using System.Collections.Concurrent;
using System.Text;
using TL;
using WTelegram;

namespace GmRelay.E2E.Runner;

public sealed class TelegramUserClient : IDisposable
{
    private readonly Client _client;
    private readonly RunnerConfig _config;
    private readonly ConcurrentDictionary<long, Channel> _knownChannels = new();

    public TelegramUserClient(RunnerConfig config)
    {
        _config = config;
        _client = new Client(_ => Environment.GetEnvironmentVariable(_));
    }

    public async Task ConnectAsync(CancellationToken cancellationToken = default)
    {
        var me = await _client.LoginUserIfNeeded();
        Console.WriteLine($"Logged in as {me.first_name} {me.last_name} (id={me.id})");
    }

    public async Task<ChatGroup> CreateGroupAsync(string title, string about = "", CancellationToken cancellationToken = default)
    {
        var updates = await _client.Channels_CreateChannel(title, about, megagroup: true);
        var channel = updates.Chats.Values.OfType<Channel>().FirstOrDefault()
                      ?? throw new InvalidOperationException("Failed to create a supergroup.");

        _knownChannels[channel.id] = channel;
        return new ChatGroup(channel.id, channel.title);
    }

    public async Task InviteBotToGroupAsync(ChatGroup group, string botUsername, CancellationToken cancellationToken = default)
    {
        if (botUsername.StartsWith('@'))
            botUsername = botUsername[1..];

        var resolved = await _client.Contacts_ResolveUsername(botUsername);
        if (resolved.User is null)
            throw new InvalidOperationException($"Could not resolve bot @{botUsername}.");

        var channel = await ResolveChannelAsync(group.Id, cancellationToken);
        var inputUser = new InputUser(resolved.User.id, resolved.User.access_hash);
        await _client.Channels_InviteToChannel(channel, new InputUserBase[] { inputUser });
    }

    public async Task DeleteGroupAsync(ChatGroup group, CancellationToken cancellationToken = default)
    {
        var channel = await ResolveChannelAsync(group.Id, cancellationToken);
        await _client.Channels_DeleteChannel(channel);
        _knownChannels.TryRemove(group.Id, out _);
    }

    public async Task SendMessageAsync(ChatGroup group, string text, CancellationToken cancellationToken = default)
    {
        var channel = await ResolveChannelAsync(group.Id, cancellationToken);
        await _client.SendMessageAsync(channel, text);
    }

    public async Task<IReadOnlyList<Message>> GetRecentMessagesAsync(ChatGroup group, int limit = 30, CancellationToken cancellationToken = default)
    {
        var channel = await ResolveChannelAsync(group.Id, cancellationToken);
        var history = await _client.Messages_GetHistory(channel, limit: limit);
        return history.Messages
            .OfType<Message>()
            .OrderByDescending(m => m.Date)
            .ToList();
    }

    public async Task<Message?> GetLatestBotMessageAsync(ChatGroup group, CancellationToken cancellationToken = default)
    {
        var messages = await GetRecentMessagesAsync(group, limit: 20, cancellationToken);
        return messages.FirstOrDefault(m => m.from_id is not PeerUser userPeer || userPeer.user_id != _client.UserId);
    }

    public async Task<Message?> WaitForBotReplyAsync(
        ChatGroup group,
        string? containsText = null,
        TimeSpan? timeout = null,
        CancellationToken cancellationToken = default)
    {
        var deadline = DateTime.UtcNow + (timeout ?? TimeSpan.FromSeconds(30));

        while (DateTime.UtcNow < deadline)
        {
            cancellationToken.ThrowIfCancellationRequested();
            var messages = await GetRecentMessagesAsync(group, limit: 50, cancellationToken);
            var match = messages.FirstOrDefault(m =>
                m.from_id is not PeerUser userPeer || userPeer.user_id != _client.UserId);

            if (match is not null)
            {
                if (containsText is null || (match.message?.Contains(containsText, StringComparison.OrdinalIgnoreCase) ?? false))
                    return match;
            }

            await Task.Delay(TimeSpan.FromSeconds(1), cancellationToken);
        }

        return null;
    }

    public async Task SendCommandAsync(ChatGroup group, string command, CancellationToken cancellationToken = default)
    {
        if (!command.StartsWith('/'))
            command = "/" + command;

        await SendMessageAsync(group, command, cancellationToken);
    }

    public async Task ClickInlineButtonAsync(
        ChatGroup group,
        string callbackData,
        int? messageId = null,
        CancellationToken cancellationToken = default)
    {
        var channel = await ResolveChannelAsync(group.Id, cancellationToken);
        var targetMessageId = messageId ?? (await GetLatestBotMessageAsync(group, cancellationToken))?.id
            ?? throw new InvalidOperationException("No bot message found to click.");

        await _client.Messages_GetBotCallbackAnswer(
            channel,
            targetMessageId,
            Encoding.UTF8.GetBytes(callbackData));
    }

    public async Task ClickInlineButtonByTextAsync(
        ChatGroup group,
        string buttonTextContains,
        int? messageId = null,
        CancellationToken cancellationToken = default)
    {
        var message = messageId.HasValue
            ? (await GetRecentMessagesAsync(group, limit: 20, cancellationToken)).FirstOrDefault(m => m.id == messageId.Value)
            : await GetLatestBotMessageAsync(group, cancellationToken);

        if (message is null)
            throw new InvalidOperationException("No bot message found to click.");

        if (message.reply_markup is not ReplyInlineMarkup markup)
            throw new InvalidOperationException("Latest bot message has no inline keyboard.");

        var button = markup.rows
            .SelectMany(r => r.buttons)
            .OfType<KeyboardButtonCallback>()
            .FirstOrDefault(b => b.text.Contains(buttonTextContains, StringComparison.OrdinalIgnoreCase));

        if (button is null)
            throw new InvalidOperationException($"No inline button matching '{buttonTextContains}' found.");

        await ClickInlineButtonAsync(group, Encoding.UTF8.GetString(button.data), message.id, cancellationToken);
    }

    public void Dispose()
    {
        _client.Dispose();
    }

    private async Task<Channel> ResolveChannelAsync(long channelId, CancellationToken cancellationToken = default)
    {
        if (_knownChannels.TryGetValue(channelId, out var cached))
            return cached;

        var dialogs = await _client.Messages_GetAllDialogs();
        var channel = dialogs.chats.Values
            .OfType<Channel>()
            .FirstOrDefault(c => c.id == channelId);

        if (channel is null)
            throw new InvalidOperationException($"Could not resolve channel {channelId}.");

        _knownChannels[channelId] = channel;
        return channel;
    }
}

public sealed record ChatGroup(long Id, string Title);