/*
  ==============================================================================

   This file is part of the JUCE 7 technical preview.
   Copyright (c) 2022 - Raw Material Software Limited

   You may use this code under the terms of the GPL v3
   (see www.gnu.org/licenses).

   For the technical preview this file cannot be licensed commercially.

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

  ==============================================================================
*/

namespace juce
{

struct Button::CallbackHelper  : public Timer,
                                 public ApplicationCommandManagerListener,
                                 public Value::Listener,
                                 public KeyListener
{
    CallbackHelper (Button& b) : button (b)   {}

    void timerCallback() override
    {
        button.repeatTimerCallback();
    }

    bool keyStateChanged (bool, Component*) override
    {
        return button.keyStateChangedCallback();
    }

    void valueChanged (Value& value) override
    {
        if (value.refersToSameSourceAs (button.isOn))
            button.setToggleState (button.isOn.getValue(), dontSendNotification, sendNotification);
    }

    bool keyPressed (const KeyPress&, Component*) override
    {
        // returning true will avoid forwarding events for keys that we're using as shortcuts
        return button.isShortcutPressed();
    }

    void applicationCommandInvoked (const ApplicationCommandTarget::InvocationInfo& info) override
    {
        if (info.commandID == button.commandID
             && (info.commandFlags & ApplicationCommandInfo::dontTriggerVisualFeedback) == 0)
            button.flashButtonState();
    }

    void applicationCommandListChanged() override
    {
        button.applicationCommandListChangeCallback();
    }

    Button& button;

    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (CallbackHelper)
};

//==============================================================================
Button::Button (const String& name)  : Component (name), text (name)
{
    callbackHelper.reset (new CallbackHelper (*this));

    setWantsKeyboardFocus (true);
    isOn.addListener (callbackHelper.get());
}

Button::~Button()
{
    clearShortcuts();

    if (commandManagerToUse != nullptr)
        commandManagerToUse->removeListener (callbackHelper.get());

    isOn.removeListener (callbackHelper.get());
    callbackHelper.reset();
}

//==============================================================================
void Button::setButtonText (const String& newText)
{
    if (text != newText)
    {
        text = newText;
        repaint();
    }
}

void Button::setTooltip (const String& newTooltip)
{
    SettableTooltipClient::setTooltip (newTooltip);
    generateTooltip = false;
}

void Button::updateAutomaticTooltip (const ApplicationCommandInfo& info)
{
    if (generateTooltip && commandManagerToUse != nullptr)
    {
        auto tt = info.description.isNotEmpty() ? info.description
                                                : info.shortName;

        for (auto& kp : commandManagerToUse->getKeyMappings()->getKeyPressesAssignedToCommand (commandID))
        {
            auto key = kp.getTextDescription();

            tt << " [";

            if (key.length() == 1)
                tt << TRANS("shortcut") << ": '" << key << "']";
            else
                tt << key << ']';
        }

        SettableTooltipClient::setTooltip (tt);
    }
}

void Button::setConnectedEdges (int newFlags)
{
    if (connectedEdgeFlags != newFlags)
    {
        connectedEdgeFlags = newFlags;
        repaint();
    }
}

//==============================================================================
void Button::checkToggleableState (bool wasToggleable)
{
    if (isToggleable() != wasToggleable)
        invalidateAccessibilityHandler();
}

void Button::setToggleable (bool isNowToggleable)
{
    const auto wasToggleable = isToggleable();

    canBeToggled = isNowToggleable;
    checkToggleableState (wasToggleable);
}

void Button::setToggleState (bool shouldBeOn, NotificationType notification)
{
    setToggleState (shouldBeOn, notification, notification);
}

void Button::setToggleState (bool shouldBeOn, NotificationType clickNotification, NotificationType stateNotification)
{
    if (shouldBeOn != lastToggleState)
    {
        WeakReference<Component> deletionWatcher (this);

        if (shouldBeOn)
        {
            turnOffOtherButtonsInGroup (clickNotification, stateNotification);

