import warnings

from django.conf import settings
from django.core.exceptions import ImproperlyConfigured

import haystack
from haystack.backends import (
    BaseEngine,
    BaseSearchBackend,
    BaseSearchQuery,
    EmptyResults,
    log_query,
)
from haystack.constants import DJANGO_CT, DJANGO_ID, ID
from haystack.exceptions import MissingDependency, MoreLikeThisError, SkipDocument
from haystack.inputs import Clean, Exact, PythonData, Raw
from haystack.models import SearchResult
from haystack.utils import get_identifier, get_model_ct
from haystack.utils import log as logging
from haystack.utils.app_loading import haystack_get_model

try:
    from pysolr import Solr, SolrError
except ImportError:
    raise MissingDependency(
        "The 'solr' backend requires the installation of 'pysolr'. Please refer to the documentation."
    )


class SolrSearchBackend(BaseSearchBackend):
    # Word reserved by Solr for special use.
    RESERVED_WORDS = ("AND", "NOT", "OR", "TO")

    # Characters reserved by Solr for special use.
    # The '\\' must come first, so as not to overwrite the other slash replacements.
    RESERVED_CHARACTERS = (
        "\\",
        "+",
        "-",
        "&&",
        "||",
        "!",
        "(",
        ")",
        "{",
        "}",
        "[",
        "]",
        "^",
        '"',
        "~",
        "*",
        "?",
        ":",
        "/",
    )

    def __init__(self, connection_alias, **connection_options):
        super().__init__(connection_alias, **connection_options)

        if "URL" not in connection_options:
            raise ImproperlyConfigured(
                "You must specify a 'URL' in your settings for connection '%s'."
                % connection_alias
            )

        self.collate = connection_options.get("COLLATE_SPELLING", True)

        # Support to `date_facet` on Solr >= 6.6. Olders set `date`
        self.date_facet_field = connection_options.get("DATE_FACET_FIELD", "range")

        self.conn = Solr(
            connection_options["URL"],
            timeout=self.timeout,
            **connection_options.get("KWARGS", {})
        )
        self.log = logging.getLogger("haystack")

    def update(self, index, iterable, commit=True):
        docs = []

        for obj in iterable:
            try:
                docs.append(index.full_prepare(obj))
            except SkipDocument:
                self.log.debug("Indexing for object `%s` skipped", obj)
            except UnicodeDecodeError:
                if not self.silently_fail:
                    raise

                # We'll log the object identifier but won't include the actual object
                # to avoid the possibility of that generating encoding errors while
                # processing the log message:
                self.log.exception(
                    "UnicodeDecodeError while preparing object for update",
                    extra={"data": {"index": index, "object": get_identifier(obj)}},
                )

        if len(docs) > 0:
            try:
                self.conn.add(docs, commit=commit, boost=index.get_field_weights())
            except (IOError, SolrError):
                if not self.silently_fail:
                    raise

                self.log.exception("Failed to add documents to Solr")

    def remove(self, obj_or_string, commit=True):
        solr_id = get_identifier(obj_or_string)

        try:
            kwargs = {"commit": commit, "id": solr_id}
            self.conn.delete(**kwargs)
        except (IOError, SolrError):
            if not self.silently_fail:
                raise

            self.log.exception(
                "Failed to remove document '%s' from Solr",
                solr_id,
            )

    def clear(self, models=None, commit=True):
        if models is not None:
            assert isinstance(models, (list, tuple))

        try:
            if models is None:
                # *:* matches all docs in Solr
                self.conn.delete(q="*:*", commit=commit)
            else:
                models_to_delete = []

                for model in models:
                    models_to_delete.append("%s:%s" % (DJANGO_CT, get_model_ct(model)))

                self.conn.delete(q=" OR ".join(models_to_delete), commit=commit)

            if commit:
                # Run an optimize post-clear. http://wiki.apache.org/solr/FAQ#head-9aafb5d8dff5308e8ea4fcf4b71f19f029c4bb99
                self.conn.optimize()
        except (IOError, SolrError):
            if not self.silently_fail:
                raise

            if models is not None:
                self.log.exception(
                    "Failed to clear Solr index of models '%s'",
                    ",".join(models_to_delete),
                )
            else:
                self.log.exception("Failed to clear Solr index")

