"""Tornado handlers for the contents web service."""

# Copyright (c) IPython Development Team.
# Distributed under the terms of the Modified BSD License.

import json

from tornado import web

from IPython.html.utils import url_path_join, url_escape
from IPython.utils.jsonutil import date_default

from IPython.html.base.handlers import (IPythonHandler, json_errors,
                                    file_path_regex, path_regex,
                                    file_name_regex)


def sort_key(model):
    """key function for case-insensitive sort by name and type"""
    iname = model['name'].lower()
    type_key = {
        'directory' : '0',
        'notebook'  : '1',
        'file'      : '2',
    }.get(model['type'], '9')
    return u'%s%s' % (type_key, iname)

class ContentsHandler(IPythonHandler):

    SUPPORTED_METHODS = (u'GET', u'PUT', u'PATCH', u'POST', u'DELETE')

    def location_url(self, name, path):
        """Return the full URL location of a file.

        Parameters
        ----------
        name : unicode
            The base name of the file, such as "foo.ipynb".
        path : unicode
            The API path of the file, such as "foo/bar".
        """
        return url_escape(url_path_join(
            self.base_url, 'api', 'contents', path, name
        ))

    def _finish_model(self, model, location=True):
        """Finish a JSON request with a model, setting relevant headers, etc."""
        if location:
            location = self.location_url(model['name'], model['path'])
            self.set_header('Location', location)
        self.set_header('Last-Modified', model['last_modified'])
        self.finish(json.dumps(model, default=date_default))

    @web.authenticated
    @json_errors
    def get(self, path='', name=None):
        """Return a model for a file or directory.

        A directory model contains a list of models (without content)
        of the files and directories it contains.
        """
        path = path or ''
        model = self.contents_manager.get_model(name=name, path=path)
        if model['type'] == 'directory':
            # group listing by type, then by name (case-insensitive)
            # FIXME: sorting should be done in the frontends
            model['content'].sort(key=sort_key)
        self._finish_model(model, location=False)

    @web.authenticated
    @json_errors
    def patch(self, path='', name=None):
        """PATCH renames a notebook without re-uploading content."""
        cm = self.contents_manager
        if name is None:
            raise web.HTTPError(400, u'Filename missing')
        model = self.get_json_body()
        if model is None:
            raise web.HTTPError(400, u'JSON body missing')
        model = cm.update(model, name, path)
        self._finish_model(model)

    def _copy(self, copy_from, path, copy_to=None):
        """Copy a file, optionally specifying the new name.
        """
        self.log.info(u"Copying {copy_from} to {path}/{copy_to}".format(
            copy_from=copy_from,
            path=path,
            copy_to=copy_to or '',
        ))
        model = self.contents_manager.copy(copy_from, copy_to, path)
        self.set_status(201)
        self._finish_model(model)

    def _upload(self, model, path, name=None):
        """Handle upload of a new file

        If name specified, create it in path/name,
        otherwise create a new untitled file in path.
        """
        self.log.info(u"Uploading file to %s/%s", path, name or '')
        if name:
            model['name'] = name

        model = self.contents_manager.create_file(model, path)
        self.set_status(201)
        self._finish_model(model)

    def _create_empty_file(self, path, name=None, ext='.ipynb'):
        """Create an empty file in path

        If name specified, create it in path/name.
        """
        self.log.info(u"Creating new file in %s/%s", path, name or '')
        model = {}
        if name:
            model['name'] = name
        model = self.contents_manager.create_file(model, path=path, ext=ext)
        self.set_status(201)
        self._finish_model(model)

    def _save(self, model, path, name):
        """Save an existing file."""
        self.log.info(u"Saving file at %s/%s", path, name)
        model = self.contents_manager.save(model, name, path)
        if model['path'] != path.strip('/') or model['name'] != name:
            # a rename happened, set Location header
            location = True
        else:
            location = False
        self._finish_model(model, location)

    @web.authenticated
    @json_errors
    def post(self, path='', name=None):
        """Create a new file or directory in the specified path.

        POST creates new files or directories. The server always decides on the name.

