Select date format for todo tasks

app/src/main/java/net/gsantner/markor/format/todotxt/TodoTxtAutoTextFormatter.java

@@ -29,6 +29,6 @@ public CharSequence filter(CharSequence source, int start, int end, Spanned dest
     }
 
     private CharSequence autoIndent(CharSequence source) {
-        return source + TodoTxtTask.DATEF_YYYY_MM_DD.format(new Date()) + " ";
+        return source + TodoTxtTask.getDateFormat().format(new Date()) + " ";
     }
 }

app/src/main/java/net/gsantner/markor/format/todotxt/TodoTxtTask.java

@@ -14,6 +14,7 @@
 
 import net.gsantner.markor.frontend.textview.TextViewUtils;
 import net.gsantner.opoc.format.GsTextUtils;
+import net.gsantner.markor.ApplicationObject;
 
 import java.text.SimpleDateFormat;
 import java.util.ArrayList;
@@ -30,12 +31,29 @@
 public class TodoTxtTask {
 
     //
-    // Static memebers
+    // Static members - date format helpers, regex generators & constants
     //
 
     public static final SimpleDateFormat DATEF_YYYY_MM_DD = new SimpleDateFormat("yyyy-MM-dd", Locale.ROOT);
     public static final int DATEF_YYYY_MM_DD_LEN = "yyyy-MM-dd".length();
-    public static final String PT_DATE = "\\d{4}-\\d{2}-\\d{2}";
+
+    /**
+     * Returns a SimpleDateFormat for the configured todo date format.
+     * Falls back to {@link #DATE_FORMAT} if settings are not available or the configured pattern is invalid.
+     * Note: This does not cache the SimpleDateFormat instance because the pattern may change at runtime.
+     */
+    public static SimpleDateFormat getDateFormat() {
+        final String fmt = ApplicationObject.settings() != null ? ApplicationObject.settings().getTodoDateFormat() : "yyyy-MM-dd";
+
+        try {
+            return new SimpleDateFormat(fmt, Locale.ROOT);
+        } catch (IllegalArgumentException e) {
+            // Fallback: return a default format instead of throwing
+            return DATEF_YYYY_MM_DD;
+        }
+    }
+
+    public static final String PT_DATE = "\\d{4}-\\d{2}-\\d{2}(?:[ T]\\d{2}:\\d{2}(?::\\d{2})?)?";
     public static final Pattern PATTERN_PROJECTS = Pattern.compile("(?:^|\\s)(?:\\++)(\\S+)");
     public static final Pattern PATTERN_CONTEXTS = Pattern.compile("(?:^|\\s)(?:\\@+)(\\S+)");
     public static final Pattern PATTERN_DONE = Pattern.compile("(?m)(^[Xx]) (.*)$");
@@ -61,7 +79,7 @@ public enum TodoDueState {
     }
 
     public static String getToday() {
-        return DATEF_YYYY_MM_DD.format(new Date());
+        return getDateFormat().format(new Date());
     }
 
     public static List<TodoTxtTask> getTasks(final CharSequence text, final int[] sel) {

app/src/main/java/net/gsantner/markor/model/AppSettings.java

@@ -347,6 +347,10 @@ public boolean isTodoAddCompletionDateEnabled() {
         return getBool(R.string.pref_key__todotxt__add_completion_date_for_todos, true);
     }
 
+    public String getTodoDateFormat() {
+        return getString(R.string.pref_key__todotxt__set_date_format, "yyyy-MM-dd");
+    }
+
     public boolean isAppCurrentVersionFirstStart(boolean doSet) {
         int value = getInt(R.string.pref_key__app_first_start_current_version, -1);
         if (doSet) {

app/src/main/res/values/arrays.xml

@@ -132,6 +132,18 @@
         <item translatable="false">+</item>
     </string-array>
 
