import os
import pickle
import sys
import tempfile
import unittest
from pathlib import Path

from django.core.exceptions import SuspiciousFileOperation
from django.core.files import File, temp
from django.core.files.base import ContentFile
from django.core.files.uploadedfile import TemporaryUploadedFile
from django.db import IntegrityError, models
from django.test import TestCase, override_settings
from django.test.utils import isolate_apps

from .models import Document


class FileFieldTests(TestCase):

    def test_clearable(self):
        """
        FileField.save_form_data() will clear its instance attribute value if
        passed False.
        """
        d = Document(myfile='something.txt')
        self.assertEqual(d.myfile, 'something.txt')
        field = d._meta.get_field('myfile')
        field.save_form_data(d, False)
        self.assertEqual(d.myfile, '')

    def test_unchanged(self):
        """
        FileField.save_form_data() considers None to mean "no change" rather
        than "clear".
        """
        d = Document(myfile='something.txt')
        self.assertEqual(d.myfile, 'something.txt')
        field = d._meta.get_field('myfile')
        field.save_form_data(d, None)
        self.assertEqual(d.myfile, 'something.txt')

    def test_changed(self):
        """
        FileField.save_form_data(), if passed a truthy value, updates its
        instance attribute.
        """
        d = Document(myfile='something.txt')
        self.assertEqual(d.myfile, 'something.txt')
        field = d._meta.get_field('myfile')
        field.save_form_data(d, 'else.txt')
        self.assertEqual(d.myfile, 'else.txt')

    def test_delete_when_file_unset(self):
        """
        Calling delete on an unset FileField should not call the file deletion
        process, but fail silently (#20660).
        """
        d = Document()
        d.myfile.delete()

    def test_refresh_from_db(self):
        d = Document.objects.create(myfile='something.txt')
        d.refresh_from_db()
        self.assertIs(d.myfile.instance, d)

    @unittest.skipIf(sys.platform == 'win32', "Crashes with OSError on Windows.")
    def test_save_without_name(self):
        with tempfile.NamedTemporaryFile(suffix='.txt') as tmp:
            document = Document.objects.create(myfile='something.txt')
            document.myfile = File(tmp)
            msg = f"Detected path traversal attempt in '{tmp.name}'"
            with self.assertRaisesMessage(SuspiciousFileOperation, msg):
                document.save()

    def test_defer(self):
        Document.objects.create(myfile='something.txt')
        self.assertEqual(Document.objects.defer('myfile')[0].myfile, 'something.txt')

    def test_unique_when_same_filename(self):
        """
        A FileField with unique=True shouldn't allow two instances with the
        same name to be saved.
        """
        Document.objects.create(myfile='something.txt')
        with self.assertRaises(IntegrityError):
            Document.objects.create(myfile='something.txt')

    @unittest.skipIf(sys.platform == 'win32', "Windows doesn't support moving open files.")
    # The file's source and destination must be on the same filesystem.
    @override_settings(MEDIA_ROOT=temp.gettempdir())
    def test_move_temporary_file(self):
        """
        The temporary uploaded file is moved rather than copied to the
        destination.
        """
        with TemporaryUploadedFile('something.txt', 'text/plain', 0, 'UTF-8') as tmp_file:
            tmp_file_path = tmp_file.temporary_file_path()
            Document.objects.create(myfile=tmp_file)
            self.assertFalse(os.path.exists(tmp_file_path), 'Temporary file still exists')

    def test_open_returns_self(self):
        """
        FieldField.open() returns self so it can be used as a context manager.
        """
        d = Document.objects.create(myfile='something.txt')
        # Replace the FileField's file with an in-memory ContentFile, so that
        # open() doesn't write to disk.
        d.myfile.file = ContentFile(b'', name='bla')
        self.assertEqual(d.myfile, d.myfile.open())

    def test_media_root_pathlib(self):
        with tempfile.TemporaryDirectory() as tmp_dir:
            with override_settings(MEDIA_ROOT=Path(tmp_dir)):
                with TemporaryUploadedFile('foo.txt', 'text/plain', 1, 'utf-8') as tmp_file:
                    Document.objects.create(myfile=tmp_file)
                    self.assertTrue(os.path.exists(os.path.join(tmp_dir, 'unused', 'foo.txt')))

    def test_pickle(self):
        with tempfile.TemporaryDirectory() as tmp_dir:
            with override_settings(MEDIA_ROOT=Path(tmp_dir)):
                with open(__file__, 'rb') as fp:
                    file1 = File(fp, name='test_file.py')
                    document = Document(myfile='test_file.py')
                    document.myfile.save('test_file.py', file1)
                    try:
                        dump = pickle.dumps(document)
                        loaded_document = pickle.loads(dump)
                        self.assertEqual(document.myfile, loaded_document.myfile)
                        self.assertEqual(
                            document.myfile.url,
                            loaded_document.myfile.url,
                        )
                        self.assertEqual(
                            document.myfile.storage,
                            loaded_document.myfile.storage,
                        )
                        self.assertEqual(
                            document.myfile.instance,
                            loaded_document.myfile.instance,
                        )
                        self.assertEqual(
                            document.myfile.field,
                            loaded_document.myfile.field,
                        )
                        myfile_dump = pickle.dumps(document.myfile)
                        loaded_myfile = pickle.loads(myfile_dump)
                        self.assertEqual(document.myfile, loaded_myfile)
                        self.assertEqual(document.myfile.url, loaded_myfile.url)
                        self.assertEqual(
                            document.myfile.storage,
                            loaded_myfile.storage,
                        )
                        self.assertEqual(
                            document.myfile.instance,
                            loaded_myfile.instance,
                        )
                        self.assertEqual(document.myfile.field, loaded_myfile.field)
                    finally:
                        document.myfile.delete()

    @isolate_apps('model_fields')
    def test_abstract_filefield_model(self):
        """
        FileField.model returns the concrete model for fields defined in an
        abstract model.
        """
        class AbstractMyDocument(models.Model):
            myfile = models.FileField(upload_to='unused')

            class Meta:
                abstract = True

        class MyDocument(AbstractMyDocument):
            pass

        document = MyDocument(myfile='test_file.py')
        self.assertEqual(document.myfile.field.model, MyDocument)
