Rework the handling of FMTID0 in OLEPropertiesContainer

sources/OpenMcdf.Extensions/OLEProperties/OLEPropertiesContainer.cs

@@ -2,7 +2,6 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
-using System.Text;
 using OpenMcdf.Extensions.OLEProperties.Interfaces;
 
 namespace OpenMcdf.Extensions.OLEProperties
@@ -16,7 +15,15 @@ public class OLEPropertiesContainer
 
         public bool HasUserDefinedProperties { get; private set; }
 
-        public ContainerType ContainerType { get; internal set; }
+        /// <summary>
+        /// Gets the type of the container.
+        /// </summary>
+        public ContainerType ContainerType { get; }
+
+        /// <summary>
+        /// Gets the FMTID of the properties container.
+        /// </summary>
+        public Guid FMTID0 { get; }
 
         public PropertyContext Context { get; private set; }
 
@@ -69,6 +76,11 @@ public static OLEPropertiesContainer CreateNewSummaryInfo(SummaryInfoProperties
             return null;
         }
 
+        /// <summary>
+        /// Create a new instance of <see cref="OLEPropertiesContainer"/> with the specified code page and container type.
+        /// </summary>
+        /// <param name="codePage">The code page to use for the new container.</param>
+        /// <param name="containerType">The type of the new container.</param>
         public OLEPropertiesContainer(int codePage, ContainerType containerType)
         {
             Context = new PropertyContext
@@ -78,6 +90,7 @@ public OLEPropertiesContainer(int codePage, ContainerType containerType)
             };
 
             this.ContainerType = containerType;
+            this.FMTID0 = FmtIdFromContainerType(containerType);
         }
 
         internal OLEPropertiesContainer(CFStream cfStream)
@@ -87,19 +100,8 @@ internal OLEPropertiesContainer(CFStream cfStream)
             this.cfStream = cfStream;
             pStream.Read(new BinaryReader(new StreamDecorator(cfStream)));
 
-            switch (pStream.FMTID0.ToString("B").ToUpperInvariant())
-            {
-                case WellKnownFMTID.FMTID_SummaryInformation:
-                    this.ContainerType = ContainerType.SummaryInfo;
-                    break;
-                case WellKnownFMTID.FMTID_DocSummaryInformation:
-                    this.ContainerType = ContainerType.DocumentSummaryInfo;
-                    break;
-                default:
-                    this.ContainerType = ContainerType.AppSpecific;
-                    break;
-            }
-
+            this.FMTID0 = pStream.FMTID0;
+            this.ContainerType = ContainerTypeFromFmtId(pStream.FMTID0);
 
             this.PropertyNames = (Dictionary<uint, string>)pStream.PropertySet0.Properties
                 .Where(p => p.PropertyType == PropertyType.DictionaryProperty).FirstOrDefault()?.Value;
@@ -134,8 +136,6 @@ internal OLEPropertiesContainer(CFStream cfStream)
                 UserDefinedProperties = new OLEPropertiesContainer(pStream.PropertySet1.PropertyContext.CodePage, ContainerType.UserDefinedProperties);
                 this.HasUserDefinedProperties = true;
 
-                UserDefinedProperties.ContainerType = ContainerType.UserDefinedProperties;
-
                 for (int i = 0; i < pStream.PropertySet1.Properties.Count; i++)
                 {
                     if (pStream.PropertySet1.PropertyIdentifierAndOffsets[i].PropertyIdentifier == 0) continue;
@@ -247,7 +247,7 @@ public void Save(CFStream cfStream)
 
                 NumPropertySets = 1,
 
-                FMTID0 = this.ContainerType == ContainerType.SummaryInfo ? new Guid(WellKnownFMTID.FMTID_SummaryInformation) : new Guid(WellKnownFMTID.FMTID_DocSummaryInformation),
+                FMTID0 = this.FMTID0,
                 Offset0 = 0,
 
                 FMTID1 = Guid.Empty,
@@ -311,5 +311,41 @@ public void Save(CFStream cfStream)
 
             ps.Write(bw);
         }
+
+        // Determine the type of the container from the FMTID0 property.
+        private static ContainerType ContainerTypeFromFmtId(Guid fmtId0)
+        {
+            if (fmtId0 == Guid.Parse(WellKnownFMTID.FMTID_SummaryInformation))
+                return ContainerType.SummaryInfo;
+            else if (fmtId0 == Guid.Parse(WellKnownFMTID.FMTID_DocSummaryInformation))
+                return ContainerType.DocumentSummaryInfo;
+            else if (fmtId0 == Guid.Parse(WellKnownFMTID.FMTID_GlobalInfo))
+                return ContainerType.GlobalInfo;
+            else if (fmtId0 == Guid.Parse(WellKnownFMTID.FMTID_ImageInfo))
+                return ContainerType.ImageInfo;
+            else if (fmtId0 == Guid.Parse(WellKnownFMTID.FMTID_ImageContents))
+                return ContainerType.ImageContents;
+
+            return ContainerType.AppSpecific;
+        }
+
+        // Determine the FMTID property from the container type.
+        // Note: Uses FMTID_DocSummaryInformation by default to match the previous behavior.
+        private static Guid FmtIdFromContainerType(ContainerType containerType)
+        {
+            switch (containerType)
+            {
+                case ContainerType.SummaryInfo:
+                    return Guid.Parse(WellKnownFMTID.FMTID_SummaryInformation);
+                case ContainerType.GlobalInfo:
+                    return Guid.Parse(WellKnownFMTID.FMTID_GlobalInfo);
+                case ContainerType.ImageContents:
+                    return Guid.Parse(WellKnownFMTID.FMTID_ImageContents);
+                case ContainerType.ImageInfo:
+                    return Guid.Parse(WellKnownFMTID.FMTID_ImageInfo);
+                default:
+                    return Guid.Parse(WellKnownFMTID.FMTID_DocSummaryInformation);
+            }
+        }
     }
 }