/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the Elastic License
 * 2.0; you may not use this file except in compliance with the Elastic License
 * 2.0.
 */

package org.elasticsearch.xpack.spatial.index.mapper;

import org.apache.lucene.document.ShapeField;
import org.apache.lucene.geo.Component2D;
import org.apache.lucene.index.BinaryDocValues;
import org.apache.lucene.index.DocValues;
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.search.ConstantScoreScorer;
import org.apache.lucene.search.ConstantScoreWeight;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.QueryVisitor;
import org.apache.lucene.search.ScoreMode;
import org.apache.lucene.search.Scorer;
import org.apache.lucene.search.ScorerSupplier;
import org.apache.lucene.search.TwoPhaseIterator;
import org.apache.lucene.search.Weight;
import org.elasticsearch.xpack.spatial.index.fielddata.Component2DVisitor;
import org.elasticsearch.xpack.spatial.index.fielddata.CoordinateEncoder;
import org.elasticsearch.xpack.spatial.index.fielddata.GeometryDocValueReader;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/** Lucene geometry query for {@link BinaryShapeDocValuesField}. */
abstract class ShapeDocValuesQuery<GEOMETRY> extends Query {

    private final String field;
    private final CoordinateEncoder encoder;
    private final ShapeField.QueryRelation relation;
    private final GEOMETRY[] geometries;

    ShapeDocValuesQuery(String field, CoordinateEncoder encoder, ShapeField.QueryRelation relation, GEOMETRY[] geometries) {
        if (field == null) {
            throw new IllegalArgumentException("field must not be null");
        }
        this.field = field;
        this.encoder = encoder;
        this.relation = relation;
        this.geometries = geometries;
    }

    protected abstract Component2D create(GEOMETRY geometry);

    protected abstract Component2D create(GEOMETRY[] geometries);

    /** Override if special cases, like dateline support, should be considered */
    protected void add(List<Component2D> components2D, GEOMETRY geometry) {
        components2D.add(create(geometry));
    }

    @Override
    public String toString(String otherField) {
        StringBuilder sb = new StringBuilder();
        if (this.field.equals(otherField) == false) {
            sb.append(this.field);
            sb.append(':');
            sb.append(relation);
            sb.append(':');
        }
        sb.append(Arrays.toString(geometries));
        return sb.toString();
    }

    @Override
    public boolean equals(Object obj) {
        if (sameClassAs(obj) == false) {
            return false;
        }
        ShapeDocValuesQuery<?> other = (ShapeDocValuesQuery<?>) obj;
        return field.equals(other.field) && relation == other.relation && Arrays.equals(geometries, other.geometries);
    }

    @Override
    public int hashCode() {
        int h = classHash();
        h = 31 * h + field.hashCode();
        h = 31 * h + relation.hashCode();
        h = 31 * h + Arrays.hashCode(geometries);
        return h;
    }

    @Override
    public void visit(QueryVisitor visitor) {
        if (visitor.acceptField(field)) {
            visitor.visitLeaf(this);
        }
    }

    @Override
    public Weight createWeight(IndexSearcher searcher, ScoreMode scoreMode, float boost) {
        if (relation == ShapeField.QueryRelation.CONTAINS) {
            return getContainsWeight(scoreMode, boost);
        } else {
            return getStandardWeight(scoreMode, boost);
        }
    }

    private ConstantScoreWeight getStandardWeight(ScoreMode scoreMode, float boost) {
        final Component2D component2D = create(geometries);
        return new ConstantScoreWeight(this, boost) {

            @Override
            public Scorer scorer(LeafReaderContext context) throws IOException {
                final ScorerSupplier scorerSupplier = scorerSupplier(context);
                if (scorerSupplier == null) {
                    return null;
                }
                return scorerSupplier.get(Long.MAX_VALUE);
            }

            @Override
            public ScorerSupplier scorerSupplier(LeafReaderContext context) {
                final Weight weight = this;
                // implement ScorerSupplier, since we do some expensive stuff to make a scorer
                return new ScorerSupplier() {

                    @Override
                    public Scorer get(long leadCost) throws IOException {
                        // binary doc values allocate an array upfront, lets only allocate it if we are going to use it
                        final BinaryDocValues values = context.reader().getBinaryDocValues(field);
                        if (values == null) {
                            return null;
                        }
                        final GeometryDocValueReader reader = new GeometryDocValueReader();
                        final Component2DVisitor visitor = Component2DVisitor.getVisitor(component2D, relation, encoder);
                        final TwoPhaseIterator iterator = new TwoPhaseIterator(values) {
                            @Override
                            public boolean matches() throws IOException {
                                reader.reset(values.binaryValue());
                                visitor.reset();
                                reader.visit(visitor);
                                return visitor.matches();
                            }

                            @Override
                            public float matchCost() {
                                return 1000f; // TODO: what should it be?
                            }
                        };
                        return new ConstantScoreScorer(weight, score(), scoreMode, iterator);
                    }

                    @Override
                    public long cost() {
                        return context.reader().maxDoc();
                    }
                };
            }

            @Override
            public boolean isCacheable(LeafReaderContext ctx) {
                return DocValues.isCacheable(ctx, field);
            }
        };
    }

    private ConstantScoreWeight getContainsWeight(ScoreMode scoreMode, float boost) {
        final List<Component2D> components2D = new ArrayList<>(geometries.length);
        for (GEOMETRY geometry : geometries) {
            add(components2D, geometry);
        }
        return new ConstantScoreWeight(this, boost) {

            @Override
            public Scorer scorer(LeafReaderContext context) throws IOException {
                final ScorerSupplier scorerSupplier = scorerSupplier(context);
                if (scorerSupplier == null) {
                    return null;
                }
                return scorerSupplier.get(Long.MAX_VALUE);
            }

            @Override
            public ScorerSupplier scorerSupplier(LeafReaderContext context) {
                final Weight weight = this;
                // implement ScorerSupplier, since we do some expensive stuff to make a scorer
                return new ScorerSupplier() {

                    @Override
                    public Scorer get(long leadCost) throws IOException {
                        // binary doc values allocate an array upfront, lets only allocate it if we are going to use it
                        final BinaryDocValues values = context.reader().getBinaryDocValues(field);
                        if (values == null) {
                            return null;
                        }
                        final Component2DVisitor[] visitors = new Component2DVisitor[components2D.size()];
                        for (int i = 0; i < components2D.size(); i++) {
                            visitors[i] = Component2DVisitor.getVisitor(components2D.get(i), relation, encoder);
                        }
                        final GeometryDocValueReader reader = new GeometryDocValueReader();
                        final TwoPhaseIterator iterator = new TwoPhaseIterator(values) {

                            @Override
                            public boolean matches() throws IOException {
                                reader.reset(values.binaryValue());
                                for (Component2DVisitor visitor : visitors) {
                                    visitor.reset();
                                    reader.visit(visitor);
                                    if (visitor.matches() == false) {
                                        return false;
                                    }
                                }
                                return true;
                            }

                            @Override
                            public float matchCost() {
                                return 1000f; // TODO: what should it be?
                            }
                        };
                        return new ConstantScoreScorer(weight, score(), scoreMode, iterator);
                    }

                    @Override
                    public long cost() {
                        return context.reader().maxDoc();
                    }
                };
            }

            @Override
            public boolean isCacheable(LeafReaderContext ctx) {
                return DocValues.isCacheable(ctx, field);
            }
        };
    }
}