    @log_query
    def search(self, query_string, **kwargs):
        if len(query_string) == 0:
            return {"results": [], "hits": 0}

        search_kwargs = self.build_search_kwargs(query_string, **kwargs)

        try:
            raw_results = self.conn.search(query_string, **search_kwargs)
        except (IOError, SolrError):
            if not self.silently_fail:
                raise

            self.log.exception("Failed to query Solr using '%s'", query_string)
            raw_results = EmptyResults()

        return self._process_results(
            raw_results,
            highlight=kwargs.get("highlight"),
            result_class=kwargs.get("result_class", SearchResult),
            distance_point=kwargs.get("distance_point"),
        )

    def build_search_kwargs(
        self,
        query_string,
        sort_by=None,
        start_offset=0,
        end_offset=None,
        fields="",
        highlight=False,
        facets=None,
        date_facets=None,
        query_facets=None,
        narrow_queries=None,
        spelling_query=None,
        within=None,
        dwithin=None,
        distance_point=None,
        models=None,
        limit_to_registered_models=None,
        result_class=None,
        stats=None,
        collate=None,
        **extra_kwargs
    ):
        index = haystack.connections[self.connection_alias].get_unified_index()

        kwargs = {"fl": "* score", "df": index.document_field}

        if fields:
            if isinstance(fields, (list, set)):
                fields = " ".join(fields)

            kwargs["fl"] = fields

        if sort_by is not None:
            if sort_by in ["distance asc", "distance desc"] and distance_point:
                # Do the geo-enabled sort.
                lng, lat = distance_point["point"].coords
                kwargs["sfield"] = distance_point["field"]
                kwargs["pt"] = "%s,%s" % (lat, lng)

                if sort_by == "distance asc":
                    kwargs["sort"] = "geodist() asc"
                else:
                    kwargs["sort"] = "geodist() desc"
            else:
                if sort_by.startswith("distance "):
                    warnings.warn(
                        "In order to sort by distance, you must call the '.distance(...)' method."
                    )

                # Regular sorting.
                kwargs["sort"] = sort_by

        if start_offset is not None:
            kwargs["start"] = start_offset

        if end_offset is not None:
            kwargs["rows"] = end_offset - start_offset

        if highlight:
            # `highlight` can either be True or a dictionary containing custom parameters
            # which will be passed to the backend and may override our default settings:

            kwargs["hl"] = "true"
            kwargs["hl.fragsize"] = "200"

            if isinstance(highlight, dict):
                # autoprefix highlighter options with 'hl.', all of them start with it anyway
                # this makes option dicts shorter: {'maxAnalyzedChars': 42}
                # and lets some of options be used as keyword arguments: `.highlight(preserveMulti=False)`
                kwargs.update(
                    {
                        key if key.startswith("hl.") else ("hl." + key): highlight[key]
                        for key in highlight.keys()
                    }
                )

        if collate is None:
            collate = self.collate
        if self.include_spelling is True:
            kwargs["spellcheck"] = "true"
            kwargs["spellcheck.collate"] = str(collate).lower()
            kwargs["spellcheck.count"] = 1

            if spelling_query:
                kwargs["spellcheck.q"] = spelling_query

        if facets is not None:
            kwargs["facet"] = "on"
            kwargs["facet.field"] = facets.keys()

            for facet_field, options in facets.items():
                for key, value in options.items():
                    kwargs["f.%s.facet.%s" % (facet_field, key)] = (
                        self.conn._from_python(value)
                    )

        if date_facets is not None:
            kwargs["facet"] = "on"
            kwargs["facet.%s" % self.date_facet_field] = date_facets.keys()
            kwargs["facet.%s.other" % self.date_facet_field] = "none"

            for key, value in date_facets.items():
                kwargs["f.%s.facet.%s.start" % (key, self.date_facet_field)] = (
                    self.conn._from_python(value.get("start_date"))
                )
                kwargs["f.%s.facet.%s.end" % (key, self.date_facet_field)] = (
                    self.conn._from_python(value.get("end_date"))
                )
                gap_by_string = value.get("gap_by").upper()
                gap_string = "%d%s" % (value.get("gap_amount"), gap_by_string)

