"""Example implementation of using a marshmallow Schema for both request input
and output with a `use_schema` decorator.
Run the app:

    $ python examples/schema_example.py

Try the following with httpie (a cURL-like utility, http://httpie.org):

    $ pip install httpie
    $ http GET :5001/users/
    $ http GET :5001/users/42
    $ http POST :5001/users/ username=brian first_name=Brian last_name=May
    $ http PATCH :5001/users/42 username=freddie
    $ http GET :5001/users/ limit==1
"""
import functools
from flask import Flask, request
import random

from marshmallow import Schema, fields, post_dump
from webargs.flaskparser import parser, use_kwargs

app = Flask(__name__)

##### Fake database and model #####


class Model:
    def __init__(self, **kwargs):
        self.__dict__.update(kwargs)

    def update(self, **kwargs):
        self.__dict__.update(kwargs)

    @classmethod
    def insert(cls, db, **kwargs):
        collection = db[cls.collection]
        new_id = None
        if "id" in kwargs:  # for setting up fixtures
            new_id = kwargs.pop("id")
        else:  # find a new id
            found_id = False
            while not found_id:
                new_id = random.randint(1, 9999)
                if new_id not in collection:
                    found_id = True
        new_record = cls(id=new_id, **kwargs)
        collection[new_id] = new_record
        return new_record


class User(Model):
    collection = "users"


db = {"users": {}}


##### use_schema #####


def use_schema(schema_cls, list_view=False, locations=None):
    """View decorator for using a marshmallow schema to
    (1) parse a request's input and
    (2) serializing the view's output to a JSON response.
    """

    def decorator(func):
        @functools.wraps(func)
        def wrapped(*args, **kwargs):
            partial = request.method != "POST"
            schema = schema_cls(partial=partial)
            use_args_wrapper = parser.use_args(schema, locations=locations)
            # Function wrapped with use_args
            func_with_args = use_args_wrapper(func)
            ret = func_with_args(*args, **kwargs)
            return schema.dump(ret, many=list_view)

        return wrapped

    return decorator


##### Schemas #####


class UserSchema(Schema):
    id = fields.Int(dump_only=True)
    username = fields.Str(required=True)
    first_name = fields.Str()
    last_name = fields.Str()

    @post_dump(pass_many=True)
    def wrap_with_envelope(self, data, many, **kwargs):
        return {"data": data}


##### Routes #####


@app.route("/users/<int:user_id>", methods=["GET", "PATCH"])
@use_schema(UserSchema)
def user_detail(reqargs, user_id):
    user = db["users"].get(user_id)
    if not user:
        return {"message": "User not found"}, 404
    if request.method == "PATCH" and reqargs:
        user.update(**reqargs)
    return user


# You can add additional arguments with use_kwargs
@app.route("/users/", methods=["GET", "POST"])
@use_kwargs({"limit": fields.Int(missing=10, location="query")})
@use_schema(UserSchema, list_view=True)
def user_list(reqargs, limit):
    users = db["users"].values()
    if request.method == "POST":
        User.insert(db=db, **reqargs)
    return list(users)[:limit]


# Return validation errors as JSON
@app.errorhandler(422)
@app.errorhandler(400)
def handle_validation_error(err):
    exc = getattr(err, "exc", None)
    if exc:
        headers = err.data["headers"]
        messages = exc.messages
    else:
        headers = None
        messages = ["Invalid request."]
    if headers:
        return {"errors": messages}, err.code, headers
    else:
        return {"errors": messages}, err.code


if __name__ == "__main__":
    User.insert(
        db=db, id=42, username="fred", first_name="Freddie", last_name="Mercury"
    )
    app.run(port=5001, debug=True)