using UnityEngine;
using UnityEngine.InputSystem;

[DisallowMultipleComponent]
public sealed class MapCrosshairController : MonoBehaviour
{
    [Header("Nearest Target (Runtime)")]
    [SerializeField] private MapTarget nearestTarget = null;
    [SerializeField] private float distanceToNearestTarget = -1f;

    private MapCoordinateSystem coordinateSystem;
    private MapTargetController targetController;
    private Transform relayX;
    private Transform relayY;
    private Transform crosshairVisual;
    private float movementSpeed;
    private bool useKeyboardInput;
    private float horizontalAxis;
    private float verticalAxis;
    private Vector2 crosshairCoordinates;
    private Vector3 relayXOffset;
    private Vector3 relayYOffset;
    private bool isConfigured;

    public MapCoordinateSystem CoordinateSystem => coordinateSystem;

    public void Configure(
        MapCoordinateSystem newCoordinateSystem,
        Transform newRelayX,
        Transform newRelayY,
        Transform newCrosshairVisual,
        float newMovementSpeed,
        bool enableKeyboardInput,
        MapTargetController newTargetController)
    {
        coordinateSystem = newCoordinateSystem;
        relayX = newRelayX;
        relayY = newRelayY;
        crosshairVisual = newCrosshairVisual;
        movementSpeed = Mathf.Max(0f, newMovementSpeed);
        useKeyboardInput = enableKeyboardInput;
        targetController = newTargetController;
        crosshairCoordinates = Vector2.zero;
        isConfigured = CalibrateObjects();

        if (isConfigured)
            ApplyCoordinates();
    }

    private void Update()
    {
        if (!isConfigured)
            return;

        if (useKeyboardInput)
            ReadKeyboardInput();

        Vector2 movement = new(horizontalAxis, verticalAxis);
        crosshairCoordinates += movement * (movementSpeed * Time.deltaTime);
        crosshairCoordinates = coordinateSystem.ClampCoordinates(crosshairCoordinates);
        ApplyCoordinates();
        UpdateNearestTarget();
    }

    public void SetHorizontalAxis(float value)
    {
        horizontalAxis = Mathf.Clamp(value, -1f, 1f);
    }

    public void SetVerticalAxis(float value)
    {
        verticalAxis = Mathf.Clamp(value, -1f, 1f);
    }

    public Vector2 GetCrosshairCoordinates()
    {
        return crosshairCoordinates;
    }

    public MapTarget GetNearestTarget()
    {
        return nearestTarget;
    }

    public float GetDistanceToNearestTarget()
    {
        return distanceToNearestTarget;
    }

    public bool TryGetNearestTarget(out MapTarget target, out float distance)
    {
        target = nearestTarget;
        distance = distanceToNearestTarget;
        return target != null;
    }

    private void ReadKeyboardInput()
    {
        Keyboard keyboard = Keyboard.current;
        if (keyboard == null)
        {
            SetHorizontalAxis(0f);
            SetVerticalAxis(0f);
            return;
        }

        SetHorizontalAxis(
            (keyboard.lKey.isPressed ? 1f : 0f) - (keyboard.jKey.isPressed ? 1f : 0f));
        SetVerticalAxis(
            (keyboard.iKey.isPressed ? 1f : 0f) - (keyboard.kKey.isPressed ? 1f : 0f));
    }

    private void ApplyCoordinates()
    {
        Vector3 targetWorldPosition = coordinateSystem.CoordinatesToWorldPosition(crosshairCoordinates);
        crosshairVisual.position = targetWorldPosition;

        if (relayX != null)
            relayX.position = coordinateSystem.CoordinatesToWorldPosition(
                new Vector2(crosshairCoordinates.x, 0f)) + relayXOffset;

        if (relayY != null)
            relayY.position = coordinateSystem.CoordinatesToWorldPosition(
                new Vector2(0f, crosshairCoordinates.y)) + relayYOffset;
    }

    private bool CalibrateObjects()
    {
        if (coordinateSystem == null || crosshairVisual == null || !coordinateSystem.HasValidCorners())
            return false;

        Vector3 origin = coordinateSystem.CoordinatesToWorldPosition(Vector2.zero);
        Vector3 horizontalDirection =
            coordinateSystem.CoordinatesToWorldPosition(new Vector2(MapCoordinateSystem.CoordinateMaximum, 0f)) -
            origin;
        Vector3 verticalDirection =
            coordinateSystem.CoordinatesToWorldPosition(new Vector2(0f, MapCoordinateSystem.CoordinateMaximum)) -
            origin;

        if (horizontalDirection.sqrMagnitude <= Mathf.Epsilon ||
            verticalDirection.sqrMagnitude <= Mathf.Epsilon)
            return false;

        horizontalDirection.Normalize();
        verticalDirection.Normalize();

        if (relayX != null)
            relayXOffset = Vector3.ProjectOnPlane(relayX.position - origin, horizontalDirection);

        if (relayY != null)
            relayYOffset = Vector3.ProjectOnPlane(relayY.position - origin, verticalDirection);

        return true;
    }

    private void UpdateNearestTarget()
    {
        nearestTarget = null;
        distanceToNearestTarget = -1f;

        if (targetController == null)
            return;

        float nearestSqrDistance = float.PositiveInfinity;
        foreach (MapTarget target in targetController.Targets)
        {
            if (target == null)
                continue;

            float sqrDistance = (target.MapCoordinates - crosshairCoordinates).sqrMagnitude;
            if (sqrDistance >= nearestSqrDistance)
                continue;

            nearestSqrDistance = sqrDistance;
            nearestTarget = target;
        }

        if (nearestTarget != null)
            distanceToNearestTarget = Mathf.Sqrt(nearestSqrDistance);
    }
}