"""a query preprocesser to handle quick search shortcuts for cubicweb

:organization: Logilab

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

:license: GNU Lesser General Public License, v2.1 - http://www.gnu.org/licenses

"""

__docformat__ = "restructuredtext en"

import re

from logging import getLogger

from rql import RQLSyntaxError, BadRQLQuery, parse

from rql.nodes import Relation

from cubicweb import Unauthorized

from cubicweb.view import Component

LOGGER = getLogger('cubicweb.magicsearch')

def _get_approriate_translation(translations_found, eschema):

    """return the first (should be the only one) possible translation according

    to the given entity type

    """

    # get the list of all attributes / relations for this kind of entity

    existing_relations = set(eschema.subject_relations())

    consistent_translations = translations_found & existing_relations

    if len(consistent_translations) == 0:

        return None

    return consistent_translations.pop()

def translate_rql_tree(rqlst, translations, schema):

    """Try to translate each relation in the RQL syntax tree

    :type rqlst: `rql.stmts.Statement`

    :param rqlst: the RQL syntax tree

    :type translations: dict

    :param translations: the reverted l10n dict

    :type schema: `cubicweb.schema.Schema`

    :param schema: the instance's schema

    """

    # var_types is used as a map : var_name / var_type

    vartypes = {}

    # ambiguous_nodes is used as a map : relation_node / (var_name, available_translations)

    ambiguous_nodes = {}

    # For each relation node, check if it's a localized relation name

    # If it's a localized name, then use the original relation name, else

    # keep the existing relation name

    for relation in rqlst.get_nodes(Relation):

        rtype = relation.r_type

        lhs, rhs = relation.get_variable_parts()

        if rtype == 'is':

            try:

                etype = translations[rhs.value]

                rhs.value = etype

            except KeyError:

                # If no translation found, leave the entity type as is

                etype = rhs.value

            # Memorize variable's type

            vartypes[lhs.name] = etype

        else:

            try:

                translation_set = translations[rtype]

            except KeyError:

                pass # If no translation found, leave the relation type as is

            else:

                # Only one possible translation, no ambiguity

                if len(translation_set) == 1:

                    relation.r_type = iter(translations[rtype]).next()

                # More than 1 possible translation => resolve it later

                else:

                    ambiguous_nodes[relation] = (lhs.name, translation_set)

    if ambiguous_nodes:

        resolve_ambiguities(vartypes, ambiguous_nodes, schema)

def resolve_ambiguities(var_types, ambiguous_nodes, schema):

    """Tries to resolve remaining ambiguities for translation

    /!\ An ambiguity is when two different string can be localized with

        the same string

    A simple example:

      - 'name' in a company context will be localized as 'nom' in French

      - but ... 'surname' will also be localized as 'nom'

    :type var_types: dict

    :param var_types: a map : var_name / var_type

    :type ambiguous_nodes: dict

    :param ambiguous_nodes: a map : relation_node / (var_name, available_translations)

    :type schema: `cubicweb.schema.Schema`

    :param schema: the instance's schema

    """

    # Now, try to resolve ambiguous translations

    for relation, (var_name, translations_found) in ambiguous_nodes.items():

        try:

            vartype = var_types[var_name]

        except KeyError:

            continue

        # Get schema for this entity type

        eschema = schema.eschema(vartype)

        rtype = _get_approriate_translation(translations_found, eschema)

        if rtype is None:

            continue

        relation.r_type = rtype

QUOTED_SRE = re.compile(r'(.*?)(["\'])(.+?)\2')

TRANSLATION_MAPS = {}

def trmap(config, schema, lang):

    try:

        return TRANSLATION_MAPS[lang]

    except KeyError:

        assert lang in config.translations, '%s %s' % (lang, config.translations)

        tr, ctxtr = config.translations[lang]

        langmap = {}

        for etype in schema.entities():

            etype = str(etype)

            langmap[tr(etype).capitalize()] = etype

            langmap[etype.capitalize()] = etype

        for rtype in schema.relations():

            rtype = str(rtype)

            langmap.setdefault(tr(rtype).lower(), set()).add(rtype)

            langmap.setdefault(rtype, set()).add(rtype)

        TRANSLATION_MAPS[lang] = langmap

        return langmap

class BaseQueryProcessor(Component):

