PdfPig/src/UglyToad.PdfPig.Tests/Parser/FileStructure/FirstPassParserTests.cs

namespace UglyToad.PdfPig.Tests.Parser.FileStructure;

using PdfPig.Core;
using PdfPig.Parser.FileStructure;
using PdfPig.Tokenization.Scanner;
using PdfPig.Tokens;

public class FirstPassParserTests
{
    [Fact]
    public void FindsTwoXrefs()
    {
        var content =
            """
            %PDF-1.7
            %âãÏÓ
            5 0 obj
            <</Filter/FlateDecode/Length 66>>stream
            abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz
            endstream
            endobj
            xref7 1
            0000000000 65535 f 
            0000000500 00000 n 
            4 0 obj
            <</Contents 5 0 R/MediaBox[0 0 595 842]/Parent 2 0 R/Resources<</Font<</F1 6 0 R>>>>/TrimBox[0 0 595 842]/Type/Page>>
            endobj
            xref
            0 3
            0000000000 65535 f 
            0000000443 00000 n 
            0000000576 00000 n
            trailer
            << /Size 100 /Root 100 >>
            startxref
            9000
            %%EOF
            """;

        var ib = StringBytesTestConverter.Convert(content, false);

        var results = FirstPassParser.Parse(
            new FileHeaderOffset(0),
            ib.Bytes,
            new CoreTokenScanner(ib.Bytes, true, new StackDepthGuard(256)));

        Assert.Equal(2, results.Parts.Count);
        Assert.NotNull(results.Trailer);

        Assert.Equal(results.XrefOffsets[new IndirectReference(8, 0)], 500);
    }

    [Fact]
    public void FindsXrefsFromRealFileTruncated()
    {
        var content =
            """
            %PDF-1.5
            %âãÏÓ
            5 0 obj <</Linearized 1/L 4631/O 8/E 1125/N 1/T 4485/H [ 436 129]>>
            endobj
            xref
            5 7
            0000000016 00000 n
            0000000565 00000 n
            0000000436 00000 n
            0000000639 00000 n
            0000000796 00000 n
            0000001001 00000 n
            0000001098 00000 n
            trailer
            <</Size 12/Prev 4475/Root 6 0 R/Info 4 0 R/ID[<2c9c3edf9641f1459e947e7f933f6da0><2c9c3edf9641f1459e947e7f933f6da0>]>>
            startxref
            0
            %%EOF
            7 0 obj<</Length 52/Filter/FlateDecode/O 67/S 38>>stream
            3842973893927327893237832738923732923782987348
            endstream
            endobj
            6 0 obj<</Pages 2 0 R/Outlines 1 0 R/Type/Catalog/Metadata 3 0 R>>
            endobj
            8 0 obj<</Contents 9 0 R/Type/Page/Parent 2 0 R/Rotate 0/MediaBox[0 0 612 792]/CropBox[0 0 612 792]/Resources<</Font<</F1 10 0 R>>/ProcSet 11 0 R>>>>
            endobj
            9 0 obj<</Length 137/Filter/FlateDecode>>stream
            abajsgiwgbkeeuuehxh9x3oihx2h802chc280h2082x
            endstream
            endobj
            10 0 obj<</Type/Font/Name/F1/Encoding/MacRomanEncoding/BaseFont/Helvetica/Subtype/Type1>>
            endobj
            11 0 obj[/PDF/Text]
            endobj
            1 0 obj<</Count 0/Type/Outlines>>
            endobj
            2 0 obj<</Count 1/Kids[8 0 R]/Type/Pages>>
            endobj
            4 0 obj<</ModDate(D:20070213222810-05'00')/CreationDate(D:20070213222810-05'00')>>
            endobj
            xref
            0 5
            0000000000 65535 f
            0000001125 00000 n
            0000001166 00000 n
            0000001216 00000 n
            0000004385 00000 n
            trailer
            <</Size 5>>
            startxref
            116
            %%EOF
            """;

        // Handle "\r\n" or "\n" in the sourcecode in the same way
        content = content.Replace("\r\n", "\n").Replace("\n", "\r\n");

        var ib = StringBytesTestConverter.Convert(content, false);

        var results = FirstPassParser.Parse(new FileHeaderOffset(0), ib.Bytes, new CoreTokenScanner(ib.Bytes, true, new StackDepthGuard(256)));

        var offsets = results.Parts.Select(x => x.Offset).OrderBy(x => x).ToList();
        
        Assert.Equal(98, offsets[0]);
        Assert.Equal(1186, offsets[1]);
        Assert.NotNull(results.Trailer);

        ib.Bytes.Seek(98);
        var scanner = new CoreTokenScanner(ib.Bytes, false, new StackDepthGuard(256));
        scanner.MoveNext();
        Assert.Equal(scanner.CurrentToken, OperatorToken.Xref);
    }
}