import json
import os

class SettingsCache:
    """
    Utility to save settings into a cache file.
    """

    cache_default_dir = '.sceptic_cache'

    def __init__(self, cache_element, cache_target):
        """
        :param cache_element: the name of the cached element (will be a directory)
        :param cache_target: the specific target of the cache (e.g. a specific configuration)
        """
        # Create dir
        cache_dir = os.path.join(self.cache_default_dir, cache_element)
        os.makedirs(cache_dir, exist_ok=True)

        # File name
        name = "{}.json".format(cache_target.replace("/", "_"))
        self.cache_file = os.path.join(cache_dir, name)

        self.data = None


    def load(self):
        """
        Load data from the cache file
        """
        if not os.path.exists(self.cache_file):
            self.data = {}
            return

        with open(self.cache_file) as fp:
            self.data = json.load(fp)


    def save(self):
        """
        Save data into the cache file
        """
        with open(self.cache_file, "w") as fp:
            json.dump(self.data, fp)
            fp.write("\n")