    __abstract__ = True

    id = 'magicsearch_processor'

    # set something if you want explicit component search facility for the

    # component

    name = None

    def process_query(self, uquery, req):

        args = self.preprocess_query(uquery, req)

        try:

            return req.execute(*args)

        finally:

            # rollback necessary to avoid leaving the connection in a bad state

            req.cnx.rollback()

    def preprocess_query(self, uquery, req):

        raise NotImplementedError()

class DoNotPreprocess(BaseQueryProcessor):

    """this one returns the raw query and should be placed in first position

    of the chain

    """

    name = 'rql'

    priority = 0

    def preprocess_query(self, uquery, req):

        return uquery,

class QueryTranslator(BaseQueryProcessor):

    """ parses through rql and translates into schema language entity names

    and attributes

    """

    priority = 2

    def preprocess_query(self, uquery, req):

        rqlst = parse(uquery, print_errors=False)

        schema = self.vreg.schema

        # rql syntax tree will be modified in place if necessary

        translate_rql_tree(rqlst, trmap(self.config, schema, req.lang), schema)

        return rqlst.as_string(),

class QSPreProcessor(BaseQueryProcessor):

    """Quick search preprocessor

    preprocessing query in shortcut form to their RQL form

    """

    priority = 4

    def preprocess_query(self, uquery, req):

        """try to get rql from an unicode query string"""

        args = None

        self.req = req

        try:

            # Process as if there was a quoted part

            args = self._quoted_words_query(uquery)

        ## No quoted part

        except BadRQLQuery:

            words = uquery.split()

            if len(words) == 1:

                args = self._one_word_query(*words)

            elif len(words) == 2:

                args = self._two_words_query(*words)

            elif len(words) == 3:

                args = self._three_words_query(*words)

            else:

                raise

        return args

    def _get_entity_type(self, word):

        """check if the given word is matching an entity type, return it if

        it's the case or raise BadRQLQuery if not

        """

        etype = word.capitalize()

        try:

            return trmap(self.config, self.vreg.schema, self.req.lang)[etype]

        except KeyError:

            raise BadRQLQuery('%s is not a valid entity name' % etype)

    def _get_attribute_name(self, word, eschema):

        """check if the given word is matching an attribute of the given entity type,

        return it normalized if found or return it untransformed else

        """

        """Returns the attributes's name as stored in the DB"""

        # Need to convert from unicode to string (could be whatever)

        rtype = word.lower()

        # Find the entity name as stored in the DB

        translations = trmap(self.config, self.vreg.schema, self.req.lang)

        try:

            translations = translations[rtype]

        except KeyError:

            raise BadRQLQuery('%s is not a valid attribute for %s entity type'

                              % (word, eschema))

        rtype = _get_approriate_translation(translations, eschema)

        if rtype is None:

            raise BadRQLQuery('%s is not a valid attribute for %s entity type'

                              % (word, eschema))

        return rtype

    def _one_word_query(self, word):

        """Specific process for one word query (case (1) of preprocess_rql)

        """

        # if this is an integer, then directly go to eid

        try:

            eid = int(word)

            return 'Any X WHERE X eid %(x)s', {'x': eid}, 'x'

        except ValueError:

            etype = self._get_entity_type(word)

            return '%s %s' % (etype, etype[0]),

    def _complete_rql(self, searchstr, etype, rtype=None, var=None, searchattr=None):

        searchop = ''

        if '%' in searchstr:

            if rtype:

                possible_etypes = self.schema.rschema(rtype).objects(etype)

            else:

                possible_etypes = [self.schema.eschema(etype)]

            if searchattr or len(possible_etypes) == 1:

                searchattr = searchattr or possible_etypes[0].main_attribute()

                searchop = 'LIKE '

        searchattr = searchattr or 'has_text'

        if var is None:

            var = etype[0]

        return '%s %s %s%%(text)s' % (var, searchattr, searchop)

    def _two_words_query(self, word1, word2):

        """Specific process for two words query (case (2) of preprocess_rql)

        """

        etype = self._get_entity_type(word1)

