from abc import ABCMeta, abstractmethod
import datetime
import mistune
import peewee
from typing import Optional
import slugify

import by.config as c
import by.error as e
import by.view as v


class Model(peewee.Model):
    class Meta:
        database = c.db

class User(Model):
    name = peewee.TextField(unique=True)
    passhash = peewee.TextField()


class Contents(Model):
    source = peewee.TextField()


class Page(Model):
    slug = peewee.TextField(unique=True)
    title = peewee.TextField()

    @staticmethod
    def new_page(title: str, contents: str) -> "Page":
        p = Page.create(
            slug=slugify.slugify(title),
            title=title,
        )
        p.update_page(contents)
        p.update_references()
        return p

    def update_page(self, source: str):
        now = datetime.datetime.now()
        c = Contents.create(source=source)
        r = Revision.create(
            modified=now,
            contents=c,
            page=self,
        )

    def update_references(self):
        Ref.delete().where(Ref.parent == self)

    @staticmethod
    def id_from_slug(slug: str) -> Optional[int]:
        if (p := Page.get_or_none(Page.slug == slug)):
            return p.id
        return None

    @staticmethod
    def view_from_slug(slug: str) -> v.Page:
        query = list(Revision.select()
                     .join(Page, on=(Revision.page == Page.id))
                     .join(Contents, on=(Revision.contents == Contents.id))
                     .where(Page.slug == slug)
                     .order_by(-Revision.modified)
                     .limit(1))
        if len(query) != 1:
            raise e.PageNotFound()
        q = query[0]
        return v.Page(
            title=q.page.title,
            slug=q.page.slug,
            modified=q.modified,
            source=q.contents.source,
            rendered=mistune.html(q.contents.source),
        )


class Revision(Model):
    modified = peewee.DateTimeField()
    contents = peewee.ForeignKeyField(Contents)
    page = peewee.ForeignKeyField(Page)


class Ref(Model):
    parent = peewee.ForeignKeyField(Page)
    target = peewee.ForeignKeyField(Page)


MODELS = [
    User,
    Page,
    Ref,
    Revision,
    Contents,
]


def create_tables():
    c.db.create_tables(MODELS, safe=True)