use std::fs::File;
use std::io::{BufReader, Error as IOError, ErrorKind};
use std::sync::Arc;

use async_trait::async_trait;
use futures::{stream, StreamExt};
use rustls_pemfile::{certs, pkcs8_private_keys};
use rustls_pki_types::{CertificateDer, PrivateKeyDer};
use tokio::net::TcpListener;
use tokio_rustls::rustls::ServerConfig;
use tokio_rustls::TlsAcceptor;

use pgwire::api::auth::noop::NoopStartupHandler;
use pgwire::api::copy::NoopCopyHandler;
use pgwire::api::query::{PlaceholderExtendedQueryHandler, SimpleQueryHandler};
use pgwire::api::results::{DataRowEncoder, FieldFormat, FieldInfo, QueryResponse, Response, Tag};
use pgwire::api::{ClientInfo, PgWireHandlerFactory, Type};
use pgwire::error::PgWireResult;
use pgwire::tokio::process_socket;

pub struct DummyProcessor;

impl NoopStartupHandler for DummyProcessor {}

#[async_trait]
impl SimpleQueryHandler for DummyProcessor {
    async fn do_query<'a, C>(
        &self,
        _client: &mut C,
        query: &'a str,
    ) -> PgWireResult<Vec<Response<'a>>>
    where
        C: ClientInfo + Unpin + Send + Sync,
    {
        println!("{:?}", query);
        if query.starts_with("SELECT") {
            let f1 = FieldInfo::new("id".into(), None, None, Type::INT4, FieldFormat::Text);
            let f2 = FieldInfo::new("name".into(), None, None, Type::VARCHAR, FieldFormat::Text);
            let schema = Arc::new(vec![f1, f2]);

            let data = vec![
                (Some(0), Some("Tom")),
                (Some(1), Some("Jerry")),
                (Some(2), None),
            ];
            let schema_ref = schema.clone();
            let data_row_stream = stream::iter(data.into_iter()).map(move |r| {
                let mut encoder = DataRowEncoder::new(schema_ref.clone());
                encoder.encode_field(&r.0)?;
                encoder.encode_field(&r.1)?;

                encoder.finish()
            });

            Ok(vec![Response::Query(QueryResponse::new(
                schema,
                data_row_stream,
            ))])
        } else {
            Ok(vec![Response::Execution(Tag::new("OK").with_rows(1))])
        }
    }
}

fn setup_tls() -> Result<TlsAcceptor, IOError> {
    let cert = certs(&mut BufReader::new(File::open("examples/ssl/server.crt")?))
        .collect::<Result<Vec<CertificateDer>, IOError>>()?;

    let key = pkcs8_private_keys(&mut BufReader::new(File::open("examples/ssl/server.key")?))
        .map(|key| key.map(PrivateKeyDer::from))
        .collect::<Result<Vec<PrivateKeyDer>, IOError>>()?
        .remove(0);

    let mut config = ServerConfig::builder()
        .with_no_client_auth()
        .with_single_cert(cert, key)
        .map_err(|err| IOError::new(ErrorKind::InvalidInput, err))?;

    config.alpn_protocols = vec![b"postgresql".to_vec()];

    Ok(TlsAcceptor::from(Arc::new(config)))
}

struct DummyProcessorFactory {
    handler: Arc<DummyProcessor>,
}

impl PgWireHandlerFactory for DummyProcessorFactory {
    type StartupHandler = DummyProcessor;
    type SimpleQueryHandler = DummyProcessor;
    type ExtendedQueryHandler = PlaceholderExtendedQueryHandler;
    type CopyHandler = NoopCopyHandler;

    fn simple_query_handler(&self) -> Arc<Self::SimpleQueryHandler> {
        self.handler.clone()
    }

    fn extended_query_handler(&self) -> Arc<Self::ExtendedQueryHandler> {
        Arc::new(PlaceholderExtendedQueryHandler)
    }

    fn startup_handler(&self) -> Arc<Self::StartupHandler> {
        self.handler.clone()
    }

    fn copy_handler(&self) -> Arc<Self::CopyHandler> {
        Arc::new(NoopCopyHandler)
    }
}

#[tokio::main]
pub async fn main() {
    let factory = Arc::new(DummyProcessorFactory {
        handler: Arc::new(DummyProcessor),
    });

    let server_addr = "127.0.0.1:5433";
    let tls_acceptor = Arc::new(setup_tls().unwrap());
    let listener = TcpListener::bind(server_addr).await.unwrap();

    println!("Listening to {}", server_addr);
    loop {
        let incoming_socket = listener.accept().await.unwrap();
        let tls_acceptor_ref = tls_acceptor.clone();
        let factory_ref = factory.clone();
        tokio::spawn(async move {
            process_socket(incoming_socket.0, Some(tls_acceptor_ref), factory_ref).await
        });
    }
}