            if (deletionWatcher == nullptr)
                return;
        }

        // This test is done so that if the value is void rather than explicitly set to
        // false, the value won't be changed unless the required value is true.
        if (getToggleState() != shouldBeOn)
        {
            isOn = shouldBeOn;

            if (deletionWatcher == nullptr)
                return;
        }

        lastToggleState = shouldBeOn;
        repaint();

        if (clickNotification != dontSendNotification)
        {
            // async callbacks aren't possible here
            jassert (clickNotification != sendNotificationAsync);

            sendClickMessage (ModifierKeys::currentModifiers);

            if (deletionWatcher == nullptr)
                return;
        }

        if (stateNotification != dontSendNotification)
            sendStateMessage();
        else
            buttonStateChanged();

        if (auto* handler = getAccessibilityHandler())
            handler->notifyAccessibilityEvent (AccessibilityEvent::valueChanged);
    }
}

void Button::setToggleState (bool shouldBeOn, bool sendChange)
{
    setToggleState (shouldBeOn, sendChange ? sendNotification : dontSendNotification);
}

void Button::setClickingTogglesState (bool shouldToggle) noexcept
{
    const auto wasToggleable = isToggleable();

    clickTogglesState = shouldToggle;
    checkToggleableState (wasToggleable);

    // if you've got clickTogglesState turned on, you shouldn't also connect the button
    // up to be a command invoker. Instead, your command handler must flip the state of whatever
    // it is that this button represents, and the button will update its state to reflect this
    // in the applicationCommandListChanged() method.
    jassert (commandManagerToUse == nullptr || ! clickTogglesState);
}

void Button::setRadioGroupId (int newGroupId, NotificationType notification)
{
    if (radioGroupId != newGroupId)
    {
        radioGroupId = newGroupId;

        if (lastToggleState)
            turnOffOtherButtonsInGroup (notification, notification);

        setToggleable (true);
        invalidateAccessibilityHandler();
    }
}

void Button::turnOffOtherButtonsInGroup (NotificationType clickNotification, NotificationType stateNotification)
{
    if (auto* p = getParentComponent())
    {
        if (radioGroupId != 0)
        {
            WeakReference<Component> deletionWatcher (this);

            for (auto* c : p->getChildren())
            {
                if (c != this)
                {
                    if (auto b = dynamic_cast<Button*> (c))
                    {
                        if (b->getRadioGroupId() == radioGroupId)
                        {
                            b->setToggleState (false, clickNotification, stateNotification);

                            if (deletionWatcher == nullptr)
                                return;
                        }
                    }
                }
            }
        }
    }
}

//==============================================================================
void Button::enablementChanged()
{
    updateState();
    repaint();
}

Button::ButtonState Button::updateState()
{
    return updateState (isMouseOver (true), isMouseButtonDown());
}

Button::ButtonState Button::updateState (bool over, bool down)
{
    ButtonState newState = buttonNormal;

    if (isEnabled() && isVisible() && ! isCurrentlyBlockedByAnotherModalComponent())
    {
        if ((down && (over || (triggerOnMouseDown && buttonState == buttonDown))) || isKeyDown)
            newState = buttonDown;
        else if (over)
            newState = buttonOver;
    }

    setState (newState);
    return newState;
}

void Button::setState (ButtonState newState)
{
    if (buttonState != newState)
    {
        buttonState = newState;
        repaint();

        if (buttonState == buttonDown)
        {
            buttonPressTime = Time::getApproximateMillisecondCounter();
            lastRepeatTime = 0;
        }

        sendStateMessage();
    }
}

bool Button::isDown() const noexcept    { return buttonState == buttonDown; }
bool Button::isOver() const noexcept    { return buttonState != buttonNormal; }

void Button::buttonStateChanged() {}

uint32 Button::getMillisecondsSinceButtonDown() const noexcept
{
    auto now = Time::getApproximateMillisecondCounter();
    return now > buttonPressTime ? now - buttonPressTime : 0;
}

void Button::setTriggeredOnMouseDown (bool isTriggeredOnMouseDown) noexcept
{
    triggerOnMouseDown = isTriggeredOnMouseDown;
}

bool Button::getTriggeredOnMouseDown() const noexcept
{
    return triggerOnMouseDown;
}

