/*
 * 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.
 */
package org.apache.pdfbox.text;

import difflib.ChangeDelta;
import difflib.DeleteDelta;
import difflib.DiffUtils;
import difflib.InsertDelta;
import difflib.Patch;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertNotEquals;
import static org.junit.jupiter.api.Assertions.assertTrue;
import static org.junit.jupiter.api.Assertions.fail;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.LineNumberReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintStream;
import java.io.Writer;

import java.net.URISyntaxException;

import java.nio.file.Files;

import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.fontbox.util.BoundingBox;
import org.apache.pdfbox.Loader;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.PDPageContentStream;
import org.apache.pdfbox.pdmodel.font.PDFont;
import org.apache.pdfbox.pdmodel.font.PDFontDescriptor;
import org.apache.pdfbox.pdmodel.font.PDType1Font;
import org.apache.pdfbox.pdmodel.font.PDType3Font;
import org.apache.pdfbox.pdmodel.font.Standard14Fonts;
import org.apache.pdfbox.pdmodel.interactive.documentnavigation.destination.PDPageDestination;
import org.apache.pdfbox.pdmodel.interactive.documentnavigation.outline.PDDocumentOutline;
import org.apache.pdfbox.pdmodel.interactive.documentnavigation.outline.PDOutlineItem;

import org.junit.jupiter.api.BeforeAll;
import org.junit.jupiter.api.Test;


/**
 * Test suite for PDFTextStripper.
 *
 * FILE SET VALIDATION
 *
 * This test suite is designed to test PDFTextStripper using a set of PDF
 * files and known good output for each.  The default mode of testAll()
 * is to process each *.pdf file in "src/test/resources/input".  An output
 * file is created in "target/test-output" with the same name as the PDF file,
 * plus an additional ".txt" suffix.  
 *
 * The output file is then tested against a known good result file from
 * the input directory (again, with the same name as the tested PDF file,
 * but with the additional ".txt" suffix).  The process is performed both
 * with and without sorting enabled.  The sorted files have a "-sorted.txt" 
 * suffix. 
 *
 * So for the file "src/test/resources/input/hello.pdf", an output file will
 * be generated named "target/test-output/hello.pdf.txt".  Then that file
 * will be compared to the known good file
 * "src/test/resources/input/hello.pdf.txt", if it exists.
 * 
 * To support testing with files that are not officially distributed 
 * with PDFBox, this test will also look in the "target/test-input-ext"
 * directory.
 *
 * Any errors are logged, and at the end of processing all *.pdf files, if
 * there were any errors, the test fails.  The logging is at INFO, as the
 * general goal is overall validation, and on failure, the indication of
 * which file or files failed.
 *
 * When processing new PDF files, you may use testAll() to generate output,
 * verify the output manually, then move the output file to the test input
 * directory to use as the basis for future validations.
 *
 * SINGLE FILE VALIDATION
 *
 * To further research individual failures, the org.apache.pdfbox.util.TextStripper.file
 * system property may be set with the name of a single file in the "test/input"
 * directory.  In this mode, testAll() will evaluate only that file, and will
 * do so with DEBUG level logging.
 *
 * @author Robert Dickinson
 * @author Ben Litchfield
 */
class TestTextStripper
{

    /**
     * Logger instance.
     */
    private static final Log log = LogFactory.getLog(TestTextStripper.class);

    private boolean bFail = false;
    private static PDFTextStripper stripper;
    private static final String ENCODING = "UTF-8";

    /**
     * Test class initialization.
     *
     * @throws IOException If there is an error initializing the test.
     */
    @BeforeAll
    static void init() throws IOException
    {
        stripper = new PDFTextStripper();
        stripper.setLineSeparator("\n");
        // If you want to test a single file using DEBUG logging, from an IDE,
        // you can do something like this:
        // System.setProperty("org.apache.pdfbox.util.TextStripper.file", "FVS318Ref.pdf");
    }

