""" The default resource manager.

A resource manager locates and loads application resources such as images and
sounds etc.

"""


# Standard library imports.
import glob, inspect, operator, os
from os.path import join
from zipfile import ZipFile

# Enthought library imports.
from matplotlib.enthought.traits import HasTraits, Instance
from matplotlib.enthought.util.resource import get_path

# Local imports.
from resource_factory import ResourceFactory
from resource_reference import ImageReference
    
class ResourceManager(HasTraits):
    """ The default resource manager.

    A resource manager locates and loads application resources such as images
    and sounds etc.

    """

    # Allowed extensions for image resources.
    IMAGE_EXTENSIONS = ['.png', '.jpg', '.bmp', '.gif', '.ico']

    # The resource factory is responsible for actually creating resources.
    # This is used so that (for example) different GUI toolkits can create
    # a images in the format that they require.
    resource_factory = Instance(ResourceFactory)

    
    ###########################################################################
    # 'ResourceManager' interface.
    ###########################################################################

    def locate_image(self, image_name, path):
        """ Locates an image. """

        if not operator.isSequenceType(path):
            path = [path]

        resource_path = []
        for item in path:
            if type(item) is str:
                resource_path.append(item)
            else:
                resource_path.extend(self._get_resource_path(item))
                
        return self._locate_image(image_name, resource_path)

    def load_image(self, image_name, path):
        """ Loads an image. """

        reference = self.locate_image(image_name, path)
        if reference is not None:
            image = reference.load()

        else:
            image = None

        return image
    
    ###########################################################################
    # Private interface.
    ###########################################################################

    def _locate_image(self, image_name, resource_path):
        """ Attempts to locate an image resource.

        If the image is found, an image resource reference is returned.
        If the image is NOT found None is returned.

        """

        # If the image name contains a file extension (eg. '.jpg') then we will
        # only accept an an EXACT filename match.
        basename, extension = os.path.splitext(image_name)
        if len(extension) > 0:
            extensions = [extension]
            pattern = image_name
            
        # Otherwise, we will search for common image suffixes.
        else:
            extensions = self.IMAGE_EXTENSIONS
            pattern = image_name + '.*'

        for dirname in resource_path:
            # Try the 'images' sub-directory first (since that is commonly
            # where we put them!).  If the image is not found there then look
            # in the directory itself.
            for path in ['images', '']:
                # Is there anything resembling the image name in the directory?
                filenames = glob.glob(join(dirname, path, pattern))
                for filename in filenames:
                    not_used, extension = os.path.splitext(filename)
                    if extension in extensions:
                        reference = ImageReference(
                            self.resource_factory, filename=filename
                        )

                        return reference
                    
            # Is there an 'images' zip file in the directory?
            zip_filename = join(dirname, 'images.zip')
            if os.path.isfile(zip_filename):
                zip_file = ZipFile(zip_filename, 'r')
                # Try the image name itself, and then the image name with
                # common images suffixes.
                for extension in extensions:
                    try:
                        image_data = zip_file.read(basename + extension)
                        reference = ImageReference(
                            self.resource_factory, data=image_data
                        )

                        return reference
                    
                    except:
                        pass

        return None

    def _get_resource_path(self, object):
        """ Returns the resource path for an object. """
            
        if hasattr(object, 'resource_path'):
            resource_path = object.resource_path
                
        else:
            resource_path = self._get_default_resource_path(object)

        return resource_path
    
    def _get_default_resource_path(self, object):
        """ Returns the default resource path for an object. """

        resource_path = []
        for klass in inspect.getmro(object.__class__):
            try:
                resource_path.append(get_path(klass))

            # We get an attribute error when we get to a C extension type (in
            # our case it will most likley be 'CHasTraits'.  We simply ignore
            # everything after this point!
            except AttributeError:
                break

        return resource_path
    
#### EOF ######################################################################