#include "Platform/Win32/WindowManager/TabDragDropTarget.h"

#include <algorithm>

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

namespace {

using ::XCEngine::UI::UIPoint;
using ::XCEngine::UI::UIRect;

bool IsPointInsideRect(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;
}

std::size_t ResolveDropInsertionIndex(
    const Widgets::UIEditorDockHostTabStackLayout& tabStack,
    const UIPoint& point) {
    if (!IsPointInsideRect(tabStack.tabStripLayout.headerRect, point)) {
        return Widgets::UIEditorTabStripInvalidIndex;
    }

    std::size_t insertionIndex = 0u;
    for (const UIRect& rect : tabStack.tabStripLayout.tabHeaderRects) {
        const float midpoint = rect.x + rect.width * 0.5f;
        if (point.x > midpoint) {
            ++insertionIndex;
        }
    }
    return insertionIndex;
}

UIEditorWorkspaceDockPlacement ResolveDropPlacement(
    const Widgets::UIEditorDockHostTabStackLayout& tabStack,
    const UIPoint& point) {
    if (IsPointInsideRect(tabStack.tabStripLayout.headerRect, point)) {
        return UIEditorWorkspaceDockPlacement::Center;
    }

    const float leftDistance = point.x - tabStack.bounds.x;
    const float rightDistance = tabStack.bounds.x + tabStack.bounds.width - point.x;
    const float topDistance = point.y - tabStack.bounds.y;
    const float bottomDistance = tabStack.bounds.y + tabStack.bounds.height - point.y;
    const float minHorizontalThreshold = tabStack.bounds.width * 0.25f;
    const float minVerticalThreshold = tabStack.bounds.height * 0.25f;
    const float nearestEdge = (std::min)(
        (std::min)(leftDistance, rightDistance),
        (std::min)(topDistance, bottomDistance));

    if (nearestEdge == leftDistance && leftDistance <= minHorizontalThreshold) {
        return UIEditorWorkspaceDockPlacement::Left;
    }
    if (nearestEdge == rightDistance && rightDistance <= minHorizontalThreshold) {
        return UIEditorWorkspaceDockPlacement::Right;
    }
    if (nearestEdge == topDistance && topDistance <= minVerticalThreshold) {
        return UIEditorWorkspaceDockPlacement::Top;
    }
    if (nearestEdge == bottomDistance && bottomDistance <= minVerticalThreshold) {
        return UIEditorWorkspaceDockPlacement::Bottom;
    }

    return UIEditorWorkspaceDockPlacement::Center;
}

} // namespace

EditorWindowTabDragDropTarget ResolveEditorWindowTabDragDropTarget(
    const Widgets::UIEditorDockHostLayout& layout,
    const UIPoint& point) {
    EditorWindowTabDragDropTarget result = {};
    if (!IsPointInsideRect(layout.bounds, point)) {
        return result;
    }

    const Widgets::UIEditorDockHostHitTarget hitTarget =
        Widgets::HitTestUIEditorDockHost(layout, point);
    for (const Widgets::UIEditorDockHostTabStackLayout& tabStack : layout.tabStacks) {
        if ((!hitTarget.nodeId.empty() && tabStack.nodeId != hitTarget.nodeId) ||
            !IsPointInsideRect(tabStack.bounds, point)) {
            continue;
        }

        result.valid = true;
        result.nodeId = tabStack.nodeId;
        result.placement = ResolveDropPlacement(tabStack, point);
        if (result.placement == UIEditorWorkspaceDockPlacement::Center) {
            result.insertionIndex = ResolveDropInsertionIndex(tabStack, point);
            if (result.insertionIndex == Widgets::UIEditorTabStripInvalidIndex) {
                result.insertionIndex = tabStack.items.size();
            }
        }
        return result;
    }

    for (const Widgets::UIEditorDockHostTabStackLayout& tabStack : layout.tabStacks) {
        if (!IsPointInsideRect(tabStack.bounds, point)) {
            continue;
        }

        result.valid = true;
        result.nodeId = tabStack.nodeId;
        result.placement = ResolveDropPlacement(tabStack, point);
        if (result.placement == UIEditorWorkspaceDockPlacement::Center) {
            result.insertionIndex = tabStack.items.size();
        }
        return result;
    }

    return result;
}

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