#include <gtest/gtest.h>

#include <XCEngine/Input/InputTypes.h>
#include <XCEngine/UI/Input/UIFocusController.h>
#include <XCEngine/UI/Input/UIInputDispatcher.h>
#include <XCEngine/UI/Input/UIInputRouter.h>
#include <XCEngine/UI/Input/UIShortcutRegistry.h>

#include <cstdint>
#include <string>
#include <vector>

namespace {

using XCEngine::Input::KeyCode;
using XCEngine::UI::UIElementId;
using XCEngine::UI::UIFocusController;
using XCEngine::UI::UIInputDispatchDecision;
using XCEngine::UI::UIInputDispatcher;
using XCEngine::UI::UIInputEvent;
using XCEngine::UI::UIInputEventType;
using XCEngine::UI::UIInputPath;
using XCEngine::UI::UIInputRouteContext;
using XCEngine::UI::UIInputRouter;
using XCEngine::UI::UIInputRoutingPhase;
using XCEngine::UI::UIInputTargetKind;
using XCEngine::UI::UIPointerButton;
using XCEngine::UI::UIShortcutBinding;
using XCEngine::UI::UIShortcutContext;
using XCEngine::UI::UIShortcutRegistry;
using XCEngine::UI::UIShortcutScope;

std::string BuildTraceLabel(
    UIElementId elementId,
    UIInputRoutingPhase phase) {
    char phaseChar = 'T';
    switch (phase) {
    case UIInputRoutingPhase::Capture:
        phaseChar = 'C';
        break;
    case UIInputRoutingPhase::Bubble:
        phaseChar = 'B';
        break;
    case UIInputRoutingPhase::Target:
    default:
        phaseChar = 'T';
        break;
    }

    return std::to_string(elementId) + phaseChar;
}

} // namespace

TEST(XCUIFocusControllerTest, SetFocusedPathTracksLostAndGainedSuffixes) {
    UIFocusController controller = {};
    EXPECT_FALSE(controller.HasFocus());

    const auto initialChange = controller.SetFocusedPath({ 1u, 2u, 3u });
    EXPECT_TRUE(initialChange.Changed());
    EXPECT_EQ(initialChange.gainedPath.elements, (std::vector<UIElementId>{ 1u, 2u, 3u }));
    EXPECT_TRUE(initialChange.lostPath.elements.empty());
    EXPECT_TRUE(controller.HasFocus());

    const auto change = controller.SetFocusedPath({ 1u, 4u });
    EXPECT_TRUE(change.Changed());
    EXPECT_EQ(change.previousPath.elements, (std::vector<UIElementId>{ 1u, 2u, 3u }));
    EXPECT_EQ(change.currentPath.elements, (std::vector<UIElementId>{ 1u, 4u }));
    EXPECT_EQ(change.lostPath.elements, (std::vector<UIElementId>{ 2u, 3u }));
    EXPECT_EQ(change.gainedPath.elements, (std::vector<UIElementId>{ 4u }));
}

TEST(XCUIInputRouterTest, PointerCaptureOverridesHoveredPath) {
    UIInputEvent event = {};
    event.type = UIInputEventType::PointerMove;

    UIInputRouteContext context = {};
    context.hoveredPath = { 10u, 20u, 30u };
    context.capturePath = { 90u, 100u };

    const auto plan = UIInputRouter::BuildRoutingPlan(event, context);

    EXPECT_EQ(plan.targetKind, UIInputTargetKind::Captured);
    EXPECT_EQ(plan.targetPath.elements, (std::vector<UIElementId>{ 90u, 100u }));
    ASSERT_EQ(plan.steps.size(), 3u);
    EXPECT_EQ(plan.steps[0].elementId, 90u);
    EXPECT_EQ(plan.steps[0].phase, UIInputRoutingPhase::Capture);
    EXPECT_EQ(plan.steps[1].elementId, 100u);
    EXPECT_EQ(plan.steps[1].phase, UIInputRoutingPhase::Target);
    EXPECT_EQ(plan.steps[2].elementId, 90u);
    EXPECT_EQ(plan.steps[2].phase, UIInputRoutingPhase::Bubble);
}

TEST(XCUIInputRouterTest, KeyboardEventsRouteThroughFocusedPathInCaptureTargetBubbleOrder) {
    UIInputEvent event = {};
    event.type = UIInputEventType::KeyDown;
    event.keyCode = static_cast<std::int32_t>(KeyCode::Enter);

    UIInputRouteContext context = {};
    context.focusedPath = { 1u, 2u, 3u };

    std::vector<std::string> trace = {};
    const auto result = UIInputRouter::Dispatch(
        event,
        context,
        [&trace](const auto& request) {
            trace.push_back(BuildTraceLabel(request.elementId, request.phase));
            return UIInputDispatchDecision{};
        });

    EXPECT_FALSE(result.handled);
    EXPECT_EQ(trace, (std::vector<std::string>{ "1C", "2C", "3T", "2B", "1B" }));
}

