Image Widgets
=============

This is an infrastructure to create an image file widget that behaves
as much as possible like a normal text widget in formlib. Normally a
file widget loses its file data when a form is re-presented for
reasons of failing form validation. A ``hurry.file`` widget retains
the file, for example by storing it in a session.

In order to do this, we have a special way to store file data along with
its filename:

  >>> import os
  >>> from waeup.ikoba.image import IkobaImageFile
  >>> testimage = os.path.join(os.path.dirname(__file__), 'sample.jpg')
  >>> testimage2 = os.path.join(os.path.dirname(__file__), 'sample2.jpg')
  >>> some_file = IkobaImageFile('foo.jpg', open(testimage, 'rb').read())
  >>> some_file.filename
  'foo.jpg'
  >>> 'Created with GIMP' in some_file.data
  True

We can provide a download widget. In this case, there's nothing
to download:

  >>> from hurry.file.browser import DownloadWidget
  >>> from hurry.file.schema import File
  >>> from waeup.ikoba.image.schema import ImageFile
  >>> from zope.publisher.browser import TestRequest
  >>> field = ImageFile(__name__='foo', title=u'Foo')
  >>> field = field.bind(None)
  >>> request = TestRequest()
  >>> widget = DownloadWidget(field, request)
  >>> widget()
  u'<div>Download not available</div>'

Even if there were data in the request, there'd be nothing to download:

  >>> from zope.publisher.browser import FileUpload
  >>> request = TestRequest(form={'field.foo': FileUpload(some_file)})
  >>> widget = DownloadWidget(field, request)
  >>> widget()
  u'<div>Download not available</div>'

Now set a value:

  >>> widget.setRenderedValue(some_file)
  >>> widget()
  u'<a href="foo.jpg">foo.jpg</a>'

Instead of downloading, we can also use a thumbnail widget:

  >>> from waeup.ikoba.image.browser import ThumbnailWidget
  >>> request = TestRequest(form={'field.foo': FileUpload(some_file)})
  >>> widget = ThumbnailWidget(field, request)
  >>> widget.setRenderedValue(some_file)
  >>> widget()
  u'<img src="foo.jpg" />'

Now on to an edit widget. First the case in an add form with no
data already available, and no data in request:

  >>> from waeup.ikoba.image.browser import EncodingImageFileWidget
  >>> field = ImageFile(__name__='foo', title=u'Foo', required=False)
  >>> field = field.bind(None)
  >>> request = TestRequest()
  >>> widget = EncodingImageFileWidget(field, request)

  >>> def normalize(s):
  ...   return u'\n  '.join(filter(None, s.split(' ')))

  >>> print normalize(widget())
  <input
    class="fileType"
    id="field.foo"
    name="field.foo"
    size="20"
    type="file"
    />

Now let's try a situation where data is available in the request, but
it's an empty string for the file:

  >>> request = TestRequest(form={'field.foo': u''})
  >>> widget = EncodingImageFileWidget(field, request)

  >>> def normalize(s):
  ...   return '\n  '.join(filter(None, s.split(' ')))

  >>> print normalize(widget())
  <input
    class="fileType"
    id="field.foo"
    name="field.foo"
    size="20"
    type="file"
    />

Now let's render again when there's already available data. What should show
up is an extra, hidden field which contains the file_id:

  >>> widget.setRenderedValue(some_file)
  >>> print normalize(widget())
  <img... />...
  ...<input
    class="fileType"
    id="field.foo"
    name="field.foo"
    size="20"
    type="file"
    />
    (foo.jpg)<input
    class="hiddenType"
    id="field.foo.file_id"
    name="field.foo.file_id"
    type="hidden"
    value="Zm9vLmpw...="
    />

Now let's render again, this time with file data available in the request
instead. The same should happen:

  >>> request = TestRequest(form={'field.foo': FileUpload(some_file)})
  >>> widget = EncodingImageFileWidget(field, request)
  >>> print normalize(widget())
  <img... />...
  ...<input
    class="fileType"
    id="field.foo"
    name="field.foo"
    size="20"
    type="file"
    />
    (foo.jpg)<input
    class="hiddenType"
    id="field.foo.file_id"
    name="field.foo.file_id"
    type="hidden"
    value="Zm9vLmpwZ...="
    />

Now let's render again, this time not with file data available in the
request, but an id. Again, we should see the same:

  >>> request = TestRequest(form={'field.foo.file_id':
  ...                             'Zm9vLnR4dAp0aGUgY29udGVudHM='})
  >>> widget = EncodingImageFileWidget(field, request)
  >>> print normalize(widget())
  <img... />...
  ...<input
    class="fileType"
    id="field.foo"
    name="field.foo"
    size="20"
    type="file"
    />
    (foo.txt)<input
    class="hiddenType"
    id="field.foo.file_id"
    name="field.foo.file_id"
    type="hidden"
    value="Zm9vLnR4dAp0aGUgY29udGVudHM="
    />

If there is both file data and an id, something else happens. First, let's
prepare some new file:

  >>> another_file = IkobaImageFile('bar.txt', 'bar contents')

We happen to know, due to the implementation of
EncodingImageFileWidget, that the file_id is going to be
"Zm9vLnR4dAp0aGUgY29udGVudHM=". Let's make a request with the original
id, but a new file upload:

  >>> request = TestRequest(form={'field.foo': FileUpload(another_file),
  ...                             'field.foo.file_id':
  ...                             'Zm9vLnR4dAp0aGUgY29udGVudHM='})

We expect the new file to be the one that's uploaded:

  >>> widget = EncodingImageFileWidget(field, request)
  >>> print normalize(widget())
  <img... />...
  ...<input
    class="fileType"
    id="field.foo"
    name="field.foo"
    size="20"
    type="file"
    />
    (bar.txt)<input
    class="hiddenType"
    id="field.foo.file_id"
    name="field.foo.file_id"
    type="hidden"
    value="YmFyLnR4dApiYXIgY29udGVudHM="
    />

Support for File Retrievals
---------------------------

As :class:`waeup.ikoba.image.IkobaImageFile` objects support storing
image data by using external 'storages', also our widgets should do
so.

We create a simple IFileRetrieval utility and enable it:

  >>> import hashlib
  >>> from zope.component import provideUtility
  >>> from hurry.file.interfaces import IFileRetrieval
  >>> from StringIO import StringIO
  >>> class MyFileRetrieval(object):
  ...     storage = dict()
  ...     def getFile(self, data):
  ...         entry = self.storage.get(data, None)
  ...         if entry is None:
  ...             return None
  ...         return StringIO(entry)
  ...     def createFile(self, filename, f):
  ...         contents = f.read()
  ...         id_string = hashlib.md5(contents).hexdigest()
  ...         result = IkobaImageFile(filename, id_string)
  ...         self.storage[id_string] = contents
  ...         return result

  >>> retrieval = MyFileRetrieval()
  >>> provideUtility(retrieval, IFileRetrieval)

With this utility in place we can post requests. When no data was
posted and the field also contains no data, we will get a simple
input as appropriate for add forms:

  >>> field = ImageFile(__name__='foo', title=u'Foo', required=False)
  >>> field = field.bind(None)
  >>> request = TestRequest()
  >>> widget = EncodingImageFileWidget(field, request)
  >>> print normalize(widget())
  <input
    class="fileType"
    id="field.foo"
    name="field.foo"
    size="20"
    type="file"
    />

If the request contains empty data but it is only an empty string, the
result will be the same:

  >>> request = TestRequest(form={'field.foo': u''})
  >>> widget = EncodingImageFileWidget(field, request)
  >>> print normalize(widget())
  <input
    class="fileType"
    id="field.foo"
    name="field.foo"
    size="20"
    type="file"
    />

We now want to simulate, that the field contains already data,
identified by some `file_id`. To do so, we first store the data in our
file retrieval and then create a IkobaImageFile object with that
file_id stored:

  >>> from waeup.ikoba.image import createIkobaImageFile
  >>> image = createIkobaImageFile(
  ...     'sample.jpg', open(testimage, 'rb'))
  >>> file_id = image.data
  >>> file_id    # MD5 sum of the file contents
  '9feac4265077922000aa8b88748e25be'

  >>> import hashlib
  >>> hashlib.md5(open(testimage, 'rb').read()).hexdigest()
  '9feac4265077922000aa8b88748e25be'

The new file was stored by our utility, as createIkobaImageFile looks
up IFileRetrieval utilities and uses them:

  >>> retrieval.storage.keys()
  ['9feac4265077922000aa8b88748e25be']

We set this image as value of the widget:

  >>> widget.setRenderedValue(image)
  >>> print normalize(widget())
  <img
    src="sample.jpg"
    /><br
    /><input
    class="fileType"
    id="field.foo"
    name="field.foo"
    size="20"
    type="file"
    />
    (sample.jpg)<input
    class="hiddenType"
    id="field.foo.file_id"
    name="field.foo.file_id"
    type="hidden"
    value="c2FtcGxlLmpwZwo5ZmVhYzQyNjUwNzc5MjIwMDBhYThiODg3NDhlMjViZQ=="
    />

