"""
Helpers to make elasticsearch queries.
"""

import copy
import datetime
import logging
from gettext import gettext
from typing import Any, List, Optional

import elasticsearch
import fatcat_openapi_client
import sentry_sdk
from elasticsearch_dsl import Q, Search
from elasticsearch_dsl.response import Response

# pytype: disable=import-error
from pydantic import BaseModel

from fatcat_scholar.config import settings
from fatcat_scholar.identifiers import clean_doi, clean_pmcid
from fatcat_scholar.query_citation import try_fuzzy_match
from fatcat_scholar.query_parse import pre_parse_query, sniff_citation_query
from fatcat_scholar.schema import ScholarDoc

# pytype: enable=import-error


# i18n note: the use of gettext below doesn't actually do the translation here,
# it just ensures that the strings are caught by babel for translation later


class FulltextQuery(BaseModel):
    q: Optional[str] = None
    parsed_q: Optional[str] = None
    limit: Optional[int] = None
    offset: Optional[int] = None
    filter_time: Optional[str] = None
    filter_type: Optional[str] = None
    filter_availability: Optional[str] = None
    sort_order: Optional[str] = None
    collapse_key: Optional[str] = None
    debug: Optional[bool] = False
    time_options: Any = {
        "label": gettext("Release Date"),
        "slug": "filter_time",
        "default": "all_time",
        "list": [
            {"label": gettext("All Time"), "slug": "all_time"},
            {"label": gettext("Past Week"), "slug": "past_week"},
            {"label": gettext("Past Year"), "slug": "past_year"},
            {"label": gettext("Since 2000"), "slug": "since_2000"},
            {"label": gettext("Before 1927"), "slug": "before_1927"},
        ],
    }
    type_options: Any = {
        "label": gettext("Resource Type"),
        "slug": "filter_type",
        "default": "papers",
        "list": [
            {"label": gettext("Papers"), "slug": "papers"},
            {"label": gettext("Reports"), "slug": "reports"},
            {"label": gettext("Datasets"), "slug": "datasets"},
            {"label": gettext("Everything"), "slug": "everything"},
        ],
    }
    availability_options: Any = {
        "label": gettext("Availability"),
        "slug": "filter_availability",
        "default": "fulltext",
        "list": [
            {"label": gettext("Fulltext"), "slug": "fulltext"},
            {"label": gettext("Microfilm"), "slug": "microfilm"},
            {"label": gettext("Open Access"), "slug": "oa"},
            {"label": gettext("All Records"), "slug": "everything"},
        ],
    }
    sort_options: Any = {
        "label": gettext("Sort Order"),
        "slug": "sort_order",
        "default": "relevancy",
        "list": [
            {"label": gettext("Relevancy"), "slug": "relevancy"},
            {"label": gettext("Recent First"), "slug": "time_desc"},
            {"label": gettext("Oldest First"), "slug": "time_asc"},
        ],
    }


class FulltextHits(BaseModel):
    query_type: str
    count_returned: int
    count_found: int
    offset: int
    limit: int
    deep_page_limit: int
    query_time_ms: int
    query_wall_time_ms: int
    results: List[Any]


# global sync client connection
es_client = elasticsearch.Elasticsearch(settings.ELASTICSEARCH_QUERY_BASE, timeout=50.0)


def transform_es_results(resp: Response) -> List[dict]:
    # convert from ES objects to python dicts
    results = []
    for h in resp:
        r = h._d_
        # print(h.meta._d_)
        r["_highlights"] = []
        if "highlight" in dir(h.meta):
            highlights = h.meta.highlight._d_
            for k in highlights:
                r["_highlights"] += highlights[k]
        r["_collapsed"] = []
        r["_collapsed_count"] = 0
        if "inner_hits" in dir(h.meta):
            if isinstance(h.meta.inner_hits.more_pages.hits.total, int):
                r["_collapsed_count"] = h.meta.inner_hits.more_pages.hits.total - 1
            else:
                r["_collapsed_count"] = (
                    h.meta.inner_hits.more_pages.hits.total["value"] - 1
                )
            for k in h.meta.inner_hits.more_pages:
                if k["key"] != r["key"]:
                    r["_collapsed"].append(k)
        results.append(r)