//==============================================================================
void Button::clicked()
{
}

void Button::clicked (const ModifierKeys&)
{
    clicked();
}

enum { clickMessageId = 0x2f3f4f99 };

void Button::triggerClick()
{
    postCommandMessage (clickMessageId);
}

void Button::internalClickCallback (const ModifierKeys& modifiers)
{
    if (clickTogglesState)
    {
        const bool shouldBeOn = (radioGroupId != 0 || ! lastToggleState);

        if (shouldBeOn != getToggleState())
        {
            setToggleState (shouldBeOn, sendNotification);
            return;
        }
    }

    sendClickMessage (modifiers);
}

void Button::flashButtonState()
{
    if (isEnabled())
    {
        needsToRelease = true;
        setState (buttonDown);
        callbackHelper->startTimer (100);
    }
}

void Button::handleCommandMessage (int commandId)
{
    if (commandId == clickMessageId)
    {
        if (isEnabled())
        {
            flashButtonState();
            internalClickCallback (ModifierKeys::currentModifiers);
        }
    }
    else
    {
        Component::handleCommandMessage (commandId);
    }
}

//==============================================================================
void Button::addListener (Listener* l)      { buttonListeners.add (l); }
void Button::removeListener (Listener* l)   { buttonListeners.remove (l); }

void Button::sendClickMessage (const ModifierKeys& modifiers)
{
    Component::BailOutChecker checker (this);

    if (commandManagerToUse != nullptr && commandID != 0)
    {
        ApplicationCommandTarget::InvocationInfo info (commandID);
        info.invocationMethod = ApplicationCommandTarget::InvocationInfo::fromButton;
        info.originatingComponent = this;

        commandManagerToUse->invoke (info, true);
    }

    clicked (modifiers);

    if (checker.shouldBailOut())
        return;

    buttonListeners.callChecked (checker, [this] (Listener& l) { l.buttonClicked (this); });

    if (checker.shouldBailOut())
        return;

    if (onClick != nullptr)
        onClick();
}

void Button::sendStateMessage()
{
    Component::BailOutChecker checker (this);

    buttonStateChanged();

    if (checker.shouldBailOut())
        return;

    buttonListeners.callChecked (checker, [this] (Listener& l) { l.buttonStateChanged (this); });

    if (checker.shouldBailOut())
        return;

    if (onStateChange != nullptr)
        onStateChange();
}

//==============================================================================
void Button::paint (Graphics& g)
{
    if (needsToRelease && isEnabled())
    {
        needsToRelease = false;
        needsRepainting = true;
    }

    paintButton (g, isOver(), isDown());
    lastStatePainted = buttonState;
}

//==============================================================================
void Button::mouseEnter (const MouseEvent&)     { updateState (true,  false); }
void Button::mouseExit (const MouseEvent&)      { updateState (false, false); }

void Button::mouseDown (const MouseEvent& e)
{
    updateState (true, true);

    if (isDown())
    {
        if (autoRepeatDelay >= 0)
            callbackHelper->startTimer (autoRepeatDelay);

        if (triggerOnMouseDown)
            internalClickCallback (e.mods);
    }
}

void Button::mouseUp (const MouseEvent& e)
{
    const auto wasDown = isDown();
    const auto wasOver = isOver();
    updateState (isMouseSourceOver (e), false);

    if (wasDown && wasOver && ! triggerOnMouseDown)
    {
        if (lastStatePainted != buttonDown)
            flashButtonState();

