"""A notebook manager that uses the local file system for storage.

Authors:

* Brian Granger
* Zach Sailer
"""

#-----------------------------------------------------------------------------
#  Copyright (C) 2011  The IPython Development Team
#
#  Distributed under the terms of the BSD License.  The full license is in
#  the file COPYING, distributed as part of this software.
#-----------------------------------------------------------------------------

#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------

import io
import os
import glob
import shutil

from tornado import web

from .nbmanager import NotebookManager
from IPython.nbformat import current
from IPython.utils.io import atomic_writing
from IPython.utils.traitlets import Unicode, Bool, TraitError
from IPython.utils.py3compat import getcwd
from IPython.utils import tz
from IPython.html.utils import is_hidden, to_os_path

def sort_key(item):
    """Case-insensitive sorting."""
    return item['name'].lower()

#-----------------------------------------------------------------------------
# Classes
#-----------------------------------------------------------------------------

class FileNotebookManager(NotebookManager):
    
    save_script = Bool(False, config=True,
        help="""Automatically create a Python script when saving the notebook.
        
        For easier use of import, %run and %load across notebooks, a
        <notebook-name>.py script will be created next to any
        <notebook-name>.ipynb on each save.  This can also be set with the
        short `--script` flag.
        """
    )
    notebook_dir = Unicode(getcwd(), config=True)
    
    def _notebook_dir_changed(self, name, old, new):
        """Do a bit of validation of the notebook dir."""
        if not os.path.isabs(new):
            # If we receive a non-absolute path, make it absolute.
            self.notebook_dir = os.path.abspath(new)
            return
        if not os.path.exists(new) or not os.path.isdir(new):
            raise TraitError("notebook dir %r is not a directory" % new)
    
    checkpoint_dir = Unicode('.ipynb_checkpoints', config=True,
        help="""The directory name in which to keep notebook checkpoints
        
        This is a path relative to the notebook's own directory.
        
        By default, it is .ipynb_checkpoints
        """
    )
    
    def _copy(self, src, dest):
        """copy src to dest
        
        like shutil.copy2, but log errors in copystat
        """
        shutil.copyfile(src, dest)
        try:
            shutil.copystat(src, dest)
        except OSError as e:
            self.log.debug("copystat on %s failed", dest, exc_info=True)
    
    def get_notebook_names(self, path=''):
        """List all notebook names in the notebook dir and path."""
        path = path.strip('/')
        if not os.path.isdir(self._get_os_path(path=path)):
            raise web.HTTPError(404, 'Directory not found: ' + path)
        names = glob.glob(self._get_os_path('*'+self.filename_ext, path))
        names = [os.path.basename(name)
                 for name in names]
        return names

    def path_exists(self, path):
        """Does the API-style path (directory) actually exist?
        
        Parameters
        ----------
        path : string
            The path to check. This is an API path (`/` separated,
            relative to base notebook-dir).
        
        Returns
        -------
        exists : bool
            Whether the path is indeed a directory.
        """
        path = path.strip('/')
        os_path = self._get_os_path(path=path)
        return os.path.isdir(os_path)

    def is_hidden(self, path):
        """Does the API style path correspond to a hidden directory or file?
        
        Parameters
        ----------
        path : string
            The path to check. This is an API path (`/` separated,
            relative to base notebook-dir).
        
        Returns
        -------
        exists : bool
            Whether the path is hidden.
        
        """
        path = path.strip('/')
        os_path = self._get_os_path(path=path)
        return is_hidden(os_path, self.notebook_dir)

    def _get_os_path(self, name=None, path=''):
        """Given a notebook name and a URL path, return its file system
        path.

        Parameters
        ----------
        name : string
            The name of a notebook file with the .ipynb extension
        path : string
            The relative URL path (with '/' as separator) to the named
            notebook.

        Returns
        -------
        path : string
            A file system path that combines notebook_dir (location where
            server started), the relative path, and the filename with the
            current operating system's url.
        """
        if name is not None:
            path = path + '/' + name
        return to_os_path(path, self.notebook_dir)

    def notebook_exists(self, name, path=''):
        """Returns a True if the notebook exists. Else, returns False.

