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

public class selectSettingsOptions : MonoBehaviour
{
    [Header("esc")]
    public Button escButton;
    public GameObject selfGO;

    [Header("Inspector")]
    public Button userSettingsButton;
    public GameObject userSettingsGameObject;
    public Image userSettings_selectedMark;

    [Header("Inspector")]
    public Button graphicSettingsButton;
    public GameObject graphicSettingsGameObject;
    public Image graphicSettings_selectedMark;

    [Header("Inspector")]
    public Button audioSettingsButton;
    public GameObject audioSettingsGameObject;
    public Image audioSettings_selectedMark;

    [Header("Inspector")]
    public Button controlSettingsButton;
    public GameObject controlSettingsGameObject;
    public Image controlSettings_selectedMark;

    [Header("Inspector")]
    public Button gameSettingsButton;
    public GameObject gameSettingsGameObject;
    public Image gameSettings_selectedMark;

    [Header("Inspector")]
    public Button aboutUsButton;
    public GameObject aboutUsGameObject;
    public Image aboutUs_selectedMark;

    [Header("Inspector")]
    public Button deviceInfoButton;
    public GameObject deviceInfoGameObject;
    public Image deviceInfo_selectedMark;

    [Header("Fade Settings")]
    [Tooltip("Hover alpha when mouse over (0-1).")]
    [Range(0f, 1f)]
    public float hoverAlpha = 0.75f;

    [Tooltip("Selected mark alpha when option is selected (0-1).")]
    [Range(0f, 1f)]
    public float selectedAlpha = 1f;

    [Tooltip("Fade duration in seconds.")]
    [Min(0f)]
    public float fadeDuration = 0.1f;

    // internal state
    private class OptionEntry
    {
        public Button button;
        public GameObject panel;
        public Image mark;
        public Coroutine fadeCoroutine;
        public bool selected;
    }

    private List<OptionEntry> options = new List<OptionEntry>();
    private OptionEntry currentSelected = null;

    void Awake()
    {
        options.Clear();
        AddOption(userSettingsButton, userSettingsGameObject, userSettings_selectedMark);
        AddOption(graphicSettingsButton, graphicSettingsGameObject, graphicSettings_selectedMark);
        AddOption(audioSettingsButton, audioSettingsGameObject, audioSettings_selectedMark);
        AddOption(controlSettingsButton, controlSettingsGameObject, controlSettings_selectedMark);
        AddOption(gameSettingsButton, gameSettingsGameObject, gameSettings_selectedMark);
        AddOption(aboutUsButton, aboutUsGameObject, aboutUs_selectedMark);
        AddOption(deviceInfoButton, deviceInfoGameObject, deviceInfo_selectedMark);
    }

    void Start()
    {
        // default select userSettings
        if (userSettingsButton != null)
            SelectOptionByButton(userSettingsButton);

        // listen for esc to close this panel if active
        if (escButton != null && selfGO != null)
        {
            escButton.onClick.AddListener(OnEscButtonClicked);
        }
    }

    void OnDestroy()
    {
        foreach (var opt in options)
        {
            if (opt.button != null)
                opt.button.onClick.RemoveAllListeners();
            RemoveEventTrigger(opt.button);
        }

        if (escButton != null && selfGO != null)
        {
            escButton.onClick.RemoveListener(OnEscButtonClicked);
        }
    }

    private void OnEscButtonClicked()
    {
        if (selfGO != null && selfGO.activeSelf)
        {
            selfGO.SetActive(false);
        }
    }

    void AddOption(Button btn, GameObject panel, Image mark)
    {
        var entry = new OptionEntry { button = btn, panel = panel, mark = mark, selected = false, fadeCoroutine = null };
        options.Add(entry);

        if (btn != null)
        {
            btn.onClick.AddListener(() => OnOptionClicked(entry));
            EnsureEventTrigger(btn, entry);
        }

        if (mark != null)
        {
            var c = mark.color;
            c.a = 0f;
            mark.color = c;
            mark.enabled = false;
        }

        if (panel != null)
            panel.SetActive(false);
    }

    void EnsureEventTrigger(Button btn, OptionEntry entry)
    {
        if (btn == null) return;
        EventTrigger trig = btn.GetComponent<EventTrigger>();
        if (trig == null) trig = btn.gameObject.AddComponent<EventTrigger>();

        // pointer enter
        var entryEnter = new EventTrigger.Entry { eventID = EventTriggerType.PointerEnter };
        entryEnter.callback.AddListener((data) => { OnOptionPointerEnter(entry); });
        trig.triggers.Add(entryEnter);

        // pointer exit
        var entryExit = new EventTrigger.Entry { eventID = EventTriggerType.PointerExit };
        entryExit.callback.AddListener((data) => { OnOptionPointerExit(entry); });
        trig.triggers.Add(entryExit);
    }

    void RemoveEventTrigger(Button btn)
    {
        if (btn == null) return;
        var trig = btn.GetComponent<EventTrigger>();
        if (trig != null) Destroy(trig);
    }

    void OnOptionPointerEnter(OptionEntry entry)
    {
        if (entry == null) return;
        if (entry.selected) return;
        StartFade(entry, hoverAlpha);
    }

    void OnOptionPointerExit(OptionEntry entry)
    {
        if (entry == null) return;
        if (entry.selected) return;
        StartFade(entry, 0f);
    }

    void OnOptionClicked(OptionEntry entry)
    {
        if (entry == null) return;
        SelectEntry(entry);
    }

    void SelectOptionByButton(Button btn)
    {
        var entry = options.Find(o => o.button == btn);
        if (entry != null) SelectEntry(entry);
    }

    void SelectEntry(OptionEntry entry)
    {
        if (entry == null) return;

        if (currentSelected != null && currentSelected != entry)
        {
            currentSelected.selected = false;
            StartFade(currentSelected, 0f);
            if (currentSelected.panel != null) currentSelected.panel.SetActive(false);
        }

        currentSelected = entry;
        currentSelected.selected = true;
        if (currentSelected.panel != null) currentSelected.panel.SetActive(true);
        StartFade(currentSelected, selectedAlpha);
    }

    void StartFade(OptionEntry entry, float targetAlpha)
    {
        if (entry == null || entry.mark == null) return;
        entry.mark.enabled = true;
        if (entry.fadeCoroutine != null) StopCoroutine(entry.fadeCoroutine);
        entry.fadeCoroutine = StartCoroutine(FadeImage(entry.mark, targetAlpha, fadeDuration, () =>
        {
            if (Mathf.Approximately(targetAlpha, 0f))
            {
                if (!entry.selected)
                    entry.mark.enabled = false;
            }
        }));
    }

    IEnumerator FadeImage(Image img, float targetAlpha, float duration, System.Action onComplete = null)
    {
        if (img == null) yield break;
        float start = img.color.a;
        float t = 0f;
        while (t < duration)
        {
            t += Time.unscaledDeltaTime;
            float a = Mathf.Lerp(start, targetAlpha, duration <= 0f ? 1f : (t / duration));
            var c = img.color;
            c.a = a;
            img.color = c;
            yield return null;
        }
        var fc = img.color;
        fc.a = targetAlpha;
        img.color = fc;
        onComplete?.Invoke();
    }
}