using System;
using System.Collections.Generic;
using System.Net.Http;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;
using Gott.Models;

namespace Gott.Services;

public class TelegramService
{
    private readonly IHttpClientFactory _httpFactory;
    private readonly DatabaseService _db;
    private readonly ChatService _chatService;
    private readonly AnthropicService _anthropic;
    private readonly int _maxIterations;

    public TelegramService(
        IHttpClientFactory httpFactory,
        DatabaseService db,
        ChatService chatService,
        AnthropicService anthropic,
        int maxIterations = 100)
    {
        _httpFactory = httpFactory;
        _db = db;
        _chatService = chatService;
        _anthropic = anthropic;
        _maxIterations = maxIterations;
    }

    // ── Bot-Token / Secret aus Session laden ──

    public string GetBotTokenForSession(SessionRecord session)
    {
        return session?.TelegramBotToken;
    }

    public string GetWebhookSecretForSession(SessionRecord session)
    {
        return session?.TelegramWebhookSecret;
    }

    // ── Webhook-Update verarbeiten ──

    public async Task HandleUpdate(JsonElement update, SessionRecord session)
    {
        if (!update.TryGetProperty("message", out var message)) return;
        if (!message.TryGetProperty("chat", out var chat)) return;
        if (!message.TryGetProperty("text", out var textEl)) return;

        var chatId = chat.GetProperty("id").GetInt64();
        var text = textEl.GetString()?.Trim() ?? "";

        if (string.IsNullOrEmpty(text)) return;

        var botToken = session.TelegramBotToken;
        if (string.IsNullOrEmpty(botToken)) return;

        if (text.StartsWith("/start"))
        {
            await _db.SetSessionTelegramChatId(session.SessionId, chatId.ToString());
            var sessionName = session.Name ?? session.SessionId;
            await SendMessage(chatId, botToken,
                $"✅ *Verbunden mit Session: {EscapeMd(sessionName)}*\n\n" +
                "Du kannst jetzt einfach drauflos schreiben\\!\n\n" +
                "Befehle:\n" +
                "/clear – History archivieren\n" +
                "/status – Aktuelle Session\\-Info\n" +
                "/unlink – Verknüpfung aufheben",
                parseMode: "MarkdownV2");
            return;
        }

        if (text.StartsWith("/"))
        {
            await HandleCommand(chatId, text, botToken, session);
            return;
        }

        await HandleMessage(chatId, text, botToken, session);
    }

    // ── Commands ──

    private async Task HandleCommand(long chatId, string text, string botToken, SessionRecord session)
    {
        var parts = text.Split(' ', 2, StringSplitOptions.RemoveEmptyEntries);
        var cmd = parts[0].ToLowerInvariant().Split('@')[0];

        switch (cmd)
        {
            case "/clear":
                var archive = await _db.CreateArchive(session.SessionId);
                await SendMessage(chatId, botToken, archive == null
                    ? "History ist bereits leer."
                    : $"✅ History archiviert ({archive.MessageCount} Nachrichten).");
                break;

            case "/status":
                var agent = !string.IsNullOrEmpty(session.AgentId) ? await _db.GetAgent(session.AgentId) : null;
                var sb = new StringBuilder("📊 *Status:*\n\n");
                sb.AppendLine($"Session: *{EscapeMd(session.Name ?? session.SessionId)}*");
                if (agent != null)
                    sb.AppendLine($"Agent: *{EscapeMd(agent.Name)}* \\({EscapeMd(agent.Model)}\\)");
                await SendMessage(chatId, botToken, sb.ToString(), parseMode: "MarkdownV2");
                break;

            case "/unlink":
                await _db.ClearSessionTelegramChatId(session.SessionId);
                await SendMessage(chatId, botToken, "✅ Verknüpfung aufgehoben. Sende /start um erneut zu verbinden.");
                break;

            default:
                await SendMessage(chatId, botToken, "❓ Unbekannter Befehl. Sende /start für Hilfe.");
                break;
        }
    }

    // ── Nachricht an Claude weiterleiten ──

    private async Task HandleMessage(long chatId, string userText, string botToken, SessionRecord session)
    {
        if (session.TelegramChatId != chatId.ToString())
        {
            await SendMessage(chatId, botToken, "❌ Bitte sende zuerst /start um dich mit dieser Session zu verbinden.");
            return;
        }

        // ChatService für Setup nutzen (userId = null → kein Auth-Check, Session ist bereits authentifiziert via Webhook-Secret)
        var ctx = await _chatService.PrepareContext(session.SessionId, null, _maxIterations);
        if (ctx == null)
        {
            await SendMessage(chatId, botToken, "❌ Kein Agent konfiguriert. Bitte weise der Session im Web-UI einen Agent zu.");
            return;
        }

        await SendChatAction(chatId, botToken, "typing");

        try
        {
            // History aus DB laden + User-Nachricht anhängen
            var history = await _chatService.BuildHistoryFromDb(session.SessionId);
            history.Add(new Dictionary<string, object>
            {
                ["role"] = "user",
                ["content"] = userText
            });

