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 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)]
struct RedisMessageData {
    payload: HashMap<String, String>,
    kind: 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 => 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, mut 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!("followers:{}", listener_id);
        pubsub.subscribe(followers_channel.clone()).await.unwrap();
        println!("'{}' subscribed", followers_channel);
        pubsub.subscribe("new_shout").await.unwrap();
        println!("'new_shout' subscribed");
        pubsub.subscribe("new_reaction").await.unwrap();
        println!("'new_reaction' 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 message_str: String = msg.get_payload().unwrap();
            let message_data: RedisMessageData = serde_json::from_str(&message_str).unwrap();
            if msg.get_channel_name().starts_with("chat:")
                || msg.get_channel_name().starts_with("followers:")
                || data::is_fitting(
                    listener_id,
                    message_data.kind.to_string(),
                    message_data.payload,
                )
                .await
                .is_ok()
            {
                let send_result = tx.send(message_str);
                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;
                }
            };
        }
    });
    state
        .tasks
        .lock()
        .unwrap()
        .insert(format!("{}", listener_id.clone()), handle);

    let server_event = rx.recv().await.map_err(|e| {
        eprintln!("Failed to receive server event: {}", e);
        ServerError("Internal Server Error")
    })?;

    let server_event_stream =
        futures::stream::once(async move { Ok::<_, actix_web::Error>(Bytes::from(server_event)) });

    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))
    })
    .bind("0.0.0.0:8080")?
    .run()
    .await
}