    /**
     * Determine whether two strings are equal, where two null strings are
     * considered equal.
     *
     * @param expected Expected string
     * @param actual Actual String
     * @return <code>true</code> is the strings are both null,
     * or if their contents are the same, otherwise <code>false</code>.
     */
    private boolean stringsEqual(String expected, String actual)
    {
        boolean equals = true;
        if( (expected == null) && (actual == null) )
        {
            return true;
        }
        else if( expected != null && actual != null )
        {
            expected = expected.trim();
            actual = actual.trim();
            char[] expectedArray = expected.toCharArray();
            char[] actualArray = actual.toCharArray();
            int expectedIndex = 0;
            int actualIndex = 0;
            while( expectedIndex<expectedArray.length && actualIndex<actualArray.length )
            {
                if( expectedArray[expectedIndex] != actualArray[actualIndex] )
                {
                    equals = false;
                    log.warn("Lines differ at index"
                     + " expected:" + expectedIndex + "-" + (int)expectedArray[expectedIndex]
                     + " actual:" + actualIndex + "-" + (int)actualArray[actualIndex] );
                    break;
                }
                expectedIndex = skipWhitespace( expectedArray, expectedIndex );
                actualIndex = skipWhitespace( actualArray, actualIndex );
                expectedIndex++;
                actualIndex++;
            }
            if( equals )
            {
                if( expectedIndex != expectedArray.length )
                {
                    equals = false;
                    log.warn("Expected line is longer at:" + expectedIndex );
                }
                if( actualIndex != actualArray.length )
                {
                    equals = false;
                    log.warn("Actual line is longer at:" + actualIndex );
                }
                if (expectedArray.length != actualArray.length)
                {
                    equals = false;
                    log.warn("Expected lines: " + expectedArray.length + ", actual lines: " + actualArray.length);
                }
            }
        }
        else
        {
            equals = (expected == null && actual != null && actual.trim().isEmpty())
                    || (actual == null && expected != null && expected.trim().isEmpty());
        }
        return equals;
    }

    /**
     * If the current index is whitespace then skip any subsequent whitespace.
     */
    private int skipWhitespace( char[] array, int index )
    {
        //if we are at a space character then skip all space
        //characters, but when all done rollback 1 because stringsEqual
        //will roll forward 1
        if( array[index] == ' ' || array[index] > 256 )
        {
            while( index < array.length && (array[index] == ' ' || array[index] > 256))
            {
                index++;
            }
            index--;
        }
        return index;
    }

    /**
     * Validate text extraction on a single file.
     *
     * @param inFile The PDF file to validate
     * @param outDir The directory to store the output in
     * @param bLogResult Whether to log the extracted text
     * @param bSort Whether or not the extracted text is sorted
     * @throws Exception when there is an exception
     */
    private void doTestFile(File inFile, File outDir, boolean bLogResult, boolean bSort)
    throws Exception
    {
        if(bSort)
        {
            log.info("Preparing to parse " + inFile.getName() + " for sorted test");
        }
        else
        {
            log.info("Preparing to parse " + inFile.getName() + " for standard test");
        }

        Files.createDirectories(outDir.toPath());

        try (PDDocument document = Loader.loadPDF(inFile))
        {
            File outFile;
            File diffFile;
            File expectedFile;

            if(bSort)
            {
                outFile = new File(outDir,  inFile.getName() + "-sorted.txt");
                diffFile = new File(outDir, inFile.getName() + "-sorted-diff.txt");
                expectedFile = new File(inFile.getParentFile(), inFile.getName() + "-sorted.txt");
            }
            else
            {
                outFile = new File(outDir, inFile.getName() + ".txt");
                diffFile = new File(outDir, inFile.getName() + "-diff.txt");
                expectedFile = new File(inFile.getParentFile(), inFile.getName() + ".txt");
            }
            
