# copyright 2003-2011 LOGILAB S.A. (Paris, FRANCE), all rights reserved.

# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr

#

# This file is part of CubicWeb.

#

# CubicWeb is free software: you can redistribute it and/or modify it under the

# terms of the GNU Lesser General Public License as published by the Free

# Software Foundation, either version 2.1 of the License, or (at your option)

# any later version.

#

# CubicWeb is distributed in the hope that it will be useful, but WITHOUT

# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

# FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more

# details.

#

# You should have received a copy of the GNU Lesser General Public License along

# with CubicWeb.  If not, see <http://www.gnu.org/licenses/>.

"""This module provides some generic components to navigate in the web

application.

Pagination

----------

Several implementations for large result set pagination are provided:

.. autoclass:: PageNavigation

.. autoclass:: PageNavigationSelect

.. autoclass:: SortedNavigation

Pagination will appear when needed according to the `page-size` ui property.

This module monkey-patch the :func:`paginate` function to the base :class:`View`

class, so that you can ask pagination explicitly on every result-set based views.

.. autofunction:: paginate

Previous / next navigation

--------------------------

An adapter and its related component for the somewhat usal "previous / next"

navigation are provided.

  .. autoclass:: IPrevNextAdapter

  .. autoclass:: NextPrevNavigationComponent

"""

__docformat__ = "restructuredtext en"

_ = unicode

from datetime import datetime

from rql.nodes import VariableRef, Constant

from logilab.mtconverter import xml_escape

from logilab.common.deprecation import deprecated

from cubicweb.predicates import (paginated_rset, sorted_rset,

                                adaptable, implements)

from cubicweb.uilib import cut

from cubicweb.view import EntityAdapter, implements_adapter_compat

from cubicweb.web.component import EmptyComponent, EntityCtxComponent, NavigationComponent

class PageNavigation(NavigationComponent):

    """The default pagination component: display link to pages where each pages

    is identified by the item number of its first and last elements.

    """

    def call(self):

        """displays a resultset by page"""

        params = dict(self._cw.form)

        self.clean_params(params)

        basepath = self._cw.relative_path(includeparams=False)

        self.w(u'<div class="pagination">')

        self.w(self.previous_link(basepath, params))

        self.w(u'[ %s ]' %

               u' | '.join(self.iter_page_links(basepath, params)))

        self.w(u'  %s' % self.next_link(basepath, params))

        self.w(u'</div>')

    def index_display(self, start, stop):

        return u'%s - %s' % (start+1, stop+1)

    def iter_page_links(self, basepath, params):

        rset = self.cw_rset

        page_size = self.page_size

        start = 0

        while start < rset.rowcount:

            stop = min(start + page_size - 1, rset.rowcount - 1)

            yield self.page_link(basepath, params, start, stop,

                                 self.index_display(start, stop))

            start = stop + 1

class PageNavigationSelect(PageNavigation):

    """This pagination component displays a result-set by page as

    :class:`PageNavigation` but in a <select>, which is better when there are a

    lot of results.

    By default it will be selected when there are more than 4 pages to be

    displayed.

    """

    __select__ = paginated_rset(4)

    page_link_templ = u'<option value="%s" title="%s">%s</option>'

    selected_page_link_templ = u'<option value="%s" selected="selected" title="%s">%s</option>'

    def call(self):

        params = dict(self._cw.form)

        self.clean_params(params)

        basepath = self._cw.relative_path(includeparams=False)

        w = self.w

        w(u'<div class="pagination">')

        w(self.previous_link(basepath, params))

        w(u'<select onchange="javascript: document.location=this.options[this.selectedIndex].value">')

        for option in self.iter_page_links(basepath, params):

            w(option)

        w(u'</select>')

        w(u'  %s' % self.next_link(basepath, params))

        w(u'</div>')

class SortedNavigation(NavigationComponent):

    """This pagination component will be selected by default if there are less

    than 4 pages and if the result set is sorted.

    Displayed links to navigate accross pages of a result set are done according

    to the first variable on which the sort is done, and looks like:

        [ana - cro] | [cro - ghe] | ... | [tim - zou]

    You may want to override this component to customize display in some cases.

