Page.py

#!/usr/bin/env python
#  -*- mode: python; indent-tabs-mode: nil; -*- coding: utf-8 -*-

"""
Page.py

Copyright 2009-2010 by Marcello Perathoner

Distributable under the GNU General Public License Version 3 or newer.

Base class for all pages.

"""

from __future__ import unicode_literals

import logging

import cherrypy

from libgutenberg.MediaTypes import mediatypes as mt
from libgutenberg.GutenbergDatabase import DatabaseError

import BaseSearcher
import Formatters
from i18n_tool import ugettext as _

class Page (object):
    """ Base for all pages. """

    def __init__ (self):
        self.supported_book_mediatypes = [ mt.epub, mt.mobi ]


    @staticmethod
    def format (os):
        """ Output page. """
        return Formatters.formatters[os.format].format (os.template, os)


    def client_book_mediatypes (self):
        """ Return the book mediatypes accepted by the client. """
        client_accepted_book_mediatypes = []

        accept_header = cherrypy.request.headers.get ('Accept')

        if accept_header is None:
            client_accepted_book_mediatypes = self.supported_book_mediatypes
        else:
            #cherrypy.log ("Accept: %s" % accept_header,
            #              context = 'REQUEST', severity = logging.DEBUG)

            client_accepted_book_mediatypes = []
            accepts = cherrypy.request.headers.elements ('Accept')
            for accept in accepts:
                if accept.value in self.supported_book_mediatypes:
                    if accept.qvalue > 0:
                        client_accepted_book_mediatypes.append (accept.value)

        return client_accepted_book_mediatypes


class NullPage (Page):
    """ An empty page. """

    def index (self, **dummy_kwargs):
        """ Output an empty page. """
        return '<html/>'

class GoHomePage (Page):
    """ Go to start page. """
    def index (self, **kwargs):
        os = BaseSearcher.OpenSearch ()
        raise cherrypy.HTTPRedirect (os.url ('start'))

class SearchPage (Page):
    """ Abstract base class for all search page classes. """

    def setup (self, dummy_os, dummy_sql):
        """ Let derived classes setup the query. """
        raise NotImplementedError

    def fixup (self, os):
        """ Give derived classes a chance to further manipulate database results. """
        pass

    def finalize (self, os):
        """ Give derived classes a chance to fix default finalization. """
        pass

    def nothing_found (self, os):
        """ Give derived class a chance to react if no records were found. """
        os.entries.insert (0, self.no_records_found (os))


    def output_suggestions (self, os, max_suggestions_per_word = 3):
        """ Make suggestions. """

        # similarity == matching_trigrams / (len1 + len2 - matching_trigrams)

        sql_query = """
            SELECT
               word,
               nentry,
               similarity (word, %(word)s) AS sml
            FROM terms
            WHERE word %% %(word)s
            ORDER BY sml DESC, nentry DESC LIMIT %(suggestions)s;"""

        q = os.query.lower ()
        sugg = []
        for word in q.split ():
            if len (word) > 3:
                try:
                    rows = BaseSearcher.SQLSearcher().execute (
                        sql_query,
                        { 'word': word, 'suggestions': max_suggestions_per_word + 1})
                    for i, row in enumerate (rows):
                        if i >= max_suggestions_per_word:
                            break
                        corr = row.word
                        if corr != word:
                            sugg.append ( (word, corr) )
                except DatabaseError:
                    pass

        for word, corr in reversed (sugg):
            os.entries.insert (0, self.did_you_mean (os, corr, q.replace (word, corr)))



    def index (self, **kwargs):
        """ Output a search result page. """

        os = BaseSearcher.OpenSearch ()
        os.log_request ('search')

        if 'default_prefix' in kwargs:
            raise cherrypy.HTTPError (400, 'Bad Request. Unknown parameter: default_prefix')

        if os.start_index > BaseSearcher.MAX_RESULTS:
            raise cherrypy.HTTPError (400, 'Bad Request. Parameter start_index too high')

        sql = BaseSearcher.SQLStatement ()
        sql.query = 'SELECT *'
        sql.from_ = ['v_appserver_books_4 as books']

        # let derived classes prepare the query
        try:
            self.setup (os, sql)
        except ValueError as what:
            raise cherrypy.HTTPError (400, 'Bad Request. ' + str (what))

        os.fix_sortorder ()

        # execute the query
        try:
            BaseSearcher.SQLSearcher ().search (os, sql)
        except DatabaseError as what:
            cherrypy.log ("SQL Error: " + str (what),
                          context = 'REQUEST', severity = logging.ERROR)
            raise cherrypy.HTTPError (400, 'Bad Request. Check your query.')