            // delete possible leftover
            diffFile.delete();

            try (OutputStream os = new FileOutputStream(outFile))
            {
                os.write (0xEF);
                os.write (0xBB);
                os.write (0xBF);

                try (Writer writer = new BufferedWriter(new OutputStreamWriter(os, ENCODING)))
                {
                    //Allows for sorted tests 
                    stripper.setSortByPosition(bSort);
                    stripper.writeText(document, writer);
                    // close the written file before reading it again
                }
            }

            if (bLogResult)
            {
                log.info("Text for " + inFile.getName() + ":");
                log.info(stripper.getText(document));
            }

            if (!expectedFile.exists())
            {
                this.bFail = true;
                log.error("FAILURE: Input verification file: " + expectedFile.getAbsolutePath() +
                        " did not exist");
                return;
            }
            
            compareResult(expectedFile, outFile, inFile, bSort, diffFile);
        }
    }

    private void compareResult(File expectedFile, File outFile, File inFile, boolean bSort, File diffFile)
            throws IOException
    {
        boolean localFail = false;
        
        try (LineNumberReader expectedReader =
                new LineNumberReader(new InputStreamReader(new FileInputStream(expectedFile), ENCODING));
                LineNumberReader actualReader =
                        new LineNumberReader(new InputStreamReader(new FileInputStream(outFile), ENCODING)))
        {
            while (true)
            {
                String expectedLine = expectedReader.readLine();
                while (expectedLine != null && expectedLine.trim().isEmpty())
                {
                    expectedLine = expectedReader.readLine();
                }
                String actualLine = actualReader.readLine();
                while (actualLine != null && actualLine.trim().isEmpty())
                {
                    actualLine = actualReader.readLine();
                }
                if (!stringsEqual(expectedLine, actualLine))
                {
                    this.bFail = true;
                    localFail = true;
                    log.error("FAILURE: Line mismatch for file " + inFile.getName() +
                            " (sort = "+bSort+")" +
                                    " at expected line: " + expectedReader.getLineNumber() +
                            " at actual line: " + actualReader.getLineNumber() +
                            "\nexpected line was: \"" + expectedLine + "\"" +
                                    "\nactual line was:   \"" + actualLine + "\"" + "\n");
                    
                    //lets report all lines, even though this might produce some verbose logging
                    //break;
                }
                
                if (expectedLine == null || actualLine == null)
                {
                    break;
                }
            }
        }
        if (!localFail)
        {
            outFile.delete();
        }
        else
        {
            // https://code.google.com/p/java-diff-utils/wiki/SampleUsage
            List<String> original = fileToLines(expectedFile);
            List<String> revised = fileToLines(outFile);
            
            // Compute diff. Get the Patch object. Patch is the container for computed deltas.
            Patch<String> patch = DiffUtils.diff(original, revised);
            
            try (PrintStream diffPS = new PrintStream(diffFile, ENCODING))
            {
                patch.getDeltas().forEach(delta ->
                {
                    if (delta instanceof ChangeDelta)
                    {
                        ChangeDelta<String> cdelta = (ChangeDelta<String>) delta;
                        diffPS.println("Org: " + cdelta.getOriginal());
                        diffPS.println("New: " + cdelta.getRevised());
                        diffPS.println();
                    }
                    else if (delta instanceof DeleteDelta)
                    {
                        DeleteDelta<String> ddelta = (DeleteDelta<String>) delta;
                        diffPS.println("Org: " + ddelta.getOriginal());
                        diffPS.println("New: " + ddelta.getRevised());
                        diffPS.println();
                    }
                    else if (delta instanceof InsertDelta)
                    {
                        InsertDelta<String> idelta = (InsertDelta<String>) delta;
                        diffPS.println("Org: " + idelta.getOriginal());
                        diffPS.println("New: " + idelta.getRevised());
                        diffPS.println();
                    }
                    else
                    {
                        diffPS.println(delta);
                    }
                });
            }
        }
    }
    
