using System;
using UnityEngine;

namespace AppleHills.UI.CardSystem
{
    /// <summary>
    /// Base class for UI pages that can transition in and out.
    /// Extended by specific UI page implementations for the card system.
    /// </summary>
    public abstract class UIPage : MonoBehaviour
    {
        [Header("Page Settings")]
        public string PageName;
        
        // Events using System.Action instead of UnityEvents
        public event Action OnTransitionInStarted;
        public event Action OnTransitionInCompleted;
        public event Action OnTransitionOutStarted;
        public event Action OnTransitionOutCompleted;
        
        // Default duration for transitions
        [SerializeField] protected float transitionDuration = 0.3f;
        
        // State flags
        protected bool _isTransitioning = false;
        protected bool _isVisible = false;

        /// <summary>
        /// Called when the page is shown. Handles the transition in animation.
        /// </summary>
        public virtual void TransitionIn()
        {
            gameObject.SetActive(true);
            _isTransitioning = true;
            OnTransitionInStarted?.Invoke();
            
            // Override in child classes for specific transition animations
            DoTransitionIn(() => {
                _isTransitioning = false;
                _isVisible = true;
                OnTransitionInCompleted?.Invoke();
            });
        }

        /// <summary>
        /// Called when the page is hidden. Handles the transition out animation.
        /// </summary>
        public virtual void TransitionOut()
        {
            _isTransitioning = true;
            OnTransitionOutStarted?.Invoke();
            
            // Override in child classes for specific transition animations
            DoTransitionOut(() => {
                _isTransitioning = false;
                _isVisible = false;
                OnTransitionOutCompleted?.Invoke();
                gameObject.SetActive(false);
            });
        }

        /// <summary>
        /// Called when the back button is pressed while this page is active.
        /// Default implementation pops the page from the stack.
        /// </summary>
        public virtual void OnBackPressed()
        {
            if (!_isTransitioning)
            {
                UIPageController.Instance.PopPage();
            }
        }
        
        /// <summary>
        /// Implement transition in animation in child classes.
        /// </summary>
        protected virtual void DoTransitionIn(Action onComplete)
        {
            // Default implementation - instant transition
            onComplete?.Invoke();
        }
        
        /// <summary>
        /// Implement transition out animation in child classes.
        /// </summary>
        protected virtual void DoTransitionOut(Action onComplete)
        {
            // Default implementation - instant transition
            onComplete?.Invoke();
        }
    }
}