use std::cell::RefCell;
use std::rc::Rc;

use deno_core::error::bad_resource_id;
use deno_core::error::custom_error;
use deno_core::error::AnyError;
use deno_core::op;
use deno_core::Extension;
use deno_core::OpState;
use deno_core::RcRef;
use deno_core::ResourceId;
use deno_core::ZeroCopyBuf;
use deno_http::http_create_conn_resource;
use deno_http::HttpRequestReader;
use deno_http::HttpStreamResource;
use deno_net::io::TcpStreamResource;
use deno_net::ops_tls::TlsStream;
use deno_net::ops_tls::TlsStreamResource;
use hyper::upgrade::Parts;
use serde::Serialize;
use tokio::net::TcpStream;

pub fn init() -> Extension {
  Extension::builder()
    .ops(vec![op_http_start::decl(), op_http_upgrade::decl()])
    .build()
}

#[op]
fn op_http_start(
  state: &mut OpState,
  tcp_stream_rid: ResourceId,
) -> Result<ResourceId, AnyError> {
  if let Ok(resource_rc) = state
    .resource_table
    .take::<TcpStreamResource>(tcp_stream_rid)
  {
    let resource = Rc::try_unwrap(resource_rc)
      .expect("Only a single use of this resource should happen");
    let (read_half, write_half) = resource.into_inner();
    let tcp_stream = read_half.reunite(write_half)?;
    let addr = tcp_stream.local_addr()?;
    return http_create_conn_resource(state, tcp_stream, addr, "http");
  }

  if let Ok(resource_rc) = state
    .resource_table
    .take::<TlsStreamResource>(tcp_stream_rid)
  {
    let resource = Rc::try_unwrap(resource_rc)
      .expect("Only a single use of this resource should happen");
    let (read_half, write_half) = resource.into_inner();
    let tls_stream = read_half.reunite(write_half);
    let addr = tls_stream.get_ref().0.local_addr()?;
    return http_create_conn_resource(state, tls_stream, addr, "https");
  }

  #[cfg(unix)]
  if let Ok(resource_rc) = state
    .resource_table
    .take::<deno_net::io::UnixStreamResource>(tcp_stream_rid)
  {
    super::check_unstable(state, "Deno.serveHttp");

    let resource = Rc::try_unwrap(resource_rc)
      .expect("Only a single use of this resource should happen");
    let (read_half, write_half) = resource.into_inner();
    let unix_stream = read_half.reunite(write_half)?;
    let addr = unix_stream.local_addr()?;
    return http_create_conn_resource(state, unix_stream, addr, "http+unix");
  }

  Err(bad_resource_id())
}

#[derive(Serialize)]
#[serde(rename_all = "camelCase")]
pub struct HttpUpgradeResult {
  conn_rid: ResourceId,
  conn_type: &'static str,
  read_buf: ZeroCopyBuf,
}

#[op]
async fn op_http_upgrade(
  state: Rc<RefCell<OpState>>,
  rid: ResourceId,
  _: (),
) -> Result<HttpUpgradeResult, AnyError> {
  let stream = state
    .borrow_mut()
    .resource_table
    .get::<HttpStreamResource>(rid)?;
  let mut rd = RcRef::map(&stream, |r| &r.rd).borrow_mut().await;

  let request = match &mut *rd {
    HttpRequestReader::Headers(request) => request,
    _ => {
      return Err(custom_error(
        "Http",
        "cannot upgrade because request body was used",
      ))
    }
  };

  let transport = hyper::upgrade::on(request).await?;
  let transport = match transport.downcast::<TcpStream>() {
    Ok(Parts {
      io: tcp_stream,
      read_buf,
      ..
    }) => {
      return Ok(HttpUpgradeResult {
        conn_type: "tcp",
        conn_rid: state
          .borrow_mut()
          .resource_table
          .add(TcpStreamResource::new(tcp_stream.into_split())),
        read_buf: read_buf.to_vec().into(),
      });
    }
    Err(transport) => transport,
  };
  match transport.downcast::<TlsStream>() {
    Ok(Parts {
      io: tls_stream,
      read_buf,
      ..
    }) => Ok(HttpUpgradeResult {
      conn_type: "tls",
      conn_rid: state
        .borrow_mut()
        .resource_table
        .add(TlsStreamResource::new(tls_stream.into_split())),
      read_buf: read_buf.to_vec().into(),
    }),
    Err(_) => Err(custom_error(
      "Http",
      "encountered unsupported transport while upgrading",
    )),
  }
}