    // Helper method for get the file content
    private static List<String> fileToLines(File file) throws IOException
    {
        List<String> lines = new LinkedList<>();
        String line;

        try (BufferedReader in = new BufferedReader(new InputStreamReader(new FileInputStream(file), ENCODING)))
        {
            while ((line = in.readLine()) != null)
            {
                lines.add(line);
            }
        }

        return lines;
    }

    private int findOutlineItemDestPageNum(PDDocument doc, PDOutlineItem oi) throws IOException
    {
        PDPageDestination pageDest = (PDPageDestination) oi.getDestination();
        
        // two methods to get the page index, the result should be identical!
        int indexOfPage = doc.getPages().indexOf(oi.findDestinationPage(doc));
        int pageNum = pageDest.retrievePageNumber();
        assertEquals(indexOfPage, pageNum);
                
        return pageNum;
    }

    /**
     * Test whether stripping controlled by outline items works properly. The test file has 4
     * outline items at the top level, that point to 0-based pages 0, 2, 3 and 4. We are testing
     * text stripping by outlines pointing to 0-based pages 2 and 3, and also text stripping of the
     * 0-based page 2. The test makes sure that the output is different to a complete strip, not
     * empty, different to each other when different bookmark intervals are used, but identical from
     * bookmark intervals to strips with page intervals. When fed with orphan bookmarks, stripping
     * must be empty.
     *
     * @throws IOException
     * @throws URISyntaxException
     */
    @Test
    void testStripByOutlineItems() throws IOException, URISyntaxException
    {
        PDDocument doc = Loader
                .loadPDF(new File(this.getClass().getResource("../pdmodel/with_outline.pdf").toURI()));
        PDDocumentOutline outline = doc.getDocumentCatalog().getDocumentOutline();
        Iterable<PDOutlineItem> children = outline.children();
        Iterator<PDOutlineItem> it = children.iterator();
        PDOutlineItem oi0 = it.next();
        PDOutlineItem oi2 = it.next();
        PDOutlineItem oi3 = it.next();
        PDOutlineItem oi4 = it.next();

        assertEquals(0, findOutlineItemDestPageNum(doc, oi0));
        assertEquals(2, findOutlineItemDestPageNum(doc, oi2));
        assertEquals(3, findOutlineItemDestPageNum(doc, oi3));
        assertEquals(4, findOutlineItemDestPageNum(doc, oi4));

        String textFull = stripper.getText(doc);
        assertFalse(textFull.isEmpty());
        
        String expectedTextFull = 
                "First level 1\n"
                + "First level 2\n"
                + "Fist level 3\n"
                + "Some content\n"
                + "Some other content\n"
                + "Second at level 1\n"
                + "Second level 2\n"
                + "Content\n"
                + "Third level 1\n"
                + "Third level 2\n"
                + "Third level 3\n"
                + "Content\n"
                + "Fourth level 1\n"
                + "Content\n"
                + "Content\n";
        assertEquals(expectedTextFull, textFull.replaceAll("\r", ""));
        
        // this should grab 0-based pages 2 and 3, i.e. 1-based pages 3 and 4
        // by their bookmarks
        stripper.setStartBookmark(oi2);
        stripper.setEndBookmark(oi3);
        String textoi23 = stripper.getText(doc);
        assertFalse(textoi23.isEmpty());
        assertNotEquals(textoi23, textFull);
        
        String expectedTextoi23 = 
                "Second at level 1\n"
                + "Second level 2\n"
                + "Content\n"
                + "Third level 1\n"
                + "Third level 2\n"
                + "Third level 3\n"
                + "Content\n";
        assertEquals(expectedTextoi23, textoi23.replaceAll("\r", ""));
        
        // this should grab 0-based pages 2 and 3, i.e. 1-based pages 3 and 4
        // by their page numbers
        stripper.setStartBookmark(null);
        stripper.setEndBookmark(null);
        stripper.setStartPage(3);
        stripper.setEndPage(4);
        String textp34 = stripper.getText(doc);
        assertFalse(textp34.isEmpty());
        assertNotEquals(textoi23, textFull);
        assertEquals(textoi23, textp34);        

