using System.Collections.Concurrent;
using Microsoft.Extensions.Options;

namespace LehrerApp.Api;

public sealed record WebUntisConnectRequest(
    string School,
    string? Host,
    string Username,
    string Password);

public sealed record WebUntisConnectionStatus(bool Connected, string? School, string? Username);

/// <summary>
/// Hält persönliche WebUntis-Verbindungen ausschließlich im Arbeitsspeicher des Servers.
/// Passwörter werden weder protokolliert noch serverseitig persistiert. Der enthaltene Client
/// verwaltet die eigentliche WebUntis-Session und meldet sie nach Inaktivität wieder ab.
/// </summary>
public sealed class WebUntisConnectionStore(IHttpClientFactory httpClientFactory) : IAsyncDisposable
{
    private sealed record Entry(WebUntisClient Client, string School, string Username);

    private readonly ConcurrentDictionary<string, Entry> _connections = new();

    public WebUntisClient? GetClient(string userId) =>
        _connections.TryGetValue(userId, out var entry) ? entry.Client : null;

    public WebUntisConnectionStatus GetStatus(string userId) =>
        _connections.TryGetValue(userId, out var entry)
            ? new(true, entry.School, entry.Username)
            : new(false, null, null);

    public async Task<WebUntisConnectionStatus> ConnectAsync(string userId, WebUntisConnectRequest request,
        CancellationToken cancellationToken)
    {
        var options = new WebUntisOptions
        {
            School = request.School,
            Host = request.Host ?? "",
            Username = request.Username,
            Password = request.Password,
            Client = "LehrerApp",
            SessionIdleTimeoutMinutes = 10,
        };
        var client = new WebUntisClient(httpClientFactory.CreateClient("webuntis"), Options.Create(options));
        try
        {
            // Authentifiziert wirklich gegen WebUntis; ungültige Daten werden nicht gespeichert.
            await client.GetSchoolYearsAsync(cancellationToken);
        }
        catch
        {
            await client.DisposeAsync();
            throw;
        }

        var entry = new Entry(client, request.School.Trim(), request.Username.Trim());
        if (_connections.TryGetValue(userId, out var previous))
            await previous.Client.DisposeAsync();
        _connections[userId] = entry;
        return new(true, entry.School, entry.Username);
    }

    public async Task DisconnectAsync(string userId)
    {
        if (_connections.TryRemove(userId, out var entry)) await entry.Client.DisposeAsync();
    }

    public async ValueTask DisposeAsync()
    {
        var entries = _connections.Values.ToList();
        _connections.Clear();
        foreach (var entry in entries) await entry.Client.DisposeAsync();
    }
}