  >>> retrieval.storage.keys()
  ['9feac4265077922000aa8b88748e25be']

The stored hidden value contains the filename and our file_id:

  >>> "c2FtcGxlLmpwZwo5ZmVhYzQyNjUwNzc5MjIwMDBhYThiODg3NDhlMjViZQ==".decode(
  ...    'base64')
  'sample.jpg\n9feac4265077922000aa8b88748e25be'

Now, we want the the widget rendered again but this time with the data
coming from the request. To do so, we have to create a FileUpload
object that wraps the real file:

  >>> class UploadedFile(object):
  ...   headers = {}
  ...   def __init__(self, filename, f):
  ...     self.filename = filename
  ...     self.file = f

Now we can 'post' the request and will get the same result as above:

  >>> upload = FileUpload(UploadedFile('sample.jpg', open(testimage, 'rb')))
  >>> request = TestRequest(form={'field.foo': upload})
  >>> widget = EncodingImageFileWidget(field, request)
  >>> print normalize(widget())
  <img... />...
  ...<input
    class="fileType"
    id="field.foo"
    name="field.foo"
    size="20"
    type="file"
    />
    (sample.jpg)<input
    class="hiddenType"
    id="field.foo.file_id"
    name="field.foo.file_id"
    type="hidden"
    value="c2FtcGxlLmpwZwo5ZmVhYzQyNjUwNzc5MjIwMDBhYThiODg3NDhlMjViZQ=="
    />

Now let's render again, this time not with file data available in the
request, but an id. Again, we should see the same:

  >>> request = TestRequest(form={
  ...   'field.foo.file_id':
  ...   'c2FtcGxlLmpwZwo5ZmVhYzQyNjUwNzc5MjIwMDBhYThiODg3NDhlMjViZQ=='})
  >>> widget = EncodingImageFileWidget(field, request)
  >>> print normalize(widget())
  <img... />...
  ...<input
    class="fileType"
    id="field.foo"
    name="field.foo"
    size="20"
    type="file"
    />
    (sample.jpg)<input
    class="hiddenType"
    id="field.foo.file_id"
    name="field.foo.file_id"
    type="hidden"
    value="c2FtcGxlLmpwZwo5ZmVhYzQyNjUwNzc5MjIwMDBhYThiODg3NDhlMjViZQ=="
    />

If there is both file data and an id, something else happens. First, let's
prepare some new file:

  >>> upload = FileUpload(UploadedFile('sample2.jpg', open(testimage2, 'rb')))

We happen to know, due to the implementation of
EncodingImageFileWidget, that the file_id is going to be
"Zm9vLnR4dAp0aGUgY29udGVudHM=". Let's make a request with the original
id, but a new file upload:

  >>> request = TestRequest(form={'field.foo': upload,
  ...                             'field.foo.file_id':
  ...                             'Z2FtcGxlLmpwZwr/2P/gAA=='})

We expect the new file to be the one that's uploaded:

  >>> field = ImageFile(__name__='foo', title=u'Foo', required=False)
  >>> field = field.bind(None)
  >>> widget = EncodingImageFileWidget(field, request)
  >>> print normalize(widget())
  <img... />...
  ...<input
    class="fileType"
    id="field.foo"
    name="field.foo"
    size="20"
    type="file"
    />
    (sample2.jpg)<input
    class="hiddenType"
    id="field.foo.file_id"
    name="field.foo.file_id"
    type="hidden"
    value="c2FtcGxlMi5qcGcKZDk2MDkwZWRlMmRjODlkZDdkZWM5ZDU3MmFkNThjNzQ="
    />

The value displayed above again means the filename and md5 sum of the
stored file:

  >>> "c2FtcGxlMi5qcGcKZDk2MDkwZWRlMmRjODlkZDdkZWM5ZDU3MmFkNThjNzQ=".decode(
  ...      'base64')
  'sample2.jpg\nd96090ede2dc89dd7dec9d572ad58c74'

where the md5 sum is in fact correct:

  >>> import hashlib
  >>> hashlib.md5(open(testimage2, 'rb').read()).hexdigest()
  'd96090ede2dc89dd7dec9d572ad58c74'

Our file retrieval utility now contains two files:

  >>> retrieval.storage.keys()
  ['9feac4265077922000aa8b88748e25be', 'd96090ede2dc89dd7dec9d572ad58c74']