"""
SQL functions reference lists:
https://www.gaia-gis.it/gaia-sins/spatialite-sql-4.3.0.html
"""
from django.contrib.gis.db import models
from django.contrib.gis.db.backends.base.operations import BaseSpatialOperations
from django.contrib.gis.db.backends.spatialite.adapter import SpatiaLiteAdapter
from django.contrib.gis.db.backends.utils import SpatialOperator
from django.contrib.gis.geos.geometry import GEOSGeometry, GEOSGeometryBase
from django.contrib.gis.geos.prototypes.io import wkb_r
from django.contrib.gis.measure import Distance
from django.core.exceptions import ImproperlyConfigured
from django.db.backends.sqlite3.operations import DatabaseOperations
from django.utils.functional import cached_property
from django.utils.version import get_version_tuple


class SpatialiteNullCheckOperator(SpatialOperator):
    def as_sql(self, connection, lookup, template_params, sql_params):
        sql, params = super().as_sql(connection, lookup, template_params, sql_params)
        return "%s > 0" % sql, params


class SpatiaLiteOperations(BaseSpatialOperations, DatabaseOperations):
    name = "spatialite"
    spatialite = True

    Adapter = SpatiaLiteAdapter

    collect = "Collect"
    extent = "Extent"
    makeline = "MakeLine"
    unionagg = "GUnion"

    from_text = "GeomFromText"

    gis_operators = {
        # Binary predicates
        "equals": SpatialiteNullCheckOperator(func="Equals"),
        "disjoint": SpatialiteNullCheckOperator(func="Disjoint"),
        "touches": SpatialiteNullCheckOperator(func="Touches"),
        "crosses": SpatialiteNullCheckOperator(func="Crosses"),
        "within": SpatialiteNullCheckOperator(func="Within"),
        "overlaps": SpatialiteNullCheckOperator(func="Overlaps"),
        "contains": SpatialiteNullCheckOperator(func="Contains"),
        "intersects": SpatialiteNullCheckOperator(func="Intersects"),
        "relate": SpatialiteNullCheckOperator(func="Relate"),
        "coveredby": SpatialiteNullCheckOperator(func="CoveredBy"),
        "covers": SpatialiteNullCheckOperator(func="Covers"),
        # Returns true if B's bounding box completely contains A's bounding box.
        "contained": SpatialOperator(func="MbrWithin"),
        # Returns true if A's bounding box completely contains B's bounding box.
        "bbcontains": SpatialOperator(func="MbrContains"),
        # Returns true if A's bounding box overlaps B's bounding box.
        "bboverlaps": SpatialOperator(func="MbrOverlaps"),
        # These are implemented here as synonyms for Equals
        "same_as": SpatialiteNullCheckOperator(func="Equals"),
        "exact": SpatialiteNullCheckOperator(func="Equals"),
        # Distance predicates
        "dwithin": SpatialOperator(func="PtDistWithin"),
    }

    disallowed_aggregates = (models.Extent3D,)

    select = "CAST (AsEWKB(%s) AS BLOB)"

    function_names = {
        "AsWKB": "St_AsBinary",
        "ForcePolygonCW": "ST_ForceLHR",
        "Length": "ST_Length",
        "LineLocatePoint": "ST_Line_Locate_Point",
        "NumPoints": "ST_NPoints",
        "Reverse": "ST_Reverse",
        "Scale": "ScaleCoords",
        "Translate": "ST_Translate",
        "Union": "ST_Union",
    }

    @cached_property
    def unsupported_functions(self):
        unsupported = {"BoundingCircle", "GeometryDistance", "MemSize"}
        if not self.geom_lib_version():
            unsupported |= {"Azimuth", "GeoHash", "MakeValid"}
        return unsupported

