using System.Collections.Generic;
using UnityEngine;
using UnityEngine.InputSystem;

public class RouteDrawer : MonoBehaviour
{
    Unit selectedUnit;
    List<Vector2> currentRoute = new();
    LineRenderer lineRenderer;
    bool isDrawing;

    const float MinPointDistance = 0.5f;

    void Start()
    {
        CreateLineRenderer();
    }

    void CreateLineRenderer()
    {
        var lineGO = new GameObject("RouteLine");
        lineRenderer = lineGO.AddComponent<LineRenderer>();
        lineRenderer.startWidth = 0.15f;
        lineRenderer.endWidth = 0.15f;
        lineRenderer.material = new Material(Shader.Find("Sprites/Default"));
        lineRenderer.startColor = new Color(1f, 1f, 1f, 0.5f);
        lineRenderer.endColor = new Color(1f, 1f, 1f, 0.5f);
        lineRenderer.sortingOrder = 20;
        lineRenderer.positionCount = 0;
    }

    void Update()
    {
        var mouse = Mouse.current;
        var touch = Touchscreen.current;

        // Handle mouse input
        if (mouse != null)
        {
            HandlePointerInput(
                mouse.leftButton.wasPressedThisFrame,
                mouse.leftButton.wasReleasedThisFrame,
                mouse.leftButton.isPressed,
                mouse.position.ReadValue()
            );
        }
        // Handle touch input
        else if (touch != null && touch.primaryTouch.press.isPressed)
        {
            var primaryTouch = touch.primaryTouch;
            HandlePointerInput(
                primaryTouch.press.wasPressedThisFrame,
                primaryTouch.press.wasReleasedThisFrame,
                primaryTouch.press.isPressed,
                primaryTouch.position.ReadValue()
            );
        }
    }

    void HandlePointerInput(bool pressed, bool released, bool held, Vector2 screenPos)
    {
        Vector2 worldPos = Camera.main.ScreenToWorldPoint(screenPos);

        if (pressed)
        {
            OnPointerDown(worldPos);
        }
        else if (released)
        {
            OnPointerUp();
        }
        else if (held && isDrawing)
        {
            OnPointerDrag(worldPos);
        }
    }

    void OnPointerDown(Vector2 worldPos)
    {
        // Check if we clicked on a player unit
        var hit = Physics2D.OverlapPoint(worldPos);
        if (hit != null)
        {
            var unit = hit.GetComponent<Unit>();
            if (unit != null && unit.team == Unit.Team.Player && !unit.isTaggedOut)
            {
                selectedUnit = unit;
                isDrawing = true;
                currentRoute.Clear();
                currentRoute.Add(worldPos);
                UpdateLineRenderer();
            }
        }
    }

    void OnPointerDrag(Vector2 worldPos)
    {
        if (!isDrawing || selectedUnit == null) return;

        // Only add point if far enough from last point
        if (currentRoute.Count > 0)
        {
            float dist = Vector2.Distance(currentRoute[currentRoute.Count - 1], worldPos);
            if (dist >= MinPointDistance)
            {
                currentRoute.Add(worldPos);
                UpdateLineRenderer();
            }
        }
    }

    void OnPointerUp()
    {
        if (isDrawing && selectedUnit != null && currentRoute.Count > 0)
        {
            // Remove the first point (unit's current position) and apply route
            if (currentRoute.Count > 1)
            {
                currentRoute.RemoveAt(0);
            }
            selectedUnit.SetRoute(currentRoute);
        }

        // Clear drawing state
        isDrawing = false;
        selectedUnit = null;
        currentRoute.Clear();
        ClearLineRenderer();
    }

    void UpdateLineRenderer()
    {
        if (lineRenderer == null) return;

        lineRenderer.positionCount = currentRoute.Count;
        for (int i = 0; i < currentRoute.Count; i++)
        {
            lineRenderer.SetPosition(i, new Vector3(currentRoute[i].x, currentRoute[i].y, 0));
        }
    }

    void ClearLineRenderer()
    {
        if (lineRenderer == null) return;
        lineRenderer.positionCount = 0;
    }
}