/*
 * Copyright (c) Contributors to the Open 3D Engine Project.
 * For complete copyright and license terms please see the LICENSE at the root of this distribution.
 *
 * SPDX-License-Identifier: Apache-2.0 OR MIT
 *
 */

#include <AzFramework/Input/Devices/Keyboard/InputDeviceKeyboard.h>
#include <AzFramework/Input/Devices/Mouse/InputDeviceMouse.h>
#include <AzToolsFramework/Viewport/ViewportMessages.h>
#include <AzToolsFramework/Manipulators/ManipulatorManager.h>
#include <AzToolsFramework/Viewport/ViewportInteractionHelpers.h>

#include <EMStudio/AnimViewportInputController.h>


namespace EMStudio
{
    bool AnimViewportInputController::HandleInputChannelEvent(const AzFramework::ViewportControllerInputEvent& event)
    {
        using AzFramework::InputChannel;
        using AzToolsFramework::ViewportInteraction::KeyboardModifier;
        using AzToolsFramework::ViewportInteraction::MouseButton;
        using AzToolsFramework::ViewportInteraction::MouseEvent;
        using AzToolsFramework::ViewportInteraction::MouseInteraction;
        using AzToolsFramework::ViewportInteraction::MouseInteractionEvent;
        using AzToolsFramework::ViewportInteraction::ProjectedViewportRay;
        using AzToolsFramework::ViewportInteraction::ViewportInteractionRequestBus;
        using AzToolsFramework::ViewportInteraction::Helpers;

        bool interactionHandled = false;
        float wheelDelta = 0.0f;
        AZStd::optional<MouseButton> overrideButton;
        AZStd::optional<MouseEvent> eventType;

        const auto state = event.m_inputChannel.GetState();
        if (Helpers::IsMouseMove(event.m_inputChannel))
        {
            const auto* position = event.m_inputChannel.GetCustomData<AzFramework::InputChannel::PositionData2D>();
            AZ_Assert(position, "Expected PositionData2D but found nullptr");

            AzFramework::WindowSize windowSize;
            AzFramework::WindowRequestBus::EventResult(
                windowSize, event.m_windowHandle, &AzFramework::WindowRequestBus::Events::GetClientAreaSize);

            const auto screenPoint = AzFramework::ScreenPoint(
                aznumeric_cast<int>(position->m_normalizedPosition.GetX() * windowSize.m_width),
                aznumeric_cast<int>(position->m_normalizedPosition.GetY() * windowSize.m_height));

            ProjectedViewportRay ray{};
            ViewportInteractionRequestBus::EventResult(
                ray, GetViewportId(), &ViewportInteractionRequestBus::Events::ViewportScreenToWorldRay, screenPoint);

            m_mouseInteraction.m_mousePick.m_rayOrigin = ray.m_origin;
            m_mouseInteraction.m_mousePick.m_rayDirection = ray.m_direction;
            m_mouseInteraction.m_mousePick.m_screenCoordinates = screenPoint;

            eventType = MouseEvent::Move;
        }
        else if (auto mouseButton = Helpers::GetMouseButton(event.m_inputChannel); mouseButton != MouseButton::None)
        {
            const AZ::u32 mouseButtonValue = static_cast<AZ::u32>(mouseButton);
            overrideButton = mouseButton;
            if (state == InputChannel::State::Began)
            {
                m_mouseInteraction.m_mouseButtons.m_mouseButtons |= mouseButtonValue;
                eventType = MouseEvent::Down;
            }
            else if (state == InputChannel::State::Ended)
            {
                // If we've actually logged a mouse down event, forward a mouse up event.
                // This prevents corner cases like the context menu thinking it should be opened even though no one clicked in this
                // viewport, due to RenderViewportWidget ensuring all controllers get InputChannel::State::Ended events.
                if (m_mouseInteraction.m_mouseButtons.m_mouseButtons & mouseButtonValue)
                {
                    eventType = MouseEvent::Up;
                }
            }
        }
        else if (auto keyboardModifier = Helpers::GetKeyboardModifier(event.m_inputChannel); keyboardModifier != KeyboardModifier::None)
        {
            if (state == InputChannel::State::Began || state == InputChannel::State::Updated)
            {
                m_mouseInteraction.m_keyboardModifiers.m_keyModifiers |= static_cast<AZ::u32>(keyboardModifier);
            }
            else if (state == InputChannel::State::Ended)
            {
                m_mouseInteraction.m_keyboardModifiers.m_keyModifiers &= ~static_cast<AZ::u32>(keyboardModifier);
            }
        }
        else if (event.m_inputChannel.GetInputChannelId() == AzFramework::InputDeviceMouse::Movement::Z)
        {
            if (state == InputChannel::State::Began || state == InputChannel::State::Updated)
            {
                eventType = MouseEvent::Wheel;
                wheelDelta = event.m_inputChannel.GetValue();
            }
        }

        if (eventType)
        {
            MouseInteraction mouseInteraction = m_mouseInteraction;
            if (overrideButton)
            {
                mouseInteraction.m_mouseButtons.m_mouseButtons = static_cast<AZ::u32>(overrideButton.value());
            }

            mouseInteraction.m_interactionId.m_viewportId = GetViewportId();

            auto currentCursorState = AzFramework::SystemCursorState::Unknown;
            AzFramework::InputSystemCursorRequestBus::EventResult(
                currentCursorState, event.m_inputChannel.GetInputDevice().GetInputDeviceId(),
                &AzFramework::InputSystemCursorRequestBus::Events::GetSystemCursorState);

            const auto mouseInteractionEvent = [mouseInteraction, event = eventType.value(), wheelDelta,
                                                cursorCaptured = currentCursorState == AzFramework::SystemCursorState::ConstrainedAndHidden]
            {
                switch (event)
                {
                case MouseEvent::Up:
                case MouseEvent::Down:
                case MouseEvent::Move:
                case MouseEvent::DoubleClick:
                    return MouseInteractionEvent(AZStd::move(mouseInteraction), event, cursorCaptured);
                case MouseEvent::Wheel:
                    return MouseInteractionEvent(AZStd::move(mouseInteraction), wheelDelta);
                }

                AZ_Assert(false, "Unhandled MouseEvent");
                return MouseInteractionEvent(MouseInteraction{}, MouseEvent::Up, false);
            }();

            AzToolsFramework::ViewportInteraction::ViewportMouseRequestBus::EventResult(interactionHandled,
                GetViewportId(), &AzToolsFramework::ViewportInteraction::ViewportMouseRequestBus::Handler::HandleMouseInteraction,
                mouseInteractionEvent);
        }

        return interactionHandled;
    }
} // namespace EMStudio