"""A Unstructred Grid file reader object.
"""
# Author:   R.Sreekanth <sreekanth [at] aero.iitb.ac.in>
#               Suyog Dutt Jain <suyog.jain [at] aero.iitb.ac.in>
# Copyright (c) 2009-2020, Enthought, Inc.
# License: BSD Style.

from os.path import basename

# Enthought library imports.
from traits.api import Instance, Str, Dict
from traitsui.api import View, Group, Item, Include
from tvtk.api import tvtk

# Local imports.
from tvtk.common import is_old_pipeline
from mayavi.core.file_data_source import FileDataSource
from mayavi.core.pipeline_info import PipelineInfo
from mayavi.core.common import error

########################################################################
# `UnstructuredGridReader` class
########################################################################
class UnstructuredGridReader(FileDataSource):

    # The version of this class.  Used for persistence.
    __version__ = 0

    # The UnstructuredGridAlgorithm data file reader.
    reader = Instance(tvtk.Object, allow_none=False, record=True)

    # Information about what this object can produce.
    output_info = PipelineInfo(datasets=['unstructured_grid'])

    ######################################################################
    # Private Traits
    _reader_dict = Dict(Str, Instance(tvtk.Object))

    # Our view.
    view = View(Group(Include('time_step_group'),
                      Item(name='base_file_name'),
                      Item(name='reader',
                           style='custom',
                           resizable=True),
                      show_labels=False),
                resizable=True)


    ######################################################################
    # `object` interface
    ######################################################################
    def __set_pure_state__(self, state):
        # The reader has its own file_name which needs to be fixed.
        state.reader.file_name = state.file_path.abs_pth
        # Now call the parent class to setup everything.
        super(UnstructuredGridReader, self).__set_pure_state__(state)

    ######################################################################
    # `FileDataSource` interface
    ######################################################################
    def update(self):
        self.reader.update()
        if len(self.file_path.get()) == 0:
            return
        self.render()

    def has_output_port(self):
        """ Return True as the reader has output port."""
        return True

    def get_output_object(self):
        """ Return the reader output port."""
        return self.reader.output_port

    ######################################################################
    # Non-public interface
    ######################################################################
    def _file_path_changed(self, fpath):
        value = fpath.get()
        if len(value) == 0:
            return
        # Extract the file extension
        splitname = value.strip().split('.')
        extension = splitname[-1].lower()
        # Select UnstructuredGridreader based on file type
        old_reader = self.reader
        if extension in self._reader_dict:
            self.reader = self._reader_dict[extension]
        else:
            error('Invalid file extension for file: %s'%value)
            return

        old_fname = self.reader.file_name
        self.reader.file_name = value.strip()
        self.reader.update_information()
        if isinstance(self.reader, tvtk.ExodusIIReader):
            # Make sure the point fields are read during Update().
            for k in range(self.reader.number_of_point_result_arrays ):
                arr_name = self.reader.get_point_result_array_name( k )
                self.reader.set_point_result_array_status( arr_name, 1 )
        self.reader.update()

        if old_reader is not None:
            old_reader.on_trait_change(self.render, remove=True)
        self.reader.on_trait_change(self.render)

        self.outputs = [self.reader]

        if old_fname != value:
            self.data_changed = True

        # Change our name on the tree view
        self.name = self._get_name()

    def _get_name(self):
        """ Returns the name to display on the tree view.  Note that
        this is not a property getter.
        """
        fname = basename(self.file_path.get())
        ret = "%s"%fname
        if len(self.file_list) > 1:
            ret += " (timeseries)"
        if '[Hidden]' in self.name:
            ret += ' [Hidden]'

        return ret

    def __reader_dict_default(self):
        """Default value for reader dict."""
        if is_old_pipeline():
            rd = {'inp':tvtk.AVSucdReader(),
                 'neu':tvtk.GAMBITReader(),
                 'exii':tvtk.ExodusReader()
                }
        else:
            rd = {'inp':tvtk.AVSucdReader(),
                 'neu':tvtk.GAMBITReader(),
                 'ex2':tvtk.ExodusIIReader()
                }

        return rd
