use actix_web::error::{ErrorInternalServerError as ServerError, ErrorUnauthorized};
use actix_web::middleware::Logger;
use actix_web::{web, web::Bytes, App, HttpRequest, HttpResponse, HttpServer};
use futures::StreamExt;
use redis::{AsyncCommands, Client};
use serde::{Deserialize, Serialize};
use serde_json::Value;
use uuid::Uuid;
use std::collections::HashMap;
use std::env;
use std::sync::{Arc, Mutex};
use tokio::sync::broadcast;
use tokio::task::JoinHandle;
mod data;

#[derive(Clone)]
struct AppState {
    tasks: Arc<Mutex<HashMap<String, JoinHandle<()>>>>,
    redis: Client,
}

#[derive(Serialize, Deserialize, Clone, Debug)]
struct RedisMessageData {
    payload: HashMap<String, Value>,
    action: String
}

#[derive(Serialize, Deserialize, Clone, Debug, Display)]
pub struct SSEMessageData {
    payload: HashMap<String, Value>,
    action: String,
    entity: String
}

async fn connect_handler(
    req: HttpRequest,
    state: web::Data<AppState>,
) -> Result<HttpResponse, actix_web::Error> {

    let token = match req.headers().get("Authorization") {
        Some(val) => val.to_str().unwrap_or("").split(" ").last().unwrap_or(""),
        None => match req.match_info().get("token") {
            Some(val) => val,
            None => match req.query_string().split('=').last() {
                Some(val) => val,
                None => return Err(ErrorUnauthorized("Unauthorized")),
            },
        },
    };

    let listener_id = data::get_auth_id(&token).await.map_err(|e| {
        eprintln!("TOKEN check failed: {}", e);
        ErrorUnauthorized("Unauthorized")
    })?;

    let mut con = state.redis.get_async_connection().await.map_err(|e| {
        eprintln!("Failed to get async connection: {}", e);
        ServerError("Internal Server Error")
    })?;

    con.sadd::<&str, &i32, usize>("authors-online", &listener_id)
        .await
        .map_err(|e| {
            eprintln!("Failed to add author to online list: {}", e);
            ServerError("Internal Server Error")
        })?;

    let chats: Vec<String> = con
        .smembers::<String, Vec<String>>(format!("chats_by_author/{}", listener_id))
        .await
        .map_err(|e| {
            eprintln!("Failed to get chats by author: {}", e);
            ServerError("Internal Server Error")
        })?;

    let (tx, rx) = broadcast::channel(100);
    let state_clone = state.clone();
    let handle = tokio::spawn(async move {
        let conn = state_clone.redis.get_async_connection().await.unwrap();
        let mut pubsub = conn.into_pubsub();
        let followers_channel = format!("follower:{}", listener_id);
        pubsub.subscribe(followers_channel.clone()).await.unwrap();
        println!("'{}' pubsub subscribed", followers_channel);
        pubsub.subscribe("shout").await.unwrap();
        println!("'shout' pubsub subscribed");
        pubsub.subscribe("reaction").await.unwrap();
        println!("'reaction' pubsub subscribed");

        for chat_id in &chats {
            let channel_name = format!("chat:{}", chat_id);
            pubsub.subscribe(&channel_name).await.unwrap();
            println!("'{}' subscribed", channel_name);
        }

        while let Some(msg) = pubsub.on_message().next().await {
            let redis_message_str: String = msg.get_payload().unwrap();
            let redis_message_data: RedisMessageData = serde_json::from_str(&redis_message_str).unwrap();
            let prepared_message_data = SSEMessageData {
                payload: redis_message_data.payload,
                action: redis_message_data.action,
                entity: msg.get_channel_name()
                    .to_owned()
                    .split(":")
                    .next()
                    .unwrap_or("")
                    .to_string()
            };
            if data::is_fitting(
                    listener_id,
                    prepared_message_data.clone(),
                )
                .await
                .is_ok()
            {
                let prepared_message_str = serde_json::to_string(&prepared_message_data).unwrap();
                let send_result = tx.send(prepared_message_str.clone());
                if send_result.is_err() {
                    // remove author from online list
                    let _ = con
                        .srem::<&str, &i32, usize>("authors-online", &listener_id)
                        .await
                        .map_err(|e| {
                            eprintln!("Failed to remove author from online list: {}", e);
                            ServerError("Internal Server Error")
                        });
                    break;
                } else {
                    println!("[handler] message handled {}", prepared_message_str);
                }
            };
        }
    });
    state
        .tasks
        .lock()
        .unwrap()
        .insert(format!("{}", listener_id.clone()), handle);

        let server_event_stream = futures::stream::unfold(rx, |mut rx| async {
            let result = rx.recv().await;
            match result {
                Ok(server_event) => {
                    // Generate a random UUID as the event ID
                    let event_id = format!("{}", Uuid::new_v4()); 
        
                    let formatted_server_event = format!(
                        "id: {}\ndata: {}\n\n",
                        event_id,
                        server_event
                    );
        
                    Some((Ok::<_, actix_web::Error>(Bytes::from(formatted_server_event)), rx))
                },
                Err(_) => None,
            }
        });

    Ok(HttpResponse::Ok()
        .append_header(("content-type", "text/event-stream"))
        .streaming(server_event_stream))
}

#[actix_web::main]
async fn main() -> std::io::Result<()> {
    let redis_url = env::var("REDIS_URL").unwrap_or_else(|_| String::from("redis://127.0.0.1/"));
    let client = redis::Client::open(redis_url.clone()).unwrap();
    let tasks = Arc::new(Mutex::new(HashMap::new()));
    let state = AppState {
        tasks: tasks.clone(),
        redis: client.clone(),
    };
    println!("Starting...");
    HttpServer::new(move || {
        App::new()
            .wrap(Logger::default())
            .app_data(web::Data::new(state.clone()))
            .route("/", web::get().to(connect_handler))
            .route("/{token}", web::get().to(connect_handler))
    })
    .bind("0.0.0.0:8080")?
    .run()
    .await
}