terminal: hyperlink state for cursor needs to be preserved on resize

When a screen is resized, the pages are generally reallocated. This
causes the cursor hyperlink state to be lost and ultimately the
hyperlink ref count is off by one.

The unit test in this commit showcases the issue very clearly. And you
can see we do this logic already for styles. We never copied it over for
hyperlinks.

src/terminal/Screen.zig

@@ -1319,6 +1319,20 @@ fn resizeInternal(
         };
     }
 
+    // If we have a hyperlink, release it from the old page
+    // and then we need to re-add it to the new page. This needs
+    // to happen because resize below typically reallocates a
+    // new page so the old hyperlink is invalid.
+    const hyperlink_ = self.cursor.hyperlink;
+    if (self.cursor.hyperlink_id != 0) {
+        // Note we do NOT use endHyperlink because we want to keep
+        // our allocated self.cursor.hyperlink valid.
+        var page = &self.cursor.page_pin.page.data;
+        page.hyperlink_set.release(page.memory, self.cursor.hyperlink_id);
+        self.cursor.hyperlink_id = 0;
+        self.cursor.hyperlink = null;
+    }
+
     // Perform the resize operation.
     try self.pages.resize(.{
         .rows = rows,
@@ -1337,6 +1351,19 @@ fn resizeInternal(
     // If our cursor was updated, we do a full reload so all our cursor
     // state is correct.
     self.cursorReload();
+
+    // Fix up our hyperlink if we had one.
+    if (hyperlink_) |link| {
+        self.startHyperlink(link.uri, link.id) catch |err| {
+            // This shouldn't happen because startHyperlink should handle
+            // resizing. This only happens if we're truly out of RAM. Degrade
+            // to forgetting the hyperlink.
+            log.err("failed to update hyperlink on resize err={}", .{err});
+        };
+
+        // Remove our old link
+        link.destroy(self.alloc);
+    }
 }
 
 /// Set a style attribute for the current cursor.
@@ -8107,6 +8134,41 @@ test "Screen: hyperlink reuse" {
     }
 }
 
+test "Screen: hyperlink cursor state on resize" {
+    const testing = std.testing;
+    const alloc = testing.allocator;
+
+    // This test depends on underlying PageList implementation so
+    // it may be invalid one day. It's here to document/verify the
+    // current behavior.
+
+    var s = try init(alloc, 5, 10, 0);
+    defer s.deinit();
+
+    // Start a hyperlink
+    try s.startHyperlink("http://example.com", null);
+    try testing.expect(s.cursor.hyperlink_id != 0);
+    {
+        const page = &s.cursor.page_pin.page.data;
+        try testing.expectEqual(1, page.hyperlink_set.count());
+    }
+
+    // Resize. Any column growth will trigger a page to be reallocated.
+    try s.resize(10, 10);
+    try testing.expect(s.cursor.hyperlink_id != 0);
+    {
+        const page = &s.cursor.page_pin.page.data;
+        try testing.expectEqual(1, page.hyperlink_set.count());
+    }
+
+    s.endHyperlink();
+    try testing.expect(s.cursor.hyperlink_id == 0);
+    {
+        const page = &s.cursor.page_pin.page.data;
+        try testing.expectEqual(0, page.hyperlink_set.count());
+    }
+}
+
 test "Screen: adjustCapacity cursor style ref count" {
     const testing = std.testing;
     const alloc = testing.allocator;