import json

import requests

from .shared import point_has_streetview, PointSource

mapcrunch_url = "http://www.mapcrunch.com/_r/"


def generate_coord(max_retries=100, only_america=False):
    """
    Returns (latitude, longitude) of usable coord (where google has data).
    This function will attempt at most max_retries calls to map crunch to fetch
    candidate points, and will exit as soon as a suitable candidate is found.
    If no suitable candidate is found in this allotted number of retries, None is
    returned.

    This function calls the streetview metadata endpoint - there is no quota consumed.
    """
    mc_url = mapcrunch_url + ("?c=21" if only_america else "")
    for _ in range(max_retries):
        points_res = requests.get(mc_url).text
        points_js = json.loads(points_res.strip("while(1); "))
        if "c=" not in mc_url:
            mc_url += f"?c={points_js['country']}" # lock to the first country randomed
        for lat, lng in points_js["points"]:
            if point_has_streetview(lat, lng):
                return (lat, lng)


class MapCrunchPointSource(PointSource):
    def __init__(self, stock_target=20, max_retries=100, only_america=False):
        super().__init__(stock_target=stock_target)
        self.max_retries = max_retries
        self.only_america = only_america

    def _restock_impl(self, n):
        points = []
        while len(points) < n:
            pt = generate_coord(
                max_retries=self.max_retries,
                only_america=self.only_america
            )
            if pt is not None:
                points.append(pt)
        return points