                if value.get("gap_amount") != 1:
                    gap_string += "S"

                kwargs["f.%s.facet.%s.gap" % (key, self.date_facet_field)] = (
                    "+%s/%s"
                    % (
                        gap_string,
                        gap_by_string,
                    )
                )

        if query_facets is not None:
            kwargs["facet"] = "on"
            kwargs["facet.query"] = [
                "%s:%s" % (field, value) for field, value in query_facets
            ]

        if limit_to_registered_models is None:
            limit_to_registered_models = getattr(
                settings, "HAYSTACK_LIMIT_TO_REGISTERED_MODELS", True
            )

        if models and len(models):
            model_choices = sorted(get_model_ct(model) for model in models)
        elif limit_to_registered_models:
            # Using narrow queries, limit the results to only models handled
            # with the current routers.
            model_choices = self.build_models_list()
        else:
            model_choices = []

        if len(model_choices) > 0:
            if narrow_queries is None:
                narrow_queries = set()

            narrow_queries.add("%s:(%s)" % (DJANGO_CT, " OR ".join(model_choices)))

        if narrow_queries is not None:
            kwargs["fq"] = list(narrow_queries)

        if stats:
            kwargs["stats"] = "true"

            for k in stats.keys():
                kwargs["stats.field"] = k

                for facet in stats[k]:
                    kwargs["f.%s.stats.facet" % k] = facet

        if within is not None:
            from haystack.utils.geo import generate_bounding_box

            kwargs.setdefault("fq", [])
            ((min_lat, min_lng), (max_lat, max_lng)) = generate_bounding_box(
                within["point_1"], within["point_2"]
            )
            # Bounding boxes are min, min TO max, max. Solr's wiki was *NOT*
            # very clear on this.
            bbox = "%s:[%s,%s TO %s,%s]" % (
                within["field"],
                min_lat,
                min_lng,
                max_lat,
                max_lng,
            )
            kwargs["fq"].append(bbox)

        if dwithin is not None:
            kwargs.setdefault("fq", [])
            lng, lat = dwithin["point"].coords
            geofilt = "{!geofilt pt=%s,%s sfield=%s d=%s}" % (
                lat,
                lng,
                dwithin["field"],
                dwithin["distance"].km,
            )
            kwargs["fq"].append(geofilt)

        # Check to see if the backend should try to include distances
        # (Solr 4.X+) in the results.
        if self.distance_available and distance_point:
            # In early testing, you can't just hand Solr 4.X a proper bounding box
            # & request distances. To enable native distance would take calculating
            # a center point & a radius off the user-provided box, which kinda
            # sucks. We'll avoid it for now, since Solr 4.x's release will be some
            # time yet.
            # kwargs['fl'] += ' _dist_:geodist()'
            pass

        if extra_kwargs:
            kwargs.update(extra_kwargs)

        return kwargs

    def more_like_this(
        self,
        model_instance,
        additional_query_string=None,
        start_offset=0,
        end_offset=None,
        models=None,
        limit_to_registered_models=None,
        result_class=None,
        **kwargs
    ):
        from haystack import connections

        # Deferred models will have a different class ("RealClass_Deferred_fieldname")
        # which won't be in our registry:
        model_klass = model_instance._meta.concrete_model

        index = (
            connections[self.connection_alias]
            .get_unified_index()
            .get_index(model_klass)
        )
        field_name = index.get_content_field()
        params = {"fl": "*,score"}

        if start_offset is not None:
            params["start"] = start_offset

        if end_offset is not None:
            params["rows"] = end_offset

        narrow_queries = set()

        if limit_to_registered_models is None:
            limit_to_registered_models = getattr(
                settings, "HAYSTACK_LIMIT_TO_REGISTERED_MODELS", True
            )

        if models and len(models):
            model_choices = sorted(get_model_ct(model) for model in models)
        elif limit_to_registered_models:
            # Using narrow queries, limit the results to only models handled
            # with the current routers.
            model_choices = self.build_models_list()
        else:
            model_choices = []

