#region PDFsharp - A .NET library for processing PDF
//
// Authors:
//   Stefan Lange (mailto:Stefan.Lange@pdfsharp.com)
//
// Copyright (c) 2005-2007 empira Software GmbH, Cologne (Germany)
//
// http://www.pdfsharp.com
// http://sourceforge.net/projects/pdfsharp
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
// DEALINGS IN THE SOFTWARE.
#endregion

using System;
using System.Diagnostics;
using System.Collections;
using System.Text;
using System.IO;
using PdfSharp.Drawing;
using PdfSharp.Drawing.Pdf;
using PdfSharp.Pdf;
using PdfSharp.Pdf.Internal;
using PdfSharp.Pdf.Filters;
using PdfSharp.Pdf.IO;

namespace PdfSharp.Pdf.Advanced
{
  /// <summary>
  /// Represents an array of PDF content streams of a page.
  /// </summary>
  public sealed class PdfContents : PdfArray
  {
    public PdfContents(PdfDocument document)
      : base(document)
    {
    }

    internal PdfContents(PdfArray array)
      : base(array)
    {
      int count = Elements.Count;
      for (int idx = 0; idx < count; idx++)
      {
        // Convert the references from PdfDictionary to PdfContent
        PdfItem item = Elements[idx];
        PdfReference iref = item as PdfReference;
        if (iref != null && iref.Value is PdfDictionary)
        {
          // The following line is correct!
          new PdfContent((PdfDictionary)iref.Value);
        }
        else
          throw new InvalidOperationException("Unexpected item in a content stream array.");
      }
    }

    /// <summary>
    /// Appends a new content stream and returns it.
    /// </summary>
    public PdfContent AppendContent()
    {
      Debug.Assert(this.Owner != null);

      SetModified();
      PdfContent content = new PdfContent(this.Owner);
      Owner.irefTable.Add(content);
      Debug.Assert(content.Reference != null);
      Elements.Add(content.Reference);
      return content;
    }

    /// <summary>
    /// Prepends a new content stream and returns it.
    /// </summary>
    public PdfContent PrependContent()
    {
      Debug.Assert(this.Owner != null);

      SetModified();
      PdfContent content = new PdfContent(this.Owner);
      Owner.irefTable.Add(content);
      Debug.Assert(content.Reference != null);
      Elements.Insert(0, content.Reference);
      return content;
    }

    /// <summary>
    /// Creates a single content stream with the bytes from the array of the content streams.
    /// This operation does not modify any of the content streams in this array.
    /// </summary>
    public PdfContent CreateSingleContent()
    {
      byte[] bytes = new byte[0];
      byte[] bytes1;
      byte[] bytes2;
      foreach (PdfItem iref in Elements)
      {
        PdfDictionary cont = (PdfDictionary)((PdfReference)iref).Value;
        bytes1 = bytes;
        bytes2 = cont.Stream.UnfilteredValue;
        bytes = new byte[bytes1.Length + bytes2.Length + 1];
        bytes1.CopyTo(bytes, 0);
        bytes[bytes1.Length] = (byte)'\n';
        bytes2.CopyTo(bytes, bytes1.Length + 1);
      }
      PdfContent content = new PdfContent(this.Owner);
      content.Stream = new PdfDictionary.PdfStream(bytes, content);
      return content;
    }

    void SetModified()
    {
      if (!this.modified)
      {
        this.modified = true;
#if true
        int count = Elements.Count;

        if (count == 1)
        {
          PdfContent content = (PdfContent)((PdfReference)Elements[0]).Value;
          content.PreserveGraphicsState();
        }
        else if (count > 1)
        {
          // Surround content streams with q/Q operations
          byte[] value;
          int length;
          PdfContent content = (PdfContent)((PdfReference)Elements[0]).Value;
          if (content != null && content.Stream != null)
          {
            length = content.Stream.Length;
            value = new byte[length + 2];
            value[0] = (byte)'q';
            value[1] = (byte)'\n';
            Array.Copy(content.Stream.Value, 0, value, 2, length);
            content.Stream.Value = value;
            content.Elements.SetInteger("/Length", length + 2);
          }
          content = (PdfContent)((PdfReference)Elements[count - 1]).Value;
          if (content != null && content.Stream != null)
          {
            length = content.Stream.Length;
            value = new byte[length + 2];
            Array.Copy(content.Stream.Value, 0, value, 0, length);
            value[length] = (byte)'Q';
            value[length + 1] = (byte)'\n';
            content.Stream.Value = value;
            content.Elements.SetInteger("/Length", length + 2);
          }
        }
#else
        foreach (PdfReference iref in Elements)
        {
          PdfContent content = (PdfContent)iref.Value;
          content.PreserveGraphicsState();
        }
#endif
      }
    }
    bool modified;

    internal override void WriteObject(PdfWriter writer)
    {
      // Save two bytes in PDF stream...
      if (Elements.Count == 1)
        Elements[0].WriteObject(writer);
      else
        base.WriteObject(writer);
    }
  }
}
