package com.jeeww.lucene.demo;

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE
 * file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file
 * to You under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the
 * License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by
 * applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language
 * governing permissions and limitations under the License.
 */

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.nio.charset.StandardCharsets;
import java.util.Date;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.index.DirectoryReader;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.queryparser.classic.QueryParser;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.TopDocs;
import org.apache.lucene.store.FSDirectory;
import org.apache.lucene.util.Version;

/** Simple command-line based search demo. */
public class SearchFiles {

    private SearchFiles() {
    }

    /** Simple command-line based search demo. */
    public static void main(String[] args) throws Exception {
        String index = "d://test//index//";
        String field = "contents";
        String queries = null;
        int repeat = 0;
        boolean raw = false;
        String queryString = "test*";
        int hitsPerPage = 10;

        IndexReader reader = DirectoryReader.open(FSDirectory.open(new File(index)));
        IndexSearcher searcher = new IndexSearcher(reader);
        // :Post-Release-Update-Version.LUCENE_XY:
        Analyzer analyzer = new StandardAnalyzer(Version.LUCENE_48);

        BufferedReader in = null;
        if (queries != null) {
            in = new BufferedReader(new InputStreamReader(new FileInputStream(queries), StandardCharsets.UTF_8));
        } else {
            in = new BufferedReader(new InputStreamReader(System.in, StandardCharsets.UTF_8));
        }
        // :Post-Release-Update-Version.LUCENE_XY:
        QueryParser parser = new QueryParser(Version.LUCENE_48, field, analyzer);
        while (true) {
            if (queries == null && queryString == null) { // prompt the user
                System.out.println("Enter query: ");
            }

            String line = queryString != null ? queryString : in.readLine();

            if (line == null || line.length() == -1) {
                break;
            }

            line = line.trim();
            if (line.length() == 0) {
                break;
            }

            Query query = parser.parse(line);
            System.out.println("Searching for: " + query.toString(field));

            if (repeat > 0) { // repeat & time as benchmark
                Date start = new Date();
                for (int i = 0; i < repeat; i++) {
                    searcher.search(query, null, 100);
                }
                Date end = new Date();
                System.out.println("Time: " + (end.getTime() - start.getTime()) + "ms");
            }

            doPagingSearch(in, searcher, query, hitsPerPage, raw, queries == null && queryString == null);

            if (queryString != null) {
                break;
            }
        }
        reader.close();
    }

    /**
     * This demonstrates a typical paging search scenario, where the search engine presents pages of size n to the user.
     * The user can then go to the next page if interested in the next hits. When the query is executed for the first
     * time, then only enough results are collected to fill 5 result pages. If the user wants to page beyond this limit,
     * then the query is executed another time and all hits are collected.
     */
    public static void doPagingSearch(BufferedReader in, IndexSearcher searcher, Query query, int hitsPerPage,
            boolean raw, boolean interactive) throws IOException {

        // Collect enough docs to show 5 pages
        TopDocs results = searcher.search(query, 5 * hitsPerPage);
        ScoreDoc[] hits = results.scoreDocs;

        int numTotalHits = results.totalHits;
        System.out.println(numTotalHits + " total matching documents");

        int start = 0;
        int end = Math.min(numTotalHits, hitsPerPage);

        while (true) {
            if (end > hits.length) {
                System.out.println("Only results 1 - " + hits.length + " of " + numTotalHits
                        + " total matching documents collected.");
                System.out.println("Collect more (y/n) ?");
                String line = in.readLine();
                if (line.length() == 0 || line.charAt(0) == 'n') {
                    break;
                }

                hits = searcher.search(query, numTotalHits).scoreDocs;
            }

            end = Math.min(hits.length, start + hitsPerPage);

            for (int i = start; i < end; i++) {
                if (raw) { // output raw format
                    System.out.println("doc=" + hits[i].doc + " score=" + hits[i].score);
                    continue;
                }

                Document doc = searcher.doc(hits[i].doc);
                String path = doc.get("path");
                if (path != null) {
                    System.out.println((i + 1) + ". " + path);
                    String title = doc.get("title");
                    if (title != null) {
                        System.out.println("   Title: " + doc.get("title"));
                    }
                } else {
                    System.out.println((i + 1) + ". " + "No path for this document");
                }

            }

            if (!interactive || end == 0) {
                break;
            }

            if (numTotalHits >= end) {
                boolean quit = false;
                while (true) {
                    System.out.print("Press ");
                    if (start - hitsPerPage >= 0) {
                        System.out.print("(p)revious page, ");
                    }
                    if (start + hitsPerPage < numTotalHits) {
                        System.out.print("(n)ext page, ");
                    }
                    System.out.println("(q)uit or enter number to jump to a page.");

                    String line = in.readLine();
                    if (line.length() == 0 || line.charAt(0) == 'q') {
                        quit = true;
                        break;
                    }
                    if (line.charAt(0) == 'p') {
                        start = Math.max(0, start - hitsPerPage);
                        break;
                    } else if (line.charAt(0) == 'n') {
                        if (start + hitsPerPage < numTotalHits) {
                            start += hitsPerPage;
                        }
                        break;
                    } else {
                        int page = Integer.parseInt(line);
                        if ((page - 1) * hitsPerPage < numTotalHits) {
                            start = (page - 1) * hitsPerPage;
                            break;
                        } else {
                            System.out.println("No such page");
                        }
                    }
                }
                if (quit)
                    break;
                end = Math.min(numTotalHits, start + hitsPerPage);
            }
        }
    }
}