            // User-Nachricht in DB speichern
            await _db.SaveMessage(new MessageRecord
            {
                ChainId = ctx.ChainId,
                Iteration = 0,
                Role = "user",
                Type = "text",
                Content = userText
            });

            // AnthropicService für Non-Streaming-Chat nutzen
            var reply = await _anthropic.ChatNonStreaming(ctx, history, onIteration: async (iteration) =>
            {
                if (iteration % 3 == 0)
                    await SendChatAction(chatId, botToken, "typing");
            });

            await SendLongMessage(chatId, botToken, reply);
        }
        catch (Exception ex)
        {
            await SendMessage(chatId, botToken, $"❌ Fehler: {ex.Message}");
        }
    }

    // ── Notification senden (für Cronjobs) ──

    public async Task SendNotification(string sessionId, string text)
    {
        var session = await _db.GetSession(sessionId);
        if (session == null || string.IsNullOrEmpty(session.TelegramBotToken) || string.IsNullOrEmpty(session.TelegramChatId))
            return;

        var chatId = long.Parse(session.TelegramChatId);
        await SendMessage(chatId, session.TelegramBotToken, text);
    }

    // ── Telegram Bot API ──

    public async Task SendMessage(long chatId, string botToken, string text, string parseMode = null)
    {
        var client = _httpFactory.CreateClient();
        var payload = new Dictionary<string, object>
        {
            ["chat_id"] = chatId,
            ["text"] = text
        };
        if (!string.IsNullOrEmpty(parseMode))
            payload["parse_mode"] = parseMode;

        await client.PostAsync(
            $"https://api.telegram.org/bot{botToken}/sendMessage",
            new StringContent(JsonSerializer.Serialize(payload), Encoding.UTF8, "application/json"));
    }

    public async Task SendLongMessage(long chatId, string botToken, string text)
    {
        const int maxLen = 4096;
        if (text.Length <= maxLen)
        {
            await SendMessage(chatId, botToken, text);
            return;
        }

        for (var i = 0; i < text.Length; i += maxLen)
        {
            var chunk = text.Substring(i, Math.Min(maxLen, text.Length - i));
            await SendMessage(chatId, botToken, chunk);
            await Task.Delay(100);
        }
    }

    public async Task SendChatAction(long chatId, string botToken, string action)
    {
        var client = _httpFactory.CreateClient();
        await client.PostAsync(
            $"https://api.telegram.org/bot{botToken}/sendChatAction",
            new StringContent(JsonSerializer.Serialize(new { chat_id = chatId, action }), Encoding.UTF8, "application/json"));
    }

    // ── Webhook-Verwaltung (pro Session) ──

    public async Task<string> RegisterWebhook(string baseUrl, string sessionId)
    {
        var session = await _db.GetSession(sessionId);
        if (session == null || string.IsNullOrEmpty(session.TelegramBotToken))
            return JsonSerializer.Serialize(new { ok = false, error = "Kein Bot-Token für diese Session konfiguriert" });

        var webhookUrl = $"{baseUrl.TrimEnd('/')}/api/telegram/webhook/{sessionId}";
        var client = _httpFactory.CreateClient();
        var payload = new Dictionary<string, object>
        {
            ["url"] = webhookUrl,
            ["allowed_updates"] = new[] { "message" }
        };

        if (!string.IsNullOrEmpty(session.TelegramWebhookSecret))
            payload["secret_token"] = session.TelegramWebhookSecret;

        var resp = await client.PostAsync(
            $"https://api.telegram.org/bot{session.TelegramBotToken}/setWebhook",
            new StringContent(JsonSerializer.Serialize(payload), Encoding.UTF8, "application/json"));

        return await resp.Content.ReadAsStringAsync();
    }

    public async Task<string> GetWebhookInfo(string sessionId)
    {
        var session = await _db.GetSession(sessionId);
        if (session == null || string.IsNullOrEmpty(session.TelegramBotToken))
            return JsonSerializer.Serialize(new { ok = false, error = "Kein Bot-Token konfiguriert" });

        var client = _httpFactory.CreateClient();
        var resp = await client.GetAsync($"https://api.telegram.org/bot{session.TelegramBotToken}/getWebhookInfo");
        return await resp.Content.ReadAsStringAsync();
    }

    public async Task<string> DeleteWebhook(string sessionId)
    {
        var session = await _db.GetSession(sessionId);
        if (session == null || string.IsNullOrEmpty(session.TelegramBotToken))
            return JsonSerializer.Serialize(new { ok = false, error = "Kein Bot-Token konfiguriert" });

        var client = _httpFactory.CreateClient();
        var resp = await client.PostAsync(
            $"https://api.telegram.org/bot{session.TelegramBotToken}/deleteWebhook",
            new StringContent("{}", Encoding.UTF8, "application/json"));
        return await resp.Content.ReadAsStringAsync();
    }

    // ── Helper ──

    private static string EscapeMd(string text)
    {
        if (string.IsNullOrEmpty(text)) return "";
        foreach (var c in new[] { '_', '*', '[', ']', '(', ')', '~', '`', '>', '#', '+', '-', '=', '|', '{', '}', '.', '!' })
            text = text.Replace(c.ToString(), "\\" + c);
        return text;
    }
}