        Parameters
        ----------
        name : string
            The name of the notebook you are checking.
        path : string
            The relative path to the notebook (with '/' as separator)

        Returns
        -------
        bool
        """
        path = path.strip('/')
        nbpath = self._get_os_path(name, path=path)
        return os.path.isfile(nbpath)

    # TODO: Remove this after we create the contents web service and directories are
    # no longer listed by the notebook web service.
    def list_dirs(self, path):
        """List the directories for a given API style path."""
        path = path.strip('/')
        os_path = self._get_os_path('', path)
        if not os.path.isdir(os_path):
            raise web.HTTPError(404, u'directory does not exist: %r' % os_path)
        elif is_hidden(os_path, self.notebook_dir):
            self.log.info("Refusing to serve hidden directory, via 404 Error")
            raise web.HTTPError(404, u'directory does not exist: %r' % os_path)
        dir_names = os.listdir(os_path)
        dirs = []
        for name in dir_names:
            os_path = self._get_os_path(name, path)
            if os.path.isdir(os_path) and not is_hidden(os_path, self.notebook_dir)\
                    and self.should_list(name):
                try:
                    model = self.get_dir_model(name, path)
                except IOError:
                    pass
                dirs.append(model)
        dirs = sorted(dirs, key=sort_key)
        return dirs

    # TODO: Remove this after we create the contents web service and directories are
    # no longer listed by the notebook web service.
    def get_dir_model(self, name, path=''):
        """Get the directory model given a directory name and its API style path"""
        path = path.strip('/')
        os_path = self._get_os_path(name, path)
        if not os.path.isdir(os_path):
            raise IOError('directory does not exist: %r' % os_path)
        info = os.stat(os_path)
        last_modified = tz.utcfromtimestamp(info.st_mtime)
        created = tz.utcfromtimestamp(info.st_ctime)
        # Create the notebook model.
        model ={}
        model['name'] = name
        model['path'] = path
        model['last_modified'] = last_modified
        model['created'] = created
        model['type'] = 'directory'
        return model

    def list_notebooks(self, path):
        """Returns a list of dictionaries that are the standard model
        for all notebooks in the relative 'path'.
        
        Parameters
        ----------
        path : str
            the URL path that describes the relative path for the
            listed notebooks
        
        Returns
        -------
        notebooks : list of dicts
            a list of the notebook models without 'content'
        """
        path = path.strip('/')
        notebook_names = self.get_notebook_names(path)
        notebooks = [self.get_notebook(name, path, content=False)
                        for name in notebook_names if self.should_list(name)]
        notebooks = sorted(notebooks, key=sort_key)
        return notebooks

    def get_notebook(self, name, path='', content=True):
        """ Takes a path and name for a notebook and returns its model
        
        Parameters
        ----------
        name : str
            the name of the notebook
        path : str
            the URL path that describes the relative path for
            the notebook
            
        Returns
        -------
        model : dict
            the notebook model. If contents=True, returns the 'contents' 
            dict in the model as well.
        """
        path = path.strip('/')
        if not self.notebook_exists(name=name, path=path):
            raise web.HTTPError(404, u'Notebook does not exist: %s' % name)
        os_path = self._get_os_path(name, path)
        info = os.stat(os_path)
        last_modified = tz.utcfromtimestamp(info.st_mtime)
        created = tz.utcfromtimestamp(info.st_ctime)
        # Create the notebook model.
        model ={}
        model['name'] = name
        model['path'] = path
        model['last_modified'] = last_modified
        model['created'] = created
        model['type'] = 'notebook'
        if content:
            with io.open(os_path, 'r', encoding='utf-8') as f:
                try:
                    nb = current.read(f, u'json')
                except Exception as e:
                    raise web.HTTPError(400, u"Unreadable Notebook: %s %s" % (os_path, e))
            self.mark_trusted_cells(nb, name, path)
            model['content'] = nb
        return model

    def save_notebook(self, model, name='', path=''):
        """Save the notebook model and return the model with no content."""
        path = path.strip('/')

        if 'content' not in model:
            raise web.HTTPError(400, u'No notebook JSON data provided')