TEST(XCUIShortcutRegistryTest, MatchingPrefersMostSpecificScopeThenNewestBinding) {
    UIShortcutRegistry registry = {};

    UIShortcutBinding globalBinding = {};
    globalBinding.scope = UIShortcutScope::Global;
    globalBinding.chord.keyCode = static_cast<std::int32_t>(KeyCode::S);
    globalBinding.chord.modifiers.control = true;
    globalBinding.commandId = "save.global";
    registry.RegisterBinding(globalBinding);

    UIShortcutBinding panelBinding = {};
    panelBinding.scope = UIShortcutScope::Panel;
    panelBinding.ownerId = 20u;
    panelBinding.chord.keyCode = static_cast<std::int32_t>(KeyCode::S);
    panelBinding.chord.modifiers.control = true;
    panelBinding.commandId = "save.panel";
    registry.RegisterBinding(panelBinding);

    UIShortcutBinding widgetBinding = {};
    widgetBinding.scope = UIShortcutScope::Widget;
    widgetBinding.ownerId = 30u;
    widgetBinding.chord.keyCode = static_cast<std::int32_t>(KeyCode::S);
    widgetBinding.chord.modifiers.control = true;
    widgetBinding.commandId = "save.widget";
    registry.RegisterBinding(widgetBinding);

    UIInputEvent event = {};
    event.type = UIInputEventType::KeyDown;
    event.keyCode = static_cast<std::int32_t>(KeyCode::S);
    event.modifiers.control = true;

    UIShortcutContext context = {};
    context.focusedPath = { 10u, 20u, 30u };
    EXPECT_EQ(registry.Match(event, context).binding.commandId, "save.widget");

    context.focusedPath = { 10u, 20u };
    EXPECT_EQ(registry.Match(event, context).binding.commandId, "save.panel");

    context.focusedPath.Clear();
    EXPECT_EQ(registry.Match(event, context).binding.commandId, "save.global");
}

TEST(XCUIInputDispatcherTest, PointerDownTransfersFocusAndMaintainsActivePathUntilPointerUp) {
    UIInputDispatcher dispatcher;

    UIInputEvent pointerDown = {};
    pointerDown.type = UIInputEventType::PointerButtonDown;
    pointerDown.pointerButton = UIPointerButton::Left;

    const auto downSummary = dispatcher.Dispatch(
        pointerDown,
        UIInputPath{ 100u, 200u },
        [](const auto&) {
            return UIInputDispatchDecision{};
        });

    EXPECT_TRUE(downSummary.focusChange.Changed());
    EXPECT_EQ(dispatcher.GetFocusController().GetFocusedPath().elements, (std::vector<UIElementId>{ 100u, 200u }));
    EXPECT_EQ(dispatcher.GetFocusController().GetActivePath().elements, (std::vector<UIElementId>{ 100u, 200u }));
    EXPECT_EQ(downSummary.routing.plan.targetKind, UIInputTargetKind::Hovered);

    UIInputEvent pointerUp = {};
    pointerUp.type = UIInputEventType::PointerButtonUp;
    pointerUp.pointerButton = UIPointerButton::Left;
    dispatcher.Dispatch(
        pointerUp,
        UIInputPath{ 100u, 200u },
        [](const auto&) {
            return UIInputDispatchDecision{};
        });

    EXPECT_TRUE(dispatcher.GetFocusController().GetActivePath().Empty());
    EXPECT_EQ(dispatcher.GetFocusController().GetFocusedPath().elements, (std::vector<UIElementId>{ 100u, 200u }));
}

TEST(XCUIInputDispatcherTest, ShortcutMatchConsumesKeyboardDispatchBeforeRouting) {
    UIInputDispatcher dispatcher;
    dispatcher.GetFocusController().SetFocusedPath({ 1u, 2u, 3u });

    UIShortcutBinding binding = {};
    binding.scope = UIShortcutScope::Widget;
    binding.ownerId = 3u;
    binding.chord.keyCode = static_cast<std::int32_t>(KeyCode::P);
    binding.chord.modifiers.control = true;
    binding.commandId = "palette.open";
    dispatcher.GetShortcutRegistry().RegisterBinding(binding);

    UIInputEvent event = {};
    event.type = UIInputEventType::KeyDown;
    event.keyCode = static_cast<std::int32_t>(KeyCode::P);
    event.modifiers.control = true;

    bool handlerCalled = false;
    const auto summary = dispatcher.Dispatch(
        event,
        {},
        [&handlerCalled](const auto&) {
            handlerCalled = true;
            UIInputDispatchDecision decision = {};
            decision.handled = true;
            return decision;
        });

    EXPECT_TRUE(summary.shortcutHandled);
    EXPECT_EQ(summary.commandId, "palette.open");
    EXPECT_FALSE(handlerCalled);
    EXPECT_FALSE(summary.routing.plan.HasTargetPath());
}