import os

from django.core.files.base import ContentFile
from django.core.files.storage import Storage
from django.db.models import FileField
from django.test import SimpleTestCase


class AWSS3Storage(Storage):
    """
    Simulate an AWS S3 storage which uses Unix-like paths and allows any
    characters in file names but where there aren't actual folders but just
    keys.
    """
    prefix = 'mys3folder/'

    def _save(self, name, content):
        """
        This method is important to test that Storage.save() doesn't replace
        '\' with '/' (rather FileSystemStorage.save() does).
        """
        return name

    def get_valid_name(self, name):
        return name

    def get_available_name(self, name, max_length=None):
        return name

    def generate_filename(self, filename):
        """
        This is the method that's important to override when using S3 so that
        os.path() isn't called, which would break S3 keys.
        """
        return self.prefix + self.get_valid_name(filename)


class GenerateFilenameStorageTests(SimpleTestCase):

    def test_filefield_generate_filename(self):
        f = FileField(upload_to='some/folder/')
        self.assertEqual(
            f.generate_filename(None, 'test with space.txt'),
            os.path.normpath('some/folder/test_with_space.txt')
        )

    def test_filefield_generate_filename_with_upload_to(self):
        def upload_to(instance, filename):
            return 'some/folder/' + filename

        f = FileField(upload_to=upload_to)
        self.assertEqual(
            f.generate_filename(None, 'test with space.txt'),
            os.path.normpath('some/folder/test_with_space.txt')
        )

    def test_filefield_awss3_storage(self):
        """
        Simulate a FileField with an S3 storage which uses keys rather than
        folders and names. FileField and Storage shouldn't have any os.path()
        calls that break the key.
        """
        storage = AWSS3Storage()
        folder = 'not/a/folder/'

        f = FileField(upload_to=folder, storage=storage)
        key = 'my-file-key\\with odd characters'
        data = ContentFile('test')
        expected_key = AWSS3Storage.prefix + folder + key

        # Simulate call to f.save()
        result_key = f.generate_filename(None, key)
        self.assertEqual(result_key, expected_key)

        result_key = storage.save(result_key, data)
        self.assertEqual(result_key, expected_key)

        # Repeat test with a callable.
        def upload_to(instance, filename):
            # Return a non-normalized path on purpose.
            return folder + filename

        f = FileField(upload_to=upload_to, storage=storage)

        # Simulate call to f.save()
        result_key = f.generate_filename(None, key)
        self.assertEqual(result_key, expected_key)

        result_key = storage.save(result_key, data)
        self.assertEqual(result_key, expected_key)
