/*
 * 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.lucene.search.uhighlight;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.core.WhitespaceAnalyzer;
import org.apache.lucene.analysis.custom.CustomAnalyzer;
import org.apache.lucene.analysis.ngram.EdgeNGramTokenizerFactory;
import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.document.FieldType;
import org.apache.lucene.document.TextField;
import org.apache.lucene.index.DirectoryReader;
import org.apache.lucene.index.IndexOptions;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.index.Term;
import org.apache.lucene.search.BooleanClause;
import org.apache.lucene.search.BooleanQuery;
import org.apache.lucene.search.FuzzyQuery;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.MatchAllDocsQuery;
import org.apache.lucene.search.PhraseQuery;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.Sort;
import org.apache.lucene.search.TermQuery;
import org.apache.lucene.search.TopDocs;
import org.apache.lucene.search.highlight.DefaultEncoder;
import org.apache.lucene.search.uhighlight.UnifiedHighlighter;
import org.apache.lucene.store.Directory;
import org.apache.lucene.tests.index.RandomIndexWriter;
import org.elasticsearch.common.Strings;
import org.elasticsearch.common.lucene.search.MultiPhrasePrefixQuery;
import org.elasticsearch.test.ESTestCase;

import java.text.BreakIterator;
import java.util.Locale;
import java.util.Map;
import java.util.TreeMap;

import static org.elasticsearch.lucene.search.uhighlight.CustomUnifiedHighlighter.MULTIVAL_SEP_CHAR;
import static org.hamcrest.CoreMatchers.equalTo;

public class CustomUnifiedHighlighterTests extends ESTestCase {

    private void assertHighlightOneDoc(
        String fieldName,
        String[] inputs,
        Analyzer analyzer,
        Query query,
        Locale locale,
        BreakIterator breakIterator,
        int noMatchSize,
        String[] expectedPassages
    ) throws Exception {

        assertHighlightOneDoc(
            fieldName,
            inputs,
            analyzer,
            query,
            locale,
            breakIterator,
            noMatchSize,
            expectedPassages,
            Integer.MAX_VALUE,
            null
        );
    }

    private void assertHighlightOneDoc(
        String fieldName,
        String[] inputs,
        Analyzer analyzer,
        Query query,
        Locale locale,
        BreakIterator breakIterator,
        int noMatchSize,
        String[] expectedPassages,
        int maxAnalyzedOffset,
        Integer queryMaxAnalyzedOffset
    ) throws Exception {
        assertHighlightOneDoc(
            fieldName,
            inputs,
            analyzer,
            query,
            locale,
            breakIterator,
            noMatchSize,
            expectedPassages,
            maxAnalyzedOffset,
            queryMaxAnalyzedOffset,
            UnifiedHighlighter.OffsetSource.ANALYSIS
        );
    }

    private void assertHighlightOneDoc(
        String fieldName,
        String[] inputs,
        Analyzer analyzer,
        Query query,
        Locale locale,
        BreakIterator breakIterator,
        int noMatchSize,
        String[] expectedPassages,
        int maxAnalyzedOffset,
        Integer queryMaxAnalyzedOffset,
        UnifiedHighlighter.OffsetSource offsetSource
    ) throws Exception {
        try (Directory dir = newDirectory()) {
            IndexWriterConfig iwc = newIndexWriterConfig(analyzer);
            iwc.setMergePolicy(newTieredMergePolicy(random()));
            RandomIndexWriter iw = new RandomIndexWriter(random(), dir, iwc);
            FieldType ft = new FieldType(TextField.TYPE_STORED);
            ft.setIndexOptions(IndexOptions.DOCS_AND_FREQS_AND_POSITIONS_AND_OFFSETS);
            ft.freeze();
            Document doc = new Document();
            for (String input : inputs) {
                Field field = new Field(fieldName, "", ft);
                field.setStringValue(input);
                doc.add(field);
            }
            iw.addDocument(doc);
            try (DirectoryReader reader = iw.getReader()) {
                IndexSearcher searcher = newSearcher(reader);
                iw.close();
                TopDocs topDocs = searcher.search(new MatchAllDocsQuery(), 1, Sort.INDEXORDER);
                assertThat(topDocs.totalHits.value, equalTo(1L));
                String rawValue = Strings.arrayToDelimitedString(inputs, String.valueOf(MULTIVAL_SEP_CHAR));
                CustomUnifiedHighlighter highlighter = new CustomUnifiedHighlighter(
                    searcher,
                    analyzer,
                    offsetSource,
                    new CustomPassageFormatter("<b>", "</b>", new DefaultEncoder()),
                    locale,
                    breakIterator,
                    "index",
                    "text",
                    query,
                    noMatchSize,
                    expectedPassages.length,
                    name -> "text".equals(name),
                    maxAnalyzedOffset,
                    queryMaxAnalyzedOffset
                );
                final Snippet[] snippets = highlighter.highlightField(getOnlyLeafReader(reader), topDocs.scoreDocs[0].doc, () -> rawValue);
                assertEquals(snippets.length, expectedPassages.length);
                for (int i = 0; i < snippets.length; i++) {
                    assertEquals(snippets[i].getText(), expectedPassages[i]);
                }
            }
        }
    }