    .. automethod:: sort_on

    .. automethod:: display_func

    .. automethod:: format_link_content

    .. automethod:: write_links

    Below an example from the tracker cube:

    .. sourcecode:: python

      class TicketsNavigation(navigation.SortedNavigation):

          __select__ = (navigation.SortedNavigation.__select__

                        & ~paginated_rset(4) & is_instance('Ticket'))

          def sort_on(self):

              col, attrname = super(TicketsNavigation, self).sort_on()

              if col == 6:

                  # sort on state, we don't want that

                  return None, None

              return col, attrname

    The idea is that in trackers'ticket tables, result set is first ordered on

    ticket's state while this doesn't make any sense in the navigation. So we

    override :meth:`sort_on` so that if we detect such sorting, we disable the

    feature to go back to item number in the pagination.

    Also notice the `~paginated_rset(4)` in the selector so that if there are

    more than 4 pages to display, :class:`PageNavigationSelect` will still be

    selected.

    """

    __select__ = paginated_rset() & sorted_rset()

    # number of considered chars to build page links

    nb_chars = 5

    def call(self):

        # attrname = the name of attribute according to which the sort

        # is done if any

        col, attrname = self.sort_on()

        index_display = self.display_func(self.cw_rset, col, attrname)

        basepath = self._cw.relative_path(includeparams=False)

        params = dict(self._cw.form)

        self.clean_params(params)

        blocklist = []

        start = 0

        total = self.cw_rset.rowcount

        while start < total:

            stop = min(start + self.page_size - 1, total - 1)

            cell = self.format_link_content(index_display(start), index_display(stop))

            blocklist.append(self.page_link(basepath, params, start, stop, cell))

            start = stop + 1

        self.write_links(basepath, params, blocklist)

    def display_func(self, rset, col, attrname):

        """Return a function that will be called with a row number as argument

        and should return a string to use as link for it.

        """

        if attrname is not None:

            def index_display(row):

                if not rset[row][col]: # outer join

                    return u''

                entity = rset.get_entity(row, col)

                return entity.printable_value(attrname, format='text/plain')

        elif col is None: # smart links disabled.

            def index_display(row):

                return unicode(row)

        elif self._cw.vreg.schema.eschema(rset.description[0][col]).final:

            def index_display(row):

                return unicode(rset[row][col])

        else:

            def index_display(row):

                return rset.get_entity(row, col).view('text')

        return index_display

    def sort_on(self):

        """Return entity column number / attr name to use for nice display by

        inspecting the rset'syntax tree.

        """

        rschema = self._cw.vreg.schema.rschema

        for sorterm in self.cw_rset.syntax_tree().children[0].orderby:

            if isinstance(sorterm.term, Constant):

                col = sorterm.term.value - 1

                return col, None

            var = sorterm.term.get_nodes(VariableRef)[0].variable

            col = None

            for ref in var.references():

                rel = ref.relation()

                if rel is None:

                    continue

                attrname = rel.r_type

                if attrname in ('is', 'has_text'):

                    continue

                if not rschema(attrname).final:

                    col = var.selected_index()

                    attrname = None

                if col is None:

                    # final relation or not selected non final relation

                    if var is rel.children[0]:

                        relvar = rel.children[1].children[0].get_nodes(VariableRef)[0]

                    else:

                        relvar = rel.children[0].variable

                    col = relvar.selected_index()

                if col is not None:

                    break

            else:

                # no relation but maybe usable anyway if selected

                col = var.selected_index()

                attrname = None

            if col is not None:

                # if column type is date[time], set proper 'nb_chars'

                if var.stinfo['possibletypes'] & frozenset(('TZDatetime', 'Datetime',

                                                            'Date')):

                    self.nb_chars = len(self._cw.format_date(datetime.today()))

                return col, attrname

        # nothing usable found, use the first column

        return 0, None

    def format_link_content(self, startstr, stopstr):

        """Return text for a page link, where `startstr` and `stopstr` are the

        text for the lower/upper boundaries of the page.

        By default text are stripped down to :attr:`nb_chars` characters.

        """

        text = u'%s - %s' % (startstr.lower()[:self.nb_chars],

                             stopstr.lower()[:self.nb_chars])

        return xml_escape(text)

    def write_links(self, basepath, params, blocklist):

        """Return HTML for the whole navigation: `blocklist` is a list of HTML

        snippets for each page, `basepath` and `params` will be necessary to

        build previous/next links.

