import datetime
import os

from scrapy import signals
from scrapy.exceptions import NotConfigured
from scrapy.utils.project import data_path


def json_serial(obj):
    """JSON serializer for objects not serializable by default json code"""

    if isinstance(obj, (datetime.datetime, datetime.date)):
        return obj.isoformat()
    raise TypeError ("Type %s not serializable" % type(obj))


class StatsStore(object):

    def __init__(self, stats):
        self.stats = stats
        self.statsdir = data_path('stats', createdir=True)

    @classmethod
    def from_crawler(cls, crawler):
        o = cls(crawler.stats)
        crawler.signals.connect(o.spider_closed, signal=signals.spider_closed)
        return o

    def spider_closed(self, spider):
        spider_stats = self.stats.get_stats(spider)
        key = int(datetime.datetime.now().timestamp())
        stats_f = os.path.join(self.statsdir, str(key))
        import json
        with open(stats_f, "w") as s_f:
            s_f.write(json.dumps(spider_stats, default=json_serial))