    public void testSimple() throws Exception {
        final String[] inputs = {
            "This is a test. Just a test1 highlighting from unified highlighter.",
            "This is the second highlighting value to perform highlighting on a longer text that gets scored lower.",
            "This is highlighting the third short highlighting value.",
            "Just a test4 highlighting from unified highlighter." };

        String[] expectedPassages = {
            "Just a test1 <b>highlighting</b> from unified highlighter.",
            "This is the second <b>highlighting</b> value to perform <b>highlighting</b> on a" + " longer text that gets scored lower.",
            "This is <b>highlighting</b> the third short <b>highlighting</b> value.",
            "Just a test4 <b>highlighting</b> from unified highlighter." };
        Query query = new TermQuery(new Term("text", "highlighting"));
        assertHighlightOneDoc(
            "text",
            inputs,
            new StandardAnalyzer(),
            query,
            Locale.ROOT,
            BreakIterator.getSentenceInstance(Locale.ROOT),
            0,
            expectedPassages
        );
    }

    public void testNoMatchSize() throws Exception {
        final String[] inputs = { "This is a test. Just a test highlighting from unified. Feel free to ignore." };
        Query query = new TermQuery(new Term("body", "highlighting"));
        assertHighlightOneDoc(
            "text",
            inputs,
            new StandardAnalyzer(),
            query,
            Locale.ROOT,
            BreakIterator.getSentenceInstance(Locale.ROOT),
            100,
            inputs
        );
    }

    public void testMultiPhrasePrefixQuerySingleTerm() throws Exception {
        final String[] inputs = { "The quick brown fox." };
        final String[] outputs = { "The quick <b>brown</b> fox." };
        MultiPhrasePrefixQuery query = new MultiPhrasePrefixQuery("text");
        query.add(new Term("text", "bro"));
        assertHighlightOneDoc(
            "text",
            inputs,
            new StandardAnalyzer(),
            query,
            Locale.ROOT,
            BreakIterator.getSentenceInstance(Locale.ROOT),
            0,
            outputs
        );
    }

    public void testMultiPhrasePrefixQuery() throws Exception {
        final String[] inputs = { "The quick brown fox." };
        final String[] outputs = { "The <b>quick</b> <b>brown</b> <b>fox</b>." };
        MultiPhrasePrefixQuery query = new MultiPhrasePrefixQuery("text");
        query.add(new Term("text", "quick"));
        query.add(new Term("text", "brown"));
        query.add(new Term("text", "fo"));
        assertHighlightOneDoc(
            "text",
            inputs,
            new StandardAnalyzer(),
            query,
            Locale.ROOT,
            BreakIterator.getSentenceInstance(Locale.ROOT),
            0,
            outputs
        );
    }

    public void testSentenceBoundedBreakIterator() throws Exception {
        final String[] inputs = {
            "The quick brown fox in a long sentence with another quick brown fox. " + "Another sentence with brown fox." };
        final String[] outputs = {
            "The <b>quick</b> <b>brown</b>",
            "<b>fox</b> in a long",
            "with another <b>quick</b>",
            "<b>brown</b> <b>fox</b>.",
            "sentence with <b>brown</b>",
            "<b>fox</b>.", };
        BooleanQuery query = new BooleanQuery.Builder().add(new TermQuery(new Term("text", "quick")), BooleanClause.Occur.SHOULD)
            .add(new TermQuery(new Term("text", "brown")), BooleanClause.Occur.SHOULD)
            .add(new TermQuery(new Term("text", "fox")), BooleanClause.Occur.SHOULD)
            .build();
        assertHighlightOneDoc(
            "text",
            inputs,
            new StandardAnalyzer(),
            query,
            Locale.ROOT,
            BoundedBreakIteratorScanner.getSentence(Locale.ROOT, 10),
            0,
            outputs
        );
    }

