"""
The module provides access to QueryParser and QueryCreator classes.
QueryParsers parse search strings to odml query dictionaries that can be
consumed by QueryCreators. QueryCreators create RDF queries from
provided odml query dictionaries.
"""

import re
from abc import ABCMeta, abstractmethod

from rdflib import RDF
from rdflib.plugins.sparql import prepareQuery

from ..format import Document
from ..format import Property
from ..format import Section
from ..format import Format

odmlns = Format.namespace()


class BaseQueryCreator:
    """
    An abstract base class for odml specific QueryCreators.
    """

    __metaclass__ = ABCMeta

    possible_query_variables = {"d": "Document", "s": "Section",
                                "p": "Property", "v": "Bag URI", "value": "Value"}

    possible_q_dict_keys = ["Doc", "Sec", "Prop"]

    def __init__(self, q_dict=None):
        """
        :param q_dict: dictionary with query parameters
        """
        self.q_dict = q_dict if q_dict else {}
        self.query = ""
        super(BaseQueryCreator, self).__init__()

    @abstractmethod
    def get_query(self, q_str, q_parser):
        """
        Constructs a SPARQL query from an input string.

        :param q_str: input string.
        :param q_parser: parser to use on the input string.
        :return SPARQL query.
        """
        pass

    @abstractmethod
    def _prepare_query(self):
        pass


class BaseQueryParser:
    """
    An abstract base class for QueryParsers.
    """

    __metaclass__ = ABCMeta

    def __init__(self):
        self.q_dict = {}

    @abstractmethod
    def parse_query_string(self, q_str):
        """
        Parses an input string and return a dictionary consumable by a QueryCreator.
        """
        pass


class QueryParserFuzzy(BaseQueryParser):
    """
    This class parses an odml specific input string and uses
    heuristics to approximate which Section or Property attributes
    should be matched against multiple search parameters and constructs
    an odml specific SPARQL query.
    """

    def __init__(self):
        super(QueryParserFuzzy, self).__init__()

    def parse_query_string(self, q_str):
        """
        Parse query string and returns dict object with parameters.

        :param q_str: query string.
                      Example: FIND sec(name, type) prop(type) HAVING Stimulus, Contrast
        :return: dict object.
                 Example: {'Sec': ['name', 'type'],
                           'Doc': ['author'],
                           'Search': ['Stimulus', 'Contrast']}
        """
        self.q_dict = {}
        find_pattern = re.compile("FIND(.*?)HAVING")
        find_group = re.search(find_pattern, q_str).group(1).strip()
        if find_group:
            self._parse_find(find_group)

        having_pattern = re.compile("HAVING(.*)")
        having_group = re.search(having_pattern, q_str).group(1).strip()
        if having_group:
            if "Search" in self.q_dict.keys():
                raise ValueError("Search values are already parsed")
            self._parse_having(having_group)
        else:
            raise ValueError("Search values in having part were not specified")

        return self.q_dict

    def _parse_find(self, find_part):
        """
        Parses find string part into list of specific keys to which search values
        would be applied. e.g. 'sec(name, type) prop(name)'
                into {'Sec': ['name', 'type'], 'Prop': ['name']}.

        :param find_part: string which represent list of searchable odML data model
                          objects like document(doc), sections(sec) or properties(prop).
                          e.g. 'sec(name, type) prop(name)'
        """
        doc_pattern = re.compile("(doc|document)[(].*?[)]")
        doc = re.search(doc_pattern, find_part)
        if doc:
            self._parse_doc(doc)

        sec_pattern = re.compile("(sec|section)[(].*?[)]")
        sec = re.search(sec_pattern, find_part)
        if sec:
            self._parse_sec(sec)

        prop_pattern = re.compile("(prop|property)[(].*?[)]")
        prop = re.search(prop_pattern, find_part)
        if prop:
            self._parse_prop(prop)

    def _parse_doc(self, doc):
        re_obj = re.compile("[(, ](id|author|date|version|repository|sections)[),]")
        if doc:
            self.q_dict["Doc"] = re.findall(re_obj, doc.group(0))

    def _parse_sec(self, sec):
        attr_list = "id|name|definition|type|repository|reference|sections|properties"
        pattern = "[(, ](%s)[),]" % attr_list
        re_obj = re.compile(pattern)
        if sec:
            self.q_dict["Sec"] = re.findall(re_obj, sec.group(0))

    def _parse_prop(self, prop):
        attr_list = "id|name|definition|dtype|unit|uncertainty|reference|value_origin"
        pattern = "[(, ](%s)[),]" % attr_list
        re_obj = re.compile(pattern)
        if prop:
            self.q_dict["Prop"] = re.findall(re_obj, prop.group(0))

    def _parse_having(self, having_part):
        """
        Parses search value string into list of specific values.
        e.g. 'Stimulus, Contrast, Date' into list [Stimulus, Contrast, Date].

        :param having_part: string with search values, e.g. 'Stimulus, Contrast'
                      Also spaces errors in the string like 'Stimulus,   , Contrast'
                      will be ignored.
        """
        search_values_list = []
        search_params = re.compile("(.*?)(?:,|$)")
        if having_part:
            search_values = re.findall(search_params, having_part)
            for val in search_values:
                if val.strip():
                    search_values_list.append(val.strip())
        self.q_dict["Search"] = search_values_list


class QueryParser(BaseQueryParser):
    """
    This class parses an odml specific input string into an odml specific SPARQL query.
    """

    def __init__(self):
        super(QueryParser, self).__init__()