        # sync os.title and first entry header
        if os.entries:
            entry = os.entries[0]
            if os.title and not entry.header:
                entry.header = os.title
            elif entry.header and not os.title:
                os.title = entry.header

        os.template = os.page = 'results'

        # give derived class a chance to tweak result set
        self.fixup (os)

        # warn user about no records found
        if os.total_results == 0:
            self.nothing_found (os)

        # suggest alternate queries
        if os.total_results < 5:
            self.output_suggestions (os)

        # add sort by links
        if os.start_index == 1 and os.total_results > 1:
            if 'downloads' in os.alternate_sort_orders:
                self.sort_by_downloads (os)
            if 'release_date' in os.alternate_sort_orders:
                self.sort_by_release_date (os)
            if 'title' in os.alternate_sort_orders:
                self.sort_by_title (os)
            if 'alpha' in os.alternate_sort_orders:
                self.sort_alphabetically (os)
            if 'quantity' in os.alternate_sort_orders:
                self.sort_by_quantity (os)

        os.finalize ()
        self.finalize (os)

        if os.total_results > 0:
            # call this after finalize ()
            os.entries.insert (0, self.status_line (os))

        return self.format (os)


    @staticmethod
    def sort_by_downloads (os):
        """ Append the sort by downloads link. """

        cat = BaseSearcher.Cat ()
        cat.rel = 'popular'
        cat.title = _('Sort by Popularity')
        cat.url = os.url_carry (sort_order = 'downloads')
        cat.class_ += 'navlink grayed'
        cat.icon = 'popular'
        cat.order = 4.0
        os.entries.insert (0, cat)

    @staticmethod
    def sort_alphabetically (os):
        """ Append the sort alphabetically link. """

        cat = BaseSearcher.Cat ()
        cat.rel = 'alphabethical'
        cat.title = _('Sort Alphabetically')
        cat.url = os.url_carry (sort_order = 'alpha')
        cat.class_ += 'navlink grayed'
        cat.icon = 'alpha'
        cat.order = 4.1
        os.entries.insert (0, cat)

    @staticmethod
    def sort_by_title (os):
        """ Append the sort alphabetically link. """

        cat = BaseSearcher.Cat ()
        cat.rel = 'alphabethical'
        cat.title = _('Sort Alphabetically')
        cat.url = os.url_carry (sort_order = 'title')
        cat.class_ += 'navlink grayed'
        cat.icon = 'alpha'
        cat.order = 4.1
        os.entries.insert (0, cat)

    @staticmethod
    def sort_by_quantity (os):
        """ Append the sort by quantity link. """

        cat = BaseSearcher.Cat ()
        cat.rel = 'numerous'
        cat.title = _('Sort by Quantity')
        cat.url = os.url_carry (sort_order = 'quantity')
        cat.class_ += 'navlink grayed'
        cat.icon = 'quantity'
        cat.order = 4.2
        os.entries.insert (0, cat)

    @staticmethod
    def sort_by_release_date (os):
        """ Append the sort by release date link. """

        cat = BaseSearcher.Cat ()
        cat.rel = 'new'
        cat.title = _('Sort by Release Date')
        cat.url = os.url_carry (sort_order = 'release_date')
        cat.class_ += 'navlink grayed'
        cat.icon = 'date'
        cat.order = 4.3
        os.entries.insert (0, cat)

    @staticmethod
    def status_line (os):
        """ Placeholder for status line. """

        cat = BaseSearcher.Cat ()
        cat.rel = '__statusline__'
        cat.class_ += 'grayed'
        cat.icon = 'bibrec'
        cat.order = 10
        cat.header = os.title
        cat.title = _(u"Displaying results {from_}–{to}").format (
            from_ = os.start_index, to = os.end_index)
        return cat

    @staticmethod
    def no_records_found (os):
        """ Message. """

        cat = BaseSearcher.Cat ()
        cat.rel = '__notfound__'
        cat.title = _('No records found.')
        cat.url = os.url ('start')
        cat.class_ += 'navlink grayed'
        cat.icon = 'bibrec'
        cat.order = 11
        return cat

    @staticmethod
    def did_you_mean (os, corr, corrected_query):
        """ Message. """

        cat = BaseSearcher.Cat ()
        cat.rel = '__didyoumean__'
        cat.title = _('Did you mean: {correction}').format (correction = corr)
        cat.url = os.url ('search', query = corrected_query)
        cat.class_ += 'navlink'
        cat.icon = 'suggestion'
        cat.order = 12
        return cat