        if len(model_choices) > 0:
            if narrow_queries is None:
                narrow_queries = set()

            narrow_queries.add("%s:(%s)" % (DJANGO_CT, " OR ".join(model_choices)))

        if additional_query_string:
            narrow_queries.add(additional_query_string)

        if narrow_queries:
            params["fq"] = list(narrow_queries)

        query = "%s:%s" % (ID, get_identifier(model_instance))

        try:
            raw_results = self.conn.more_like_this(query, field_name, **params)
        except (IOError, SolrError):
            if not self.silently_fail:
                raise

            self.log.exception(
                "Failed to fetch More Like This from Solr for document '%s'", query
            )
            raw_results = EmptyResults()

        return self._process_results(raw_results, result_class=result_class)

    def _process_results(
        self, raw_results, highlight=False, result_class=None, distance_point=None
    ):
        from haystack import connections

        results = []
        hits = raw_results.hits
        facets = {}
        stats = {}
        spelling_suggestion = spelling_suggestions = None

        if result_class is None:
            result_class = SearchResult

        if hasattr(raw_results, "stats"):
            stats = raw_results.stats.get("stats_fields", {})

        if hasattr(raw_results, "facets"):
            facets = {
                "fields": raw_results.facets.get("facet_fields", {}),
                "dates": raw_results.facets.get("facet_dates", {}),
                "queries": raw_results.facets.get("facet_queries", {}),
                "ranges": raw_results.facets.get("facet_ranges", {}),
            }

            for key in ["fields"]:
                for facet_field in facets[key]:
                    # Convert to a two-tuple, as Solr's json format returns a list of
                    # pairs.
                    facets[key][facet_field] = list(
                        zip(
                            facets[key][facet_field][::2],
                            facets[key][facet_field][1::2],
                        )
                    )

            for key in ["ranges"]:
                for facet_field in facets[key]:
                    # Convert to a two-tuple, as Solr's json format returns a list of
                    # pairs.
                    facets[key][facet_field] = list(
                        zip(
                            facets[key][facet_field]["counts"][::2],
                            facets[key][facet_field]["counts"][1::2],
                        )
                    )

        if self.include_spelling and hasattr(raw_results, "spellcheck"):
            try:
                spelling_suggestions = self.extract_spelling_suggestions(raw_results)
            except Exception:
                self.log.exception(
                    "Error extracting spelling suggestions: %s",
                    extra={"data": {"spellcheck": raw_results.spellcheck}},
                )

                if not self.silently_fail:
                    raise

                spelling_suggestions = None

            if spelling_suggestions:
                # Maintain compatibility with older versions of Haystack which returned a single suggestion:
                spelling_suggestion = spelling_suggestions[-1]
                assert isinstance(spelling_suggestion, str)
            else:
                spelling_suggestion = None

        unified_index = connections[self.connection_alias].get_unified_index()
        indexed_models = unified_index.get_indexed_models()

        for raw_result in raw_results.docs:
            app_label, model_name = raw_result[DJANGO_CT].split(".")
            additional_fields = {}
            model = haystack_get_model(app_label, model_name)

            if model and model in indexed_models:
                index = unified_index.get_index(model)
                index_field_map = index.field_map
                for key, value in raw_result.items():
                    string_key = str(key)
                    # re-map key if alternate name used
                    if string_key in index_field_map:
                        string_key = index_field_map[key]

                    if string_key in index.fields and hasattr(
                        index.fields[string_key], "convert"
                    ):
                        additional_fields[string_key] = index.fields[
                            string_key
                        ].convert(value)
                    else:
                        additional_fields[string_key] = self.conn._to_python(value)

                del additional_fields[DJANGO_CT]
                del additional_fields[DJANGO_ID]
                del additional_fields["score"]

                if raw_result[ID] in getattr(raw_results, "highlighting", {}):
                    additional_fields["highlighted"] = raw_results.highlighting[
                        raw_result[ID]
                    ]

                if distance_point:
                    additional_fields["_point_of_origin"] = distance_point

                    if raw_result.get("__dist__"):
                        from django.contrib.gis.measure import Distance