    public void testSmallSentenceBoundedBreakIterator() throws Exception {
        final String[] inputs = { "A short sentence. Followed by a bigger sentence that should be truncated. And a last short sentence." };
        final String[] outputs = { "A short <b>sentence</b>.", "Followed by a bigger <b>sentence</b>", "And a last short <b>sentence</b>" };
        TermQuery query = new TermQuery(new Term("text", "sentence"));
        assertHighlightOneDoc(
            "text",
            inputs,
            new StandardAnalyzer(),
            query,
            Locale.ROOT,
            BoundedBreakIteratorScanner.getSentence(Locale.ROOT, 20),
            0,
            outputs
        );
    }

    public void testRepeat() throws Exception {
        final String[] inputs = { "Fun  fun fun  fun  fun  fun  fun  fun  fun  fun" };
        final String[] outputs = {
            "<b>Fun</b>  <b>fun</b> <b>fun</b>",
            "<b>fun</b>  <b>fun</b>",
            "<b>fun</b>  <b>fun</b>  <b>fun</b>",
            "<b>fun</b>  <b>fun</b>" };
        Query query = new TermQuery(new Term("text", "fun"));
        assertHighlightOneDoc(
            "text",
            inputs,
            new StandardAnalyzer(),
            query,
            Locale.ROOT,
            BoundedBreakIteratorScanner.getSentence(Locale.ROOT, 10),
            0,
            outputs
        );

        query = new PhraseQuery.Builder().add(new Term("text", "fun")).add(new Term("text", "fun")).build();
        assertHighlightOneDoc(
            "text",
            inputs,
            new StandardAnalyzer(),
            query,
            Locale.ROOT,
            BoundedBreakIteratorScanner.getSentence(Locale.ROOT, 10),
            0,
            outputs
        );
    }

    public void testGroupSentences() throws Exception {
        final String[] inputs = { "Two words. Followed by many words in a big sentence. One. Two. Three. And more words." };
        final String[] outputs = {
            "<b>Two</b> <b>words</b>.",
            "Followed by many <b>words</b>",
            "<b>One</b>. <b>Two</b>. <b>Three</b>.",
            "And more <b>words</b>.", };
        BooleanQuery query = new BooleanQuery.Builder().add(new TermQuery(new Term("text", "one")), BooleanClause.Occur.SHOULD)
            .add(new TermQuery(new Term("text", "two")), BooleanClause.Occur.SHOULD)
            .add(new TermQuery(new Term("text", "three")), BooleanClause.Occur.SHOULD)
            .add(new TermQuery(new Term("text", "words")), BooleanClause.Occur.SHOULD)
            .build();
        assertHighlightOneDoc(
            "text",
            inputs,
            new StandardAnalyzer(),
            query,
            Locale.ROOT,
            BoundedBreakIteratorScanner.getSentence(Locale.ROOT, 20),
            0,
            outputs
        );
    }

    public void testOverlappingTerms() throws Exception {
        final String[] inputs = { "bro", "brown", "brownie", "browser" };
        final String[] outputs = { "<b>bro</b>", "<b>brown</b>", "<b>browni</b>e", "<b>browser</b>" };
        BooleanQuery query = new BooleanQuery.Builder().add(new FuzzyQuery(new Term("text", "brow")), BooleanClause.Occur.SHOULD)
            .add(new TermQuery(new Term("text", "b")), BooleanClause.Occur.SHOULD)
            .add(new TermQuery(new Term("text", "br")), BooleanClause.Occur.SHOULD)
            .add(new TermQuery(new Term("text", "bro")), BooleanClause.Occur.SHOULD)
            .add(new TermQuery(new Term("text", "brown")), BooleanClause.Occur.SHOULD)
            .add(new TermQuery(new Term("text", "browni")), BooleanClause.Occur.SHOULD)
            .add(new TermQuery(new Term("text", "browser")), BooleanClause.Occur.SHOULD)
            .build();
        Analyzer analyzer = CustomAnalyzer.builder()
            .withTokenizer(EdgeNGramTokenizerFactory.class, "minGramSize", "1", "maxGramSize", "7")
            .build();
        assertHighlightOneDoc("text", inputs, analyzer, query, Locale.ROOT, BreakIterator.getSentenceInstance(Locale.ROOT), 0, outputs);
    }

    public void testExceedMaxAnalyzedOffset() throws Exception {
        TermQuery query = new TermQuery(new Term("text", "max"));
        Analyzer analyzer = CustomAnalyzer.builder()
            .withTokenizer(EdgeNGramTokenizerFactory.class, "minGramSize", "1", "maxGramSize", "10")
            .build();

        assertHighlightOneDoc(
            "text",
            new String[] { "short text" },
            analyzer,
            query,
            Locale.ROOT,
            BreakIterator.getSentenceInstance(Locale.ROOT),
            0,
            new String[] {},
            10,
            null
        );

