#!/usr/bin/python2.5

#

# Copyright 2008 the Melange authors.

#

# Licensed under the Apache License, Version 2.0 (the "License");

# you may not use this file except in compliance with the License.

# You may obtain a copy of the License at

#

#   http://www.apache.org/licenses/LICENSE-2.0

#

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS,

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

# See the License for the specific language governing permissions and

# limitations under the License.

"""Helpers for displaying arbitrarily nested menus as HTML lists.

"""

__authors__ = [

  '"Todd Larsen" <tlarsen@google.com>',

  ]

from soc.logic import menu

class HtmlMenu:

  """Ordered collection of MenuItem objects as <p>...</p> paragraphs.

  """

  ITEM_PREFIX_FMT = '%(indent)s<p>'

  ITEM_SUFFIX_FMT = '%(indent)s</p>'

  def __init__(self, menu, item_class=None):

    """Wraps an soc.logic.menu.Menu in order to render it as HTML.

    Args:

      menu: an soc.logic.menu.Menu object

      item_class: style used to render the MenuItems contained in menu;

        default is None, which causes AHrefMenuItem to be used  

    """

    self._menu = menu

    # workaround for circular dependency between AHrefMenuItem and this class

    if not item_class:

      item_class = AHrefMenuItem

    self._item_class = item_class

  def getHtmlTags(self, indent):

    """Returns list of HTML tags for arbitrarily nested items in the menu.

    Args:

      indent: string prepended to the beginning of each line of output

        (usually consists entirely of spaces)

    Returns:

      a list of strings that can be joined with '\n' into a single string

      to produce an entire <ul>...</ul> list in HTML

    """

    tags = []

    if self._menu.items:

      tags.append(self.ITEM_PREFIX_FMT % {'indent': indent})

      for item in self._menu.items:

        tags.extend(self._item_class(

            item, menu_class=self.__class__).getHtmlTags(indent + ' '))

      tags.append(self.ITEM_SUFFIX_FMT % {'indent': indent})

    return tags

  def __str__(self):

    return '\n'.join(self.getHtmlTags(''))

class UlMenu(HtmlMenu):

  """Ordered collection of MenuItem objects as a <ul> list.

  """

  ITEM_PREFIX_FMT = '%(indent)s<ul>'

  ITEM_SUFFIX_FMT = '%(indent)s</ul>'

  def __init__(self, menu, item_class=None):

    """Wraps an soc.logic.menu.Menu in order to render it as HTML.

    Args:

      menu: an soc.logic.menu.Menu object

      item_class: style used to render the MenuItems contained in menu;

        default is None, which causes LiMenuItem to be used  

    """

    # workaround for circular dependency between LiMenuItem and this class

    if not item_class:

      item_class = LiMenuItem

    HtmlMenu.__init__(self, menu, item_class=item_class)

class HtmlMenuItem:

  """Base class for specific MenuItem wrappers used by HtmlMenu sub-classes.

  """

  def __init__(self, item, menu_class=HtmlMenu):

    """Wraps an soc.logic.menu.MenuItem in order to render it as HTML.

    Args:

      item: an soc.logic.menu.MenuItem object to wrap, in order to produce

        a representation of it as HTML tags later

      menu_class: a class derived from HtmlMenu, used to style any sub-menu

        of the MenuItem; default is HtmlMenu

    """

    self._item = self.escapeItem(item)

    self._menu_class = menu_class

  def getItemHtmlTags(self, indent):

    """Returns list of HTML tags for the menu item itself.

    This method is intended to be overridden by sub-classes.