                        additional_fields["_distance"] = Distance(
                            km=float(raw_result["__dist__"])
                        )
                    else:
                        additional_fields["_distance"] = None

                result = result_class(
                    app_label,
                    model_name,
                    raw_result[DJANGO_ID],
                    raw_result["score"],
                    **additional_fields
                )
                results.append(result)
            else:
                hits -= 1

        return {
            "results": results,
            "hits": hits,
            "stats": stats,
            "facets": facets,
            "spelling_suggestion": spelling_suggestion,
            "spelling_suggestions": spelling_suggestions,
        }

    def extract_spelling_suggestions(self, raw_results):
        # There are many different formats for Legacy, 6.4, and 6.5 e.g.
        # https://issues.apache.org/jira/browse/SOLR-3029 and depending on the
        # version and configuration the response format may be a dict of dicts,
        # a list of dicts, or a list of strings.

        collations = raw_results.spellcheck.get("collations", None)
        suggestions = raw_results.spellcheck.get("suggestions", None)

        # We'll collect multiple suggestions here. For backwards
        # compatibility with older versions of Haystack we'll still return
        # only a single suggestion but in the future we can expose all of
        # them.

        spelling_suggestions = []

        if collations:
            if isinstance(collations, dict):
                # Solr 6.5
                collation_values = collations["collation"]
                if isinstance(collation_values, str):
                    collation_values = [collation_values]
                elif isinstance(collation_values, dict):
                    # spellcheck.collateExtendedResults changes the format to a dictionary:
                    collation_values = [collation_values["collationQuery"]]
            elif isinstance(collations[1], dict):
                # Solr 6.4
                collation_values = collations
            else:
                # Older versions of Solr
                collation_values = collations[-1:]

            for i in collation_values:
                # Depending on the options the values are either simple strings or dictionaries:
                spelling_suggestions.append(
                    i["collationQuery"] if isinstance(i, dict) else i
                )
        elif suggestions:
            if isinstance(suggestions, dict):
                for i in suggestions.values():
                    for j in i["suggestion"]:
                        if isinstance(j, dict):
                            spelling_suggestions.append(j["word"])
                        else:
                            spelling_suggestions.append(j)
            elif isinstance(suggestions[0], str) and isinstance(suggestions[1], dict):
                # Solr 6.4 uses a list of paired (word, dictionary) pairs:
                for suggestion in suggestions:
                    if isinstance(suggestion, dict):
                        for i in suggestion["suggestion"]:
                            if isinstance(i, dict):
                                spelling_suggestions.append(i["word"])
                            else:
                                spelling_suggestions.append(i)
            else:
                # Legacy Solr
                spelling_suggestions.append(suggestions[-1])

        return spelling_suggestions

    def build_schema(self, fields):
        content_field_name = ""
        schema_fields = []

        for _, field_class in fields.items():
            field_data = {
                "field_name": field_class.index_fieldname,
                "type": "text_en",
                "indexed": "true",
                "stored": "true",
                "multi_valued": "false",
            }

            if field_class.document is True:
                content_field_name = field_class.index_fieldname

            # DRL_FIXME: Perhaps move to something where, if none of these
            #            checks succeed, call a custom method on the form that
            #            returns, per-backend, the right type of storage?
            if field_class.field_type in ["date", "datetime"]:
                field_data["type"] = "date"
            elif field_class.field_type == "integer":
                field_data["type"] = "long"
            elif field_class.field_type == "float":
                field_data["type"] = "float"
            elif field_class.field_type == "boolean":
                field_data["type"] = "boolean"
            elif field_class.field_type == "ngram":
                field_data["type"] = "ngram"
            elif field_class.field_type == "edge_ngram":
                field_data["type"] = "edge_ngram"
            elif field_class.field_type == "location":
                field_data["type"] = "location"

            if field_class.is_multivalued:
                field_data["multi_valued"] = "true"

            if field_class.stored is False:
                field_data["stored"] = "false"

            # Do this last to override `text` fields.
            if field_class.indexed is False:
                field_data["indexed"] = "false"

                # If it's text and not being indexed, we probably don't want
                # to do the normal lowercase/tokenize/stemming/etc. dance.
                if field_data["type"] == "text_en":
                    field_data["type"] = "string"

            # If it's a ``FacetField``, make sure we don't postprocess it.
            if hasattr(field_class, "facet_for"):
                # If it's text, it ought to be a string.
                if field_data["type"] == "text_en":
                    field_data["type"] = "string"

            schema_fields.append(field_data)

        return (content_field_name, schema_fields)

    def extract_file_contents(self, file_obj, **kwargs):
        """Extract text and metadata from a structured file (PDF, MS Word, etc.)

