from __future__ import annotations

from datetime import datetime
from typing import List

from grung.types import BackReference, Collection, DateTime, Dict, Field, Password, Pointer, Record, Timestamp
from tinydb import where


class Page(Record):
    """
    A page in the wiki. Just about everything in the databse is either a Page or a subclass of a Page.
    """

    @classmethod
    def fields(cls):
        # fmt: off
        return [
            *super().fields(),                         # Pick up the UID and whatever other non-optional fields exist
            Field("uri", unique=True),                 # The URI for the page, relative to the app's VIEW_URI
            Field("name"),                             # The portion of the URI after the last /
            Field("title"),                            # The page title
            Field("body"),                             # The main content blob of the page
            Collection("members", Page),               # The pages that exist below this page's URI
            BackReference("parent", value_type=Page),  # The page that exists above this page's URI
            Pointer("author", value_type=User),        # The last user to touch the page.
            DateTime("created"),                       # When the page was created
            Timestamp("last_modified"),                # The last time the page was modified.
            Dict("acl"),
        ]
        # fmt: on

    def before_insert(self, db):
        """
        Make the following adjustments before saving this record:
          * Derive the name from the title, or the title from the name
          * Derive the URI from the hierarchy of the parent.
        """
        super().before_insert(db)

        now = datetime.utcnow()
        if not self.doc_id and self.created < now:
            self.created = now

        if not self.name and not self.title:
            raise Exception("Must provide either a name or a title!")
        if not self.name:
            self.name = self.title.title().replace(" ", "")
        if not self.title:
            self.title = self.name

        self.uri = (self.parent.uri + "/" if self.parent and self.parent.uri != "/" else "") + self.name

    def after_insert(self, db):
        """
        After saving this record, ensure that any page in the members collection is updated with the
        correct URI. This ensures that if a page is moved from one collection to another, the URI is updated.
        """
        super().after_insert(db)
        if not hasattr(self, "members"):
            return
        for child in self.members:
            obj = BackReference.dereference(child, db)
            obj.uri = f"{self.uri}/{obj.name}"
            child = db.save(obj)

    def add_member(self, child: Record):
        from ttfrog import app

        app.check_state()
        self.members = list(set(self.members + [app.db.save(child)]))
        app.db.save(self)
        return self.get_child(child)

    def get_child(self, obj: Record):
        for page in self.members:
            if page.uid == obj.uid:
                return page
        return None

    def set_permissions(self, entity: Entity, permissions: List) -> str:
        from ttfrog import app

        app.check_state()

        perms = "".join(permissions)
        self.acl[entity.reference] = perms
        app.db.save(self)
        return perms

    def get_acl_for_entity(self, entity) -> (str, str | None):
        """
        Search upward through the page hierarchy looking for one with an ACL that either
        has a grant for the entity we care about, or at least one group in which the entity is a member.
        """
        from ttfrog import app

        app.check_state()

        def find_acl(obj):
            if hasattr(obj, "acl"):
                if entity.reference in obj.acl:
                    return {entity.reference: obj.acl[entity.reference]}

                group_grants = {}
                for ref, grant in obj.acl.items():
                    if ref.startswith("Group::"):
                        group = app.db.Group.get(where("uid") == ref.split("::")[1], recurse=False)
                        if entity.reference in group.members:
                            group_grants[ref] = grant
                if group_grants:
                    return group_grants

            if hasattr(obj, "parent"):
                return find_acl(obj.parent)
            return {"": ""}

        return find_acl(self)


class Entity(Page):
    def has_permission(self, record: Record, requested: str) -> bool | None:
        for entity, grants in record.get_acl_for_entity(self).items():
            if requested in grants:
                return True
        return False

    def can_read(self, record: Record):
        return self.has_permission(record, Permissions.READ)

    def can_write(self, record: Record):
        return self.has_permission(record, Permissions.WRITE)

    def can_delete(self, record: Record):
        return self.has_permission(record, Permissions.DELETE)


class User(Entity):
    """
    A website user, editable as a wiki page.
    """

    def check_credentials(self, username: str, password: str) -> bool:
        return username == self.name and self._metadata.fields["password"].compare(password, self.password)

    @classmethod
    def fields(cls):
        return [
            field
            for field in [
                *super().fields(),
                Field("email", unique=True),
                Password("password"),
            ]
            if field.name != "members"
        ]


class Group(Entity):
    """
    A set of users, editable as a wiki page.
    """


class NPC(Page):
    """
    An NPC, editable as a wiki page.
    """


class Permissions(Record):
    READ = "r"
    WRITE = "w"
    DELETE = "d"

    @classmethod
    def fields(cls):
        return [*super().fields(), Pointer("entity", Entity), Field("grants")]