# coding: utf-8

## Importing IPython Notebooks as Modules

# It is a common problem that people want to import code from IPython Notebooks.
# This is made difficult by the fact that Notebooks are not plain Python files,
# and thus cannot be imported by the regular Python machinery.
#
# Fortunately, Python provides some fairly sophisticated [hooks]
# (http://www.python.org/dev/peps/pep-0302/) into the import machinery,
# so we can actually make IPython notebooks importable without much difficulty,
# and only using public APIs.

import io, os, sys, types, warnings

try:
    from IPython.nbformat import current
    from IPython.core.interactiveshell import InteractiveShell
except ImportError:
    warnings.warn("IPython not installed!")
else:
    def find_notebook(fullname, path=None):
        """find a notebook, given its fully qualified name and an optional path

        This turns "foo.bar" into "foo/bar.ipynb"
        and tries turning "Foo_Bar" into "Foo Bar" if Foo_Bar
        does not exist.
        """
        name = fullname.rsplit('.', 1)[-1]
        if not path:
             path = sys.path #['']
        for d in path:
            nb_path = os.path.join(d, name + ".ipynb")
            if os.path.isfile(nb_path):
                return nb_path
            # let import Notebook_Name find "Notebook Name.ipynb"
            nb_path = nb_path.replace("_", " ")
            if os.path.isfile(nb_path):
                return nb_path





    class NotebookLoader(object):
        """Module Loader for IPython Notebooks"""
        def __init__(self, path=None):
            self.shell = InteractiveShell.instance()
            self.path = path

        def load_module(self, fullname):
            """import a notebook as a module"""
            path = find_notebook(fullname, self.path)

            #print ("importing IPython notebook from %s" % path)

            # load the notebook object
            with io.open(path, 'r', encoding='utf-8') as f:
                nb = current.read(f, 'json')


            # create the module and add it to sys.modules
            # if name in sys.modules:
            #    return sys.modules[name]
            mod = types.ModuleType(fullname)
            mod.__file__ = path
            mod.__loader__ = self
            sys.modules[fullname] = mod

            # extra work to ensure that magics that would affect the user_ns
            # actually affect the notebook module's ns
            save_user_ns = self.shell.user_ns
            self.shell.user_ns = mod.__dict__

            try:
              for cell in nb.worksheets[0].cells:
                if cell.cell_type == 'code' and cell.language == 'python':
                    # transform the input to executable Python
                    code = self.shell.input_transformer_manager.transform_cell(cell.input)
                    # run the code in themodule
                    exec(code, mod.__dict__)
            finally:
                self.shell.user_ns = save_user_ns
            return mod



    class NotebookFinder(object):
        """Module finder that locates IPython Notebooks"""
        def __init__(self):
            self.loaders = {}

        def find_module(self, fullname, path=None):
            nb_path = find_notebook(fullname, path)
            if not nb_path:
                return

            key = path
            if path:
                # lists aren't hashable
                key = os.path.sep.join(path)

            if key not in self.loaders:
                self.loaders[key] = NotebookLoader(path)
            return self.loaders[key]




    sys.meta_path.append(NotebookFinder())