+    <string-array name="pref_arrdisp__todo_date_format" translatable="false">
+        <item translatable="false">@string/todo_date_format_year_month_day</item>
+        <item translatable="false">@string/todo_date_format_year_month_day_hour_minute</item>
+        <item translatable="false">@string/todo_date_format_year_month_day_hour_minute_second</item>
+    </string-array>
+
+    <string-array name="pref_arrkeys__todo_date_format" translatable="false">
+        <item translatable="false">yyyy-MM-dd</item>
+        <item translatable="false">yyyy-MM-dd HH:mm</item>
+        <item translatable="false">yyyy-MM-dd HH:mm:ss</item>
+    </string-array>
+
     <string-array name="pref_arrdisp__markdown_toc" translatable="false">
         <item translatable="false">@string/heading_1</item>
         <item translatable="false">@string/heading_2</item>

app/src/main/res/values/string-not_translatable.xml

@@ -422,6 +422,7 @@ work. If not, see <https://creativecommons.org/publicdomain/zero/1.0/>.
     <string name="pref_key__editor_tab_to_indent" translatable="false">pref_key__editor_tab_to_indent</string>
     <string name="hidden_password" translatable="false">****</string>
     <string name="pref_key__todotxt__additional_projects_contexts" translatable="false">"pref_key__todotxt__additional_projects_contexts"</string>
+    <string name="pref_key__todotxt__set_date_format" translatable="false">"pref_key__todotxt__set_date_format"</string>
     <string name="pref_key__todotxt__due_date_offset" translatable="false">pref_key__todotxt_due_date_offset</string>
     <string name="action_format_keyvalue" translatable="false">action_format_keyvalue</string>
     <string name="action_format_plaintext" translatable="false">action_format_plaintext</string>

app/src/main/res/values/strings.xml

@@ -413,6 +413,11 @@ work. If not, see <https://creativecommons.org/publicdomain/zero/1.0/>.
     <string name="code_block">Code block</string>
     <string name="add_completion_date">Add completion date</string>
     <string name="add_completion_date_for_todos_when_marking_them_as_done">Add completion date for todos when marking them as done</string>
+    <string name="set_date_format">Set date format</string>
+    <string name="set_date_format_used_in_todo_tasks">Set date format used in todo tasks</string>
+    <string name="todo_date_format_year_month_day">yyyy-MM-dd (2026-12-31)</string>
+    <string name="todo_date_format_year_month_day_hour_minute">yyyy-MM-dd HH:mm (2026-12-31 14:30)</string>
+    <string name="todo_date_format_year_month_day_hour_minute_second">yyyy-MM-dd HH:mm:ss (2026-12-31 14:30:45)</string>
     <string name="file_description_format">File description format</string>
     <string name="file_description_format_dialog">Format for the description under each file in the file browser. Follows Android\'s SimpleDateFormat rules, with the addition of FS for showing file size. Leave blank to use the default format for your locale.\n\nExample input:\nFS yyyy MMM dd hh:mm:ss aa\nOutput format:\n30KB 2020 Mar 20 11:24:52 PM</string>
     <string name="loading_default_value">Loading default value</string>

app/src/main/res/xml/preferences_master.xml

@@ -515,6 +515,15 @@
                     android:key="@string/pref_key__todotxt__add_completion_date_for_todos"
                     android:summary="@string/add_completion_date_for_todos_when_marking_them_as_done"
                     android:title="@string/add_completion_date" />
+                <ListPreference
+                    android:defaultValue="yyyy-MM-dd"
+                    android:dialogTitle="@string/theme"
+                    android:entries="@array/pref_arrdisp__todo_date_format"
+                    android:entryValues="@array/pref_arrkeys__todo_date_format"
+                    android:icon="@drawable/ic_list_black_24dp"
+                    android:key="@string/pref_key__todotxt__set_date_format"
+                    android:summary="@string/set_date_format_used_in_todo_tasks"
+                    android:title="@string/set_date_format" />
                 <CheckBoxPreference
                     android:defaultValue="true"
                     android:icon="@drawable/ic_add_white_24dp"