using System.Net.Http.Headers;
using System.Net.Http.Json;
using System.Text.Json;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Logging;

namespace SfeduSchedule.Plugin.UniVerse;

public sealed class UniverseUserLookupService(
    HttpClient httpClient,
    IConfiguration configuration,
    ILogger<UniverseUserLookupService> logger) : IUniverseUserLookupService
{
    private const string AccessControlApiPath = "access-control/api";
    private const string UsersQuery = """
                                      query($t:String!){ users(filter:{text:$t}, pager:{activePage:1,pageSize:10}) { items { id name displayName description } } }
                                      """;

    private static readonly JsonSerializerOptions JsonOptions = new(JsonSerializerDefaults.Web);

    public async Task<UniverseUserLookupResult> FindSubIdAsync(
        string fullName,
        CancellationToken cancellationToken = default)
    {
        var token = configuration["TOKEN"];
        if (string.IsNullOrWhiteSpace(token))
            return UniverseUserLookupResult.UpstreamError("Modeus TOKEN is not configured.");

        var modeusUrl = configuration["MODEUS_URL"];
        if (string.IsNullOrWhiteSpace(modeusUrl))
            return UniverseUserLookupResult.UpstreamError("MODEUS_URL is not configured.");

        httpClient.BaseAddress = new Uri(modeusUrl, UriKind.Absolute);

        using var request = new HttpRequestMessage(HttpMethod.Post, AccessControlApiPath);
        request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
        request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", token);
        request.Content = JsonContent.Create(
            new UniverseUsersGraphQlRequest(
                UsersQuery,
                new UniverseUsersGraphQlVariables(fullName)),
            options: JsonOptions);

        using var response = await httpClient.SendAsync(request, cancellationToken);
        if (!response.IsSuccessStatusCode)
        {
            logger.LogWarning(
                "Modeus access-control/api returned {StatusCode} while searching user by fullName.",
                response.StatusCode);
            return UniverseUserLookupResult.UpstreamError(
                $"Modeus access-control/api returned {(int)response.StatusCode}.");
        }

        UniverseUsersGraphQlResponse? payload;
        try
        {
            await using var contentStream = await response.Content.ReadAsStreamAsync(cancellationToken);
            payload = await JsonSerializer.DeserializeAsync<UniverseUsersGraphQlResponse>(
                contentStream,
                JsonOptions,
                cancellationToken);
        }
        catch (JsonException exception)
        {
            logger.LogWarning(exception, "Unable to deserialize Modeus access-control/api response.");
            return UniverseUserLookupResult.UpstreamError("Modeus access-control/api returned invalid JSON.");
        }

        if (payload?.Errors is { Count: > 0 })
        {
            logger.LogWarning(
                "Modeus access-control/api returned GraphQL errors: {Errors}",
                JsonSerializer.Serialize(payload.Errors, JsonOptions));
            return UniverseUserLookupResult.UpstreamError("Modeus access-control/api returned GraphQL errors.");
        }

        var users = payload?.Data?.Users?.Items;
        if (users is null || users.Count == 0)
            return UniverseUserLookupResult.NotFound();

        var subId = users[0].Name;
        return string.IsNullOrWhiteSpace(subId)
            ? UniverseUserLookupResult.NotFound()
            : UniverseUserLookupResult.Found(subId);
    }
}