        # One checkpoint should always exist
        if self.notebook_exists(name, path) and not self.list_checkpoints(name, path):
            self.create_checkpoint(name, path)

        new_path = model.get('path', path).strip('/')
        new_name = model.get('name', name)

        if path != new_path or name != new_name:
            self.rename_notebook(name, path, new_name, new_path)

        # Save the notebook file
        os_path = self._get_os_path(new_name, new_path)
        nb = current.to_notebook_json(model['content'])
        
        self.check_and_sign(nb, new_name, new_path)
        
        if 'name' in nb['metadata']:
            nb['metadata']['name'] = u''
        try:
            self.log.debug("Autosaving notebook %s", os_path)
            with atomic_writing(os_path, encoding='utf-8') as f:
                current.write(nb, f, u'json')
        except Exception as e:
            raise web.HTTPError(400, u'Unexpected error while autosaving notebook: %s %s' % (os_path, e))

        # Save .py script as well
        if self.save_script:
            py_path = os.path.splitext(os_path)[0] + '.py'
            self.log.debug("Writing script %s", py_path)
            try:
                with atomic_writing(py_path, encoding='utf-8') as f:
                    current.write(nb, f, u'py')
            except Exception as e:
                raise web.HTTPError(400, u'Unexpected error while saving notebook as script: %s %s' % (py_path, e))

        model = self.get_notebook(new_name, new_path, content=False)
        return model

    def update_notebook(self, model, name, path=''):
        """Update the notebook's path and/or name"""
        path = path.strip('/')
        new_name = model.get('name', name)
        new_path = model.get('path', path).strip('/')
        if path != new_path or name != new_name:
            self.rename_notebook(name, path, new_name, new_path)
        model = self.get_notebook(new_name, new_path, content=False)
        return model

    def delete_notebook(self, name, path=''):
        """Delete notebook by name and path."""
        path = path.strip('/')
        os_path = self._get_os_path(name, path)
        if not os.path.isfile(os_path):
            raise web.HTTPError(404, u'Notebook does not exist: %s' % os_path)
        
        # clear checkpoints
        for checkpoint in self.list_checkpoints(name, path):
            checkpoint_id = checkpoint['id']
            cp_path = self.get_checkpoint_path(checkpoint_id, name, path)
            if os.path.isfile(cp_path):
                self.log.debug("Unlinking checkpoint %s", cp_path)
                os.unlink(cp_path)
        
        self.log.debug("Unlinking notebook %s", os_path)
        os.unlink(os_path)

    def rename_notebook(self, old_name, old_path, new_name, new_path):
        """Rename a notebook."""
        old_path = old_path.strip('/')
        new_path = new_path.strip('/')
        if new_name == old_name and new_path == old_path:
            return
        
        new_os_path = self._get_os_path(new_name, new_path)
        old_os_path = self._get_os_path(old_name, old_path)

        # Should we proceed with the move?
        if os.path.isfile(new_os_path):
            raise web.HTTPError(409, u'Notebook with name already exists: %s' % new_os_path)
        if self.save_script:
            old_py_path = os.path.splitext(old_os_path)[0] + '.py'
            new_py_path = os.path.splitext(new_os_path)[0] + '.py'
            if os.path.isfile(new_py_path):
                raise web.HTTPError(409, u'Python script with name already exists: %s' % new_py_path)

        # Move the notebook file
        try:
            shutil.move(old_os_path, new_os_path)
        except Exception as e:
            raise web.HTTPError(500, u'Unknown error renaming notebook: %s %s' % (old_os_path, e))