        IllegalArgumentException e = expectThrows(IllegalArgumentException.class, () -> {
            assertHighlightOneDoc(
                "text",
                new String[] { "exceeds max analyzed offset" },
                analyzer,
                query,
                Locale.ROOT,
                BreakIterator.getSentenceInstance(Locale.ROOT),
                0,
                new String[] {},
                10,
                null
            );
        });
        assertEquals(
            "The length [27] of field [text] in doc[0]/index[index] exceeds the [index.highlight.max_analyzed_offset] limit [10]. "
                + "To avoid this error, set the query parameter [max_analyzed_offset] to a value less than index setting [10] and this "
                + "will tolerate long field values by truncating them.",
            e.getMessage()
        );

        final Integer queryMaxAnalyzedOffset = randomIntBetween(11, 1000);
        e = expectThrows(IllegalArgumentException.class, () -> {
            assertHighlightOneDoc(
                "text",
                new String[] { "exceeds max analyzed offset" },
                analyzer,
                query,
                Locale.ROOT,
                BreakIterator.getSentenceInstance(Locale.ROOT),
                0,
                new String[] {},
                10,
                queryMaxAnalyzedOffset
            );
        });
        assertEquals(
            "The length [27] of field [text] in doc[0]/index[index] exceeds the [index.highlight.max_analyzed_offset] limit [10]. "
                + "To avoid this error, set the query parameter [max_analyzed_offset] to a value less than index setting [10] and this "
                + "will tolerate long field values by truncating them.",
            e.getMessage()
        );

        assertHighlightOneDoc(
            "text",
            new String[] { "exceeds max analyzed offset" },
            analyzer,
            query,
            Locale.ROOT,
            BreakIterator.getSentenceInstance(Locale.ROOT),
            1,
            new String[] { "exceeds" },
            10,
            10
        );
    }

    public void testExceedMaxAnalyzedOffsetWithRepeatedWords() throws Exception {

        TermQuery query = new TermQuery(new Term("text", "Fun"));
        Analyzer analyzer = new WhitespaceAnalyzer();
        assertHighlightOneDoc(
            "text",
            new String[] { "Testing Fun Testing Fun" },
            analyzer,
            query,
            Locale.ROOT,
            BreakIterator.getSentenceInstance(Locale.ROOT),
            0,
            new String[] { "Testing <b>Fun</b> Testing Fun" },
            29,
            10,
            UnifiedHighlighter.OffsetSource.ANALYSIS
        );
        assertHighlightOneDoc(
            "text",
            new String[] { "Testing Fun Testing Fun" },
            analyzer,
            query,
            Locale.ROOT,
            BreakIterator.getSentenceInstance(Locale.ROOT),
            0,
            new String[] { "Testing <b>Fun</b> Testing Fun" },
            29,
            10,
            UnifiedHighlighter.OffsetSource.POSTINGS
        );
    }

    public void testExceedMaxAnalyzedOffsetRandomOffset() throws Exception {
        TermQuery query = new TermQuery(new Term("text", "fun"));
        Analyzer analyzer = new WhitespaceAnalyzer();
        UnifiedHighlighter.OffsetSource offsetSource = randomBoolean()
            ? UnifiedHighlighter.OffsetSource.ANALYSIS
            : UnifiedHighlighter.OffsetSource.POSTINGS;
        final String[] inputs = { "Fun fun fun fun fun" };
        TreeMap<Integer, String> outputs = new TreeMap<>(
            Map.of(
                7,
                "Fun <b>fun</b> fun fun fun",
                11,
                "Fun <b>fun</b> <b>fun</b> fun fun",
                15,
                "Fun <b>fun</b> <b>fun</b> <b>fun</b> fun",
                19,
                "Fun <b>fun</b> <b>fun</b> <b>fun</b> <b>fun</b>"
            )
        );
        Integer randomOffset = between(7, 19);
        String output = outputs.ceilingEntry(randomOffset).getValue();
        assertHighlightOneDoc(
            "text",
            inputs,
            analyzer,
            query,
            Locale.ROOT,
            BreakIterator.getSentenceInstance(Locale.ROOT),
            0,
            new String[] { output },
            47,
            randomOffset,
            offsetSource
        );
    }
}
