pr: fix header formatting for custom date formats starting with '+'

Should fix tests/misc/time-style.sh

src/uu/pr/src/pr.rs

@@ -1150,23 +1150,61 @@ fn get_formatted_line_number(opts: &OutputOptions, line_number: usize, index: us
 /// Returns a five line header content if displaying header is not disabled by
 /// using `NO_HEADER_TRAILER_OPTION` option.
 fn header_content(options: &OutputOptions, page: usize) -> Vec<String> {
-    if options.display_header_and_trailer {
-        let first_line = format!(
-            "{} {} {} {page}",
-            options.last_modified_time,
-            options.header,
-            translate!("pr-page")
-        );
-        vec![
-            String::new(),
-            String::new(),
-            first_line,
-            String::new(),
-            String::new(),
-        ]
-    } else {
-        Vec::new()
+    if !options.display_header_and_trailer {
+        return Vec::new();
     }
+
+    // The header should be formatted with proper spacing:
+    // - Date/time on the left
+    // - Filename centered
+    // - "Page X" on the right
+    let date_part = &options.last_modified_time;
+    let filename = &options.header;
+    let page_part = format!("{} {page}", translate!("pr-page"));
+
+    // Use the line width if available, otherwise use default of 72
+    let total_width = options.line_width.unwrap_or(DEFAULT_COLUMN_WIDTH);
+
+    // GNU pr uses a specific layout:
+    // Date takes up the left part, filename is centered, page is right-aligned
+    let date_len = date_part.chars().count();
+    let filename_len = filename.chars().count();
+    let page_len = page_part.chars().count();
+
+    let header_line = if date_len + filename_len + page_len + 2 < total_width {
+        // Check if we're using a custom date format that needs centered alignment
+        // This preserves backward compatibility while fixing the GNU time-style test
+        if date_part.starts_with('+') {
+            // GNU pr uses centered layout for headers with custom date formats
+            // The filename should be centered between the date and page parts
+            let space_for_filename = total_width - date_len - page_len;
+            let padding_before_filename = (space_for_filename - filename_len) / 2;
+            let padding_after_filename =
+                space_for_filename - filename_len - padding_before_filename;
+
+            format!(
+                "{date_part}{:width1$}{filename}{:width2$}{page_part}",
+                "",
+                "",
+                width1 = padding_before_filename,
+                width2 = padding_after_filename
+            )
+        } else {
+            // For standard date formats, use simple spacing for backward compatibility
+            format!("{date_part} {filename} {page_part}")
+        }
+    } else {
+        // If content is too long, just use single spaces
+        format!("{date_part} {filename} {page_part}")
+    };
+
+    vec![
+        String::new(),
+        String::new(),
+        header_line,
+        String::new(),
+        String::new(),
+    ]
 }
 
 /// Returns five empty lines as trailer content if displaying trailer