        # this is a valid RQL query : ("Person X", or "Person TMP1")

        if len(word2) == 1 and word2.isupper():

            return '%s %s' % (etype, word2),

        # else, suppose it's a shortcut like : Person Smith

        rql = '%s %s WHERE %s' % (etype, etype[0], self._complete_rql(word2, etype))

        return rql, {'text': word2}

    def _three_words_query(self, word1, word2, word3):

        """Specific process for three words query (case (3) of preprocess_rql)

        """

        etype = self._get_entity_type(word1)

        eschema = self.schema.eschema(etype)

        rtype = self._get_attribute_name(word2, eschema)

        # expand shortcut if rtype is a non final relation

        if not self.schema.rschema(rtype).final:

            return self._expand_shortcut(etype, rtype, word3)

        if '%' in word3:

            searchop = 'LIKE '

        else:

            searchop = ''

        rql = '%s %s WHERE %s' % (etype, etype[0],

                                  self._complete_rql(word3, etype, searchattr=rtype))

        return rql, {'text': word3}

    def _expand_shortcut(self, etype, rtype, searchstr):

        """Expands shortcut queries on a non final relation to use has_text or

        the main attribute (according to possible entity type) if '%' is used in the

        search word

        Transforms : 'person worksat IBM' into

        'Personne P WHERE P worksAt C, C has_text "IBM"'

        """

        # check out all possilbe entity types for the relation represented

        # by 'rtype'

        mainvar = etype[0]

        searchvar = mainvar  + '1'

        rql =  '%s %s WHERE %s %s %s, %s' % (etype, mainvar,  # Person P

                                             mainvar, rtype, searchvar, # P worksAt C

                                             self._complete_rql(searchstr, etype,

                                                                rtype=rtype, var=searchvar))

        return rql, {'text': searchstr}

    def _quoted_words_query(self, ori_rql):

        """Specific process when there's a "quoted" part

        """

        m = QUOTED_SRE.match(ori_rql)

        # if there's no quoted part, then no special pre-processing to do

        if m is None:

            raise BadRQLQuery("unable to handle request %r" % ori_rql)

        left_words = m.group(1).split()

        quoted_part = m.group(3)

        # Case (1) : Company "My own company"

        if len(left_words) == 1:

            try:

                word1 = left_words[0]

                return self._two_words_query(word1, quoted_part)

            except BadRQLQuery, error:

                raise BadRQLQuery("unable to handle request %r" % ori_rql)

        # Case (2) : Company name "My own company";

        elif len(left_words) == 2:

            word1, word2 = left_words

            return self._three_words_query(word1, word2, quoted_part)

            # return ori_rql

        raise BadRQLQuery("unable to handle request %r" % ori_rql)

class FullTextTranslator(BaseQueryProcessor):

    priority = 10

    name = 'text'

    def preprocess_query(self, uquery, req):

        """suppose it's a plain text query"""

        return 'Any X WHERE X has_text %(text)s', {'text': uquery}

class MagicSearchComponent(Component):

    id  = 'magicsearch'

    def __init__(self, req, rset=None):

        super(MagicSearchComponent, self).__init__(req, rset)

        processors = []

        self.by_name = {}

        for processorcls in self.vreg['components']['magicsearch_processor']:

            # instantiation needed

            processor = processorcls()

            processors.append(processor)

            if processor.name is not None:

                assert not processor.name in self.by_name

                self.by_name[processor.name.lower()] = processor

        self.processors = sorted(processors, key=lambda x: x.priority)

    def process_query(self, uquery, req):

        assert isinstance(uquery, unicode)

        try:

            procname, query = uquery.split(':', 1)

            proc = self.by_name[procname.strip().lower()]

            uquery = query.strip()

        except:

            # use processor chain

            unauthorized = None

            for proc in self.processors:

                try:

                    return proc.process_query(uquery, req)

                # FIXME : we don't want to catch any exception type here !

                except (RQLSyntaxError, BadRQLQuery):

                    pass

                except Unauthorized, ex:

                    unauthorized = ex

                    continue

                except Exception, ex:

                    LOGGER.debug('%s: %s', ex.__class__.__name__, ex)

                    continue

            if unauthorized:

                raise unauthorized

        else:

            # let exception propagate

            return proc.process_query(uquery, req)

        raise BadRQLQuery(req._('sorry, the server is unable to handle this query'))