        // this should grab 0-based page 2, i.e. 1-based page 3
        // by the bookmark
        stripper.setStartBookmark(oi2);
        stripper.setEndBookmark(oi2);
        String textoi2 = stripper.getText(doc);
        assertFalse(textoi2.isEmpty());
        assertNotEquals(textoi2, textoi23);
        assertNotEquals(textoi23, textFull);
        
        String expectedTextoi2 = 
                "Second at level 1\n"
                + "Second level 2\n"
                + "Content\n";        
        assertEquals(expectedTextoi2, textoi2.replaceAll("\r", ""));
        
         
        // this should grab 0-based page 2, i.e. 1-based page 3
        // by the page number
        stripper.setStartBookmark(null);
        stripper.setEndBookmark(null);
        stripper.setStartPage(3);
        stripper.setEndPage(3);
        String textp3 = stripper.getText(doc);
        assertFalse(textp3.isEmpty());
        assertNotEquals(textp3, textp34);
        assertNotEquals(textoi23, textFull);
        assertEquals(textoi2, textp3);

        // Test with orphan bookmark
        PDOutlineItem oiOrphan = new PDOutlineItem();
        stripper.setStartBookmark(oiOrphan);
        stripper.setEndBookmark(oiOrphan);
        String textOiOrphan = stripper.getText(doc);
        assertTrue(textOiOrphan.isEmpty());
    }

    /**
     * Process each file in the specified directory.
     * @param inDir Input directory search for PDF files in.
     * @param outDir Output directory where the temp files will be created.
     */
    private void doTestDir(File inDir, File outDir) throws Exception 
    {
        File[] testFiles = inDir.listFiles((File dir, String name) -> name.endsWith(".pdf"));
        for (File testFile : testFiles) 
        {
            //Test without sorting
            doTestFile(testFile, outDir, false, false);
            //Test with sorting
            doTestFile(testFile, outDir, false, true);
        }
    }
    
    /**
     * Test to validate text extraction of file set.
     *
     * @throws Exception when there is an exception
     */
    @Test
    void testExtract() throws Exception
    {
        String filename = System.getProperty("org.apache.pdfbox.util.TextStripper.file");
        File inDir = new File("src/test/resources/input");
        File outDir = new File("target/test-output");
        File inDirExt = new File("target/test-input-ext");
        File outDirExt = new File("target/test-output-ext");

            if (filename == null || filename.isEmpty())
            {
                doTestDir(inDir, outDir);
                if (inDirExt.exists())
                {
                    doTestDir(inDirExt, outDirExt);
                }
            }
            else 
            {
                //Test without sorting
                doTestFile(new File(inDir, filename), outDir, true, false);
                //Test with sorting
                doTestFile(new File(inDir, filename), outDir, true, true);
            }

            if (this.bFail)
            {
                fail("One or more failures, see test log for details");
            }
    }

    @Test
    void testTabula() throws IOException
    {
        File pdfFile = new File("src/test/resources/input","eu-001.pdf");
        File outFile = new File("target/test-output","eu-001.pdf-tabula.txt");
        File expectedOutFile = new File("src/test/resources/input","eu-001.pdf-tabula.txt");
        File diffFile = new File("target/test-output","eu-001.pdf-tabula-diff.txt");
        PDDocument tabulaDocument = Loader.loadPDF(pdfFile);
        PDFTextStripper tabulaStripper = new PDFTabulaTextStripper();

        try (OutputStream os = new FileOutputStream(outFile))
        {
            os.write(0xEF);
            os.write(0xBB);
            os.write(0xBF);

            try (Writer writer = new BufferedWriter(new OutputStreamWriter(os, ENCODING)))
            {
                tabulaStripper.writeText(tabulaDocument, writer);
            }
        }

        compareResult(expectedOutFile, outFile, pdfFile, false, diffFile);
        
        assertFalse(bFail);
    }

    private class PDFTabulaTextStripper extends PDFTextStripper
    {
        PDFTabulaTextStripper() throws IOException
        {
            // empty
        }

