from flask_hashids import HashidMixin
from enum import IntEnum
from typing import Union
from app import db


class CorpusFollowerPermission(IntEnum):
    VIEW = 1
    MANAGE_FILES = 2
    MANAGE_FOLLOWERS = 4
    MANAGE_CORPUS = 8

    @staticmethod
    def get(corpus_follower_permission: Union['CorpusFollowerPermission', int, str]) -> 'CorpusFollowerPermission':
        if isinstance(corpus_follower_permission, CorpusFollowerPermission):
            return corpus_follower_permission
        if isinstance(corpus_follower_permission, int):
            return CorpusFollowerPermission(corpus_follower_permission)
        if isinstance(corpus_follower_permission, str):
            return CorpusFollowerPermission[corpus_follower_permission]
        raise TypeError('corpus_follower_permission must be CorpusFollowerPermission, int, or str')


class CorpusFollowerRole(HashidMixin, db.Model):
    __tablename__ = 'corpus_follower_roles'
    # Primary key
    id = db.Column(db.Integer, primary_key=True)
    # Fields
    name = db.Column(db.String(64), unique=True)
    default = db.Column(db.Boolean, default=False, index=True)
    permissions = db.Column(db.Integer, default=0)
    # Relationships
    corpus_follower_associations = db.relationship(
        'CorpusFollowerAssociation',
        back_populates='role'
    )

    def __repr__(self):
        return f'<CorpusFollowerRole {self.name}>'

    def has_permission(self, permission: Union[CorpusFollowerPermission, int, str]):
        perm = CorpusFollowerPermission.get(permission)
        return self.permissions & perm.value == perm.value
    
    def add_permission(self, permission: Union[CorpusFollowerPermission, int, str]):
        perm = CorpusFollowerPermission.get(permission)
        if not self.has_permission(perm):
            self.permissions += perm.value
    
    def remove_permission(self, permission: Union[CorpusFollowerPermission, int, str]):
        perm = CorpusFollowerPermission.get(permission)
        if self.has_permission(perm):
            self.permissions -= perm.value

    def reset_permissions(self):
        self.permissions = 0

    def to_json_serializeable(self, backrefs=False, relationships=False):
        json_serializeable = {
            'id': self.hashid,
            'default': self.default,
            'name': self.name,
            'permissions': [
                x.name
                for x in CorpusFollowerPermission
                if self.has_permission(x)
            ]
        }
        if backrefs:
            pass
        if relationships:
            json_serializeable['corpus_follower_association'] = {
                x.hashid: x.to_json_serializeable(relationships=True)
                for x in self.corpus_follower_association
            }
        return json_serializeable

    @staticmethod
    def insert_defaults():
        roles = {
            'Anonymous': [],
            'Viewer': [
                CorpusFollowerPermission.VIEW
            ],
            'Contributor': [
                CorpusFollowerPermission.VIEW,
                CorpusFollowerPermission.MANAGE_FILES
            ],
            'Administrator': [
                CorpusFollowerPermission.VIEW,
                CorpusFollowerPermission.MANAGE_FILES,
                CorpusFollowerPermission.MANAGE_FOLLOWERS,
                CorpusFollowerPermission.MANAGE_CORPUS

            ]
        }
        default_role_name = 'Viewer'
        for role_name, permissions in roles.items():
            role = CorpusFollowerRole.query.filter_by(name=role_name).first()
            if role is None:
                role = CorpusFollowerRole(name=role_name)
            role.reset_permissions()
            for permission in permissions:
                role.add_permission(permission)
            role.default = role.name == default_role_name
            db.session.add(role)
        db.session.commit()