using OpenAI;
using OpenAI.Chat;
using System.ClientModel;
using Telegram.Bot;
using Telegram.Bot.Types;
using Telegram.Bot.Types.Enums;
using File = System.IO.File;

string GetEnv(string name) => Environment.GetEnvironmentVariable(name) ?? throw new Exception($"Environment variable {name} is not set");

string baseUrl  = GetEnv("OPENAI_BASE_URL");
string model    = GetEnv("OPENAI_MODEL");
string apiKey   = GetEnv("OPENAI_API_KEY");
Console.WriteLine("Starting the bot...");
Console.WriteLine(
    $"""
        Base URL: {baseUrl}
        Model: {model}
        API Key: {apiKey}
     """);

string nemesisPrompt = File.ReadAllText($"prompt/{GetEnv("NEMESIS_PROMPT_FILE")}");

Dictionary<long, List<ChatMessage>> oaiChats = new();

var options = new OpenAIClientOptions() {
    Endpoint = new(baseUrl),
    NetworkTimeout = new TimeSpan(0, 0, 30)
};

var openAiApiKey    = new ApiKeyCredential(apiKey);
var openAiClient    = new OpenAIClient(openAiApiKey, options);
var chatClient      = openAiClient.GetChatClient(model);

string token = GetEnv("TELEGRAM_BOT_TOKEN") ?? string.Empty;
Console.WriteLine("OpenAI Chat Client created");

using var cts = new CancellationTokenSource();
var bot = new TelegramBotClient(token, cancellationToken:cts.Token);
await bot.DropPendingUpdates();
var me = bot.GetMe();
bot.OnMessage += OnMessage;
Console.WriteLine("Bot running");
Thread.Sleep(Timeout.Infinite);
cts.Cancel(); // stop the bot

async Task OnMessage(Message msg, UpdateType type)
{
    //Discard any message that is not a text message
    if (msg.Type != MessageType.Text) return;
    //Check if the message contains the bot's username or a reply to a message sent by the bot or a private chat
    if (msg.Text!.Contains(me.Result.FirstName!, StringComparison.OrdinalIgnoreCase) ||
        msg.ReplyToMessage != null && msg.ReplyToMessage.From!.Id == me.Result.Id ||
        msg.Chat.Type == ChatType.Private) {
        Console.WriteLine(
            $"""
             Received message from {msg.Chat.Id} Type: {type}
             Message: {msg.Text} 
            """);
        var chatid = msg.Chat.Id;
        //Check if the message is a reset command
        if (msg.Text.StartsWith("/reset")) {
            ResetChat(chatid);
            await bot.SendMessage(chatid, "Chat context has been reset");
            return;
        }
        // Otherwise process it normally
        await AnswerChat(chatid, msg.Text);
    }
}

async Task AnswerChat(long chatId, string input) {
    //Check if the chat is already in the dictionary
    if (!oaiChats.ContainsKey(chatId))
        AddChatToDictionary(chatId);
        
    string text = input;
    //Limit the message to 1024 characters to avoid out of context jump
    if (input.Length > 1024) text = input.Substring(0, 1024); 
        
    //Add the current message to the chat
    //oaiChats[chatId].Add(new UserChatMessage(text));
    ChatMessageRotate(chatId, new UserChatMessage(text));
    
    //fetch existing messages history
    var messages = oaiChats[chatId];
    
    //Fetch the response from the model
    var result = chatClient.CompleteChat(messages).Value.Content[0].Text;
        
    //Add the response to the chat
    Console.WriteLine("Replying with: " + result);
    oaiChats[chatId].Add(new AssistantChatMessage(result));
        
    //Send the response to the user
    await bot.SendMessage(chatId, result);
}

void AddChatToDictionary(long id) {
    //Create a new chat object
    var chat = new List<ChatMessage>();
    chat.Add(new SystemChatMessage(nemesisPrompt));
    //add the entry to the dictionary
    oaiChats.Add(id, chat);
}

void ChatMessageRotate(long chatId, ChatMessage message){
    //Remove the first message from the chat if the chat has more than 5 couples of messages (0 is our prompt)
    if (oaiChats[chatId].Count > 10) {
        oaiChats[chatId].RemoveAt(1);
        oaiChats[chatId].RemoveAt(2);
    }
    
    //Add the new message to the chat
    oaiChats[chatId].Add(message);
}

void ResetChat(long chatId) {
    //Remove the chat from the dictionary
    oaiChats.Remove(chatId);
    //Add the chat back to the dictionary
    AddChatToDictionary(chatId);
}