_delete=models.CASCADE, related_name='projects')
    preset = models.CharField(max_length=20, choices=PRESETS, default=RESEARCH)
    data_ct = models.TextField()   # {name, description, …} encrypted
    data_iv = models.CharField(max_length=32)
    archived = models.BooleanField(default=False)
    position = models.IntegerField(default=0)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        ordering = ['position', '-updated_at']


class ProjectItem(models.Model):
    """Something in a project. Sources point at what's elsewhere in diora (a book, an episode,
    an article: ref is its id) or stand alone (a paper known by its citation data: no ref);
    notes are text of their own (no ref)."""
    BOOK = 'book'
    EPISODE = 'episode'
    ARTICLE = 'article'
    PAPER = 'paper'
    NOTE = 'note'
    KINDS = [(BOOK, 'Buch'), (EPISODE, 'Folge'), (ARTICLE, 'Artikel'), (PAPER, 'Paper'), (NOTE, 'Notiz')]
    LINKED = (BOOK, EPISODE, ARTICLE)

    project = models.ForeignKey(Project, on_delete=models.CASCADE, related_name='items')
    kind = models.CharField(max_length=10, choices=KINDS)
    ref = models.BigIntegerField(null=True, blank=True)
    data_ct = models.TextField()
    data_iv = models.CharField(max_length=32)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        ordering = ['created_at']
        constraints = [models.UniqueConstraint(fields=['project', 'kind', 'ref'], name='project_item_once',
                                               condition=models.Q(ref__isnull=False))]
        indexes = [models.Index(fields=['kind', 'ref'])]