import json
import os
from datetime import datetime

from config import CACHE_DIR

DEFAULT_CACHE_DIR = CACHE_DIR
DEFAULT_CACHE_TIME = float('inf')


class file_cache(object):
    def __init__(self, cache_dir=None, cache_time=None):
        self.cache_dir = cache_dir or DEFAULT_CACHE_DIR
        self.cache_time = cache_time or DEFAULT_CACHE_TIME

    def get_cache_file(self, f):
        my_name = __name__
        f_name = f.__name__
        return os.path.join(self.cache_dir, "{}.{}".format(my_name, f_name))

    def get_cache(self, f, args, kwargs):
        cache_file = self.get_cache_file(f)
        if os.path.exists(cache_file):
            with open(cache_file, 'r') as cf:
                cache_entries = json.load(cf)
            for cache_entry in cache_entries:
                if cache_entry.get('args') == list(args) and cache_entry.get('kwargs') == kwargs:
                    return cache_entry.get('rv')
        return None

    def set_cache(self, f, args, kwargs, rv):
        cache_file = self.get_cache_file(f)
        cache_entries = []
        if os.path.exists(cache_file):
            with open(cache_file, 'r') as cf:
                cache_entries = json.load(cf)
        for idx, cache_entry in enumerate(cache_entries):
            if cache_entry.get('args') == list(args) and cache_entry.get('kwargs') == kwargs:
                cache_entry['rv'] = rv
                cache_entries[idx] = cache_entry
                break
        else:
            cache_entry = {
                'args': list(args),
                'kwargs': kwargs,
                'rv': rv,
            }
            cache_entries.append(cache_entry)
        with open(cache_file, 'w') as cf:
            json.dump(cache_entries, cf)

    def __call__(self, f):
        def wrapped_f(*args, **kwargs):
            cached_rv = self.get_cache(f, args, kwargs)
            if cached_rv:
                return cached_rv
            rv = f(*args, **kwargs)
            self.set_cache(f, args, kwargs, rv)
            return rv

        return wrapped_f


@file_cache()
def main(query):
    return query + str(datetime.utcnow())


if __name__ == "__main__":
    print(main("helo"))