import sys
from .models import *
from flask import Flask, request, jsonify
from typing import Dict, Type, List, Final
from datetime import datetime


class ApiError(BaseException):
    def __init__(self, msg, status=400):
        super().__init__()
        self.msg = msg
        self.status = status


def connect_callback(attr, target):
    """returns a callback to connect attr with target"""
    return lambda: attr.connect(target)


def construct_object_from_request(cls, uid=None):
    if uid:
        obj: Final = cls.nodes.get_or_none(uid=uid)

        if not obj:
            raise ApiError(f"No {cls.__name__} found with uid {request.form.get('uid')}!", status=404)
    else:
        obj: Final = cls()

    relationship_attach_callbacks = list()

    for name, value in cls.__dict__.items():
        if name[0] == '_' or not name[0].islower():
            continue

        cls_name = value.__class__.__name__
        convert_with = None

        if cls_name == 'StringProperty':
            convert_with = str
        elif cls_name == 'DateProperty':
            convert_with = datetime.fromisoformat
        elif cls_name == 'IntegerProperty':
            convert_with = int
        elif cls_name == 'FloatProperty':
            convert_with = float
        elif cls_name == 'RelationshipDefinition':
            if name not in request.form:
                continue

            target_cls = value._raw_class
            # convert class string to class by loading it from module object
            if isinstance(target_cls, str):
                target_cls = getattr(cls.__module__, target_cls)

            for val in request.form.getlist(name):
                target = target_cls.nodes.first_or_none(uid=val)
                if not target:
                    raise ApiError(f'Cannot find referenced object uid={val} of type {target_cls.__name__}!')

                relationship_attach_callbacks.append(connect_callback(getattr(obj, name), target))
        if not convert_with:
            # skip this property
            continue

        if name in request.form:
            setattr(obj, name, convert_with(request.form.get(name)))

    return obj, lambda: [c() for c in relationship_attach_callbacks]


def func_api_obj(cls: Type):
    """basic method for handling /api/type calls"""
    if request.method == 'GET':
        return jsonify([p.json(include_relations=False) for p in cls.nodes.all()])
    if request.method == 'POST':
        p, attach_relationships = construct_object_from_request(cls)
        p.save()
        attach_relationships()
        return jsonify(p.json())


def func_api_obj_id(cls: Type, uid: str):
    if request.method == 'GET':
        person = Person.nodes.get_or_none(uid=uid)
        if not person:
            return "Not found", 404
        return jsonify(person.json())
    if request.method == 'PUT':
        p, attach_relationships = construct_object_from_request(cls, uid=uid)
        p.save()
        attach_relationships()
        return jsonify(p.json())


def attach_to_flask(app: Flask):
    @app.route('/api/person', methods=['POST', 'GET'])
    def func_api_person():
        return func_api_obj(Person)

    @app.route('/api/person/<uid>', methods=['PUT', 'GET'])
    def func_api_person_id(uid):
        return func_api_obj_id(Person, uid)

    @app.route('/api/event', methods=['POST', 'GET'])
    def func_api_event():
        return func_api_obj(Event)

    @app.route('/api/event/<uid>', methods=['PUT', 'GET'])
    def func_api_event_id(uid):
        return func_api_obj_id(Event, uid)

    @app.route('/api/place', methods=['POST', 'GET'])
    def func_api_place():
        return func_api_obj(Place)

    @app.route('/api/place/<uid>', methods=['PUT', 'GET'])
    def func_api_place_id(uid):
        return func_api_obj_id(Place, uid)