    @cached_property
    def spatial_version(self):
        """Determine the version of the SpatiaLite library."""
        try:
            version = self.spatialite_version_tuple()[1:]
        except Exception as exc:
            raise ImproperlyConfigured(
                'Cannot determine the SpatiaLite version for the "%s" database. '
                "Was the SpatiaLite initialization SQL loaded on this database?"
                % (self.connection.settings_dict["NAME"],)
            ) from exc
        if version < (4, 3, 0):
            raise ImproperlyConfigured("GeoDjango supports SpatiaLite 4.3.0 and above.")
        return version

    def convert_extent(self, box):
        """
        Convert the polygon data received from SpatiaLite to min/max values.
        """
        if box is None:
            return None
        shell = GEOSGeometry(box).shell
        xmin, ymin = shell[0][:2]
        xmax, ymax = shell[2][:2]
        return (xmin, ymin, xmax, ymax)

    def geo_db_type(self, f):
        """
        Return None because geometry columns are added via the
        `AddGeometryColumn` stored procedure on SpatiaLite.
        """
        return None

    def get_distance(self, f, value, lookup_type):
        """
        Return the distance parameters for the given geometry field,
        lookup value, and lookup type.
        """
        if not value:
            return []
        value = value[0]
        if isinstance(value, Distance):
            if f.geodetic(self.connection):
                if lookup_type == "dwithin":
                    raise ValueError(
                        "Only numeric values of degree units are allowed on "
                        "geographic DWithin queries."
                    )
                dist_param = value.m
            else:
                dist_param = getattr(
                    value, Distance.unit_attname(f.units_name(self.connection))
                )
        else:
            dist_param = value
        return [dist_param]

    def _get_spatialite_func(self, func):
        """
        Helper routine for calling SpatiaLite functions and returning
        their result.
        Any error occurring in this method should be handled by the caller.
        """
        cursor = self.connection._cursor()
        try:
            cursor.execute("SELECT %s" % func)
            row = cursor.fetchone()
        finally:
            cursor.close()
        return row[0]

    def geos_version(self):
        "Return the version of GEOS used by SpatiaLite as a string."
        return self._get_spatialite_func("geos_version()")

    def proj_version(self):
        """Return the version of the PROJ library used by SpatiaLite."""
        return self._get_spatialite_func("proj4_version()")

    def lwgeom_version(self):
        """Return the version of LWGEOM library used by SpatiaLite."""
        return self._get_spatialite_func("lwgeom_version()")

    def rttopo_version(self):
        """Return the version of RTTOPO library used by SpatiaLite."""
        return self._get_spatialite_func("rttopo_version()")

    def geom_lib_version(self):
        """
        Return the version of the version-dependant geom library used by
        SpatiaLite.
        """
        if self.spatial_version >= (5,):
            return self.rttopo_version()
        else:
            return self.lwgeom_version()

    def spatialite_version(self):
        "Return the SpatiaLite library version as a string."
        return self._get_spatialite_func("spatialite_version()")

    def spatialite_version_tuple(self):
        """
        Return the SpatiaLite version as a tuple (version string, major,
        minor, subminor).
        """
        version = self.spatialite_version()
        return (version,) + get_version_tuple(version)

    def spatial_aggregate_name(self, agg_name):
        """
        Return the spatial aggregate SQL template and function for the
        given Aggregate instance.
        """
        agg_name = "unionagg" if agg_name.lower() == "union" else agg_name.lower()
        return getattr(self, agg_name)

    # Routines for getting the OGC-compliant models.
    def geometry_columns(self):
        from django.contrib.gis.db.backends.spatialite.models import (
            SpatialiteGeometryColumns,
        )

        return SpatialiteGeometryColumns

    def spatial_ref_sys(self):
        from django.contrib.gis.db.backends.spatialite.models import (
            SpatialiteSpatialRefSys,
        )

        return SpatialiteSpatialRefSys

    def get_geometry_converter(self, expression):
        geom_class = expression.output_field.geom_class
        read = wkb_r().read

        def converter(value, expression, connection):
            return None if value is None else GEOSGeometryBase(read(value), geom_class)

        return converter