        WeakReference<Component> deletionWatcher (this);

        internalClickCallback (e.mods);

        if (deletionWatcher != nullptr)
            updateState (isMouseSourceOver (e), false);
    }
}

void Button::mouseDrag (const MouseEvent& e)
{
    auto oldState = buttonState;
    updateState (isMouseSourceOver (e), true);

    if (autoRepeatDelay >= 0 && buttonState != oldState && isDown())
        callbackHelper->startTimer (autoRepeatSpeed);
}

bool Button::isMouseSourceOver (const MouseEvent& e)
{
    if (e.source.isTouch() || e.source.isPen())
        return getLocalBounds().toFloat().contains (e.position);

    return isMouseOver();
}

void Button::focusGained (FocusChangeType)
{
    updateState();
    repaint();
}

void Button::focusLost (FocusChangeType)
{
    updateState();
    repaint();
}

void Button::visibilityChanged()
{
    needsToRelease = false;
    updateState();
}

void Button::parentHierarchyChanged()
{
    auto* newKeySource = shortcuts.isEmpty() ? nullptr : getTopLevelComponent();

    if (newKeySource != keySource.get())
    {
        if (keySource != nullptr)
            keySource->removeKeyListener (callbackHelper.get());

        keySource = newKeySource;

        if (keySource != nullptr)
            keySource->addKeyListener (callbackHelper.get());
    }
}

//==============================================================================
void Button::setCommandToTrigger (ApplicationCommandManager* newCommandManager,
                                  CommandID newCommandID, bool generateTip)
{
    commandID = newCommandID;
    generateTooltip = generateTip;

    if (commandManagerToUse != newCommandManager)
    {
        if (commandManagerToUse != nullptr)
            commandManagerToUse->removeListener (callbackHelper.get());

        commandManagerToUse = newCommandManager;

        if (commandManagerToUse != nullptr)
            commandManagerToUse->addListener (callbackHelper.get());

        // if you've got clickTogglesState turned on, you shouldn't also connect the button
        // up to be a command invoker. Instead, your command handler must flip the state of whatever
        // it is that this button represents, and the button will update its state to reflect this
        // in the applicationCommandListChanged() method.
        jassert (commandManagerToUse == nullptr || ! clickTogglesState);
    }

    if (commandManagerToUse != nullptr)
        applicationCommandListChangeCallback();
    else
        setEnabled (true);
}

void Button::applicationCommandListChangeCallback()
{
    if (commandManagerToUse != nullptr)
    {
        ApplicationCommandInfo info (0);

        if (commandManagerToUse->getTargetForCommand (commandID, info) != nullptr)
        {
            updateAutomaticTooltip (info);
            setEnabled ((info.flags & ApplicationCommandInfo::isDisabled) == 0);
            setToggleState ((info.flags & ApplicationCommandInfo::isTicked) != 0, dontSendNotification);
        }
        else
        {
            setEnabled (false);
        }
    }
}

//==============================================================================
void Button::addShortcut (const KeyPress& key)
{
    if (key.isValid())
    {
        jassert (! isRegisteredForShortcut (key));  // already registered!

        shortcuts.add (key);
        parentHierarchyChanged();
    }
}

void Button::clearShortcuts()
{
    shortcuts.clear();
    parentHierarchyChanged();
}

bool Button::isShortcutPressed() const
{
    if (isShowing() && ! isCurrentlyBlockedByAnotherModalComponent())
        for (auto& s : shortcuts)
            if (s.isCurrentlyDown())
                return true;

    return false;
}

bool Button::isRegisteredForShortcut (const KeyPress& key) const
{
    for (auto& s : shortcuts)
        if (key == s)
            return true;

    return false;
}

bool Button::keyStateChangedCallback()
{
    if (! isEnabled())
        return false;

    const bool wasDown = isKeyDown;
    isKeyDown = isShortcutPressed();

    if (autoRepeatDelay >= 0 && (isKeyDown && ! wasDown))
        callbackHelper->startTimer (autoRepeatDelay);

    updateState();

    if (isEnabled() && wasDown && ! isKeyDown)
    {
        internalClickCallback (ModifierKeys::currentModifiers);

