using System.Net.Http.Json;
using Microsoft.JSInterop;

namespace TuringMachine.Client.Services;

public record LanguageInfo(string Code, string DisplayName, string FlagIcon);

public class LocalizationService
{
    private readonly HttpClient _http;
    private readonly IJSRuntime _js;
    private Dictionary<string, string> _translations = new();

    public static readonly List<LanguageInfo> AvailableLanguages = new()
    {
        new("en-US", "English", "img/flags/us.svg"),
        new("ko-KR", "한국어", "img/flags/kr.svg")
    };

    public string CurrentLanguage { get; private set; } = "en-US";

    public LanguageInfo CurrentLanguageInfo =>
        AvailableLanguages.Find(l => l.Code == CurrentLanguage) ?? AvailableLanguages[0];

    public event Action? OnLanguageChanged;

    public string this[string key] =>
        _translations.TryGetValue(key, out var value) ? value : key;

    public string this[string key, params object[] args]
    {
        get
        {
            var template = this[key];
            try { return string.Format(template, args); }
            catch { return template; }
        }
    }

    public LocalizationService(HttpClient http, IJSRuntime js)
    {
        _http = http;
        _js = js;
    }

    public async Task InitializeAsync()
    {
        try
        {
            var saved = await _js.InvokeAsync<string?>("localStorage.getItem", "lang");
            CurrentLanguage = string.IsNullOrEmpty(saved) ? "en-US" : saved;
        }
        catch
        {
            CurrentLanguage = "en-US";
        }

        await LoadTranslationsAsync(CurrentLanguage);
    }

    public async Task SetLanguageAsync(string lang)
    {
        if (lang == CurrentLanguage) return;

        CurrentLanguage = lang;
        await LoadTranslationsAsync(lang);

        try
        {
            await _js.InvokeVoidAsync("localStorage.setItem", "lang", lang);
            await _js.InvokeVoidAsync("setDocumentTitle", this["app.title"]);
        }
        catch { }

        OnLanguageChanged?.Invoke();
    }

    private async Task LoadTranslationsAsync(string lang)
    {
        try
        {
            var dict = await _http.GetFromJsonAsync<Dictionary<string, string>>($"i18n/{lang}.json");
            _translations = dict ?? new();
        }
        catch
        {
            _translations = new();
        }
    }
}