        @Override
        protected float computeFontHeight(PDFont font) throws IOException
        {
            BoundingBox bbox = font.getBoundingBox();
            if (bbox.getLowerLeftY() < Short.MIN_VALUE)
            {
                // PDFBOX-2158 and PDFBOX-3130
                // files by Salmat eSolutions / ClibPDF Library
                bbox.setLowerLeftY(-(bbox.getLowerLeftY() + 65536));
            }
            // 1/2 the bbox is used as the height todo: why?
            float glyphHeight = bbox.getHeight() / 2;

            // sometimes the bbox has very high values, but CapHeight is OK
            PDFontDescriptor fontDescriptor = font.getFontDescriptor();
            if (fontDescriptor != null)
            {
                float capHeight = fontDescriptor.getCapHeight();
                if (Float.compare(capHeight, 0) != 0
                        && (capHeight < glyphHeight || Float.compare(glyphHeight, 0) == 0))
                {
                    glyphHeight = capHeight;
                }
                // PDFBOX-3464, PDFBOX-448:
                // sometimes even CapHeight has very high value, but Ascent and Descent are ok
                float ascent = fontDescriptor.getAscent();
                float descent = fontDescriptor.getDescent();
                if (ascent > 0 && descent < 0
                        && ((ascent - descent) / 2 < glyphHeight || Float.compare(glyphHeight, 0) == 0))
                {
                    glyphHeight = (ascent - descent) / 2;
                }
            }

            // transformPoint from glyph space -> text space
            float height;
            if (font instanceof PDType3Font)
            {
                height = font.getFontMatrix().transformPoint(0, glyphHeight).y;
            }
            else
            {
                height = glyphHeight / 1000;
            }

            return height;
        }
    }

    /**
     * Check that setting start and end pages work properly.
     *
     * @throws IOException 
     */
    @Test
    void testStartEndPage() throws IOException
    {
        File pdfFile = new File("src/test/resources/input", "eu-001.pdf");
        try (PDDocument doc = Loader.loadPDF(pdfFile))
        {
            PDFTextStripper textStripper = new PDFTextStripper();
            textStripper.setStartPage(2);
            textStripper.setEndPage(2);
            String text = textStripper.getText(doc).trim();
            assertTrue(text.startsWith("Pesticides"));
            assertTrue(text.endsWith("1 000 10 10"));
            assertEquals(1378, text.replaceAll("\r", "").length());
        }
    }

    /**
     * PDFBOX-3774: test the IgnoreContentStreamSpaceGlyphs option.
     *
     * @throws Exception 
     */
    @Test
    void testIgnoreContentStreamSpaceGlyphs() throws Exception
    {
        try (PDDocument doc = new PDDocument())
        {
            PDPage page = new PDPage();
            try (PDPageContentStream cs = new PDPageContentStream(doc, page))
            {
                float fontHeight = 8;
                float x = 50;
                float y = page.getMediaBox().getHeight() - 50;
                PDFont font = new PDType1Font(Standard14Fonts.FontName.HELVETICA);
                cs.beginText();
                cs.setFont(font, fontHeight);
                cs.newLineAtOffset(x, y);
                cs.showText("(                                      )");
                cs.endText();

                int indent = 6;
                float overlapX = x + indent * font.getAverageFontWidth() / 1000f * fontHeight;
                PDFont overlapFont = new PDType1Font(Standard14Fonts.FontName.TIMES_ROMAN);
                cs.beginText();
                cs.setFont(overlapFont, fontHeight * 2f);
                cs.newLineAtOffset(overlapX, y);
                cs.showText("overlap");
                cs.endText();
            }
            doc.addPage(page);

            PDFTextStripper localStripper = new PDFTextStripper();
            localStripper.setLineSeparator("\n");
            localStripper.setPageEnd("\n");
            localStripper.setStartPage(1);
            localStripper.setEndPage(1);
            localStripper.setSortByPosition(true);

            localStripper.setIgnoreContentStreamSpaceGlyphs(true);
            String text = localStripper.getText(doc);
            assertEquals("( overlap )\n", text);
        }
    }
}
