#include "Scene/SceneViewportSceneOverlay.h"

#include "Scene/SceneViewportTransformGizmoSupport.h"
#include "Assets/EditorIconService.h"
#include "Scene/EditorSceneRuntime.h"

#include <algorithm>
#include <utility>

namespace XCEngine::UI::Editor::App {

namespace {

using ::XCEngine::Math::Vector2;
using ::XCEngine::UI::UIPoint;
using ::XCEngine::UI::UIRect;
namespace SceneViewportGizmoSupport = ::XCEngine::UI::Editor::App::SceneViewportGizmoSupport;

constexpr Vector2 kCameraIconSize(90.0f, 90.0f);
constexpr Vector2 kLightIconSize(100.0f, 100.0f);

bool ContainsPoint(const UIRect& rect, const UIPoint& point) {
    return point.x >= rect.x &&
        point.x <= rect.x + rect.width &&
        point.y >= rect.y &&
        point.y <= rect.y + rect.height;
}

SceneViewportGizmoSupport::SceneViewportOverlayData BuildOverlayData(
    const EditorSceneRuntime& sceneRuntime) {
    SceneViewportGizmoSupport::SceneViewportOverlayData overlay = {};
    const EditorSceneCameraSnapshot snapshot =
        sceneRuntime.BuildSceneViewCameraSnapshot();
    if (!snapshot.valid) {
        return overlay;
    }

    overlay.valid = true;
    overlay.cameraPosition = snapshot.position;
    overlay.cameraForward = snapshot.forward;
    overlay.cameraRight = snapshot.right;
    overlay.cameraUp = snapshot.up;
    overlay.verticalFovDegrees = snapshot.verticalFovDegrees;
    overlay.nearClipPlane = snapshot.nearClipPlane;
    overlay.farClipPlane = snapshot.farClipPlane;
    overlay.orbitDistance = snapshot.orbitDistance;
    return overlay;
}

::XCEngine::UI::UITextureHandle ResolveViewportIcon(
    const EditorIconService* icons,
    EditorSceneViewportIconKind kind) {
    if (icons == nullptr) {
        return {};
    }

    switch (kind) {
    case EditorSceneViewportIconKind::Camera:
        return icons->Resolve(BuiltInIconKind::CameraGizmo);
    case EditorSceneViewportIconKind::DirectionalLight:
        return icons->Resolve(BuiltInIconKind::DirectionalLightGizmo);
    case EditorSceneViewportIconKind::PointLight:
        return icons->Resolve(BuiltInIconKind::PointLightGizmo);
    case EditorSceneViewportIconKind::SpotLight:
        return icons->Resolve(BuiltInIconKind::SpotLightGizmo);
    default:
        return {};
    }
}

Vector2 ResolveViewportIconSize(EditorSceneViewportIconKind kind) {
    return kind == EditorSceneViewportIconKind::Camera
        ? kCameraIconSize
        : kLightIconSize;
}

} // namespace

void SceneViewportSceneOverlay::SetIconService(const EditorIconService* icons) {
    m_icons = icons;
    if (m_icons == nullptr) {
        ResetFrame();
    }
}

void SceneViewportSceneOverlay::ResetFrame() {
    m_frame = {};
}

void SceneViewportSceneOverlay::Refresh(
    EditorSceneRuntime& sceneRuntime,
    const UIRect& viewportRect) {
    m_frame = {};
    m_frame.clipRect = viewportRect;

    if (m_icons == nullptr ||
        viewportRect.width <= 1.0f ||
        viewportRect.height <= 1.0f) {
        return;
    }

    const SceneViewportGizmoSupport::SceneViewportOverlayData overlay =
        BuildOverlayData(sceneRuntime);
    if (!overlay.valid) {
        return;
    }

    std::vector<IconFrame> icons = {};
    const auto tryAppendIcon =
        [&](const EditorSceneViewportIconSnapshot& snapshot) {
            const ::XCEngine::UI::UITextureHandle texture =
                ResolveViewportIcon(m_icons, snapshot.kind);
            if (!texture.IsValid()) {
                return;
            }

            const Vector2 iconSize = ResolveViewportIconSize(snapshot.kind);
            const SceneViewportGizmoSupport::SceneViewportProjectedPoint projectedPoint =
                SceneViewportGizmoSupport::ProjectSceneViewportWorldPoint(
                    overlay,
                    viewportRect.width,
                    viewportRect.height,
                    snapshot.worldPosition);
            if (!projectedPoint.visible) {
                return;
            }

            IconFrame icon = {};
            icon.entityId = snapshot.entityId;
            icon.rect = UIRect(
                viewportRect.x + projectedPoint.screenPosition.x - iconSize.x * 0.5f,
                viewportRect.y + projectedPoint.screenPosition.y - iconSize.y * 0.5f,
                iconSize.x,
                iconSize.y);
            icon.texture = texture;
            icon.sortDepth = projectedPoint.ndcDepth;
            icons.push_back(std::move(icon));
        };

    for (const EditorSceneViewportIconSnapshot& snapshot :
         sceneRuntime.BuildSceneViewportIconSnapshots()) {
        if (!snapshot.IsValid()) {
            continue;
        }

        tryAppendIcon(snapshot);
    }

    if (icons.empty()) {
        return;
    }

    std::sort(
        icons.begin(),
        icons.end(),
        [](const IconFrame& lhs, const IconFrame& rhs) {
            return lhs.sortDepth > rhs.sortDepth;
        });
    m_frame.visible = true;
    m_frame.icons = std::move(icons);
}

SceneViewportSceneOverlay::HitResult SceneViewportSceneOverlay::HitTest(
    const UIPoint& point) const {
    HitResult result = {};
    if (!m_frame.visible) {
        return result;
    }

    constexpr float kMetricEpsilon = 0.001f;
    for (const IconFrame& icon : m_frame.icons) {
        if (icon.entityId == 0 ||
            !icon.texture.IsValid() ||
            !ContainsPoint(icon.rect, point)) {
            continue;
        }

        if (!result.HasHit() ||
            icon.sortDepth + kMetricEpsilon < result.sortDepth) {
            result.entityId = icon.entityId;
            result.sortDepth = icon.sortDepth;
        }
    }

    return result;
}

void SceneViewportSceneOverlay::Append(::XCEngine::UI::UIDrawList& drawList) const {
    if (!m_frame.visible || m_frame.icons.empty()) {
        return;
    }

    drawList.PushClipRect(m_frame.clipRect);
    for (const IconFrame& icon : m_frame.icons) {
        drawList.AddImage(icon.rect, icon.texture);
    }
    drawList.PopClipRect();
}

} // namespace XCEngine::UI::Editor::App