using System.Collections.Generic;
using UnityEngine.Localization.Settings;
using UnityEngine.ResourceManagement.AsyncOperations;
using UnityEngine.UI;

namespace UnityEngine.Localization.Samples
{
    /// <summary>
    /// This example shows how a language selection menu can be implemented using UGUI toggles.
    /// </summary>
    public class LanguageSelectionMenuUGUIToggleList : MonoBehaviour
    {
        public Transform container;
        public GameObject languageTogglePrefab;

        AsyncOperationHandle m_InitializeOperation;
        Dictionary<Locale, Toggle> m_Toggles = new Dictionary<Locale, Toggle>();
        ToggleGroup m_ToggleGroup;

        void Start()
        {
            // SelectedLocaleAsync will ensure that the locales have been initialized and a locale has been selected.
            m_InitializeOperation = LocalizationSettings.SelectedLocaleAsync;
            if (m_InitializeOperation.IsDone)
            {
                InitializeCompleted(m_InitializeOperation);
            }
            else
            {
                m_InitializeOperation.Completed += InitializeCompleted;
            }
        }

        void InitializeCompleted(AsyncOperationHandle obj)
        {
            LocalizationSettings.SelectedLocaleChanged += LocalizationSettings_SelectedLocaleChanged;

            // The toggle group will ensure that only 1 language is selected at a time.
            m_ToggleGroup = container.gameObject.AddComponent<ToggleGroup>();

            // Create an option in the dropdown for each Locale
            var locales = LocalizationSettings.AvailableLocales.Locales;
            for (int i = 0; i < locales.Count; ++i)
            {
                var locale = locales[i];

                var languageToggle = Instantiate(languageTogglePrefab, container);
                languageToggle.name = locale.Identifier.CultureInfo != null ? locale.Identifier.CultureInfo.NativeName : locale.ToString();
                var label = languageToggle.GetComponentInChildren<Text>();
                label.text = languageToggle.name;

                var toggle = languageToggle.GetComponent<Toggle>();
                toggle.SetIsOnWithoutNotify(LocalizationSettings.SelectedLocale == locale);

                // We use a dictionary of the toggles so we can quickly update the selected locale if it is changed by another script.
                m_Toggles[locale] = toggle;

                toggle.onValueChanged.AddListener(val =>
                {
                    if (val)
                    {
                        // Unsubscribe from SelectedLocaleChanged so we don't get an unnecessary callback from the change we are about to make.
                        LocalizationSettings.SelectedLocaleChanged -= LocalizationSettings_SelectedLocaleChanged;

                        LocalizationSettings.SelectedLocale = locale;

                        // Resubscribe to SelectedLocaleChanged so that we can stay in sync with changes that may be made by other scripts.
                        LocalizationSettings.SelectedLocaleChanged += LocalizationSettings_SelectedLocaleChanged;
                    }
                });

                toggle.group = m_ToggleGroup;
            }
        }

        void LocalizationSettings_SelectedLocaleChanged(Locale locale)
        {
            if (m_Toggles.TryGetValue(locale, out var toggle))
            {
                toggle.SetIsOnWithoutNotify(true);
            }
        }
    }
}