using UnityEngine;
using UnityEngine.InputSystem;
using System;

public class InputManager : MonoBehaviour
{
    private static InputManager _instance;
    public static InputManager Instance
    {
        get
        {
            if (_instance == null)
            {
                _instance = FindAnyObjectByType<InputManager>();
                if (_instance == null)
                {
                    var go = new GameObject("InputManager");
                    _instance = go.AddComponent<InputManager>();
                    DontDestroyOnLoad(go);
                }
            }
            return _instance;
        }
    }

    private PlayerInput playerInput;
    private InputAction touchPressAction;
    private InputAction touchPositionAction;
    private ITouchInputConsumer defaultConsumer;

    private bool isTouchHeld = false;
    private bool lastFrameInteracted = false;

    // Tap/drag detection state
    private Vector2 pressStartPosition;
    private float pressStartTime;
    private bool isPressed = false;
    private bool isDragging = false;
    private float dragThreshold = 10f; // pixels
    private float tapTimeThreshold = 0.2f; // seconds

    void Awake()
    {
        _instance = this;
        DontDestroyOnLoad(gameObject);
        playerInput = GetComponent<PlayerInput>();
        if (playerInput == null)
        {
            Debug.LogError("[InputManager] InputManager requires a PlayerInput component attached to the same GameObject.");
            return;
        }
        // Find actions by name in the assigned action map
        touchPressAction = playerInput.actions.FindAction("TouchPress", false);
        touchPositionAction = playerInput.actions.FindAction("TouchPosition", false);
    }

    void OnEnable()
    {
        if (touchPressAction != null)
        {
            touchPressAction.started += OnTouchPressStarted;
            touchPressAction.canceled += OnTouchPressCanceled;
        }
        if (touchPositionAction != null)
            touchPositionAction.performed += OnTouchPositionPerformed;
    }

    void OnDisable()
    {
        if (touchPressAction != null)
        {
            touchPressAction.started -= OnTouchPressStarted;
            touchPressAction.canceled -= OnTouchPressCanceled;
        }
        if (touchPositionAction != null)
            touchPositionAction.performed -= OnTouchPositionPerformed;
    }

    public void SetDefaultConsumer(ITouchInputConsumer consumer)
    {
        defaultConsumer = consumer;
    }

    private void OnTouchPressStarted(InputAction.CallbackContext ctx)
    {
        // Touch started (finger down)
        Vector2 screenPos = touchPositionAction.ReadValue<Vector2>();
        Vector3 worldPos = Camera.main.ScreenToWorldPoint(screenPos);
        Vector2 worldPos2D = new Vector2(worldPos.x, worldPos.y);
        lastFrameInteracted = TryDelegateToInteractable(worldPos2D);
        if (!lastFrameInteracted)
        {
            pressStartPosition = screenPos;
            pressStartTime = Time.time;
            isPressed = true;
            isDragging = false;
            defaultConsumer?.OnHoldStart(worldPos2D);
        }
    }

    private void OnTouchPressCanceled(InputAction.CallbackContext ctx)
    {
        Vector2 screenPos = touchPositionAction.ReadValue<Vector2>();
        Vector3 worldPos = Camera.main.ScreenToWorldPoint(screenPos);
        Vector2 worldPos2D = new Vector2(worldPos.x, worldPos.y);
        if (!lastFrameInteracted)
        {
            float timeHeld = Time.time - pressStartTime;
            float dist = Vector2.Distance(screenPos, pressStartPosition);
            if (!isDragging && timeHeld < tapTimeThreshold && dist < dragThreshold)
            {
                defaultConsumer?.OnTap(worldPos2D);
            }
            defaultConsumer?.OnHoldEnd(worldPos2D);
        }
        isPressed = false;
        isDragging = false;
        lastFrameInteracted = false;
    }

    private void OnTouchPositionPerformed(InputAction.CallbackContext ctx)
    {
        // No longer needed, OnTouchHeld will be handled in Update
    }

    void Update()
    {
        if (isPressed && touchPositionAction != null)
        {
            Vector2 screenPos = touchPositionAction.ReadValue<Vector2>();
            Vector3 worldPos = Camera.main.ScreenToWorldPoint(screenPos);
            Vector2 worldPos2D = new Vector2(worldPos.x, worldPos.y);
            defaultConsumer?.OnHold(worldPos2D);
        }
    }

    private bool TryDelegateToInteractable(Vector2 worldPos)
    {
        // Raycast at the world position to find an Interactable
        Collider2D hit = Physics2D.OverlapPoint(worldPos);
        if (hit != null)
        {
            var interactable = hit.GetComponent<Interactable>();
            if (interactable != null)
            {
                interactable.OnTap(worldPos);
                return true;
            }
        }
        return false;
    }
}