    def parse_query_string(self, q_str):
        """
        :param q_str: query string
                      Example: doc(author:D. N. Adams) section(name:Stimulus)
                      prop(name:Contrast, value:20, unit:%)
        :return: dict object
                 Example: {'Sec': [('name', 'Stimulus')],
                           'Doc': [('author', 'D. N. Adams')],
                           'Prop': [('name', 'Contrast'), ('value':[20]), ('unit':'%')]}
        """
        doc_pattern = re.compile("(doc|document)[(].*?[)]")
        doc = re.search(doc_pattern, q_str)
        if doc:
            self._parse_doc(doc)

        sec_pattern = re.compile("(sec|section)[(].*?[)]")
        sec = re.search(sec_pattern, q_str)
        if sec:
            self._parse_sec(sec)

        prop_pattern = re.compile("(prop|property)[(].*?[)]")
        prop = re.search(prop_pattern, q_str)
        if prop:
            self._parse_prop(prop)

        return self.q_dict

    def _parse_doc(self, doc):
        attr_list = "id|author|date|version|repository|sections"
        pattern = "[, (](%s):(.*?)[,)]" % attr_list
        re_obj = re.compile(pattern)
        if doc:
            self.q_dict["Doc"] = re.findall(re_obj, doc.group(0))

    def _parse_sec(self, sec):
        attr_list = "id|name|definition|type|repository|reference|sections|properties"
        pattern = "[, (](%s):(.*?)[,)]" % attr_list
        re_obj = re.compile(pattern)
        if sec:
            self.q_dict["Sec"] = re.findall(re_obj, sec.group(0))

    def _parse_prop(self, prop):
        attr_list = "id|name|definition|dtype|unit|uncertainty|reference|value_origin"
        pattern = "[, (](%s):(.*?)[,)]" % attr_list
        re_obj = re.compile(pattern)
        if prop:
            self.q_dict["Prop"] = re.findall(re_obj, prop.group(0))

            p_value = re.compile(r"value:\[(.*)]")

            value_group = re.findall(p_value, prop.group(0))
            if value_group:
                values = re.split(", ?", value_group[0])
                self.q_dict["Prop"].append(("value", values))


class QueryCreator(BaseQueryCreator):
    """
    Class for simplifying the creation of prepared SPARQL queries.

    Usage:
        query = "doc(author:D. N. Adams) section(name:Stimulus)
                 prop(name:Contrast, value:20, unit:%)"
        prepared_query = QueryCreator().get_query(query, QueryParser())

        query = "FIND sec(name, type) prop(name) HAVING Recording,
                 Recording-2012-04-04-ab, Date"
        prepared_query = QueryCreator().get_query(query, QueryParser2())
    """

    def __init__(self, q_dict=None):
        """
        :param q_dict: dictionary with query parameters
        """
        super(QueryCreator, self).__init__(q_dict)

    def get_query(self, q_str=None, q_parser=None):
        """
        :param q_parser: one of possible query parsers.
        :param q_str: doc(author:D. N. Adams) section(name:Stimulus)
                      prop(name:Contrast, value:20, unit:%)
        :return rdflib prepared query.
        """
        if not self.q_dict:
            if not q_str:
                raise AttributeError("Please fulfill q_str param (query string)")
            elif not q_parser:
                raise AttributeError("Please fulfill q_parser param (query parser)")
            self.q_dict = q_parser.parse_query_string(q_str)
        self._prepare_query()

        use_ns = {"odml": odmlns, "rdf": RDF}
        return prepareQuery(self.query, initNs=use_ns)

    def _prepare_query(self):
        """
        Creates rdflib query using parameters from self.q_dict.

        :return: string representing rdflib query.
        """

        odml_uri = str(odmlns)
        self.query = "SELECT * WHERE {\n"

        if "Doc" in self.q_dict.keys():
            doc_attrs = self.q_dict["Doc"]
            if len(doc_attrs) > 0:
                self.query += "?d rdf:type odml:Document .\n"
                for i in doc_attrs:
                    if len(i) > 2:
                        msg = "Attributes in the query \"{}\" are not valid.".format(i)
                        raise ValueError(msg)
                    else:
                        attr = Document.rdf_map(i[0])
                        if attr:
                            re_sub = re.sub(odml_uri, "odml:", attr)
                            self.query += "?d {0} \"{1}\" .\n".format(re_sub, i[1])

        if "Sec" in self.q_dict.keys():
            sec_attrs = self.q_dict["Sec"]
            if len(sec_attrs) > 0:
                self.query += "?d odml:hasSection ?s .\n"
                self.query += "?s rdf:type odml:Section .\n"
                for i in sec_attrs:
                    if len(i) > 2:
                        msg = "Attributes in the query \"{}\" are not valid.".format(i)
                        raise ValueError(msg)
                    else:
                        attr = Section.rdf_map(i[0])
                        if attr:
                            re_sub = re.sub(odml_uri, "odml:", attr)
                            self.query += "?s {0} \"{1}\" .\n".format(re_sub, i[1])

        if "Prop" in self.q_dict.keys():
            prop_attrs = self.q_dict["Prop"]
            if len(prop_attrs) > 0:
                self.query += "?s odml:hasProperty ?p .\n"
                self.query += "?p rdf:type odml:Property .\n"
                for i in prop_attrs:
                    if len(i) > 2:
                        msg = "Attributes in the query \"{}\" are not valid.".format(i)
                        raise ValueError(msg)
                    elif i[0] == "value":
                        values = i[1]
                        if values:
                            self.query += "?p odml:hasValue ?v .\n?v rdf:type rdf:Bag .\n"
                            for val in values:
                                self.query += "?v rdf:li \"{}\" .\n".format(val)
                    else:
                        attr = Property.rdf_map(i[0])
                        if attr:
                            re_sub = re.sub(odml_uri, "odml:", attr)
                            self.query += "?p {0} \"{1}\" .\n".format(re_sub, i[1])

        self.query += "}\n"
        return self.query