using System.Threading.Tasks;
using eprintServer.Entities;
using eprintServer.Enums;
using eprintServer.Models;
using System.Text.Json;
using System;

namespace eprintServer.Services;

public class FacebookOAuthService : BaseOAuthService
{
    private readonly OAuthSettingsService _settingsService;
    private readonly IHttpClientFactory _httpClientFactory;

    public FacebookOAuthService(OAuthSettingsService settingsService, UserService userService, TokenService tokenService, IHttpClientFactory httpClientFactory) 
        : base(userService, tokenService)
    {
        _settingsService = settingsService;
        _httpClientFactory = httpClientFactory;
    }

   public async Task<(User? user, string? token, string? error)> HandleLoginCallbackAsync(string code)
{
    var settings = await _settingsService.GetOrCreateSettingsAsync();
    var client = _httpClientFactory.CreateClient();

    string redirectUri = "https://server.etbaaonline.com/api/v1/oauth/facebook/callback";

    // 1. Exchange Code for Access Token
    // We use QueryHelpers or string interpolation to build the request
    var url = $"https://graph.facebook.com/v12.0/oauth/access_token?" +
              $"client_id={settings.FacebookAppId}" +
              $"&redirect_uri={Uri.EscapeDataString(redirectUri)}" +
              $"&client_secret={settings.FacebookAppSecret}" +
              $"&code={code}";

    var tokenResponse = await client.GetAsync(url);
    
    if (!tokenResponse.IsSuccessStatusCode) 
    {
        var errorContent = await tokenResponse.Content.ReadAsStringAsync();
        return (null, null, $"Facebook auth failed: {errorContent}");
    }

    var tokenData = await tokenResponse.Content.ReadFromJsonAsync<JsonElement>();
    var accessToken = tokenData.GetProperty("access_token").GetString();

    // 2. Get User Profile using the token
    var userResponse = await client.GetAsync($"https://graph.facebook.com/me?fields=id,name,email&access_token={accessToken}");
    var fbUser = await userResponse.Content.ReadFromJsonAsync<JsonElement>();

    var externalUser = new ExternalUserData
    {
        // Facebook might not return email if the user didn't provide it or used a phone number
        Email = fbUser.TryGetProperty("email", out var email) ? email.GetString()! : $"{fbUser.GetProperty("id").GetString()}@facebook.com",
        Name = fbUser.GetProperty("name").GetString()!,
        ProviderUserId = fbUser.GetProperty("id").GetString()
    };

    return await SignInUserAsync(externalUser, Provider.FACEBOOK);
}
}