using System;
using System.Collections.Generic;
using System.Linq;
using UnityEngine.EventSystems;
using UnityEngine;

namespace UnityEngine.UI
{
    [AddComponentMenu("UI/UXGroup", 31)]
    [DisallowMultipleComponent]
    public class UXGroup : UIBehaviour
    {
        [SerializeField] private bool m_AllowSwitchOff = false;

        public bool allowSwitchOff
        {
            get { return m_AllowSwitchOff; }
            set { m_AllowSwitchOff = value; }
        }

        [SerializeField]
        private List<UXToggle> m_Toggles = new List<UXToggle>();

        [SerializeField]
        private UXToggle m_DefaultToggle;

        public UXToggle defaultToggle
        {
            get { return m_DefaultToggle; }
            set { m_DefaultToggle = value; EnsureValidState(); }
        }

        protected UXGroup()
        {
        }

        protected override void Start()
        {
            EnsureValidState();
            base.Start();
        }

        protected override void OnEnable()
        {
            EnsureValidState();
            base.OnEnable();
        }

        private void ValidateToggleIsInGroup(UXToggle toggle)
        {
            if (toggle == null || !m_Toggles.Contains(toggle))
                throw new ArgumentException(string.Format("UXToggle {0} is not part of ToggleGroup {1}", new object[] { toggle, this }));
        }

        public void NotifyToggleOn(UXToggle toggle, bool sendCallback = true)
        {
            ValidateToggleIsInGroup(toggle);
            for (var i = 0; i < m_Toggles.Count; i++)
            {
                if (m_Toggles[i] == toggle)
                    continue;

                if (sendCallback)
                    m_Toggles[i].isOn = false;
                else
                    m_Toggles[i].SetIsOnWithoutNotify(false);
            }
        }

        public void UnregisterToggle(UXToggle toggle)
        {
            if (toggle == null)
                return;

            if (m_Toggles.Contains(toggle))
                m_Toggles.Remove(toggle);

            if (m_DefaultToggle == toggle)
            {
                m_DefaultToggle = null;
            }
        }

        public void RegisterToggle(UXToggle toggle)
        {
            if (toggle == null)
                return;

            if (!m_Toggles.Contains(toggle))
                m_Toggles.Add(toggle);


            if (!allowSwitchOff)
            {

                var firstActive = GetFirstActiveToggle();
                if (firstActive != null && firstActive != toggle && toggle.isOn)
                {
                    toggle.SetIsOnWithoutNotify(false);
                }
                else if (firstActive == null)
                {
                    if (m_DefaultToggle != null && m_Toggles.Contains(m_DefaultToggle))
                    {
                        var dt = m_DefaultToggle;
                        if (dt != null && dt != toggle)
                        {
                            dt.isOn = true;
                            NotifyToggleOn(dt);
                        }
                        else if (dt == toggle)
                        {
                            toggle.isOn = true;
                            NotifyToggleOn(toggle);
                        }
                    }
                }
            }
        }


        public bool ContainsToggle(UXToggle toggle)
        {
            return m_Toggles != null && m_Toggles.Contains(toggle);
        }

        public void EnsureValidState()
        {
            if (m_Toggles == null)
                m_Toggles = new List<UXToggle>();

            m_Toggles.RemoveAll(x => x == null);

            if (!allowSwitchOff && !AnyTogglesOn() && m_Toggles.Count != 0)
            {
                UXToggle toSelect = null;
                if (m_DefaultToggle != null && m_Toggles.Contains(m_DefaultToggle))
                {
                    toSelect = m_DefaultToggle;
                }
                else
                {
                    toSelect = m_Toggles[0];
                }

                if (toSelect != null)
                {
                    toSelect.isOn = true;
                    NotifyToggleOn(toSelect);
                }
            }

            IEnumerable<UXToggle> activeToggles = ActiveToggles();

            if (activeToggles.Count() > 1)
            {
                UXToggle firstActive = GetFirstActiveToggle();

                foreach (UXToggle toggle in activeToggles)
                {
                    if (toggle == firstActive)
                    {
                        continue;
                    }

                    toggle.isOn = false;
                }
            }

            for (int i = 0; i < m_Toggles.Count; i++)
            {
                var t = m_Toggles[i];
                if (t == null)
                    continue;

                if (t.group != this)
                {
                    t.group = this;
                }
            }
        }

        public bool AnyTogglesOn()
        {
            return m_Toggles.Find(x => x != null && x.isOn) != null;
        }

        public IEnumerable<UXToggle> ActiveToggles()
        {
            return m_Toggles.Where(x => x != null && x.isOn);
        }

        public UXToggle GetFirstActiveToggle()
        {
            if (m_DefaultToggle != null && m_Toggles.Contains(m_DefaultToggle) && m_DefaultToggle.isOn)
                return m_DefaultToggle;

            IEnumerable<UXToggle> activeToggles = ActiveToggles();
            return activeToggles.Count() > 0 ? activeToggles.First() : null;
        }

        public void SetAllTogglesOff(bool sendCallback = true)
        {
            bool oldAllowSwitchOff = m_AllowSwitchOff;
            m_AllowSwitchOff = true;

            if (sendCallback)
            {
                for (var i = 0; i < m_Toggles.Count; i++)
                    if (m_Toggles[i] != null)
                        m_Toggles[i].isOn = false;
            }
            else
            {
                for (var i = 0; i < m_Toggles.Count; i++)
                    if (m_Toggles[i] != null)
                        m_Toggles[i].SetIsOnWithoutNotify(false);
            }

            m_AllowSwitchOff = oldAllowSwitchOff;
        }

        public void Next()
        {
            SelectAdjacent(true);
        }

        public void Preview()
        {
            SelectAdjacent(false);
        }

        private void SelectAdjacent(bool forward)
        {
            if (m_Toggles == null || m_Toggles.Count == 0)
                return;

            UXToggle current = GetFirstActiveToggle();
            int currentIndex = current != null ? m_Toggles.IndexOf(current) : -1;

            int idx = currentIndex;
            if (idx == -1 && !forward)
                idx = 0;

            for (int step = 0; step < m_Toggles.Count; step++)
            {
                if (forward)
                {
                    idx = (idx + 1) % m_Toggles.Count;
                }
                else
                {
                    idx = (idx - 1 + m_Toggles.Count) % m_Toggles.Count;
                }

                UXToggle t = m_Toggles[idx];
                if (t == null)
                    continue;

                if (!t.IsActive())
                    continue;

                if (!t.IsInteractable())
                    continue;

                t.isOn = true;
                return;
            }
        }
    }
}