#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
    openslides.projector.api
    ~~~~~~~~~~~~~~~~~~~~~~~~

    Useful functions for the projector app.

    :copyright: 2011, 2012 by OpenSlides team, see AUTHORS.
    :license: GNU GPL, see LICENSE for more details.
"""

import json

from django.conf import settings
from django.template.loader import render_to_string
from django.utils.datastructures import SortedDict
from django.utils.importlib import import_module

from openslides.config.api import config
from openslides.utils.tornado_webserver import ProjectorSocketHandler

from .signals import projector_overlays

slide_callback = {}
"""
A dictonary where the key is the name of a slide, and the value is a
callable object which returns the html code for a slide.
"""


def update_projector():
    """
    Sends the data to the clients, who listen to the projector.
    """
    # TODO: only send necessary html
    ProjectorSocketHandler.send_updates({'content': get_projector_content()})


def update_projector_overlay(overlay):
    """
    Update one or all overlay on the projector.

    Checks if the overlay is activated and updates it in this case.

    The argument 'overlay' has to be an overlay object, the name of a
    ovleray or None. If it is None, all overlays will be updated.
    """
    if overlay is None:
        overlays = [item for item in get_overlays().values()]
    elif isinstance(overlay, basestring):
        overlays = [get_overlays()[overlay]]
    else:
        overlays = [overlay]

    overlay_dict = {}
    for overlay in overlays:
        if overlay.is_active():
            overlay_dict[overlay.name] = {
                'html': overlay.get_projector_html(),
                'javascript': overlay.get_javascript()}
        else:
            overlay_dict[overlay.name] = None
    ProjectorSocketHandler.send_updates({'overlays': overlay_dict})


def get_projector_content(slide_dict=None):
    """
    Returns the HTML-Content block of the projector.
    """
    if slide_dict is None:
        slide_dict = config['projector_active_slide'].copy()
    callback = slide_dict.pop('callback', None)

    try:
        return slide_callback[callback](**slide_dict)
    except KeyError:
        return default_slide()


def default_slide():
    """
    Returns the HTML Code for the default slide.
    """
    return render_to_string('projector/default_slide.html')


def get_overlays():
    """
    Returns all overlay objects.

    The returned value is a dictonary with the name of the overlay as key, and
    the overlay object as value.
    """
    overlays = {}
    for receiver, overlay in projector_overlays.send(sender='get_overlays'):
        overlays[overlay.name] = overlay
    return overlays


def get_projector_overlays():
    """
    Returns the HTML code for all active overlays.
    """
    overlays = [{'name': key, 'html': overlay.get_projector_html()}
                for key, overlay in get_overlays().items()
                if overlay.is_active()]
    return render_to_string('projector/all_overlays.html', {'overlays': overlays})


def get_projector_overlays_js():
    """
    Returns JS-Code for the overlays.

    The retuned value is a list of json objects.
    """
    javascript = []
    for overlay in get_overlays().values():
        if overlay.is_active():
            overlay_js = overlay.get_javascript()
            if overlay_js:
                javascript.append(json.dumps(overlay_js))
    return javascript


def register_slide(name, callback):
    """
    Register a function as slide callback.
    """
    slide_callback[name] = callback


def register_slide_model(SlideModel, template):
    """
    Shortcut for register_slide for a Model with the SlideMixin.

    The Argument 'SlideModel' has to be a Django-Model-Class, which is a subclass
    of SlideMixin. Template has to be a string to the path of a template.
    """

    def model_slide(**kwargs):
        """
        Return the html code for the model slide.
        """
        slide_pk = kwargs.get('pk', None)

        try:
            slide = SlideModel.objects.get(pk=slide_pk)
        except SlideModel.DoesNotExist:
            slide = None
            context = {'slide': None}
        else:
            context = slide.get_slide_context()

        return render_to_string(template, context)

    register_slide(SlideModel.slide_callback_name, model_slide)


def set_active_slide(callback, kwargs=None):
    """
    Set the active Slide.

    callback: The name of the slide callback.
    kwargs: Keyword arguments for the slide callback.
    """
    kwargs = kwargs or {}
    kwargs.update(callback=callback)
    config['projector_active_slide'] = kwargs
    update_projector()
    update_projector_overlay(None)


def get_active_slide():
    """
    Returns the dictonary, which defines the active slide.
    """
    return config['projector_active_slide']


def get_all_widgets(request, session=False):
    """
    Collects the widgets from all apps and returns the Widget objects as sorted
    dictionary.

    The session flag decides whether to return only the widgets which are
    active, that means that they are mentioned in the session.
    """
    all_module_widgets = []
    for app in settings.INSTALLED_APPS:
        try:
            mod = import_module(app + '.views')
        except ImportError:
            continue
        try:
            mod_get_widgets = mod.get_widgets
        except AttributeError:
            continue
        else:
            module_widgets = mod_get_widgets(request)
        all_module_widgets.extend(module_widgets)
    all_module_widgets.sort(key=lambda widget: widget.default_weight)
    session_widgets = request.session.get('widgets', {})
    widgets = SortedDict()
    for widget in all_module_widgets:
        if (widget.permission_required is None or
                request.user.has_perm(widget.permission_required)):
            if not session or session_widgets.get(widget.get_name(), True):
                widgets[widget.get_name()] = widget
    return widgets