        // (return immediately - this button may now have been deleted)
        return true;
    }

    return wasDown || isKeyDown;
}

bool Button::keyPressed (const KeyPress& key)
{
    if (isEnabled() && key.isKeyCode (KeyPress::returnKey))
    {
        triggerClick();
        return true;
    }

    return false;
}

//==============================================================================
void Button::setRepeatSpeed (int initialDelayMillisecs,
                             int repeatMillisecs,
                             int minimumDelayInMillisecs) noexcept
{
    autoRepeatDelay = initialDelayMillisecs;
    autoRepeatSpeed = repeatMillisecs;
    autoRepeatMinimumDelay = jmin (autoRepeatSpeed, minimumDelayInMillisecs);
}

void Button::repeatTimerCallback()
{
    if (needsRepainting)
    {
        callbackHelper->stopTimer();
        updateState();
        needsRepainting = false;
    }
    else if (autoRepeatSpeed > 0 && (isKeyDown || (updateState() == buttonDown)))
    {
        auto repeatSpeed = autoRepeatSpeed;

        if (autoRepeatMinimumDelay >= 0)
        {
            auto timeHeldDown = jmin (1.0, getMillisecondsSinceButtonDown() / 4000.0);
            timeHeldDown *= timeHeldDown;

            repeatSpeed = repeatSpeed + (int) (timeHeldDown * (autoRepeatMinimumDelay - repeatSpeed));
        }

        repeatSpeed = jmax (1, repeatSpeed);

        auto now = Time::getMillisecondCounter();

        // if we've been blocked from repeating often enough, speed up the repeat timer to compensate..
        if (lastRepeatTime != 0 && (int) (now - lastRepeatTime) > repeatSpeed * 2)
            repeatSpeed = jmax (1, repeatSpeed / 2);

        lastRepeatTime = now;
        callbackHelper->startTimer (repeatSpeed);

        internalClickCallback (ModifierKeys::currentModifiers);
    }
    else if (! needsToRelease)
    {
        callbackHelper->stopTimer();
    }
}

//==============================================================================
class ButtonAccessibilityHandler  : public AccessibilityHandler
{
public:
    explicit ButtonAccessibilityHandler (Button& buttonToWrap, AccessibilityRole roleIn)
        : AccessibilityHandler (buttonToWrap,
                                isRadioButton (buttonToWrap) ? AccessibilityRole::radioButton : roleIn,
                                getAccessibilityActions (buttonToWrap),
                                getAccessibilityInterfaces (buttonToWrap)),
          button (buttonToWrap)
    {
    }

    AccessibleState getCurrentState() const override
    {
        auto state = AccessibilityHandler::getCurrentState();

        if (button.isToggleable())
        {
            state = state.withCheckable();

            if (button.getToggleState())
                state = state.withChecked();
        }

        return state;
    }

    String getTitle() const override
    {
        auto title = AccessibilityHandler::getTitle();

        if (title.isEmpty())
            return button.getButtonText();

        return title;
    }

    String getHelp() const override  { return button.getTooltip(); }

private:
    class ButtonValueInterface  : public AccessibilityTextValueInterface
    {
    public:
        explicit ButtonValueInterface (Button& buttonToWrap)
            : button (buttonToWrap)
        {
        }

        bool isReadOnly() const override                 { return true; }
        String getCurrentValueAsString() const override  { return button.getToggleState() ? "On" : "Off"; }
        void setValueAsString (const String&) override   {}

    private:
        Button& button;

        //==============================================================================
        JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (ButtonValueInterface)
    };

    static bool isRadioButton (const Button& button) noexcept
    {
        return button.getRadioGroupId() != 0;
    }

    static AccessibilityActions getAccessibilityActions (Button& button)
    {
        auto actions = AccessibilityActions().addAction (AccessibilityActionType::press,
                                                         [&button] { button.triggerClick(); });

        if (button.isToggleable())
            actions = actions.addAction (AccessibilityActionType::toggle,
                                         [&button] { button.setToggleState (! button.getToggleState(), sendNotification); });

        return actions;
    }

    static Interfaces getAccessibilityInterfaces (Button& button)
    {
        if (button.isToggleable())
            return { std::make_unique<ButtonValueInterface> (button) };

        return {};
    }

    Button& button;

    //==============================================================================
    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (ButtonAccessibilityHandler)
};

std::unique_ptr<AccessibilityHandler> Button::createAccessibilityHandler()
{
    return std::make_unique<ButtonAccessibilityHandler> (*this, AccessibilityRole::button);
}

} // namespace juce