From e694bf1295b1c24de4ff7eaf5dc7f960c0d0aea6 Mon Sep 17 00:00:00 2001
From: Sven <steve.vernyi@gmail.com>
Date: Mon, 1 Jan 2024 02:22:25 -0600
Subject: [PATCH] Adds operations for adding/removing pages in a PDF

---
 src/QPdfSharp/QPdf.Pages.cs | 73 +++++++++++++++++++++++++++++++++++++
 src/QPdfSharp/QPdf.cs       |  8 ----
 src/QPdfSharp/QPdfPage.cs   | 18 +++++++++
 3 files changed, 91 insertions(+), 8 deletions(-)
 create mode 100644 src/QPdfSharp/QPdf.Pages.cs
 create mode 100644 src/QPdfSharp/QPdfPage.cs

diff --git a/src/QPdfSharp/QPdf.Pages.cs b/src/QPdfSharp/QPdf.Pages.cs
new file mode 100644
index 0000000..0e9aa11
--- /dev/null
+++ b/src/QPdfSharp/QPdf.Pages.cs
@@ -0,0 +1,73 @@
+// Copyright © Stephen (Sven) Vernyi and Contributors. Licensed under the MIT License (MIT). See License.md in the repository root for more information.
+
+using QPdfSharp.Extensions;
+using QPdfSharp.Interop;
+
+namespace QPdfSharp;
+
+public unsafe partial class QPdf
+{
+    public int GetPageCount()
+    {
+        var pageCount = QPdfInterop.qpdf_get_num_pages(_qPdfData);
+        CheckError();
+
+        return pageCount;
+    }
+
+    public QPdfPage GetPage(int pageNumber)
+    {
+        var pagePtr = QPdfInterop.qpdf_get_page_n(_qPdfData, (UIntPtr)pageNumber);
+        CheckError();
+
+        return new QPdfPage(_qPdfData, pagePtr);
+    }
+
+    public QPdfPage GetPageById(int id, int generation)
+    {
+        var pageIndex = QPdfInterop.qpdf_find_page_by_id(_qPdfData, id, generation);
+        CheckError();
+
+        return GetPage(pageIndex);
+    }
+
+    public void AppendPage(QPdfPage newPage)
+    {
+        QPdfInterop.qpdf_add_page(_qPdfData, newPage._qPdfData, newPage._qPdfPage, first: 0);
+        CheckError();
+    }
+
+    public void PrependPage(QPdfPage newPage)
+    {
+        QPdfInterop.qpdf_add_page(_qPdfData, newPage._qPdfData, newPage._qPdfPage, first: 1);
+        CheckError();
+    }
+
+    public void InsertPage(QPdfPage newPage, int insertAt, bool insertBefore = true)
+    {
+        var numPages = GetPageCount();
+        if (insertAt < 0 || insertAt > numPages)
+            throw new ArgumentOutOfRangeException(nameof(insertAt), $"Insert index must be between 0 and {numPages} inclusive.");
+
+        var refPage = GetPage(insertAt);
+        InsertPage(newPage, refPage, insertBefore);
+    }
+
+    public void InsertPage(QPdfPage newPage, QPdfPage targetPage, bool insertBefore = true)
+    {
+        QPdfInterop.qpdf_add_page_at(_qPdfData, newPage._qPdfData, newPage._qPdfPage, before: insertBefore.ToQPdfBool(), targetPage._qPdfPage);
+        CheckError();
+    }
+
+    public void RemovePage(int pageNumber)
+    {
+        var page = GetPage(pageNumber);
+        RemovePage(page);
+    }
+
+    public void RemovePage(QPdfPage page)
+    {
+        QPdfInterop.qpdf_remove_page(_qPdfData, page._qPdfPage);
+        CheckError();
+    }
+}
diff --git a/src/QPdfSharp/QPdf.cs b/src/QPdfSharp/QPdf.cs
index 078ea68..2dea41d 100644
--- a/src/QPdfSharp/QPdf.cs
+++ b/src/QPdfSharp/QPdf.cs
@@ -34,14 +34,6 @@ public QPdf(ReadOnlyMemory<byte> bytes, string name = "in-memory pdf", string pa
             CheckError(QPdfInterop.qpdf_read_memory(_qPdfData, fileNameBytes, (sbyte*)fileBytesHandle.Pointer, (ulong)bytes.Length, passwordBytes));
     }
 
-    public int GetPageCount()
-    {
-        var pageCount = QPdfInterop.qpdf_get_num_pages(_qPdfData);
-        CheckError();
-
-        return pageCount;
-    }
-
     public void Dispose()
     {
         if (_outputStream is { IsDisposed: false })
diff --git a/src/QPdfSharp/QPdfPage.cs b/src/QPdfSharp/QPdfPage.cs
new file mode 100644
index 0000000..8782712
--- /dev/null
+++ b/src/QPdfSharp/QPdfPage.cs
@@ -0,0 +1,18 @@
+// Copyright © Stephen (Sven) Vernyi and Contributors. Licensed under the MIT License (MIT). See License.md in the repository root for more information.
+
+using QPdfSharp.Interop;
+
+namespace QPdfSharp;
+
+public readonly struct QPdfPage
+{
+    internal readonly unsafe QPdfData* _qPdfData;
+
+    internal readonly uint _qPdfPage;
+
+    internal unsafe QPdfPage(QPdfData* qPdfData, uint qPdfPage)
+    {
+        _qPdfData = qPdfData;
+        _qPdfPage = qPdfPage;
+    }
+}