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

#if UNITY_2019_1_OR_NEWER
using UnityEngine.UIElements;
#else
using UnityEngine.Experimental.UIElements;
#endif

namespace UnityEditor.Recorder
{
    class EditableLabel : VisualElement
    {
        readonly Label m_Label;
        readonly TextField m_TextField;

        bool m_IsEditing;

        Action<string> m_OnValueChangedCallback;
        Focusable m_PreviouslyFocused;
        
        internal string text
        {
            get { return m_Label.text; }
            set { m_Label.text = value; }
        }
        
        internal void SetLabelEnabled(bool value)
        {
            m_Label.SetEnabled(value);
        }

        internal EditableLabel()
        {
            m_IsEditing = false;
            m_Label = new Label();
            m_TextField = new TextField();
            
            UIElementHelper.SetFlex(this, 1.0f);
            UIElementHelper.SetFlex(m_TextField, 1.0f);
            
            Add(m_Label);
            
            UIElementHelper.RegisterTrickleDownCallback<KeyUpEvent>(this, OnKeyUpCallback);
            
            m_TextField.RegisterCallback<FocusOutEvent>(OnTextFieldLostFocus);
        }

        void SetValueAndNotify(string newValue)
        {
            if (EqualityComparer<string>.Default.Equals(m_Label.text, newValue))
                return;

            if (string.IsNullOrEmpty(newValue))
                return;

            m_Label.text = newValue;
            
            if (m_OnValueChangedCallback != null)
                m_OnValueChangedCallback.Invoke(newValue);
        }

        internal void OnValueChanged(Action<string> callback)
        {
            m_OnValueChangedCallback = callback;
        }
        
        internal void StartEditing()
        {
            if (m_IsEditing)
                return;

            m_IsEditing = true;
            m_TextField.value = m_Label.text;
            Remove(m_Label);
            Add(m_TextField);
            UIElementHelper.SetFocusable(m_TextField);
#if UNITY_2019_1_OR_NEWER
            m_TextField.delegatesFocus = true;
#endif
            m_PreviouslyFocused = focusController.focusedElement;    
            m_TextField.Focus();
        }

        void ApplyEditing()
        {
            if (!m_IsEditing)
                return;

            SetValueAndNotify(m_TextField.text);
            
            m_IsEditing = false;
            Remove(m_TextField);
            Add(m_Label);
        }

        void CancelEditing()
        {
            if (!m_IsEditing)
                return;

            m_IsEditing = false;
            Remove(m_TextField);
            Add(m_Label);
        }
        
        void OnTextFieldLostFocus(FocusOutEvent evt)
        {
            ApplyEditing();
        }

        void OnKeyUpCallback(KeyUpEvent evt)
        {
            if (!m_IsEditing)
                return;

            if (evt.keyCode == KeyCode.Return || evt.keyCode == KeyCode.KeypadEnter)
            {
                ApplyEditing();
                RestorePreviousFocus();
                
                evt.StopImmediatePropagation();
            }
            else if (evt.keyCode == KeyCode.Escape)
            {
                CancelEditing();
                RestorePreviousFocus();
                
                evt.StopImmediatePropagation();
            }
        }

        void RestorePreviousFocus()
        {
            if (m_PreviouslyFocused != null)
                m_PreviouslyFocused.Focus();
        }
    }
}