use log::{info, trace, warn};
use nanoid::nanoid;
use serde::{Deserialize, Serialize};
use serde_json::Value;
use std::boxed::Box;
use std::error::Error;
use std::marker::Send;
use std::{collections::HashMap, sync::Arc};
use tokio::sync::{mpsc::Sender, Mutex};

pub type Result<T> = std::result::Result<T, Box<dyn Error + Send + Sync>>;

#[derive(Clone, Debug, Serialize, Deserialize)]
pub struct JRPCRequest {
    pub jsonrpc: String,
    pub id: Option<String>,
    pub method: String,
    pub params: Value,
}

impl JRPCRequest {
    pub fn new_request(method: String, params: Value) -> JRPCRequest {
        JRPCRequest {
            jsonrpc: "2.0".to_string(),
            id: None,
            method,
            params,
        }
    }
}

#[derive(Clone, Debug, Serialize, Deserialize)]
pub struct JRPCError {
    pub code: i64,
    pub message: String,
    pub data: Value,
}

#[derive(Clone, Debug, Serialize, Deserialize)]
pub struct JRPCResult {
    pub jsonrpc: String,
    pub id: String,
    pub result: Option<Value>,
    pub error: Option<JRPCError>,
}

#[derive(Debug, Clone)]
pub struct JRPCClient {
    message_sender: Sender<JRPCRequest>,
    requests: Arc<Mutex<HashMap<String, Sender<JRPCResult>>>>,
}

impl JRPCClient {
    pub fn new(sender: Sender<JRPCRequest>) -> JRPCClient {
        JRPCClient {
            message_sender: sender,
            requests: Arc::new(Mutex::new(HashMap::new())),
        }
    }

    pub async fn send_request(&self, mut request: JRPCRequest) -> Result<Value> {
        let (sender, mut receiver) = tokio::sync::mpsc::channel(1);

        if request.id.is_none() {
            request.id = Some(nanoid!());
        }

        {
            let mut self_requests = self.requests.lock().await;
            self_requests.insert(request.id.clone().unwrap(), sender);
        }
        self.message_sender.send(request).await?;

        let result = receiver.recv().await;

        if let Some(result) = result {
            if let Some(error) = result.error {
                return Err(format!("Error while receiving result: {}", error.message).into());
            } else if let Some(result) = result.result {
                return Ok(result);
            } else {
                return Err(format!("No result received").into());
            }
        } else {
            return Err("Error while receiving result".into());
        }
    }

    pub async fn send_notification(&self, mut request: JRPCRequest) {
        request.id = None;

        _ = self.message_sender.send(request).await;
    }

    pub async fn on_result(&self, result: JRPCResult) {
        let id = result.id.clone();
        let mut self_requests = self.requests.lock().await;
        let sender = self_requests.get(&id);
        if let Some(sender) = sender {
            _ = sender.send(result).await;
            self_requests.remove(&id);
        }
    }
}

#[async_trait::async_trait]
pub trait JRPCServerService: Send + Sync + 'static {
    fn get_id(&self) -> String;
    async fn handle(&self, request: &JRPCRequest, function: &str) -> Result<(bool, Value)>;
}

pub type JRPCServiceHandle = Arc<dyn JRPCServerService>;

#[derive(Clone)]
pub struct JRPCSession {
    server: JRPCServer,
    message_sender: Sender<JRPCResult>,
}

impl JRPCSession {
    pub fn new(server: JRPCServer, sender: Sender<JRPCResult>) -> JRPCSession {
        JRPCSession {
            server,
            message_sender: sender,
        }
    }

    async fn send_error(&self, request: JRPCRequest, error_msg: String, error_code: i64) -> () {
        if let Some(request_id) = request.id {
            let error = JRPCError {
                code: error_code,
                message: error_msg,
                data: Value::Null,
            };
            let result = JRPCResult {
                jsonrpc: "2.0".to_string(),
                id: request_id,
                result: None,
                error: Some(error),
            };

            // Send result
            let result = self.message_sender.send(result).await;
            if let Err(err) = result {
                warn!("Error while sending result: {}", err);
            }
        }
    }

    pub fn handle_request(&self, request: JRPCRequest) -> () {
        let session = self.clone();
        tokio::task::spawn(async move {
            info!("Received request: {}", request.method);
            trace!("Request data: {:?}", request);
            let method: Vec<&str> = request.method.split('.').collect();
            if method.len() != 2 {
                warn!("Invalid method received: {}", request.method);
                return;
            }
            let service = method[0];
            let function = method[1];

            let service = session.server.services.get(service);
            if let Some(service) = service {
                let result = service.handle(&request, function).await;
                match result {
                    Ok((is_send, result)) => {
                        if is_send && request.id.is_some() {
                            let result = session
                                .message_sender
                                .send(JRPCResult {
                                    jsonrpc: "2.0".to_string(),
                                    id: request.id.unwrap(),
                                    result: Some(result),
                                    error: None,
                                })
                                .await;
                            if let Err(err) = result {
                                warn!("Error while sending result: {}", err);
                            }
                        }
                    }
                    Err(err) => {
                        warn!("Error while handling request: {}", err);
                        session
                            .send_error(
                                request,
                                format!("Error while handling request: {}", err),
                                1,
                            )
                            .await;
                    }
                }
            } else {
                warn!("Service not found: {}", method[0]);
                session
                    .send_error(request, "Service not found".to_string(), 1)
                    .await;
                return;
            }
        });
    }
}

#[derive(Clone)]
pub struct JRPCServer {
    services: HashMap<String, JRPCServiceHandle>,
}

impl JRPCServer {
    pub fn new() -> JRPCServer {
        JRPCServer {
            services: HashMap::new(),
        }
    }

    pub fn add_service(&mut self, service: JRPCServiceHandle) -> () {
        let id = service.get_id();
        self.services.insert(id, service);
    }

    pub fn get_session(&self, sender: Sender<JRPCResult>) -> JRPCSession {
        JRPCSession::new(self.clone(), sender)
    }
}