        # Move the checkpoints
        old_checkpoints = self.list_checkpoints(old_name, old_path)
        for cp in old_checkpoints:
            checkpoint_id = cp['id']
            old_cp_path = self.get_checkpoint_path(checkpoint_id, old_name, old_path)
            new_cp_path = self.get_checkpoint_path(checkpoint_id, new_name, new_path)
            if os.path.isfile(old_cp_path):
                self.log.debug("Renaming checkpoint %s -> %s", old_cp_path, new_cp_path)
                shutil.move(old_cp_path, new_cp_path)

        # Move the .py script
        if self.save_script:
            shutil.move(old_py_path, new_py_path)
  
    # Checkpoint-related utilities
    
    def get_checkpoint_path(self, checkpoint_id, name, path=''):
        """find the path to a checkpoint"""
        path = path.strip('/')
        basename, _ = os.path.splitext(name)
        filename = u"{name}-{checkpoint_id}{ext}".format(
            name=basename,
            checkpoint_id=checkpoint_id,
            ext=self.filename_ext,
        )
        os_path = self._get_os_path(path=path)
        cp_dir = os.path.join(os_path, self.checkpoint_dir)
        if not os.path.exists(cp_dir):
            os.mkdir(cp_dir)
        cp_path = os.path.join(cp_dir, filename)
        return cp_path

    def get_checkpoint_model(self, checkpoint_id, name, path=''):
        """construct the info dict for a given checkpoint"""
        path = path.strip('/')
        cp_path = self.get_checkpoint_path(checkpoint_id, name, path)
        stats = os.stat(cp_path)
        last_modified = tz.utcfromtimestamp(stats.st_mtime)
        info = dict(
            id = checkpoint_id,
            last_modified = last_modified,
        )
        return info
        
    # public checkpoint API
    
    def create_checkpoint(self, name, path=''):
        """Create a checkpoint from the current state of a notebook"""
        path = path.strip('/')
        nb_path = self._get_os_path(name, path)
        # only the one checkpoint ID:
        checkpoint_id = u"checkpoint"
        cp_path = self.get_checkpoint_path(checkpoint_id, name, path)
        self.log.debug("creating checkpoint for notebook %s", name)
        self._copy(nb_path, cp_path)
        
        # return the checkpoint info
        return self.get_checkpoint_model(checkpoint_id, name, path)
    
    def list_checkpoints(self, name, path=''):
        """list the checkpoints for a given notebook
        
        This notebook manager currently only supports one checkpoint per notebook.
        """
        path = path.strip('/')
        checkpoint_id = "checkpoint"
        os_path = self.get_checkpoint_path(checkpoint_id, name, path)
        if not os.path.exists(os_path):
            return []
        else:
            return [self.get_checkpoint_model(checkpoint_id, name, path)]
        
    
    def restore_checkpoint(self, checkpoint_id, name, path=''):
        """restore a notebook to a checkpointed state"""
        path = path.strip('/')
        self.log.info("restoring Notebook %s from checkpoint %s", name, checkpoint_id)
        nb_path = self._get_os_path(name, path)
        cp_path = self.get_checkpoint_path(checkpoint_id, name, path)
        if not os.path.isfile(cp_path):
            self.log.debug("checkpoint file does not exist: %s", cp_path)
            raise web.HTTPError(404,
                u'Notebook checkpoint does not exist: %s-%s' % (name, checkpoint_id)
            )
        # ensure notebook is readable (never restore from an unreadable notebook)
        with io.open(cp_path, 'r', encoding='utf-8') as f:
            current.read(f, u'json')
        self._copy(cp_path, nb_path)
        self.log.debug("copying %s -> %s", cp_path, nb_path)
    
    def delete_checkpoint(self, checkpoint_id, name, path=''):
        """delete a notebook's checkpoint"""
        path = path.strip('/')
        cp_path = self.get_checkpoint_path(checkpoint_id, name, path)
        if not os.path.isfile(cp_path):
            raise web.HTTPError(404,
                u'Notebook checkpoint does not exist: %s%s-%s' % (path, name, checkpoint_id)
            )
        self.log.debug("unlinking %s", cp_path)
        os.unlink(cp_path)
    
    def info_string(self):
        return "Serving notebooks from local directory: %s" % self.notebook_dir