#!/usr/bin/env python
# vim: set fileencoding=utf-8 :

import bob.bio.base
import bob.io.base
import six

from .. import utils


class Wrapper(bob.bio.base.preprocessor.Preprocessor):
    """Wrapper class to run image preprocessing algorithms on video data.

    This class provides functionality to read original video data from several databases.
    So far, the video content from :ref:`bob.db.mobio <bob.db.mobio>` and the image list content from :ref:`bob.db.youtube <bob.db.youtube>` are supported.

    Furthermore, frames are extracted from these video data, and a ``preprocessor`` algorithm is applied on all selected frames.
    The preprocessor can either be provided as a registered resource, i.e., one of :ref:`bob.bio.face.preprocessors`, or an instance of a preprocessing class.
    Since most of the databases do not provide annotations for all frames of the videos, commonly the preprocessor needs to apply face detection.

    The ``frame_selector`` can be chosen to select some frames from the video.
    By default, a few frames spread over the whole video sequence are selected.

    The ``quality_function`` is used to assess the quality of the frame.
    If no ``quality_function`` is given, the quality is based on the face detector, or simply left as ``None``.
    So far, the quality of the frames are not used, but it is foreseen to select frames based on quality.

    **Parameters:**

    preprocessor : str or :py:class:`bob.bio.base.preprocessor.Preprocessor` instance
      The preprocessor to be used to preprocess the frames.

    frame_selector : :py:class:`bob.bio.video.FrameSelector`
      A frame selector class to define, which frames of the video to use.

    quality_function : function or ``None``
      A function assessing the quality of the preprocessed image.
      If ``None``, no quality assessment is performed.
      If the preprocessor contains a ``quality`` attribute, this is taken instead.

    compressed_io : bool
      Use compression to write the resulting preprocessed HDF5 files.
      This is experimental and might cause trouble.
      Use this flag with care.

    read_original_data: callable or ``None``
       Function that loads the raw data.
       If not explicitly defined the raw data will be loaded by :py:meth:`bob.bio.video.database.VideoBioFile.load`
       using the specified ``frame_selector``

    """

    def __init__(self,
                 preprocessor='landmark-detect',
                 frame_selector=utils.FrameSelector(),
                 quality_function=None,
                 compressed_io=False,
                 read_original_data=None
                 ):

        def _read_video_data(biofile, directory, extension):
          """Read video data using the frame_selector of this object"""
          return biofile.load(directory, extension, frame_selector)

        if read_original_data is None:
          read_original_data = _read_video_data

        # load preprocessor configuration
        if isinstance(preprocessor, six.string_types):
            self.preprocessor = bob.bio.base.load_resource(preprocessor, "preprocessor")
        elif isinstance(preprocessor, bob.bio.base.preprocessor.Preprocessor):
            self.preprocessor = preprocessor
        else:
            raise ValueError("The given preprocessor could not be interpreted")


        bob.bio.base.preprocessor.Preprocessor.__init__(
            self,
            preprocessor=preprocessor,
            frame_selector=frame_selector,
            compressed_io=compressed_io,
            read_original_data=read_original_data
        )

        self.quality_function = quality_function
        self.compressed_io = compressed_io

    def _check_data(self, frames):
        """Checks if the given video is in the desired format."""
        assert isinstance(frames, utils.FrameContainer)

    def __call__(self, frames, annotations=None):
        """__call__(frames, annotations = None) -> preprocessed

        Preprocesses the given frames using the desired ``preprocessor``.

        Faces are extracted for all frames in the given frame container, using the ``preprocessor`` specified in the constructor.

        If given, the annotations need to be in a dictionary.
        The key is either the frame number (for video data) or the image name (for image list data).
        The value is another dictionary, building the relation between facial landmark names and their location, e.g. ``{'leye' : (le_y, le_x), 'reye' : (re_y, re_x)}``

        The annotations for the according frames, if present, are passed to the preprocessor.
        Please assure that your database interface provides the annotations in the desired format.

        **Parameters:**

        frames : :py:class:`bob.bio.video.FrameContainer`
          The pre-selected frames, as returned by :py:meth:`read_original_data`.

        annotations : dict or ``None``
          The annotations for the frames, if any.

        **Returns:**

        preprocessed : :py:class:`bob.bio.video.FrameContainer`
          A frame container that contains the preprocessed frames.
        """

        fc = utils.FrameContainer()

        for index, frame, _ in frames:

            # if annotations are given, and if particular frame annotations are not missing we take them:
            annots = annotations[index] if annotations is not None and index in annotations else None

            # preprocess image (by default: detect a face)
            preprocessed = self.preprocessor(frame, annots)
            if preprocessed is not None:
                # compute the quality of the detection
                if self.quality_function is not None:
                    quality = self.quality_function(preprocessed)
                elif hasattr(self.preprocessor, 'quality'):
                    quality = self.preprocessor.quality
                else:
                    quality = None
                # add image to frame container
                fc.add(index, preprocessed, quality)

        if not len(fc):
          return None

        return fc


    def read_data(self, filename):
        """read_data(filename) -> frames

        Reads the preprocessed data from file and returns them in a frame container.
        The preprocessors ``read_data`` function is used to read the data for each frame.

        **Parameters:**

        filename : str
          The name of the preprocessed data file.

        **Returns:**

        frames : :py:class:`bob.bio.video.FrameContainer`
          The read frames, stored in a frame container.
        """
        if self.compressed_io:
            return utils.load_compressed(filename, self.preprocessor.read_data)
        else:
            return utils.FrameContainer(bob.io.base.HDF5File(filename), self.preprocessor.read_data)

    def write_data(self, frames, filename):
        """Writes the preprocessed data to file.

        The preprocessors ``write_data`` function is used to write the data for each frame.

        **Parameters:**

        frames : :py:class:`bob.bio.video.FrameContainer`
          The preprocessed frames, as returned by the `__call__` function.

        filename : str
          The name of the preprocessed data file to write.
        """
        self._check_data(frames)

        if self.compressed_io:
            return utils.save_compressed(frames, filename, self.preprocessor.write_data)
        else:
            frames.save(bob.io.base.HDF5File(filename, 'w'), self.preprocessor.write_data)
