/*
 * 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 and the Server Side Public License, v 1; you may not use this file except
 * in compliance with, at your election, the Elastic License 2.0 or the Server
 * Side Public License, v 1.
 */
package org.elasticsearch.search.suggest;

import org.apache.lucene.util.CharsRefBuilder;
import org.elasticsearch.ElasticsearchException;
import org.elasticsearch.search.internal.SearchContext;
import org.elasticsearch.search.suggest.Suggest.Suggestion;
import org.elasticsearch.search.suggest.Suggest.Suggestion.Entry;
import org.elasticsearch.search.suggest.Suggest.Suggestion.Entry.Option;
import org.elasticsearch.search.suggest.SuggestionSearchContext.SuggestionContext;

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

/**
 * Suggest phase of a search request, used to collect suggestions
 */
public class SuggestPhase {

    private SuggestPhase() {}

    public static void execute(SearchContext context) {
        final SuggestionSearchContext suggest = context.suggest();
        if (suggest == null) {
            return;
        }
        try {
            CharsRefBuilder spare = new CharsRefBuilder();
            final List<Suggestion<? extends Entry<? extends Option>>> suggestions = new ArrayList<>(suggest.suggestions().size());

            for (Map.Entry<String, SuggestionSearchContext.SuggestionContext> entry : suggest.suggestions().entrySet()) {
                SuggestionSearchContext.SuggestionContext suggestion = entry.getValue();
                Suggester<SuggestionContext> suggester = suggestion.getSuggester();
                Suggestion<? extends Entry<? extends Option>> result = suggester.execute(
                    entry.getKey(),
                    suggestion,
                    context.searcher(),
                    spare
                );
                if (result != null) {
                    assert entry.getKey().equals(result.name);
                    suggestions.add(result);
                }
            }
            context.queryResult().suggest(new Suggest(suggestions));
        } catch (IOException e) {
            throw new ElasticsearchException("I/O exception during suggest phase", e);
        }
    }

}