        Uses the Solr ExtractingRequestHandler, which is based on Apache Tika.
        See the Solr wiki for details:

            http://wiki.apache.org/solr/ExtractingRequestHandler

        Due to the way the ExtractingRequestHandler is implemented it completely
        replaces the normal Haystack indexing process with several unfortunate
        restrictions: only one file per request, the extracted data is added to
        the index with no ability to modify it, etc. To simplify the process and
        allow for more advanced use we'll run using the extract-only mode to
        return the extracted data without adding it to the index so we can then
        use it within Haystack's normal templating process.

        Returns None if metadata cannot be extracted; otherwise returns a
        dictionary containing at least two keys:

            :contents:
                        Extracted full-text content, if applicable
            :metadata:
                        key:value pairs of text strings
        """

        try:
            return self.conn.extract(file_obj, **kwargs)
        except Exception:
            self.log.warning(
                "Unable to extract file contents",
                extra={"data": {"file": file_obj}},
            )
            return None


class SolrSearchQuery(BaseSearchQuery):
    def matching_all_fragment(self):
        return "*:*"

    def build_query_fragment(self, field, filter_type, value):
        from haystack import connections

        query_frag = ""

        if not hasattr(value, "input_type_name"):
            # Handle when we've got a ``ValuesListQuerySet``...
            if hasattr(value, "values_list"):
                value = list(value)

            if isinstance(value, str):
                # It's not an ``InputType``. Assume ``Clean``.
                value = Clean(value)
            else:
                value = PythonData(value)

        # Prepare the query using the InputType.
        prepared_value = value.prepare(self)

        if not isinstance(prepared_value, (set, list, tuple)):
            # Then convert whatever we get back to what pysolr wants if needed.
            prepared_value = self.backend.conn._from_python(prepared_value)

        # 'content' is a special reserved word, much like 'pk' in
        # Django's ORM layer. It indicates 'no special field'.
        if field == "content":
            index_fieldname = ""
        else:
            index_fieldname = "%s:" % connections[
                self._using
            ].get_unified_index().get_index_fieldname(field)

        filter_types = {
            "content": "%s",
            "contains": "*%s*",
            "endswith": "*%s",
            "startswith": "%s*",
            "exact": "%s",
            "gt": "{%s TO *}",
            "gte": "[%s TO *]",
            "lt": "{* TO %s}",
            "lte": "[* TO %s]",
            "fuzzy": "%s~",
        }

        if value.post_process is False:
            query_frag = prepared_value
        else:
            if filter_type in [
                "content",
                "contains",
                "startswith",
                "endswith",
                "fuzzy",
            ]:
                if value.input_type_name == "exact":
                    query_frag = prepared_value
                else:
                    # Iterate over terms & incorporate the converted form of each into the query.
                    terms = []

                    for possible_value in prepared_value.split(" "):
                        terms.append(
                            filter_types[filter_type]
                            % self.backend.conn._from_python(possible_value)
                        )

                    if len(terms) == 1:
                        query_frag = terms[0]
                    else:
                        query_frag = "(%s)" % " AND ".join(terms)
            elif filter_type == "in":
                in_options = []

                if not prepared_value:
                    query_frag = "(!*:*)"
                else:
                    for possible_value in prepared_value:
                        in_options.append(
                            '"%s"' % self.backend.conn._from_python(possible_value)
                        )

                    query_frag = "(%s)" % " OR ".join(in_options)
            elif filter_type == "range":
                start = self.backend.conn._from_python(prepared_value[0])
                end = self.backend.conn._from_python(prepared_value[1])
                query_frag = '["%s" TO "%s"]' % (start, end)
            elif filter_type == "exact":
                if value.input_type_name == "exact":
                    query_frag = prepared_value
                else:
                    prepared_value = Exact(prepared_value).prepare(self)
                    query_frag = filter_types[filter_type] % prepared_value
            else:
                if value.input_type_name != "exact":
                    prepared_value = Exact(prepared_value).prepare(self)