        """

        self.w(u'<div class="pagination">')

        self.w(u'%s ' % self.previous_link(basepath, params))

        self.w(u'[ %s ]' % u' | '.join(blocklist))

        self.w(u' %s' % self.next_link(basepath, params))

        self.w(u'</div>')

def do_paginate(view, rset=None, w=None, show_all_option=True, page_size=None):

    """write pages index in w stream (default to view.w) and then limit the

    result set (default to view.rset) to the currently displayed page if we're

    not explicitly told to display everything (by setting __force_display in

    req.form)

    """

    req = view._cw

    if rset is None:

        rset = view.cw_rset

    if w is None:

        w = view.w

    nav = req.vreg['components'].select_or_none(

        'navigation', req, rset=rset, page_size=page_size, view=view)

    if nav:

        if w is None:

            w = view.w

        if req.form.get('__force_display'):

            # allow to come back to the paginated view

            params = dict(req.form)

            basepath = req.relative_path(includeparams=False)

            del params['__force_display']

            url = nav.page_url(basepath, params)

            w(u'<div class="displayAllLink"><a href="%s">%s</a></div>\n'

              % (xml_escape(url), req._('back to pagination (%s results)')

                                  % nav.page_size))

        else:

            # get boundaries before component rendering

            start, stop = nav.page_boundaries()

            nav.render(w=w)

            params = dict(req.form)

            nav.clean_params(params)

            # make a link to see them all

            if show_all_option:

                basepath = req.relative_path(includeparams=False)

                params['__force_display'] = 1

                params['__fromnavigation'] = 1

                url = nav.page_url(basepath, params)

                w(u'<div class="displayAllLink"><a href="%s">%s</a></div>\n'

                  % (xml_escape(url), req._('show %s results') % len(rset)))

            rset.limit(offset=start, limit=stop-start, inplace=True)

def paginate(view, show_all_option=True, w=None, page_size=None, rset=None):

    """paginate results if the view is paginable

    """

    if view.paginable:

        do_paginate(view, rset, w, show_all_option, page_size)

# monkey patch base View class to add a .paginate([...])

# method to be called to write pages index in the view and then limit the result

# set to the current page

from cubicweb.view import View

View.do_paginate = do_paginate

View.paginate = paginate

View.handle_pagination = False

from cubicweb.interfaces import IPrevNext

class IPrevNextAdapter(EntityAdapter):

    """Interface for entities which can be linked to a previous and/or next

    entity

    .. automethod:: next_entity

    .. automethod:: previous_entity

    """

    __needs_bw_compat__ = True

    __regid__ = 'IPrevNext'

    __select__ = implements(IPrevNext, warn=False) # XXX for bw compat, else should be abstract

    @implements_adapter_compat('IPrevNext')

    def next_entity(self):

        """return the 'next' entity"""

        raise NotImplementedError

    @implements_adapter_compat('IPrevNext')

    def previous_entity(self):

        """return the 'previous' entity"""

        raise NotImplementedError

class NextPrevNavigationComponent(EntityCtxComponent):

    """Entities adaptable to the 'IPrevNext' should have this component

    automatically displayed. You may want to override this component to have a

    different look and feel.

    """

    __regid__ = 'prevnext'

    # register msg not generated since no entity implements IPrevNext in cubicweb

    # itself

    help = _('ctxcomponents_prevnext_description')

    __select__ = EntityCtxComponent.__select__ & adaptable('IPrevNext')

    context = 'navbottom'

    order = 10

    @property

    def prev_icon(self):

        return '<img src="%s" alt="%s" />' % (

            xml_escape(self._cw.data_url('go_prev.png')), self._cw._('previous page'))

    @property

    def next_icon(self):

        return '<img src="%s" alt="%s" />' % (

            xml_escape(self._cw.data_url('go_next.png')), self._cw._('next page'))

    def init_rendering(self):

        adapter = self.entity.cw_adapt_to('IPrevNext')

        self.previous = adapter.previous_entity()

        self.next = adapter.next_entity()

        if not (self.previous or self.next):

            raise EmptyComponent()

    def render_body(self, w):

        w(u'<div class="prevnext">')

        self.prevnext(w)

        w(u'</div>')

        w(u'<div class="clear"></div>')