feat(odt): conditionals for OpenDocument Text templates (#138)

TriasDev.Templify.Tests/Odt/OdtLibreOfficeRoundTripTests.cs

@@ -97,6 +97,48 @@ public void LibreOfficeGeneratedDocument_IsProcessed()
         Assert.Equal("\tTabbed World", lines[1]);
     }
 
+    [Fact]
+    public void Conditionals_RoundTripThroughLibreOffice()
+    {
+        LibreOfficeRunner.RequireExecutable();
+
+        OdtDocumentBuilder template = new OdtDocumentBuilder()
+            .AddParagraph("{{#if Premium}}")
+            .AddParagraph("Premium customer")
+            .AddParagraph("{{#else}}")
+            .AddParagraph("Standard customer")
+            .AddParagraph("{{/if}}")
+            .AddXml("<text:p>Dear {{#if IsMale}}Mr.{{#else}}<text:span text:style-name=\"T1\">Ms.</text:span>{{/if}} {{Name}}</text:p>")
+            .AddTable(new[] { "{{#if ShowRow}}" }, new[] { "Hidden row" }, new[] { "{{/if}}" }, new[] { "Kept row" })
+            .AddXml(
+                "<text:list><text:list-item><text:p>First</text:p></text:list-item>" +
+                "<text:list-item><text:p>{{#if ShowItem}}</text:p></text:list-item>" +
+                "<text:list-item><text:p>Hidden item</text:p></text:list-item>" +
+                "<text:list-item><text:p>{{/if}}</text:p></text:list-item>" +
+                "<text:list-item><text:p>Last</text:p></text:list-item></text:list>")
+            .AddParagraph("End");
+
+        byte[] output = ProcessToBytes(template, new Dictionary<string, object>
+        {
+            ["Premium"] = false,
+            ["IsMale"] = false,
+            ["Name"] = "Smith",
+            ["ShowRow"] = false,
+            ["ShowItem"] = false,
+        });
+
+        string[] lines = LibreOfficeRunner.ConvertToTextLines(output);
+        string all = string.Join("\n", lines);
+        Assert.Equal("Standard customer", lines[0]);
+        Assert.Equal("Dear Ms. Smith", lines[1]);
+        Assert.Contains("Kept row", all, StringComparison.Ordinal);
+        Assert.DoesNotContain("Hidden", all, StringComparison.Ordinal);
+        Assert.DoesNotContain("{{", all, StringComparison.Ordinal);
+        Assert.Contains("First", all, StringComparison.Ordinal);
+        Assert.Contains("Last", all, StringComparison.Ordinal);
+        Assert.Equal("End", lines[^1]);
+    }
+
     private static byte[] ProcessToBytes(OdtDocumentBuilder template, Dictionary<string, object> data)
     {
         OdtTemplateProcessor processor = new OdtTemplateProcessor(new PlaceholderReplacementOptions { Culture = CultureInfo.InvariantCulture });

TriasDev.Templify.Tests/Odt/OdtPlaceholderTests.cs

@@ -554,13 +554,14 @@ public void NullValue_IsReplacedWithEmpty()
     }
 
     [Fact]
-    public void ConditionalAndLoopMarkers_AreLeftAsText_ForNow()
+    public void LoopMarkers_AreLeftAsText_ForNow()
     {
         (_, OdtDocumentVerifier output) = OdtTestHelper.Process(
-            new OdtDocumentBuilder().AddParagraph("{{#if Show}}{{Name}}{{/if}}"),
-            new Dictionary<string, object> { ["Show"] = true, ["Name"] = "N" });
+            new OdtDocumentBuilder().AddParagraph("{{#foreach Items}}{{Name}}{{/foreach}}"),
+            new Dictionary<string, object> { ["Items"] = new List<string> { "a" }, ["Name"] = "N" });
 
-        Assert.Equal("{{#if Show}}N{{/if}}", output.GetParagraphTexts()[0]);
+        // Marker paragraphs are not processed for placeholders, as in Word documents.
+        Assert.Equal("{{#foreach Items}}{{Name}}{{/foreach}}", output.GetParagraphTexts()[0]);
     }
 
     [Fact]

TriasDev.Templify/Core/OdtTemplateProcessor.cs

@@ -24,7 +24,15 @@ namespace TriasDev.Templify.Core;
 /// sections, text boxes, footnotes and endnotes, and headers and footers. Placeholders split across
 /// formatting spans are found; the replacement takes the formatting of the placeholder's first character.
 /// Newlines in values become line breaks (<see cref="PlaceholderReplacementOptions.EnableNewlineSupport"/>).
-/// Markdown in values is inserted as literal text, and conditional and loop markers are not evaluated yet.
+/// </para>
+/// <para>
+/// Conditionals (<c>{{#if}}</c>, <c>{{#elseif}}</c>, <c>{{#else}}</c>, <c>{{/if}}</c>, with the full condition syntax)
+/// work as block conditionals (markers in their own paragraphs), inline within one paragraph, over table rows (markers
+/// in their own rows) and over list items (markers in their own items). Content left empty by a conditional gets an
+/// empty paragraph (cells, text boxes, notes, headers and footers); empty list items, lists and tables are removed.
+/// </para>
+/// <para>
+/// Markdown in values is inserted as literal text, and loop markers are not evaluated yet.
 /// </para>
 /// <para>
 /// <see cref="PlaceholderReplacementOptions.UpdateFieldsOnOpen"/> and

TriasDev.Templify/OpenDocument/OdtConditionalBlock.cs

@@ -0,0 +1,50 @@
+// Copyright (c) 2026 TriasDev GmbH & Co. KG
+// Licensed under the MIT License. See LICENSE file in the project root for full license information.
+
+using System.Xml.Linq;
+
+namespace TriasDev.Templify.OpenDocument;
+
+/// <summary>
+/// A branch of an OpenDocument conditional block: its condition (null for <c>{{#else}}</c>), its marker
+/// element and the elements between its marker and the next marker.
+/// </summary>
+internal sealed record OdtConditionalBranch(string? ConditionExpression, IReadOnlyList<XElement> ContentElements, XElement Marker)
+{
+    /// <summary>Gets whether this is the <c>{{#else}}</c> branch.</summary>
+    public bool IsElseBranch => ConditionExpression == null;
+}
+
+/// <summary>
+/// A conditional block (<c>{{#if}}</c> … <c>{{/if}}</c>) over sibling OpenDocument elements
+/// (paragraphs, or table rows for a table-row conditional). The counterpart of <c>ConditionalBlock</c>.
+/// </summary>
+internal sealed class OdtConditionalBlock
+{
+    public OdtConditionalBlock(
+        IReadOnlyList<OdtConditionalBranch> branches,
+        XElement endMarker,
+        bool isTableRowConditional,
+        int nestingLevel)
+    {
+        Branches = branches;
+        EndMarker = endMarker;
+        IsTableRowConditional = isTableRowConditional;
+        NestingLevel = nestingLevel;
+    }
+
+    /// <summary>Gets the branches in order (if, elseif…, else).</summary>
+    public IReadOnlyList<OdtConditionalBranch> Branches { get; }
+
+    /// <summary>Gets the element holding <c>{{#if}}</c>.</summary>
+    public XElement StartMarker => Branches[0].Marker;
+
+    /// <summary>Gets the element holding <c>{{/if}}</c>.</summary>
+    public XElement EndMarker { get; }
+
+    /// <summary>Gets whether the markers are table rows.</summary>
+    public bool IsTableRowConditional { get; }
+
+    /// <summary>Gets the nesting level (0 for top level).</summary>
+    public int NestingLevel { get; }
+}