import datetime

import json

import pathlib

import pytest

from . import any_date, relpath, StringIO

import oxrlib.cache

import oxrlib.errors

CACHE_PATH = relpath('writecache')

HISTORICAL_PATTERN = '{date}_{base}_cache.json'

class TestCacheFile(oxrlib.cache.WriteCacheFile):

    def __init__(self, path, *args, **kwargs):

        self.path = path

        assert args[0].startswith('w')

class FakeRate:

    def __init__(self, date, base):

        self.timestamp = datetime.datetime(date.year, date.month, date.day)

        self.base = base

    def serialize(self):

        return "test data for {} in {}".format(self.base, self.timestamp.date())

@pytest.fixture

def dummycache():

    cache = oxrlib.cache.CacheWriter(CACHE_PATH, file_class=TestCacheFile)

    cache.setup(historical=HISTORICAL_PATTERN)

    return cache

def test_cache_success(dummycache, any_date):

    base = 'USD'

    expect_name = CACHE_PATH / HISTORICAL_PATTERN.format(date=any_date.isoformat(), base=base)

    with dummycache.historical(any_date, base) as cache_file:

        assert pathlib.Path(cache_file.name) == expect_name

def test_save_rate(dummycache, any_date):

    rate = FakeRate(any_date, 'USD')

    dummycache.save_rate(rate)

    assert TestCacheFile.last_file.last_value == json.dumps(rate.serialize())