    for h in results:
        # Handle surrogate strings that elasticsearch returns sometimes,
        # probably due to mangled data processing in some pipeline.
        # "Crimes against Unicode"; production workaround
        for key in h:
            if type(h[key]) is str:
                h[key] = h[key].encode("utf8", "ignore").decode("utf8")
        # ensure collapse_key is a single value, not an array
        if type(h["collapse_key"]) == list:
            h["collapse_key"] = h["collapse_key"][0]
        # add ScholarDoc object as a helper (eg, to call python helpers)
        try:
            h["_obj"] = ScholarDoc.parse_obj(h)
        except Exception:
            pass
    return results


def apply_filters(search: Search, query: FulltextQuery) -> Search:
    """
    Applies query filters to ES Search object based on query
    """
    # type filters
    if query.filter_type == "papers" or query.filter_type is None:
        search = search.filter(
            "terms", type=["article-journal", "paper-conference", "chapter", "article"]
        )
    elif query.filter_type == "reports":
        search = search.filter(
            "terms",
            type=[
                "report",
                "standard",
            ],
        )
    elif query.filter_type == "datasets":
        search = search.filter(
            "terms",
            type=[
                "dataset",
                "software",
            ],
        )
    elif query.filter_type == "everything":
        pass
    else:
        raise ValueError(
            f"Unknown 'filter_type' parameter value: '{query.filter_type}'"
        )

    # time filters
    if query.filter_time == "past_week":
        date_today = datetime.date.today()
        week_ago_date = str(date_today - datetime.timedelta(days=7))
        tomorrow_date = str(date_today + datetime.timedelta(days=1))
        search = search.filter("range", date=dict(gte=week_ago_date, lte=tomorrow_date))
    elif query.filter_time == "past_year":
        # (date in the past year) or (year is this year)
        # the later to catch papers which don't have release_date defined
        date_today = datetime.date.today()
        this_year = date_today.year
        tomorrow_date = str(date_today + datetime.timedelta(days=1))
        year_ago_date = str(date_today - datetime.timedelta(days=365))
        search = search.filter(
            Q("range", date=dict(gte=year_ago_date, lte=tomorrow_date))
            | Q("term", year=this_year)
        )
    elif query.filter_time == "since_2000":
        this_year = datetime.date.today().year
        search = search.filter("range", year=dict(gte=2000, lte=this_year))
    elif query.filter_time == "before_1925" or query.filter_time == "before_1927":
        # 1925 value retained for backwards compatibility in URLs
        search = search.filter("range", year=dict(lt=1927))
    elif query.filter_time == "all_time" or query.filter_time is None:
        pass
    else:
        raise ValueError(
            f"Unknown 'filter_time' parameter value: '{query.filter_time}'"
        )

    # availability filters
    if query.filter_availability == "oa":
        search = search.filter("term", tags="oa")
    elif query.filter_availability == "everything":
        pass
    elif query.filter_availability == "fulltext" or query.filter_availability is None:
        search = search.filter(
            "terms", **{"access.access_type": ["wayback", "ia_file", "ia_sim"]}
        )
    elif query.filter_availability == "microfilm":
        search = search.filter("term", **{"access.access_type": "ia_sim"})
    else:
        raise ValueError(
            f"Unknown 'filter_availability' parameter value: '{query.filter_availability}'"
        )

    return search


def process_query(query: FulltextQuery) -> FulltextHits:

    if not query.q:
        return do_fulltext_search(query)

    # try handling raw identifier queries
    if len(query.q.strip().split()) == 1 and '"' not in query.q:
        doi = clean_doi(query.q)
        if doi:
            return do_lookup_query(f'doi:"{doi}"')
        pmcid = clean_pmcid(query.q)
        if pmcid:
            return do_lookup_query(f'pmcid:"{pmcid}"')
        if query.q.strip().startswith("key:"):
            return do_lookup_query(query.q)

