Prototype generic llc request builder

llc.py

import json
import typing

import purl

HeadersType = typing.Union[typing.Sequence[typing.Tuple[str, typing.Any]], typing.Mapping[str, typing.Any], None]
JsonBodyType = typing.Union[typing.Mapping[str, "JsonBodyType"], str, int, float, bool, None]
ParamType2 = typing.Union[typing.Sequence[typing.Tuple[str, typing.Any]], typing.Mapping[str, typing.Any]]
ParamType = typing.Union[typing.Sequence[typing.Tuple[str, typing.Any]], typing.Mapping[str, typing.Any]]

LIST_COLLECTION = 'https://www.dn.se/{collection}{?page,top}'
COLLECTION_ITEM = 'https://www.dn.se/{collection}/{item}'

@typing.overload
def HttpRequest(verb: typing.Literal['get'], path_template:typing.Literal['https://www.dn.se/{collection}{?page,top}'], *, collection, page=None, top=None, headers=None):
    ...

@typing.overload
def HttpRequest(verb:typing.Literal['get'], path_template:typing.Literal['https://www.dn.se/{collection}/{item}'], *, collection, item, headers=None):
    ...

@typing.overload
def HttpRequest(verb:typing.Literal['post'], path_template:typing.Literal['https://www.dn.se/{collection}/{item}'], *, collection, item, json, headers=None):
    ...

def HttpRequest(verb: str, path_template: str, *, json:JsonBodyType=None, headers:HeadersType=None, params:ParamType={}, **kwargs:typing.Any):
    return _HttpRequest(verb, path_template, json=json, headers=headers, params=params, **kwargs)

class _HttpRequest(object):

    def __init__(self, verb: str, path_template: str, *, json:JsonBodyType=None, headers:HeadersType=None, params:ParamType={}, **kwargs):
        self.verb = verb
        self.template = purl.Template(path_template)
        variables = dict(params)
        variables.update(kwargs)
        self.path = self.template.expand(variables)
        self.headers = headers.items() if isinstance(headers, dict) else (headers or [])
        self.json = json
        
    def __str__(self):
        request = f"{self.verb.upper()} {self.path} HTTP/1.1"
        for header, value in self.headers:
            request = request + '\n' + f'{header}: {value}'
        request = request + '\n'
        if self.json is not None:
            request = request + f'\n{json.dumps(self.json, indent=True)}'
        return request
    
request1 = HttpRequest('get', COLLECTION_ITEM, collection='yeah', item=14)
print(request1)
request2 = HttpRequest('get', 'https://www.dn.se/{collection}{?page,top}', collection='smurfs', page=2, top=17, headers=[('Accept-Encoding', 'application/json')])
print(request2)
request3 = HttpRequest('post', 'https://www.dn.se/{collection}/{item}', collection='smurfettes', item=12, json=dict(hello='world'), headers={'Accept-Language': 'en-us', 'Content-Encoding': 'application/smurf+json'})
print(request3)