@using Microsoft.AspNetCore.Components

<!-- Robot goal pose: line robot->goal, line goal->mouse (with arrow), circle at goal with radius = distance(goal,mouse).
     _goalOrientationRad được tính trong SetMousePosition: hướng từ goal đến mouse; 0 khi goal trùng mouse. -->
<g visibility="@_visibility" @ref="_groupRef">
    <defs>
        <marker id="@_arrowMarkerId" markerWidth="0.15" markerHeight="0.15" refX="0" refY="0.075" orient="auto" markerUnits="userSpaceOnUse">
            <path d="M 0 0 L 0.15 0.075 L 0 0.15 Z" fill="#FF0000" stroke="none" />
        </marker>
    </defs>
    <!-- Line 1: RobotPosition -> GoalPosition (red, dashed, 0.1); zero length when robot==goal is valid -->
    <line x1="@_robotX" y1="@_robotY" x2="@_goalX" y2="@_goalY"
          stroke="green" stroke-width="0.03" stroke-dasharray="0.3,0.2" fill="none" />
    <!-- Line 2: GoalPosition -> current mouse (blue, dashed, 0.1, arrow at mouse) -->
    <line x1="@_goalX" y1="@_goalY" x2="@_mouseX" y2="@_mouseY"
          stroke="#FF0000" stroke-width="0.03" stroke-dasharray="0.3,0.2" fill="none"
          marker-end="url(#@_arrowMarkerId)" />
    <!-- Circle: center GoalPosition, radius = distance(Goal, mouse); r=0 when goal==mouse is valid -->
    <circle cx="@_goalX" cy="@_goalY" r="@_radius"
            stroke="green" stroke-width="0.03" stroke-dasharray="0.3,0.2" fill="none" />
</g>

@code {
    private ElementReference _groupRef;
    private string _arrowMarkerId = "goal-mouse-arrow-" + Guid.NewGuid().ToString("N")[..8];

    private double _robotX;
    private double _robotY;
    private double _goalX;
    private double _goalY;
    private double _goalOrientationRad;
    private double _mouseX;
    private double _mouseY;
    private string _visibility = "hidden";

    /// <summary>Tọa độ X điểm đích (world coordinates).</summary>
    public double GoalX => _goalX;
    /// <summary>Tọa độ Y điểm đích (world coordinates).</summary>
    public double GoalY => _goalY;
    /// <summary>Hướng điểm đích (yaw, radians) — hướng từ goal đến mouse; 0 khi goal trùng mouse.</summary>
    public double GoalYaw => _goalOrientationRad;

    /// <summary>Bán kính circle = khoảng cách Goal -> mouse; 0 khi goal trùng mouse (hợp lệ).</summary>
    private double _radius => Math.Sqrt((_mouseX - _goalX) * (_mouseX - _goalX) + (_mouseY - _goalY) * (_mouseY - _goalY));

    /// <summary>
    /// Hiển thị nhóm line và circle (robot->goal, goal->mouse, circle).
    /// </summary>
    public void Show()
    {
        _visibility = "visible";
        StateHasChanged();
    }

    /// <summary>
    /// Ẩn nhóm line và circle.
    /// </summary>
    public void Hide()
    {
        _visibility = "hidden";
        StateHasChanged();
    }

    /// <summary>
    /// Đặt tọa độ robot (world coordinates).
    /// </summary>
    public void SetRobotPosition(double x, double y)
    {
        _robotX = x;
        _robotY = y;
        StateHasChanged();
    }

    /// <summary>
    /// Đặt tọa độ điểm đích (world coordinates).
    /// </summary>
    public void SetGoalPosition(double x, double y)
    {
        _goalX = x;
        _goalY = y;
        StateHasChanged();
    }

    /// <summary>
    /// Cập nhật vị trí chuột (world coordinates). Parent gọi từ OnMouseMove để vẽ line goal->mouse và circle.
    /// Tự tính _goalOrientationRad = hướng từ goal đến mouse (radians); 0 khi goal trùng mouse.
    /// </summary>
    public void SetMousePosition(double x, double y)
    {
        _mouseX = x;
        _mouseY = y;
        var dx = _mouseX - _goalX;
        var dy = _mouseY - _goalY;
        _goalOrientationRad = (Math.Abs(dx) < 1e-9 && Math.Abs(dy) < 1e-9) ? 0 : Math.Atan2(dy, dx);
        StateHasChanged();
    }

    private const double OptimizeMinDistanceMeters = 1.0;

    /// <summary>
    /// Nếu khoảng cách từ (GoalX, GoalY) đến (mouseX, mouseY) &lt; 1 m thì gọi Hide().
    /// Nếu khoảng cách &gt;= 1 m thì đặt lại _mouseX, _mouseY sao cho khoảng cách đúng 1 m (giữ hướng).
    /// Tọa độ trong SVG là mét (viewBox + scaleY(-1) trong MapLocalization).
    /// </summary>
    public void Optimize()
    {
        var dx = _mouseX - _goalX;
        var dy = _mouseY - _goalY;
        var d = Math.Sqrt(dx * dx + dy * dy);
        if (d < OptimizeMinDistanceMeters)
        {
            Hide();
            return;
        }
        var scale = OptimizeMinDistanceMeters / d;
        _mouseX = _goalX + dx * scale;
        _mouseY = _goalY + dy * scale;
        _goalOrientationRad = (Math.Abs(dx) < 1e-9 && Math.Abs(dy) < 1e-9) ? 0 : Math.Atan2(dy, dx);
        StateHasChanged();
    }
}