Rewrite search integration

This huge commit is a nearly complete rewrite of the Dolphin search
code. It implements most of the improved Dolphin search UI/UX as
designed and discussed in a collaborative effort by Kristen McWilliam,
Jin Liu, Andy Betts, Tagwerk, a few others and me.
See https://invent.kde.org/system/dolphin/-/issues/46.

# Notable changes

- A toggle to change the search tool is provided as most contributors
deemed that useful in
https://invent.kde.org/system/dolphin/-/merge_requests/642#note_985112.
- The default search is changed to filenamesearch for maximum
reliability.
- Removing all search parameters will take users back to the view state
prior to starting a search instead of keeping the search results open.
- The UI for choosing file types or modification dates has been made
more powerful with more granularity and more options.
- Most search parameters can be configured from a popup menu which
gives us extra space for extra clarity.
- Labels and help buttons as well as hyperlinks to settings makes sure
the user always knows why some search parameters are unavailable in
some contexts.
- Chips show important search parameters while the popup is closed.
They allow quickly removing filters.
- The titles of the search and the input field placeholder message
change to make clear whether file names or file contents are searched.
- When the user actively switches the search tool, whether content
should be searched, or whether to search everywhere, this is preserved
for the initial state of the search bar when the user opens it the next
time after restarting Dolphin.

# Architecture

- The new DolphinQuery class is independent of the UI and contains all
search parameters modifiable in Dolphin as easy setters and getters.
- DolphinQuery objects are also used to update the states of every
component in the search UI. There is now a clear separation of UI and
search configuration/DolphinQuery.
- DolphinQuery is responsible for exporting to and importing from
search URLs.
- The search UI always reflects the currently configured DolphinQuery
no matter if the user changed the UI to change the DolphinQuery or
loaded a DolphinQuery/older search URL which then is reflected in the
UI.
- I tried to simplify all classes and their interaction between each
other as much as possible.
- I added some tests

BUG: 386754
CCBUG: 435119
CCBUG: 458761
BUG: 446387
BUG: 470136
CCBUG: 471556
CCBUG: 475439
CCBUG: 477969
BUG: 480001
BUG: 483578
BUG: 488047
BUG: 488845
BUG: 500103
FIXED-IN: 25.08

1 files changed, 101 insertions, 0 deletions

diff --git a/src/search/chip.h b/src/search/chip.h
new file mode 100644
index 000000000..94e51968d
--- /dev/null
+++ b/src/search/chip.h
@@ -0,0 +1,101 @@
+/*
+    SPDX-FileCopyrightText: 2025 Felix Ernst <[email protected]>
+
+    SPDX-License-Identifier: LGPL-2.1-only OR LGPL-3.0-only OR LicenseRef-KDE-Accepted-LGPL
+*/
+
+#ifndef CHIP_H
+#define CHIP_H
+
+#include "dolphinquery.h"
+#include "selectors/dateselector.h"
+#include "selectors/filetypeselector.h"
+#include "selectors/minimumratingselector.h"
+#include "selectors/tagsselector.h"
+#include "updatablestateinterface.h"
+
+#include <QComboBox>
+#include <QLayout>
+#include <QToolButton>
+#include <QWidget>
+
+#include <type_traits>
+
+namespace Search
+{
+
+/**
+ * @brief The non-template base class for the template class Chip.
+ *
+ * @see Chip below.
+ *
+ * Template classes cannot have Qt signals. This class works around that by being a non-template class which the template Chip class then inherits from.
+ * This base class contains all non-template logic of Chip.
+ */
+class ChipBase : public QWidget, public UpdatableStateInterface
+{
+    Q_OBJECT
+
+public:
+    ChipBase(std::shared_ptr<const DolphinQuery> dolphinQuery, QWidget *parent = nullptr);
+
+Q_SIGNALS:
+    /** Is emitted whenever settings have changed and a new search might be necessary. */
+    void configurationChanged(const DolphinQuery &dolphinQuery);
+
+protected:
+    void paintEvent(QPaintEvent *event) override;
+
+protected:
+    QToolButton *m_removeButton = nullptr;
+};
+
+/**
+ * @brief A button-sized UI component for modifying or removing search filters.
+ *
+ * A template widget is taken and this Chip forms a button-like outline around it. The Chip has a close button on the side to remove itself, which communicates
+ * to the user that the effect of the widget inside this Chip no longer applies. The functionality of the widget inside is not affected by the Chip.
+ *
+ * Most logic of this class is in the non-template ChipBase base class.
+ * @see ChipBase above.
+ */
+template<class Selector>
+class Chip : public ChipBase
+{
+public:
+    Chip(std::shared_ptr<const DolphinQuery> dolphinQuery, QWidget *parent = nullptr)
+        : ChipBase{dolphinQuery, parent}
+        , m_selector{new Selector{dolphinQuery, this}}
+    {
+        // Make the selector flat within the chip.
+        if constexpr (std::is_base_of<QComboBox, Selector>::value) {
+            m_selector->setFrame(false);
+        } else if constexpr (std::is_base_of<QToolButton, Selector>::value) {
+            m_selector->setAutoRaise(true);
+        }
+        setFocusProxy(m_selector);
+        setTabOrder(m_selector, m_removeButton);
+
+        connect(m_selector, &Selector::configurationChanged, this, &ChipBase::configurationChanged);
+
+        // The m_removeButton does not directly remove the Chip. Instead the Selector's removeRestriction() method will emit ChipBase::configurationChanged()
+        // with a DolphinQuery object that effectively removes the effects of the Selector. This in turn will then eventually remove this Chip when the new
+        // state of the Search UI components is propagated through the various UpdatableStateInterface::updateStateToMatch() methods.
+        connect(m_removeButton, &QAbstractButton::clicked, m_selector, &Selector::removeRestriction);
+
+        layout()->addWidget(m_selector);
+        layout()->addWidget(m_removeButton);
+    };
+
+private:
+    void updateState(const std::shared_ptr<const DolphinQuery> &dolphinQuery) override
+    {
+        m_selector->updateStateToMatch(dolphinQuery);
+    }
+
+private:
+    Selector *const m_selector;
+};
+}
+
+#endif