# coding: utf-8
#
#    Project: FabIO X-ray image reader
#
#    Copyright (C) 2010-2016 European Synchrotron Radiation Facility
#                       Grenoble, France
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"""HDF5 image for FabIO

Authors: Jerome Kieffer
email:  Jerome.Kieffer@terre-adelie.org

Specifications:
input should being the form:

filename::path

Only supports ndim=2 or 3 (exposed as a stack of images
"""

__authors__ = ["Jérôme Kieffer"]
__contact__ = "Jerome.Kieffer@terre-adelie.org"
__license__ = "MIT"
__copyright__ = "Jérôme Kieffer"
__date__ = "03/04/2020"

import logging
import os
import posixpath
from . import fabioimage

logger = logging.getLogger(__name__)

try:
    import h5py
except ImportError:
    h5py = None
from .fabioutils import previous_filename, next_filename


class Hdf5Frame(fabioimage.FabioFrame):
    """Identify a slice of dataset from an HDF5 file"""

    def __init__(self, hdf5image, frame_num):
        if not isinstance(hdf5image, Hdf5Image):
            raise TypeError("Expected class %s", Hdf5Image)
        data = hdf5image.dataset[frame_num, :, :]
        super(Hdf5Frame, self).__init__(data=data, header=hdf5image.header)
        self.hdf5 = hdf5image.hdf5
        self.dataset = hdf5image.dataset
        self.filename = hdf5image.filename
        self._nframes = hdf5image.nframes
        self.header = hdf5image.header
        self.currentframe = frame_num


class Hdf5Image(fabioimage.FabioImage):
    """
    FabIO image class for Images from an HDF file

    filename::dataset
    """

    DESCRIPTION = "Hierarchical Data Format HDF5 flat reader"

    DEFAULT_EXTENSIONS = ["h5"]

    def __init__(self, *arg, **kwargs):
        """
        Generic constructor
        """
        if not h5py:
            raise RuntimeError("fabio.Hdf5Image cannot be used without h5py. Please install h5py and restart")

        fabioimage.FabioImage.__init__(self, *arg, **kwargs)
        self.hdf5 = None
        self.dataset = None

    def read(self, fname, frame=None):
        """
        try to read image
        :param fname: filename::datasetpath
        """

        self.resetvals()
        if "::" not in fname:
            err = "the '::' separator in mandatory for HDF5 container, absent in %s" % fname
            logger.error(err)
            raise RuntimeError(err)
        filename, datapath = fname.split("::", 1)

        self.filename = filename
        if os.path.isfile(self.filename):
            self.hdf5 = h5py.File(self.filename, mode="r")
        else:
            error = "No such file or directory: %s" % self.filename
            logger.error(error)
            raise RuntimeError(error)
        try:
            self.dataset = self.hdf5[datapath]
        except Exception as err:
            logger.error("No such datapath %s in %s, %s", datapath, filename, err)
            raise
        if isinstance(self.dataset, h5py.Group) and ("data" in self.dataset):
            datapath = posixpath.join(datapath, "data")
            logger.warning("The actual dataset is ")
            self.dataset = self.dataset["data"]

        # ndim does not exist for external links ?
        ndim = len(self.dataset.shape)
        if ndim == 3:
            self._nframes = self.dataset.shape[0]
            if frame is not None:
                self.currentframe = int(frame)
            else:
                self.currentframe = 0
            self.data = self.dataset[self.currentframe, :, :]
        elif ndim == 2:
            self.data = self.dataset[:, :]
        else:
            err = "Only 2D and 3D datasets are supported by FabIO, here %sD" % self.dataset.ndim
            logger.error(err)
            raise RuntimeError(err)
        return self

    def _get_frame(self, num):
        return self.getframe(num)

    def getframe(self, num):
        """
        Returns a frame as a new FabioImage object
        :param num: frame number
        """
        if num < 0 or num >= self.nframes:
            raise IndexError("Requested frame number %i is out of range [0, %i[ " % (num, self.nframes))
        # Do a deep copy of the header to make a new one
        frame = Hdf5Frame(self, num)
        frame._set_container(self, num)
        frame._set_file_container(self, num)
        return frame

    def next(self):
        """
        Get the next image in a series as a fabio image
        """
        if self.currentframe < (self.nframes - 1):
            return self.getframe(self.currentframe + 1)
        else:
            newobj = Hdf5Image()
            newobj.read(next_filename(self.filename))
            return newobj

    def previous(self):
        """
        Get the previous image in a series as a fabio image
        """
        if self.currentframe > 0:
            return self.getframe(self.currentframe - 1)
        else:
            newobj = Hdf5Image()
            newobj.read(previous_filename(self.filename))
            return newobj

    def close(self):
        if self.hdf5 is not None:
            self.hdf5.close()
            self.dataset = None


hdf5image = Hdf5Image