using System.Net.Http;
using System.Threading;
using System.Threading.Tasks;
using ytLive.Models;

namespace ytLive.Services;

public sealed class SocialLookupResult
{
    public bool Success { get; init; }
    public string ProfileUrl { get; init; } = string.Empty;
    public string Handle { get; init; } = string.Empty;
    public string Error { get; init; } = string.Empty;
}

public interface ISocialValidator
{
    Task<SocialLookupResult> LookupAsync(SocialService service, string handleOrUrl);
}

/// <summary>
/// Validates a social handle/URL by constructing the canonical profile URL and
/// issuing an HTTP GET — the "act of validation" the creator trusts before the
/// icon lands on their bar. Best-effort: some platforms return challenges/blocks
/// to HEAD requests, so a 200 OR a 301/302 redirect counts as "exists"; 404 or
/// connection failure = rejected. Never blind trust.
/// </summary>
public sealed class HttpSocialValidator : ISocialValidator
{
    private readonly HttpClient _client;

    public HttpSocialValidator(HttpClient? client = null)
    {
        _client = client ?? new HttpClient();
        _client.DefaultRequestHeaders.UserAgent.ParseAdd(
            "Mozilla/5.0 (compatible; ytLlive social validator)");
    }

    public async Task<SocialLookupResult> LookupAsync(SocialService service, string handleOrUrl)
    {
        var input = handleOrUrl.Trim();
        if (string.IsNullOrWhiteSpace(input))
            return new SocialLookupResult { Error = "Enter a handle or URL." };

        var handle = input;
        if (input.StartsWith("http://", System.StringComparison.OrdinalIgnoreCase) ||
            input.StartsWith("https://", System.StringComparison.OrdinalIgnoreCase))
        {
            var uri = new System.Uri(input);
            handle = uri.AbsolutePath.Trim('/');
        }

        var url = SocialServiceIcons.CanonicalUrlFor(service, handle);

        try
        {
            using var resp = await _client.GetAsync(url, CancellationToken.None);
            if (resp.IsSuccessStatusCode || (int)resp.StatusCode is 301 or 302 or 303 or 307 or 308)
                return new SocialLookupResult
                {
                    Success = true,
                    ProfileUrl = url,
                    Handle = handle.TrimStart('@'),
                };
            return new SocialLookupResult
            {
                Error = $"{service} returned {resp.StatusCode} for '{handle}'. The handle may be wrong or the page doesn't exist.",
            };
        }
        catch (System.Net.Http.HttpRequestException)
        {
            return new SocialLookupResult
            {
                Error = $"Couldn't reach {service} to validate '{handle}'. Check your connection and try again.",
            };
        }
        catch (System.Exception ex)
        {
            return new SocialLookupResult { Error = ex.Message };
        }
    }
}