    Args:

      indent: string prepended to the beginning of each line of output

        (usually consists entirely of spaces)

    Returns:

      a list of strings that can be joined with '\n' into a single string

      to produce:

        <b>name</b> value <i>(annotation)</i>

      with value and/or <i>(annotation)</i> omitted if either is missing

    """

    # TODO(tlarsen): implement "selected" style

    tags = ['%s<b>%s</b>' % (indent, self._item.name)]

    if self._item.value:

      tags.append('%s%s' % (indent, self._item.value))

    if self._item.annotation:

      tags.append('%s<i>(%s)</i>' % (indent, self._item.annotation))

    return tags

  def getSubMenuHtmlTags(self, indent):

    """Returns list of HTML tags for any sub-menu, if one exists.

    Args:

      indent: string prepended to the beginning of each line of output

        (usually consists entirely of spaces)

    Returns:

      an empty list if there is no sub-menu

        -OR-

      the list of HTML tags that render the entire sub-menu (depends on the

      menu_class that was provided to __init__()

    """

    if not self._item.sub_menu:

      return []

    return self._menu_class(self._item.sub_menu,

        item_class=self.__class__).getHtmlTags(indent)

  def getHtmlTags(self, indent):

    """Returns list of HTML tags for a menu item (and possibly its sub-menus).

    Args:

      indent: string prepended to the beginning of each line of output

        (usually consists entirely of spaces)

    Returns:

      a list of strings that can be joined with '\n' into a single string

      to produce an HTML representation of the wrapped MenuItem, with

      arbitrarily nested sub-menus possibly appended

    """

    return self.getItemHtmlTags(indent) + self.getSubMenuHtmlTags(indent)

  def escapeItem(self, item):

    """HTML-escapes possibly user-supplied fields to prevent XSS.

    Args:

      item: an soc.logic.menu.MenuItem that is altered in-place; the

        fields that are potentially user-provided (name, value, annotation)

        are escaped using self.escapeText()

    Returns:

      the originally supplied item, for convenience, so that this method can

      be combined with an assignment

    """

    item.name = self.escapeText(item.name)

    item.value = self.escapeText(item.value)

    item.annotation = self.escapeText(item.annotation)

    return item

  def escapeText(self, text):

    """

    """

    # TODO(tlarsen): user-supplied content *must* be escaped to prevent XSS

    return text

  def __str__(self):

    return '\n'.join(self.getHtmlTags(''))

class AHrefMenuItem(HtmlMenuItem):

  """Provides HTML menu item properties as attributes as an <a href> link. 

  """

  def getItemHtmlTags(self, indent):

    """Returns list of HTML tags for the menu item itself.

    Args:

      indent: string prepended to the beginning of each line of output

        (usually consists entirely of spaces)

    Returns:

      a list of strings that can be joined with '\n' into a single string

      to produce an <a href="...">...</a> link, or just the MenuItem.name

      as plain text if there was no AHrefMenuItem.value URL

    """

    # TODO(tlarsen): implement "selected" style

    if not self._item.value:

      # if no URL, then not a link, so just display item.name as text

      return [self._item.name]

    # URL supplied, so make an <a href="item.value">item.name</a> link

    return ['%s<a href=' % indent,

            '%s "%s"' % (indent, self._item.value),

            '%s>%s</a>' % (indent, self._item.name)]

class LiMenuItem(AHrefMenuItem):

  """Provides HTML menu item properties as attributes as an <li> list item.

  """

  def __init__(self, item, menu_class=UlMenu):

    """Wraps an soc.logic.menu.MenuItem in order to render it as HTML.

    Args:

      item: an soc.logic.menu.MenuItem object to wrap, in order to produce

        a representation of it as HTML tags later

      menu_class: a class derived from HtmlMenu, used to style any sub-menu

        of the MenuItem; default is UlMenu

    """

    AHrefMenuItem.__init__(self, item, menu_class=menu_class)

  def getHtmlTags(self, indent):

    """Returns <a href> link wrapped as an <li> list item.

    See also AHrefMenuItem.getHtmlTags().

    """

    return (['%s<li>' % indent]

            + AHrefMenuItem.getHtmlTags(self, indent + ' ')

            + ['%s</li>' % indent])