    # if this is a citation string, do a fuzzy lookup
    if settings.ENABLE_CITATION_QUERY and sniff_citation_query(query.q):
        api_conf = fatcat_openapi_client.Configuration()
        api_conf.host = settings.FATCAT_API_HOST
        api_client = fatcat_openapi_client.DefaultApi(
            fatcat_openapi_client.ApiClient(api_conf)
        )
        fatcat_es_client = elasticsearch.Elasticsearch("https://search.fatcat.wiki")
        key: Optional[str] = None
        # "best effort" fuzzy match lookup (but aggressively skip on any exception)
        try:
            key = try_fuzzy_match(
                query.q,
                grobid_host=settings.GROBID_HOST,
                es_client=fatcat_es_client,
                fatcat_api_client=api_client,
            )
        except Exception as e:
            logging.warn(f"citation fuzzy failure: {e}")
            sentry_sdk.set_level("warning")
            sentry_sdk.capture_exception(e)
            pass
        if key:
            result = do_lookup_query(f"key:{key}")
            if result:
                result.query_type = "citation"
                return result

    # fall through to regular query, with pre-parsing
    query = copy.copy(query)
    if query.q:
        query.parsed_q = pre_parse_query(query.q)

    return do_fulltext_search(query)


def do_lookup_query(lookup: str) -> FulltextHits:
    logging.info(f"lookup query: {lookup}")
    query = FulltextQuery(
        q=lookup,
        filter_type="everything",
        filter_availability="everything",
        filter_time="all_time",
    )
    result = do_fulltext_search(query)
    result.query_type = "lookup"
    return result


def do_fulltext_search(
    query: FulltextQuery, deep_page_limit: int = 2000
) -> FulltextHits:

    search = Search(using=es_client, index=settings.ELASTICSEARCH_QUERY_FULLTEXT_INDEX)

    if query.collapse_key:
        search = search.filter("term", collapse_key=query.collapse_key)
    else:
        search = search.extra(
            collapse={
                "field": "collapse_key",
                "inner_hits": {
                    "name": "more_pages",
                    "size": 0,
                },
            }
        )

    # apply filters from query
    search = apply_filters(search, query)

    # we combined several queries to improve scoring.

    # this query use the fancy built-in query string parser
    basic_fulltext = Q(
        "query_string",
        query=query.parsed_q or query.q,
        default_operator="AND",
        analyze_wildcard=True,
        allow_leading_wildcard=False,
        lenient=True,
        quote_field_suffix=".exact",
        fields=[
            "title^4",
            "biblio_all^3",
            "everything",
        ],
    )
    has_fulltext = Q("terms", **{"access_type": ["ia_sim", "ia_file", "wayback"]})
    poor_metadata = Q(
        "bool",
        should=[
            # if these fields aren't set, metadata is poor. The more that do
            # not exist, the stronger the signal.
            Q("bool", must_not=Q("exists", field="year")),
            Q("bool", must_not=Q("exists", field="type")),
            Q("bool", must_not=Q("exists", field="stage")),
            Q("bool", must_not=Q("exists", field="biblio.container_name")),
        ],
    )

    if query.filter_availability == "fulltext" or query.filter_availability is None:
        base_query = basic_fulltext
    else:
        base_query = Q("bool", must=basic_fulltext, should=[has_fulltext])

    if query.q == "*":
        search = search.query("match_all")
        search = search.sort("_doc")
    else:
        search = search.query(
            "boosting",
            positive=base_query,
            negative=poor_metadata,
            negative_boost=0.5,
        )

    # simplified version of basic_fulltext query, for highlighting
    highlight_query = Q(
        "query_string",
        query=query.parsed_q or query.q,
        default_operator="AND",
        lenient=True,
    )
    search = search.highlight(
        "abstracts.body",
        "fulltext.body",
        "fulltext.acknowledgement",
        "fulltext.annex",
        highlight_query=highlight_query.to_dict(),
        require_field_match=False,
        number_of_fragments=2,
        fragment_size=200,
        order="score",
        # TODO: this will fix highlight encoding, but requires ES 7.x
        # encoder="html",
    )