                query_frag = filter_types[filter_type] % prepared_value

        if len(query_frag) and not isinstance(value, Raw):
            if not query_frag.startswith("(") and not query_frag.endswith(")"):
                query_frag = "(%s)" % query_frag

        return "%s%s" % (index_fieldname, query_frag)

    def build_alt_parser_query(self, parser_name, query_string="", **kwargs):
        if query_string:
            query_string = Clean(query_string).prepare(self)

        kwarg_bits = []

        for key in sorted(kwargs.keys()):
            if isinstance(kwargs[key], str) and " " in kwargs[key]:
                kwarg_bits.append("%s='%s'" % (key, kwargs[key]))
            else:
                kwarg_bits.append("%s=%s" % (key, kwargs[key]))

        return '_query_:"{!%s %s}%s"' % (
            parser_name,
            Clean(" ".join(kwarg_bits)),
            query_string,
        )

    def build_params(self, spelling_query=None, **kwargs):
        search_kwargs = {
            "start_offset": self.start_offset,
            "result_class": self.result_class,
        }
        order_by_list = None

        if self.order_by:
            if order_by_list is None:
                order_by_list = []

            for order_by in self.order_by:
                if order_by.startswith("-"):
                    order_by_list.append("%s desc" % order_by[1:])
                else:
                    order_by_list.append("%s asc" % order_by)

            search_kwargs["sort_by"] = ", ".join(order_by_list)

        if self.date_facets:
            search_kwargs["date_facets"] = self.date_facets

        if self.distance_point:
            search_kwargs["distance_point"] = self.distance_point

        if self.dwithin:
            search_kwargs["dwithin"] = self.dwithin

        if self.end_offset is not None:
            search_kwargs["end_offset"] = self.end_offset

        if self.facets:
            search_kwargs["facets"] = self.facets

        if self.fields:
            search_kwargs["fields"] = self.fields

        if self.highlight:
            search_kwargs["highlight"] = self.highlight

        if self.models:
            search_kwargs["models"] = self.models

        if self.narrow_queries:
            search_kwargs["narrow_queries"] = self.narrow_queries

        if self.query_facets:
            search_kwargs["query_facets"] = self.query_facets

        if self.within:
            search_kwargs["within"] = self.within

        if spelling_query:
            search_kwargs["spelling_query"] = spelling_query
        elif self.spelling_query:
            search_kwargs["spelling_query"] = self.spelling_query

        if self.stats:
            search_kwargs["stats"] = self.stats

        return search_kwargs

    def run(self, spelling_query=None, **kwargs):
        """Builds and executes the query. Returns a list of search results."""
        final_query = self.build_query()
        search_kwargs = self.build_params(spelling_query, **kwargs)

        if kwargs:
            search_kwargs.update(kwargs)

        results = self.backend.search(final_query, **search_kwargs)

        self._results = results.get("results", [])
        self._hit_count = results.get("hits", 0)
        self._facet_counts = self.post_process_facets(results)
        self._stats = results.get("stats", {})
        self._spelling_suggestion = results.get("spelling_suggestion", None)

    def run_mlt(self, **kwargs):
        """Builds and executes the query. Returns a list of search results."""
        if self._more_like_this is False or self._mlt_instance is None:
            raise MoreLikeThisError(
                "No instance was provided to determine 'More Like This' results."
            )

        additional_query_string = self.build_query()
        search_kwargs = {
            "start_offset": self.start_offset,
            "result_class": self.result_class,
            "models": self.models,
        }

        if self.end_offset is not None:
            search_kwargs["end_offset"] = self.end_offset - self.start_offset

        results = self.backend.more_like_this(
            self._mlt_instance, additional_query_string, **search_kwargs
        )
        self._results = results.get("results", [])
        self._hit_count = results.get("hits", 0)


class SolrEngine(BaseEngine):
    backend = SolrSearchBackend
    query = SolrSearchQuery