using System;
using ADOFAIRenderer.Localization;
using TMPro;
using UnityEngine;

namespace ADOFAIRenderer.UI;

/// <summary>
/// Component that binds a TextMeshProUGUI component to a localization key or dynamic string provider,
/// automatically updating the displayed text whenever the active language changes.
/// </summary>
internal class LocalizedText : MonoBehaviour
{
    private TextMeshProUGUI? _textComponent;
    private string? _key;
    private Func<string>? _dynamicProvider;

    /// <summary>
    /// Gets or sets the localization key. Setting this will clear any dynamic provider.
    /// </summary>
    public string? Key
    {
        get => _key;
        set
        {
            _key = value;
            _dynamicProvider = null;
            Refresh();
        }
    }

    /// <summary>
    /// Sets a dynamic string provider function.
    /// </summary>
    public void SetDynamic(Func<string> provider)
    {
        _dynamicProvider = provider;
        _key = null;
        Refresh();
    }

    private void Awake()
    {
        EnsureComponent();
        LocalizationManager.OnLanguageChanged += HandleLanguageChanged;
    }

    private void OnEnable()
    {
        Refresh();
    }

    private void OnDestroy()
    {
        LocalizationManager.OnLanguageChanged -= HandleLanguageChanged;
    }

    private void HandleLanguageChanged(SystemLanguage language)
    {
        Refresh();
    }

    private void EnsureComponent()
    {
        if (_textComponent == null)
        {
            _textComponent = GetComponent<TextMeshProUGUI>();
        }
    }

    /// <summary>
    /// Refreshes the text using either the dynamic provider or the static localization key.
    /// </summary>
    public void Refresh()
    {
        EnsureComponent();
        if (_textComponent == null) return;

        if (_dynamicProvider != null)
        {
            _textComponent.text = _dynamicProvider();
        }
        else if (!string.IsNullOrEmpty(_key))
        {
            _textComponent.text = LocalizationManager.Get(_key);
        }
    }

    /// <summary>
    /// Binds a TextMeshProUGUI component to a localization key.
    /// </summary>
    public static LocalizedText Bind(TextMeshProUGUI target, string key)
    {
        if (target == null) throw new ArgumentNullException(nameof(target));
        var component = target.GetComponent<LocalizedText>() ?? target.gameObject.AddComponent<LocalizedText>();
        component._textComponent = target;
        component.Key = key;
        return component;
    }

    /// <summary>
    /// Binds a TextMeshProUGUI component to a dynamic string provider function.
    /// </summary>
    public static LocalizedText Bind(TextMeshProUGUI target, Func<string> provider)
    {
        if (target == null) throw new ArgumentNullException(nameof(target));
        var component = target.GetComponent<LocalizedText>() ?? target.gameObject.AddComponent<LocalizedText>();
        component._textComponent = target;
        component.SetDynamic(provider);
        return component;
    }
}