import os
import shutil

from testfixtures import LogCapture
from twisted.internet import defer
from twisted.trial.unittest import TestCase
from w3lib.url import add_or_replace_parameter

from scrapy.crawler import CrawlerRunner
from scrapy import signals
from tests.mockserver import MockServer
from tests.spiders import SimpleSpider


class MediaDownloadSpider(SimpleSpider):
    name = 'mediadownload'

    def _process_url(self, url):
        return url

    def parse(self, response):
        self.logger.info(response.headers)
        self.logger.info(response.text)
        item = {
            self.media_key: [],
            self.media_urls_key: [
                self._process_url(response.urljoin(href))
                for href in response.xpath(
                    '//table[thead/tr/th="Filename"]/tbody//a/@href'
                ).getall()],
        }
        yield item


class BrokenLinksMediaDownloadSpider(MediaDownloadSpider):
    name = 'brokenmedia'

    def _process_url(self, url):
        return url + '.foo'


class RedirectedMediaDownloadSpider(MediaDownloadSpider):
    name = 'redirectedmedia'

    def _process_url(self, url):
        return add_or_replace_parameter(self.mockserver.url('/redirect-to'), 'goto', url)


class FileDownloadCrawlTestCase(TestCase):
    pipeline_class = 'scrapy.pipelines.files.FilesPipeline'
    store_setting_key = 'FILES_STORE'
    media_key = 'files'
    media_urls_key = 'file_urls'
    expected_checksums = {
        '5547178b89448faf0015a13f904c936e',
        'c2281c83670e31d8aaab7cb642b824db',
        'ed3f6538dc15d4d9179dae57319edc5f'}

    def setUp(self):
        self.mockserver = MockServer()
        self.mockserver.__enter__()

        # prepare a directory for storing files
        self.tmpmediastore = self.mktemp()
        os.mkdir(self.tmpmediastore)
        self.settings = {
            'ITEM_PIPELINES': {self.pipeline_class: 1},
            self.store_setting_key: self.tmpmediastore,
        }
        self.runner = CrawlerRunner(self.settings)
        self.items = []

    def tearDown(self):
        shutil.rmtree(self.tmpmediastore)
        self.items = []
        self.mockserver.__exit__(None, None, None)

    def _on_item_scraped(self, item):
        self.items.append(item)

    def _create_crawler(self, spider_class, **kwargs):
        crawler = self.runner.create_crawler(spider_class, **kwargs)
        crawler.signals.connect(self._on_item_scraped, signals.item_scraped)
        return crawler

    def _assert_files_downloaded(self, items, logs):
        self.assertEqual(len(items), 1)
        self.assertIn(self.media_key, items[0])

        # check that logs show the expected number of successful file downloads
        file_dl_success = 'File (downloaded): Downloaded file from'
        self.assertEqual(logs.count(file_dl_success), 3)

        # check that the images/files status is `downloaded`
        for item in items:
            for i in item[self.media_key]:
                self.assertEqual(i['status'], 'downloaded')

        # check that the images/files checksums are what we know they should be
        if self.expected_checksums is not None:
            checksums = set(
                i['checksum']
                for item in items
                for i in item[self.media_key]
            )
            self.assertEqual(checksums, self.expected_checksums)

        # check that the image files where actually written to the media store
        for item in items:
            for i in item[self.media_key]:
                self.assertTrue(
                    os.path.exists(
                        os.path.join(self.tmpmediastore, i['path'])))

    def _assert_files_download_failure(self, crawler, items, code, logs):

        # check that the item does NOT have the "images/files" field populated
        self.assertEqual(len(items), 1)
        self.assertIn(self.media_key, items[0])
        self.assertFalse(items[0][self.media_key])

        # check that there was 1 successful fetch and 3 other responses with non-200 code
        self.assertEqual(crawler.stats.get_value('downloader/request_method_count/GET'), 4)
        self.assertEqual(crawler.stats.get_value('downloader/response_count'), 4)
        self.assertEqual(crawler.stats.get_value('downloader/response_status_count/200'), 1)
        self.assertEqual(crawler.stats.get_value(f'downloader/response_status_count/{code}'), 3)

        # check that logs do show the failure on the file downloads
        file_dl_failure = f'File (code: {code}): Error downloading file from'
        self.assertEqual(logs.count(file_dl_failure), 3)

        # check that no files were written to the media store
        self.assertEqual(os.listdir(self.tmpmediastore), [])

    @defer.inlineCallbacks
    def test_download_media(self):
        crawler = self._create_crawler(MediaDownloadSpider)
        with LogCapture() as log:
            yield crawler.crawl(
                self.mockserver.url("/files/images/"),
                media_key=self.media_key,
                media_urls_key=self.media_urls_key)
        self._assert_files_downloaded(self.items, str(log))

    @defer.inlineCallbacks
    def test_download_media_wrong_urls(self):
        crawler = self._create_crawler(BrokenLinksMediaDownloadSpider)
        with LogCapture() as log:
            yield crawler.crawl(
                self.mockserver.url("/files/images/"),
                media_key=self.media_key,
                media_urls_key=self.media_urls_key)
        self._assert_files_download_failure(crawler, self.items, 404, str(log))

    @defer.inlineCallbacks
    def test_download_media_redirected_default_failure(self):
        crawler = self._create_crawler(RedirectedMediaDownloadSpider)
        with LogCapture() as log:
            yield crawler.crawl(
                self.mockserver.url("/files/images/"),
                media_key=self.media_key,
                media_urls_key=self.media_urls_key,
                mockserver=self.mockserver)
        self._assert_files_download_failure(crawler, self.items, 302, str(log))

    @defer.inlineCallbacks
    def test_download_media_redirected_allowed(self):
        settings = dict(self.settings)
        settings.update({'MEDIA_ALLOW_REDIRECTS': True})
        self.runner = CrawlerRunner(settings)

        crawler = self._create_crawler(RedirectedMediaDownloadSpider)
        with LogCapture() as log:
            yield crawler.crawl(
                self.mockserver.url("/files/images/"),
                media_key=self.media_key,
                media_urls_key=self.media_urls_key,
                mockserver=self.mockserver)
        self._assert_files_downloaded(self.items, str(log))
        self.assertEqual(crawler.stats.get_value('downloader/response_status_count/302'), 3)


try:
    from PIL import Image  # noqa: imported just to check for the import error
except ImportError:
    skip_pillow = 'Missing Python Imaging Library, install https://pypi.python.org/pypi/Pillow'
else:
    skip_pillow = None


class ImageDownloadCrawlTestCase(FileDownloadCrawlTestCase):

    skip = skip_pillow

    pipeline_class = 'scrapy.pipelines.images.ImagesPipeline'
    store_setting_key = 'IMAGES_STORE'
    media_key = 'images'
    media_urls_key = 'image_urls'

    # somehow checksums for images are different for Python 3.3
    expected_checksums = None