        POST /api/contents/path
          New untitled notebook in path. If content specified, upload a
          notebook, otherwise start empty.
        POST /api/contents/path
          with body {"copy_from" : "OtherNotebook.ipynb"}
          New copy of OtherNotebook in path
        """

        if name is not None:
            path = u'{}/{}'.format(path, name)

        cm = self.contents_manager

        if cm.file_exists(path):
            raise web.HTTPError(400, "Cannot POST to existing files, use PUT instead.")

        if not cm.path_exists(path):
            raise web.HTTPError(404, "No such directory: %s" % path)

        model = self.get_json_body()

        if model is not None:
            copy_from = model.get('copy_from')
            ext = model.get('ext', '.ipynb')
            if model.get('content') is not None:
                if copy_from:
                    raise web.HTTPError(400, "Can't upload and copy at the same time.")
                self._upload(model, path)
            elif copy_from:
                self._copy(copy_from, path)
            else:
                self._create_empty_file(path, ext=ext)
        else:
            self._create_empty_file(path)

    @web.authenticated
    @json_errors
    def put(self, path='', name=None):
        """Saves the file in the location specified by name and path.

        PUT is very similar to POST, but the requester specifies the name,
        whereas with POST, the server picks the name.

        PUT /api/contents/path/Name.ipynb
          Save notebook at ``path/Name.ipynb``. Notebook structure is specified
          in `content` key of JSON request body. If content is not specified,
          create a new empty notebook.
        PUT /api/contents/path/Name.ipynb
          with JSON body::

            {
              "copy_from" : "[path/to/]OtherNotebook.ipynb"
            }

          Copy OtherNotebook to Name
        """
        if name is None:
            raise web.HTTPError(400, "name must be specified with PUT.")

        model = self.get_json_body()
        if model:
            copy_from = model.get('copy_from')
            if copy_from:
                if model.get('content'):
                    raise web.HTTPError(400, "Can't upload and copy at the same time.")
                self._copy(copy_from, path, name)
            elif self.contents_manager.file_exists(name, path):
                self._save(model, path, name)
            else:
                self._upload(model, path, name)
        else:
            self._create_empty_file(path, name)

    @web.authenticated
    @json_errors
    def delete(self, path='', name=None):
        """delete a file in the given path"""
        cm = self.contents_manager
        self.log.warn('delete %s:%s', path, name)
        cm.delete(name, path)
        self.set_status(204)
        self.finish()


class CheckpointsHandler(IPythonHandler):

    SUPPORTED_METHODS = ('GET', 'POST')

    @web.authenticated
    @json_errors
    def get(self, path='', name=None):
        """get lists checkpoints for a file"""
        cm = self.contents_manager
        checkpoints = cm.list_checkpoints(name, path)
        data = json.dumps(checkpoints, default=date_default)
        self.finish(data)

    @web.authenticated
    @json_errors
    def post(self, path='', name=None):
        """post creates a new checkpoint"""
        cm = self.contents_manager
        checkpoint = cm.create_checkpoint(name, path)
        data = json.dumps(checkpoint, default=date_default)
        location = url_path_join(self.base_url, 'api/contents',
            path, name, 'checkpoints', checkpoint['id'])
        self.set_header('Location', url_escape(location))
        self.set_status(201)
        self.finish(data)


class ModifyCheckpointsHandler(IPythonHandler):

    SUPPORTED_METHODS = ('POST', 'DELETE')

    @web.authenticated
    @json_errors
    def post(self, path, name, checkpoint_id):
        """post restores a file from a checkpoint"""
        cm = self.contents_manager
        cm.restore_checkpoint(checkpoint_id, name, path)
        self.set_status(204)
        self.finish()

    @web.authenticated
    @json_errors
    def delete(self, path, name, checkpoint_id):
        """delete clears a checkpoint for a given file"""
        cm = self.contents_manager
        cm.delete_checkpoint(checkpoint_id, name, path)
        self.set_status(204)
        self.finish()


class NotebooksRedirectHandler(IPythonHandler):
    """Redirect /api/notebooks to /api/contents"""
    SUPPORTED_METHODS = ('GET', 'PUT', 'PATCH', 'POST', 'DELETE')

    def get(self, path):
        self.log.warn("/api/notebooks is deprecated, use /api/contents")
        self.redirect(url_path_join(
            self.base_url,
            'api/contents',
            path
        ))

    put = patch = post = delete = get


#-----------------------------------------------------------------------------
# URL to handler mappings
#-----------------------------------------------------------------------------


_checkpoint_id_regex = r"(?P<checkpoint_id>[\w-]+)"

default_handlers = [
    (r"/api/contents%s/checkpoints" % file_path_regex, CheckpointsHandler),
    (r"/api/contents%s/checkpoints/%s" % (file_path_regex, _checkpoint_id_regex),
        ModifyCheckpointsHandler),
    (r"/api/contents%s" % file_path_regex, ContentsHandler),
    (r"/api/contents%s" % path_regex, ContentsHandler),
    (r"/api/notebooks/?(.*)", NotebooksRedirectHandler),
]