GDROMExplorer/Formats/GDI/GDIFileSystemValidator.cs

// Decompiled with JetBrains decompiler
// Type: GDRomExplorer.ImageFileFormat.GDI.GDIFileSystemValidator
// Assembly: GDI, Version=1.0.0.0, Culture=neutral, PublicKeyToken=611be24fdeb07e08
// MVID: F4295E7C-8421-4324-B5B1-F38932DD6235
// Assembly location: Formats\GDI.dll

using SEGATools.DiscFileSystem;
using SEGATools.Security;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;

namespace GDRomExplorer.ImageFileFormat.GDI
{
  internal class GDIFileSystemValidator : IGDIFileSystemValidator
  {
    private static readonly int TRACK_MINIMUM_SIZE_IN_SECTORS = 300;
    private IInitialProgramProvider IpProvider;

    public GDIFileSystemValidator(IInitialProgramProvider IpProvider) => this.IpProvider = IpProvider;

    public void CheckDiscFileSystem(IDiscFileSystem disc)
    {
      IDiscSession session1 = disc.Sessions[0];
      IDiscSession session2 = disc.Sessions[1];
      InitialProgram initialProgram = this.IpProvider.GetInitialProgram(session2.FirstDataTrack);
      this.CheckInitialProgramAndHighDensityTracksMatch(initialProgram, session2);
      this.CheckInitialProgramAndHighDensitySizesMatch(initialProgram, session2);
      List<IDiscTrack> list = session1.Tracks.Concat<IDiscTrack>((IEnumerable<IDiscTrack>) session2.Tracks).ToList<IDiscTrack>();
      this.CheckTrackIndexesAreConsecutive((IList<IDiscTrack>) list);
      this.CheckTrackGapAndOverlap((IList<IDiscTrack>) list);
    }

    public void CheckDiscTrackSize(IDiscTrack track)
    {
      if (track.Length % (long) track.TrackSector.Size != 0L || track.Length / (long) track.TrackSector.Size < (long) GDIFileSystemValidator.TRACK_MINIMUM_SIZE_IN_SECTORS)
        throw new DiscFormatException(string.Format("Invalid track size: {0} must be at least {1} bytes long and its size must a multiple of {2}.", (object) Path.GetFileName(track.FileName), (object) GDIFileSystemValidator.TRACK_MINIMUM_SIZE_IN_SECTORS, (object) track.TrackSector.Size));
    }

    private void CheckTrackIndexesAreConsecutive(IList<IDiscTrack> tracks)
    {
      IDiscTrack discTrack = (IDiscTrack) null;
      foreach (IDiscTrack track in (IEnumerable<IDiscTrack>) tracks)
      {
        if (discTrack != null && discTrack.Index + 1 != track.Index)
          throw new DiscFormatException(string.Format("Track indexes are not consecutive: track with index {0} is missing", (object) track.Index));
        discTrack = track;
      }
    }

    private void CheckTrackGapAndOverlap(IList<IDiscTrack> tracks)
    {
      IDiscTrack discTrack = (IDiscTrack) null;
      foreach (IDiscTrack track in (IEnumerable<IDiscTrack>) tracks)
      {
        if (discTrack != null)
        {
          long num1 = (long) discTrack.LogicalBlockAddress + discTrack.Length / (long) discTrack.TrackSector.Size - 1L;
          int num2 = discTrack.TrackData != track.TrackData ? 150 : 0;
          if (this.AreTracksOverlapping(num1 + (long) num2, (long) track.LogicalBlockAddress))
            throw new DiscFormatException(string.Format("Tracks overlap detected: track {0} overlaps track {1}", (object) Path.GetFileName(discTrack.FileName), (object) Path.GetFileName(track.FileName)));
          if (discTrack.Session == track.Session && !this.AreTracksContinuous(num1 + (long) num2, (long) track.LogicalBlockAddress))
            throw new DiscFormatException(string.Format("Gap between tracks: tracks {0} and {1} are not continuous", (object) Path.GetFileName(discTrack.FileName), (object) Path.GetFileName(track.FileName)));
        }
        discTrack = track;
      }
    }

    private void CheckInitialProgramAndHighDensityTracksMatch(
      InitialProgram initialProgram,
      IDiscSession highDensity)
    {
      this.CheckInitialProgramAndHighDensityTrackCountsMatch(initialProgram, highDensity);
      for (int index = 0; index < initialProgram.TableOfContent.Tracks.Count; ++index)
      {
        InitialProgramTrackInfo track1 = initialProgram.TableOfContent.Tracks[index];
        IDiscTrack track2 = highDensity.Tracks[index];
        long track2size = track2.Length / (long)track2.TrackSector.Size;
        if (track2size != (long) track1.Size)
          throw new DiscFormatException(string.Format("Invalid track size: {0} must be {1} sectors long", (object) track2, (object) track1.Size));
      }
    }

    private void CheckInitialProgramAndHighDensitySizesMatch(
      InitialProgram initialProgram,
      IDiscSession highDensity)
    {
      long num1 = 0;
      foreach (IDiscTrack track in highDensity.Tracks)
        num1 += track.Length / (long) track.TrackSector.Size;
      long num2 = initialProgram.TableOfContent.Tracks.Sum<InitialProgramTrackInfo>((Func<InitialProgramTrackInfo, long>) (track => (long) track.Size));
      if (num1 != num2)
        throw new DiscFormatException(string.Format("Invalid session size: the high density session must be {0} sectors long", (object) num2));
    }

    private void CheckInitialProgramAndHighDensityTrackCountsMatch(
      InitialProgram initialProgram,
      IDiscSession highDensity)
    {
      if (initialProgram.TableOfContent == null)
        throw new DiscFormatException("Invalid boot sector: the boot sector does not contain a valid TOC");
      if (initialProgram.TableOfContent.Tracks.Count != highDensity.Tracks.Count)
        throw new DiscFormatException(string.Format("Invalid number of tracks: the boot sector indicates {0} tracks whereas the {1} contains {2}", (object) initialProgram.TableOfContent.Tracks.Count, (object) highDensity.Name, (object) highDensity.Tracks.Count));
    }

    private bool AreTracksOverlapping(long firstTrackEndLBA, long secondTrackStartLBA) => firstTrackEndLBA >= secondTrackStartLBA;

    private bool AreTracksContinuous(long firstTrackEndLBA, long secondTrackStartLBA) => firstTrackEndLBA + 1L == secondTrackStartLBA;
  }
}