    # sort order
    if query.sort_order == "time_asc":
        search = search.sort("year", "date")
    elif query.sort_order == "time_desc":
        search = search.sort("-year", "-date")
    elif query.sort_order == "relevancy" or query.sort_order is None:
        pass
    else:
        raise ValueError(f"Unknown 'sort_order' parameter value: '{query.sort_order}'")

    # Sanity checks
    limit = min((int(query.limit or 15), 100))
    offset = max((int(query.offset or 0), 0))
    if offset > deep_page_limit:
        # Avoid deep paging problem.
        offset = deep_page_limit

    search = search.params(track_total_hits=True)
    search = search[offset : (offset + limit)]

    if settings.ELASTICSEARCH_QUERY_PREFERENCE:
        search = search.params(preference=settings.ELASTICSEARCH_QUERY_PREFERENCE)

    query_start = datetime.datetime.now()
    try:
        resp = search.execute()
    except elasticsearch.exceptions.RequestError as e_raw:
        # this is a "user" error
        e: Any = e_raw
        logging.warn("elasticsearch 400: " + str(e.info))
        if e.info.get("error", {}).get("root_cause", {}):
            raise ValueError(str(e.info["error"]["root_cause"][0].get("reason"))) from e
        else:
            raise ValueError(str(e.info)) from e
    except elasticsearch.exceptions.TransportError as e:
        # all other errors
        logging.warn(f"elasticsearch non-200 status code: {e.info}")
        raise IOError(str(e.info)) from e
    query_delta = datetime.datetime.now() - query_start

    # convert from API objects to dicts
    results = transform_es_results(resp)

    count_found: int = 0
    if isinstance(resp.hits.total, int):
        count_found = int(resp.hits.total)
    else:
        count_found = int(resp.hits.total["value"])
    count_returned = len(results)

    # if we grouped to less than a page of hits, update returned count
    if (not query.collapse_key) and offset == 0 and (count_returned < limit):
        count_found = count_returned

    return FulltextHits(
        query_type="fulltext",
        count_returned=count_returned,
        count_found=count_found,
        offset=offset,
        limit=limit,
        deep_page_limit=deep_page_limit,
        query_time_ms=int(resp.took),
        query_wall_time_ms=int(query_delta.total_seconds() * 1000),
        results=results,
    )


def es_scholar_index_alive() -> bool:
    """
    Checks if the configured back-end elasticsearch index exists and can
    service queries. Intended to be used in health checks, called every couple
    seconds.

    Note that the regular client.indices.exists(index) function call will
    return an error if the cluster leader can not be reached, even if the local
    node could service queries in a read-only manner.

    The client.count(body=None, index=index) API returns quickly enough (though
    might be slow during indexing?), and returns context about the number of
    shards queried, and thus seems like a good fit for this check.
    """
    try:
        resp = es_client.count(
            body=None,
            index=settings.ELASTICSEARCH_QUERY_FULLTEXT_INDEX,
            request_timeout=90.0,
        )
    except elasticsearch.exceptions.RequestError as e_raw:
        if e_raw.status_code == 404:
            return False
        else:
            raise e_raw
    try:
        return bool(resp["_shards"]["successful"] == resp["_shards"]["total"])
    except KeyError:
        return False


def get_es_scholar_doc(key: str) -> Optional[dict]:
    """
    Fetch a single document from search index, by key. Returns None if not found.
    """
    try:
        resp = es_client.get(settings.ELASTICSEARCH_QUERY_FULLTEXT_INDEX, key)
    except elasticsearch.exceptions.NotFoundError:
        return None
    doc = resp["_source"]
    try:
        doc["_obj"] = ScholarDoc.parse_obj(doc)
    except Exception:
        pass
    return doc